Go Back |
|
|
A B
C D
E
F G
H I
J K
L M
N O
P Q
R S
T U
V W
X Y
Z
|
| 2.5% Design |
|
Outside summer temperatures and coincident air moisture content that
will be exceeded only 2.5% of the hours from June to September. In other
words, 2.5% design conditions are outdoor temperatures historically exceeded
73 out of the 2,928 hours in these summer months. |
| Abatement |
|
Reduction or removal of a contaminant. |
| Absolute Humidity |
|
This is often confused with mixing ratio. It is the ratio of the mass of
water vapor to the unit volume of moist air. Vaisala products give this
output as grams of water per cubic metre of air (g/m3). |
| Absolute Pressure |
|
Gauge pressure plus atmospheric pressure (14.7 lb.per sq.in.) equals
absolute pressure. |
| Absolute Temperature |
|
Temperature measured from absolute zero. |
| Absolute Zero Temperature |
|
Temperature at which all molecular motion ceases (-460 F. and -273 C.) |
| Absorbent |
|
Substance with the ability to take up or absorb another substance. |
| Absorption Refrigerator |
|
Refrigerator which creates low temperature by using the cooling effect
formed when a refrigerant is absorbed by chemical substance. |
| ACCA |
|
A leading HVAC/R Association - http://www.acca.org/ |
| Acceptable indoor air quality |
|
Indoor air that does not contain harmful concentrations of contaminants;
air with which at least 80% of building occupants do not express
dissatisfaction. |
| Accessible Hermetic |
|
Assembly of a motor and compressor inside a single bolted housing unit.
|
| Accumulator |
|
Storage tank which receives liquid refrigerant from evaporator and
prevents it from flowing into suction line before vaporizing. Tank on the
suction side of a system that holds excess refrigerant to prevent slugging
the compressor with liquid. |
| ACGIH |
|
American Conference of Governmental Industrial Hygienists. |
| ACH |
|
Air Changes Per Hour. The number of times that air in a house is
completely replaced with outdoor air in one hour. |
| Acid Condition In System |
|
Condition in which refrigerant or oil in system is mixed with fluids
that are acid in nature. |
| ACR Tubing |
|
Tubing used in air conditioning and refrigeration. Ends are sealed to
keep tubing clean and dry. |
| Action Level |
|
A term used to identify the level of indoor radon at which remedial
action is recommended. |
| Action Packet |
|
In reference to the indoor air quality Tools for Schools Kit. The packet
contains three components - an introductory memo, IAQ Backgrounder, and IAQ
Checklist - to assist school personnel to implement an effective yet simple
indoor air quality program in their school. |
| Activated Alumina |
|
Chemical which is a form of aluminum oxide. It is used as a drier or
desiccant. |
| Activated Carbon |
|
Specially processed carbon used as a filter drier ; commonly used to
clean air. |
| Actuator |
|
That portion of a regulating valve which converts mechanical fluid,
thermal energy or electrical energy into mechanical motion to open or close
the valve seats. |
| Add On Heat Pump |
|
Installing a heat pump in conjunction with an existing fossil fuel
furnace. The result is a dual fuel system. |
| Adiabatic Compression |
|
Compressing refrigerant gas without removing or adding heat. |
| Adjustable Grille |
|
A grille with linear blades which can be adjusted to vary the direction
of the discharged air. The linear blades are normally either vertical or
horizontal, or both horizontal and vertical. |
| Adsorbent |
|
Substance with the property to hold molecules of fluids without causing
a chemical or physical damage. |
| Aeration |
|
Act of combining substance with air. |
| Aerosol |
|
A suspension of liquid or solid particles in air. |
| AFLU (Annual Fuel Utilization Efficiency) |
|
A rating that reflects the efficiency of a gas furnace in converting
fuel to energy. A rating of 90 means that approximately 90% of the fuel is
utilized to provide warmth to your home, while the remaining 10% escapes as
exhaust. |
| AFUE (Annual Fuel Utilization Efficiency ) |
|
This number represents how efficiently a furnace converts fuel to
energy. The ratio of annual output of useful energy or heat to the annual
energy input to the furnace. The higher the AFUE, the more efficient the
furnace -- higher efficiency translates to more savings on fuel bills. This
will range from 80% to 95%. Percentage of fuel used for heating. A measure
of heating efficiency, in consistent units, determined by applying the
federal test method for furnaces. This value is intended to represent the
ratio of heat transferred to the conditioned space by the fuel energy
supplied over one year. |
| Agitator |
|
Device used to cause motion in confined fluid. |
| AHU (Air Handler Unit) |
|
The inside part of the A/C system that contains the blower, cooling
(evaporator) coil, and heater. The part of an HVAC system responsible for
moving air, which may also clean, heat, or cool the air. This refers to
equipment used to provide conditioned air to a space. The air handler unit
generally includes a blower or fan, heating and/or cooling coils, and
related equipment such as controls, condensate drain pans, and air filters.
Does not include ductwork, registers or grilles, or boilers and chillers. |
| Air Change |
|
The amount of air required to completely replace the air in a room or
building; not to be confused with recirculated air. |
| Air Cleaner |
|
Device used for removal of airborne impurities. A device that actively
removes impurities from the air, including forced air filtration systems and
electronic air cleaners. Air cleaners may be added to HVAC systems or
stand-alone room units. |
| Air Cleaning |
|
An indoor air quality control strategy to remove various airborne
particulates and/or gases from the air. The three types of air cleaning most
commonly used are particulate filtration, electrostatic precipitation, and
gas sorption. |
| Air Coil |
|
Coil on some types of heat pumps used either as an evaporator or
condenser. |
| Air Conditioner |
|
Device used to control temperature, humidity, cleanliness and movement
of air in a confined space. |
| Air Conditioning |
|
Control of the temperature, humidity, air movement and cleaning of air
in a confined space. |
| Air Cooler |
|
Mechanism designed to lower temperature of air passing through it. |
| Air Core Solenoid |
|
Solenoid that has a hollow core instead of a solid core. |
| Air Diffuser |
|
An air distribution outlet or grille designed to direct airflow into
desired patterns. Supply air terminal device, designed to direct airflow
into desired patterns, usually placed in the ceiling, generally of circular,
square or rectangular shape, and composed of divergent deflecting members.
|
| Air Diffusion |
|
Distribution of the air in a space, called the treated space, by means
of devices, called air terminal devices, in a manner so as to meet certain
specified conditions, such as air change rate, pressure, cleanliness,
temperature, humidity, air velocity and noise level. |
| Air Distribution |
|
The transportation of a specified air flow to or from the treated space
or spaces, generally by means of ductwork. |
| Air Exchange Rate |
|
The rate of air flow moving through a space, usually expressed in terms
of room volume units per unit of time such as room air changes per hour.
|
| Air Exchange Rate |
|
The rate at which outside air replaces indoor air in a space. Expressed
in one of two ways: the number of changes of outside air per unit of time in
air changes per hour (ACH); or the rate at which a volume of outside air
enters per unit of time - cubic feet per minute (cfm). |
| Air Gap |
|
The space between magnetic poles or between rotating and stationary
assemblies in a motor or generator. |
| Air Handler |
|
Fan-blower, filter and housing parts of a system. Fan-blower, filter,
heat transfer coil, and housing parts of a system. Also known as the blower
section and part of the split system, this unit is commonly in your home or
attic and blows the air through your house. This has to be matched with the
condenser properly to assure maximum efficiency. This will contain your
heating and evaporator coil. |
| Air Infiltration |
|
Leakage of air into rooms through cracks, windows doors and other
openings. |
| Air Quality Standard |
|
A government-mandated regulation that specifies the maximum contaminant
concentration beyond which health risks are considered to be unacceptable.
|
| Air Source Equipment |
|
Heat pumps or air conditioners that uses the outdoor air to transfer
heat to and from the refrigerant in the unit. |
| Air Terminal Device |
|
A device located in an opening provided at the boundaries of the treated
space to ensure a predetermined motion of air in this space. |
| Air Terminal Device, Lighting Troffer |
|
An air terminal device, usually in the form of a slot or combination of
slots, designed for use with a troffer unit. |
| Air Terminal Device, Linear |
|
Air terminal device (grille) with an aspect ratio of 10: 1 or more. |
| Air Terminal Device, Slot |
|
A device with one or several slots with an aspect ratio of 10: 1 or more
for each slot (the aspect ratio is the ratio of the length to the width of
the closed rectangular opening). A slot may or may not have an adjustable
member to vary the direction of the air jet(s) or air flow rate. |
| Air Terminal Device, Supply |
|
An air terminal device through which air enters a treated space. It
usually consists of one or several deflecting members which ensure reduction
of the air velocity in the occupied zone as well as efficient mixing of the
supply air with the air in the treated space. Moreover supply air terminal
devices usually determine the direction of the air jet(s). |
| Air-Cooled Condenser |
|
Heat of compression, plus the heat of absorption, is transferred from
refrigerant within coil to surrounding air, either by convection or fan or
blower. |
| Airflow |
|
The distribution or movement of air. |
| Ak value (of an air terminal device) |
|
Quotient obtained by dividing a measured air flow rate by a measured air
velocity according to a specific process and a specific instrument. |
| Algaecide |
|
Normally in tablet form, placed in evaporator drain pan. Used to help
slow the growth of bacteria. |
| Allergens and Pathogens |
|
Biological material, including bacteria, viruses, fungi, mold spores,
pollens, skin flakes and insect parts are ubiquitous in indoor environments.
These particulates range from less than one to several microns in size. When
airborne, they are usually attached to dust particulates of various sizes so
that all sizes of airborne particulates may include them. |
| Alternating Current (AC) |
|
Flow of electricity that constantly changes direction between positive
and negative sides. Almost all power produced by electric utilities in the
United States moves in current that shifts direction at a rate of 60 times
per second. |
| Ambient |
|
The surrounding atmosphere; encompassing on all sides; the environment
surrounding a body but undisturbed or unaffected by it. |
| Ambient Air |
|
The air surrounding a building; outside air. |
| Ambient Air Temperature |
|
Surrounding temperature, such as the outdoor air temperature around a
building. |
| Ampere (A or Amp) |
|
The primary unit of measurement of electrical current. One ampere of
current is produced in a circuit by 1 volt acting through a resistance of 1
ohm. |
| Amplification |
|
An increase in the numbers or concentration of a microbe or its products
through reproduction and growth of the microbe. |
| Annual Effects |
|
The total effects in energy use (measured in megawatthours) and peak
load (measured in kilowatts) caused by all participants in the DSM programs
that are in effect during a given year. It includes new and existing
participants in existing programs (those implemented in prior years that are
in place during the given year) and all participants in new programs (those
implemented during the given year). The effects of new participants in
existing programs and all participants in new programs should be based on
their start-up dates (i.e., if participants enter a program in July, only
the effects from July to December should be reported). If start-up dates are
unknown and cannot be reasonably estimated, the effects can be annualized
(i.e., assume the participants were initiated into the program on January 1
of the given year). The annual effects should consider the useful life of
efficiency measures, by accounting for building demolition, equipment
degradation and attrition. |
| Antimicrobial |
|
Agent that kills microbial growth. |
| Appliance Efficiency Standards |
|
California Code of Regulations, Title 20, Chapter 2, Subchapter 4:
Energy Conservation, Article 4: Appliance Efficiency Standards. Appliance
Efficiency Standards regulate the minimum performance requirements for
appliances sold in California and apply to refrigerators, freezers, room air
conditioners, central air conditioners, gas space heaters, water heaters,
plumbing fittings, fluorescent lamp ballasts and luminaires, and ignition
devices for gas cooking appliances and gas pool heaters. New National
Appliance Standards are in place for some of these appliances and will
become effective for others at a future date. |
| APR |
|
Air Purifying Respirator |
| ARI (Air-Conditioning and Refrigeration Institute)
|
|
Air-Conditioning and Refrigeration Institute is a nonprofit, voluntary
organization comprised of heating,air conditioning and refrigeration
manufacturers. ARI publishes standards for testing and rating heat pumps and
air conditioners to provide you with a standardized measure of comparison.
So, ARI ensures a level of performance within the industry. |
| Asbestos |
|
A class of silicate minerals composed of long, thin fibers. |
| ASHRAE |
|
A leading HVAC/R Association - American Society of Heating,
Refrigerating and Air Conditioning Engineers - http://www.ashrae.org/ The
trade association that provides information and sets standards for the
industry. |
| ASTM |
|
American Society for Testing and Materials. |
| ASTM |
|
American Society for Testing and Materials. |
|
|
|
A
B C
D E
F G
H I
J K
L M
N O
P Q
R S
T U
V W
X Y
Z
|
| Backdrafting |
|
Reverse flow of combustion gases down the chimney of a vented combustion
appliance, which is often caused by depressurization of the room where the
appliance is located. A condition where the normal movement of combustion
products from a combustion appliance up a flue is reversed so that the
combustion products can enter the building. |
| Background Concentration |
|
The level of a contaminant present before the introduction of a new
source. |
| Balance Point |
|
The lowest outdoor temperature at which the refrigeration cycle of a
heat pump will supply the heating requirements. Usually a temperatyre
between 30°F to 45°F -- at which a heat pump's output exactly equals the
heating needs of the house. Below the balance point, supplementary electric
resistance heat is needed to maintain indoor comfort. |
| Balancing |
|
The process of adjusting the flow of air in duct systems, or water flow
in hot-water heating systems. Proper balancing is performed using accurate
instrumentation to deliver the right amount of heating or cooling to each
area or room of the home. |
| Bioaerosol |
|
An airborne microbial contaminant, such as a virus, bacteria, fungus,
algae, or protozoa, or particulate material associated with one of these
microorganisms. |
| Biocide |
|
Substance or chemicals that kills organisms such as molds. |
| Biological Contaminants |
|
Agents derived from, or that are, living organisms (e.g., viruses,
bacteria, fungi, and mammal and bird antigens) that can be inhaled and can
cause many types of health effects including allergic reactions, respiratory
disorders, hypersensitivity diseases, and infectious diseases. Also referred
to as "microbiologicals" or "microbials." |
| Blower door |
|
A large powerful variable-speed fan mounted in a doorway that blows air
into (pressurizes) or sucks air out of (depressurizes) a house. It's used to
test for air leakage in a house. The size and complexity of the fan varies,
but all blower doors have adjustable frames around the fan so that they can
fit snugly into most doorways. |
| Blower (Fan) |
|
An air handling device for moving air in a distribution system. |
| Boiler |
|
A device for generating steam for power, processing, or heating purposes
or for producing hot water for heating purposes or hot water supply. Heat
from an external combustion source is transmitted to a fluid contained
within the tubes in a boiler shell, a closed vessel in which water is
converted to pressurized steam. This fluid is delivered to an end-use at a
desired pressure, temperature, and quality. |
| Boot |
|
A piece of duct used to connect ducts with registers. |
| Breathing Zone |
|
The area of a room in which occupants breathe as they stand, sit, and
lie down. |
| Breathing Zone |
|
That area of a room in which occupants breathe as they stand, sit, or
lie down. |
| BRI (Building-Related Illness) |
|
Diagnosable illness whose symptoms can be identified and whose cause can
be directly attributed to airborne building pollutants (e.g., Legionnaire's
disease, hypersensitivity pneumonitis). Also: A discrete, identifiable
disease or illness that can be traced to a specific pollutant or source
within a building. (Contrast with "Sick building syndrome"). |
| BTU (British Thermal Unit) |
|
The amount of heat that will raise or lower one pound of water 1 degree
F. at 39.2 degrees F. One BTU is the equivalent of the heat given off by a
single wooden kitchen match. The British Thermal Unit is a standard of
measure for cooling and heating capacities. This is how the capacity of air
conditioning is measured. A standard measure of heat energy in the U.S.,
commonly used to measure the energy content of various fuels and steam. It
takes one Btu to raise the temperature of one pound of water by one degree
Fahrenheit at sea level. For example, it takes about 2,000 Btus to make a
pot of coffee. One Btu is equivalent to 252 calories, 778 foot-pounds, 1055
joules, and 0.293 watt-hours. Note: In the abbreviation, only the B is
capitalized. For your home, it represents the measure of heat givens off
when fuel is burned for heating or the measure of heat extracted from your
home for cooling. |
| BTUH (British Thermal Unit Per Hour) |
|
Establishes a time reference to btu input or output rates. A BTUH is how
many BTUs are used per hour. |
| Buffer zone |
|
An area within the home between the conditioned zones and the outside.
Thus it normally is not conditioned (for instance, attics, attached garages,
crawlspaces, basements, and enclosed porches). |
| Building Energy Efficiency Standards |
|
California Code of Regulations, Title 24, Part 2, Chapter 2-53;
regulating the energy efficiency of buildings constructed in California.
|
| Building, Envelope |
|
the outer walls, windows, doors, roof, and floors of a building; the
building shell. |
| Building Envelope |
|
Elements of the building, including all external building materials,
windows, and walls, that enclose the internal space. |
| Butane |
|
A hydrocarbon gas found in the earth along with natural gas and oil.
Butane turns into a liquid when put under pressure. It is sold as bottled
gas. It is used to run heaters, stoves and motors, and to help make
petrochemicals. |
|
|
|
A
B C
D E
F G
H I
J K
L M
N O
P Q
R S
T U
V W
X Y
Z
|
| CAE (Combined Annual Efficiency) |
|
A measure of the amount of heat produced for every dollar of fuel
consumed for both home heating and water heating. |
| Calorie |
|
One energy calorie is equivalent to 4.2 joules. Thus, it takes 500,000
calories of energy to boil a pot of coffee. One food calorie equals 1,000
energy calories. |
| Capacitor |
|
A device used to start a motor or compressor (or to keep it running
after start up.) |
| Capacity (or System Capacity ) |
|
The output or producing ability of a piece of cooling or heating
equipment. Cooling and heating capacity are normally referred to in BTUs.
The capacity of an air conditioner is measured by the amount of cooling it
can do when running continuously. The total capacity is the sum of the
latent capacity (ability to remove moisture from the air) and sensible
capacity (ability to reduce the dry-bulb temperature). Each of these
capacities is rated in Btus per hour (Btu/h). The capacity depends on the
outside and inside conditions. As it gets hotter outside (or cooler inside)
the capacity drops. The capacity at a standard set of conditions is often
referred to as "tons of cooling." |
| Carbon Dioxide (CO2) |
|
A colorless, odorless, non-poisonous gas that is a normal part of the
air. Carbon dioxide, also called CO2, is exhaled by humans and animals and
is absorbed by green growing things and by the sea. A gas which can at high
levels (above 1.5 % or 15,000 parts per million), have physiological
effects. Main indoor source is human respiration; measurements used as
indicators of ventilation conditions. |
| Carbon Monoxide (CO) |
|
An colorless, odorless gas that is the product of incomplete fuel
combustion or carbon burns without sufficient air nearby. It is a chemical
asphyxiant; in the bloodstream it effectively prevents the transport of
oxygen to the body's tissues. CO exposure can affect the lungs, heart, and
nervous system, and can cause death. Sources include cooling and heating
appliances, tobacco smoke, and entrained exhaust from parking garages and
truck idling areas. A gas, made up of carbon and oxygen molecules, produced
by incomplete burning of carbon or carbonaceous materials, including
carbon-based fuels. including coal, natural gas, gasoline, oil and wood. It
is a major air pollutant on the basis of weight. Carbon monoxide is also
produced from incomplete combustion of many natural and synthetic products.
For instance, cigarette smoke contains carbon monoxide. When carbon monoxide
gets into the body, the carbon monoxide combines with chemicals in the blood
and prevents the blood from bringing oxygen to cells, tissues and organs.
The body's parts need oxygen for energy, so high-level exposures to carbon
monoxide can cause serious health effects, with death possible from massive
exposures. Symptoms of exposure to carbon monoxide can include vision
problems, reduced alertness, and general reduction in mental and physical
functions. Carbon monoxide exposures are especially harmful to people with
heart, lung and circulatory system diseases. |
| Carboxyhemogoblin Saturation |
|
Carbon monoxide poisoning. |
| Carcinogen |
|
An agent suspected or known to cause cancer. |
| Ceiling Plenum |
|
The space between the suspended and structural ceiling used as part of
the air distribution system that accomodates the mechanical and electrical
equipment. This space usually accommodates electrical, communications, and
mechanical connections as well. The space is kept under negative pressure. |
| Celsius |
|
A temperature scale based on the freezing (0 degrees) and boiling (100
degrees) points of water. Abbreviated as C in second and subsequent
references in text. Formerly known as Centigrade. To convert Celsius to
Fahrenheit, multiply the number by 9, divide by 5, and add 32. For example:
10 degrees Celsius x 9 = 90; 90 / 5 = 12; 18 + 32 = 50 degrees Fahrenheit. |
| Central Air Handling Unit (Central AHU) |
|
This is the same as an Air Handling Unit, but serves more than one area. |
| Central Forced-Air Heating System |
|
A piece of equipment that produces heat in a centralized area, then
distributes it throughout the home through a duct system. |
| CFC (Chlorofluorocarbons or Chlorinated Fluorocarbons)
|
|
A class of refrigerants. Generally refers to the Chlorofluorocarbon
family of refrigerants. Sometimes called Freon A family of artificially
produced chemicals receiving much attention for their role in stratospheric
ozone depletion. Since they were introduced in the mid-1930s, CFCs have been
used as refrigerants, solvents and in the production of foam material. These
chemicals and some related chemicals have been used in great quantities in
industry, for refrigeration and air conditioning, and in consumer products.
CFCs and their relatives, when released into the air, rise into the
stratosphere, a layer of the atmosphere high above the Earth. In the
stratosphere, CFCs and their relatives take part in chemical reactions which
result in reduction of the stratospheric ozone layer, which protects the
Earth's surface from harmful effects of radiation from the sun. On a per
molecule basis, these chemicals are several thousand times more effective as
greenhouse gases than carbon dioxide. The 1987 Montreal protocol on CFCs
seeks to reduce their production by one-half by the year 1998. The 1990
CLEAN AIR ACT includes provisions for reducing releases (emissions) and
eliminating production and use of these ozone-destroying chemicals. |
| CFM (Cubic Feet per Minute) |
|
A standard measurement of airflow that indicates how many cubic feet of
air pass by a stationary point in one minute. The higher the number, the
more air is being forced through the system. A typical system produces 400
CFM per ton of air conditioning. |
| Charge |
|
Amount of refrigerant placed in a refrigerating unit. |
| Chemical Sensitization |
|
Evidence suggests that some people may develop health problems
characterized by effects such as dizziness, eye and throat irritation, chest
tightness, and nasal congestion that appear whenever they are exposed to
certain chemicals. People may react to even trace amounts of chemicals to
which they have become "sensitized." |
| Chiller |
|
A device that produces chilled water to provide air conditioning for
large buildings or cooling for process applications. A device that cools
water, usually to between 40 and 50 degrees Fahrenheit for eventual use in
cooling air. |
| Circuit |
|
One complete run of a set of electric conductors from a power source to
various electrical devices (appliances, lights, etc.) and back to the same
power source. |
| Clean Air Act |
|
The original Clean Air Act was passed in 1963, but the national air
pollution control program is actually based on the 1970 version of the law.
The 1990 Clean Air Act Amendments are the most far-reaching revisions of the
1970 law. The 1990 amendments are often referred to as as the 1990 Clean Air
Act. |
| Clean Air Act Amendments of 1990 |
|
These ammendments represent a major overhaul of the earlier Clean Air
Act of 1970. Changes include revised provisions for attainment and
maintenance of National Ambient Air Quality Standards, mobile sources,
hazardous air pollutants, and other assorted air quality issues. In
addition, it establishes guidelines for reductions in air pollution. The Act
also specifically limits sulfur dioxide and nitrogen oxide emissions of
power plants. |
| Cogeneration |
|
Simultaneous production of two or more forms of useable energy from a
single fuel source, e.g., heat energy and electrical or mechanical power, in
the same facility. Because a typical cogeneration facility uses thermal
energy which is generally vented in a traditional power plant, the process
can be 50 to 70 percent more efficient. Fuels used in cogeneration
facilities may take the form of natural gas, biomass, oil or coal. Most
cogeneration systems are designed to simultaneously produce electric power
(to be used on site or sold back to an investor-owned utility or both) and
thermal heat for industrial processes or the heating and cooling of
buildings. Cogeneration projects can be any size, from 10 kilowatts to 1,000
megawatts or more. |
| Coil |
|
A cooling or heating element, often including fins, through which
treated gas or liquid is passed, exchanging thermal energy with air
surrounding it for heating or cooling. |
| Colony Forming Unit (CFU) |
|
A laboratory measure of fungal concentration, indicating the quantity of
viable organisms collected for a given unit sample. |
| Comfort Conditioning |
|
The process of treating air to simultaneously control its temperature,
humidity, cleanliness, and distribution to meet the comfort requirements of
the occupants of the conditioned space. |
| Comfort Zone |
|
The range of temperatures, humidities and air velocities at which the
greatest percentage of people feel comfortable. The range of temperatures
over which the majority of persons feel comfortable (neither too hot nor too
cold). |
| Commercial |
|
The commercial sector is generally defined as nonmanufacturing business
establishments, including hotels, motels, restaurants, wholesale businesses,
retail stores, and health, social, and educational institutions. The utility
may classify commercial service as all consumers whose demand or annual use
exceeds some specified limit. The limit may be set by the utility based on
the rate schedule of the utility. |
| Commissioning |
|
The testing of HVAC systems prior to building occupancy to check whether
the systems meet the operational needs of the building within the
capabilities of the system design. Start-up of a building that includes
testing and adjusting HVAC, electrical, plumbing, and other systems to
assure proper functioning and adherence to design criteria. Commissioning
also includes the instruction of building representatives in the use of the
building systems. |
| Compressor |
|
The heart of an air conditioning or heat pump system. The large (usually
black) part in the condenser (outdoor unit) that pumps refrigerant. The pump
of a refrigerating mechanism which draws a low pressure on cooling side of
refrigerant cycle and squeezes or compresses the gas into the high pressure
or condensing side of the cycle. The compressor maintains adequate pressure
to cause refrigerant to flow in sufficient quantities to meet the cooling
requirements of the system. |
| Condenser |
|
This is the unit that will sit outside and is part of a split system, it
contains the compressor which is the heart of your air conditioner or Heat
Pump, it pumps the refrigerant through your system. Some people call the
condenser the compressor, but the compressor is a component of the condenser
along with the fan motor and condenser coil. Coil or outdoor coil dissipates
heat from the refrigerant, changing the refrigerant from vapor to liquid. |
| Condenser Approach Temperature |
|
The temperature difference between the condenser's refrigerant
temperature and the leaving condenser water temperature. An ideal indicator
of fouling of condenser tubes, which can significantly degrade chiller
efficiency. |
| Condenser Coil |
|
[Also see Outdoor Coil] The outdoor portion of a heating or cooling
system that either releases or collects heat from the outside air, depending
on the time of year. The Condenser Coil is connected directly to the home's
Air Handler and is also known as the Outdoor Coil. |
| Condensing Unit |
|
Part of a refrigerating mechanism which pumps vaporized refrigerant from
the evaporator, compresses it, liquefies it in the condenser and returns it
to the refrigerant control. The outdoor portion of a split system air
conditioner contains the compressor and outdoor coil ignoring the reverse
cycle operation, also the outdoor in a heat pump system. |
| Conditioned Air |
|
The air that has been heated, cooled, humidified, or dehumidified to
maintain an interior space within the "comfort zone." |
| Conditioned Floor Area |
|
The floor area of enclosed conditioned spaces on all floors measured
from the interior surfaces of exterior partitions for nonresidential
buildings and from the exterior surfaces of exterior partitions for
residential buildings. |
| Conditioned Space |
|
Enclosed space that is either directly conditioned space or indirectly
conditioned space. |
| Conditioned Space, Directly |
|
An enclosed space that is provided with heating equipment that has a
capacity exceeding 10 Btus/(hr-ft2), or with cooling equipment that has a
capacity exceeding 10 Btus/(hr-ft2). An exception is if the heating and
cooling equipment is designed and thermostatically controlled to maintain a
process environment temperature less than 65 degrees Fahrenheit or greater
than 85 degrees Fahrenheit for the whole space the equipment serves. |
| Conditioned Space, Indirectly |
|
Enclosed space that: (1) has a greater area weighted heat transfer
coefficient (u-value) between it and directly conditioned spaces than
between it and the outdoors or unconditioned space; (2) has air transferred
from directly conditioned space moving through it at a rate exceeding three
air changes per hour. |
| Conductance |
|
The quantity of heat, in Btu's, that will flow through one square foot
of material in one hour, when there is a 1 degree F temperature difference
between both surfaces. Conductance can be expressed in other units as well.
Conductance values are given for a specific thickness of material, not per
inch thickness. |
| Conduction |
|
The transfer of heat through a solid material. The transfer of heat
energy through a material (solid, liquid or gas) by the motion of adjacent
atoms and molecules without gross displacement of the particles. |
| Configuration |
|
This describes the direction in which a furnace outputs heat. A furnace
may have an upflow, downflow or crossflow (horizontal) configuration. |
| Constant Air Volume Systems |
|
Air handling system that provides a constant air flow while varying the
temperature to meet heating and cooling needs. |
| Contactor |
|
In the condenser, the main switch that turns the condenser on. |
| Contaminant |
|
An unwanted constituent that may or may not be associated with adverse
health or comfort effects. |
| Convection |
|
The movement of heat by air flow. |
| Cooling Capacity |
|
The maximum rate at which cooling equipment removes heat from airflow at
operating conditions. |
| Cooling Capacity, Latent |
|
Available refrigerating capacity of an air conditioning unit for
removing latent heat from the space to be conditioned. |
| Cooling Capacity, Sensible |
|
Available refrigerating capacity of an air conditioning unit for
removing sensible heat from the space to be conditioned. |
| Cooling Capacity, Total |
|
Available refrigerating capacity of an air conditioner for removing
sensible heat and latent heat from the space to be conditioned. |
| Cooling Degree Day |
|
A unit of measure that indicates how heavy the air conditioning needs
are under certain weather conditions. |
| Cooling Load |
|
The rate at which heat must be extracted from a space in order to
maintain the desired temperature within the space. |
| Cooling Load Temperature Difference (CLTD) |
|
A value used in cooling load calculations for the effective temperature
difference (delta T) across a wall or ceiling, which accounts for the effect
of radiant heat as well as the temperature difference. |
| Cooling System |
|
A system of air-to-air, liquid-to-air, liquid-to-liquid, etc., heat
exchangers, ducts and/or pipes, etc., for removing head from a system
contianing heat sources, such as power plants, automobile engines, and
homes. Also, an energy Efficiency program promotion aimed at improving the
efficiency of the cooling delivery system, including replacement, in the
residential, commercial, or industrial sectors. |
| Cooling tower |
|
A heat transfer device, which cools warm water using outside air. |
| COP (Coefficient Of Performance) |
|
COP compares the heating capacity of a heat pump to the amount of
electricity required to operate the heat pump in the heating mode. COPs vary
with the outside temperature: as the temperature falls, the COP falls also,
since the heat pump is less efficient at lower temperatures. ARI standards
compare equipment at two temperatures, 47 F and 17 F, to give you an idea of
the COP in both mild and colder temperatures. Geothermal equipment is
compared at 32 F enter water temperature. COP & HSPF can not be compared
equally. Air Source Equipment is rated by HSPF or COP and Geothermal
equipment is rated by COP. |
| Current (Electric) |
|
A flow of electrons in an electrical conductor. The strength or rate of
movement of the electricity is measured, e.g., in amperes. |
|
|
|
A
B C
D E
F G
H I
J K
L M
N O
P Q
R S
T U
V W
X Y
Z
|
| Damper |
|
A device that is located in ductwork to adjust air flow. This movable
plate opens and closes to control airflow. Dampers are used effectively in
zoning to regulate airflow to certain rooms. There are basically two types
of dampers: Manual and motorized. A manual damper generally consists of a
sheet metal (or similar material) flap, shaped to fit the inside of a round
or rectangular duct. By rotating a handle located outside of the duct a
technician can adjust (see Balancing) air flow to match the needs of a
particular area or room. A motorized damper is generally used in a zoned
system (see Zoning) to automatically deliver conditioned air to specific
rooms or zones. In particular, the following types, can be distinguished:
Multiple leaf dampers, comprising of a number of blades (or shutters)
of opposed or parallel leaf type.
Single leaf dampers (the flap being mounted at one end), commonly called
splitter dampers.
Hit-and-miss dampers, having two or more slotted slide mechanism.
Butterfly dampers, with two flaps in "V" arrangement.
|
| Dampers |
|
Controls that vary airflow through an air outlet, inlet, or duct. A
damper position may be immovable, manually adjustable or part of an
automated control system. |
| db (Decibel) |
|
A decibel describes the relative loudness of a sound. Some common sounds
are fairly close to a typical air conditioner or heat pump's sound level:
human voice, 7.0 decibels; blender, 8.8 decibels. |
| DDC (Direct Digital Control) |
|
Direct Digital Control |
| Defrost Cycle |
|
The process of removing ice or frost buildup from the outdoor coil
during the heating season. |
| Degree Day |
|
A unit, based upon temperature difference and time, used in estimating
fuel consumption and specifying nominal annual heating load of a building.
When the mean temperature is less than 65 degrees Fahrenheit the heating
degree days are equal to the total number of hours that temperature is less
than 65 degrees Fahrenheit for an entire year. |
| Dehumidification |
|
The reduction of water vapor in air by cooling the air below the dew
point; removal of water vapor from air by chemical means, refrigeration,
etc. |
| Delta (or Delta T) |
|
A difference in temperature. Often used in the context of the difference
between the design indoor temperature and the outdoor temperature. |
| Demand Billing |
|
The electric capacity requirement for which a large user pays. It may be
based on the customer's peak demand during the contract year, on a previous
maximum or on an agreed minimum. Measured in kilowatts. |
| Demand Charge |
|
The sum to be paid by a large electricity consumer for its peak usage
level. |
| Demand (Utility) |
|
The rate at which electricity or natural gas is delivered to or by a
system,, part of a system, or piece of equipment, e.g., to end users, at a
given instant or averaged over any designated period of time. Electricity
demand is typically expressed in kilowatts. |
| Design Conditions |
|
Cooling loads vary with inside and outside conditions. A set of
conditions specific to the local climate are necessary to calculate the
expected cooling load for a home. Inside conditions of 75 degrees Fahrenheit
and 50% relative humidity are usually recommended as a guideline. Outside
conditions are selected for the 2.5% design point. |
| Dewpoint |
|
Is the temperature at which air becomes saturated with water and begins
to condense - forming a dew. Therefore at 100 % RH the ambient or process
temperature equals the dewpoint temperature. The more negative the dewpoint
temperature is from the ambient temperature the less the risk of
condensation and the drier the gas or air stream. |
| Diffusers and Grilles |
|
Components of the ventilation system that distribute and return air to
promote air circulation in the occupied space. Generally speaking, supply
air enters a space through a diffuser or vent and return air leaves a space
through a grille. |
| Dilution |
|
A mitigation strategy that lowers the concentration of airborne
contaminants by increasing the fraction of outdoor air in the supply
airstream. |
| Direct Current (DC) |
|
Electricity that flows continuously in the same direction. |
| Direct Expansion (Refrigeration) |
|
Any system that, in operation between an environment where heat is
absorbed (heat source), and an environment into which unwanted heat is
directed (heat sink) at two different temperatures, is able to absorb heat
from the heat source at the lower temperature and reject heat to the heat
sink at the higher temperature. The cooling effect is obtained directly from
a fluid called a refrigerant that absorbs heat at a low temperature and
pressure, and transfers heat at a higher temperature and higher pressure. |
| Direct Gas-Fired Heater |
|
The burner fires directly in the air stream being heated, rather than
through a heat exchanger. 100% of available BTUs are delivered to the heated
space because no flue or heat exchanger is required. This results in no
wasted energy. |
| DOE (Department of Energy) |
|
The Department of Energy is a federal agency in charge of setting
industry efficiency standards and monitoring the consumption of energy
sources. |
| Double Glazing |
|
Windows having two sheets of glass with an airspace between. |
| Downflow |
|
A type of furnace that takes cool air from the top and blows warm air to
the bottom - common where your furnace must be located in a second-floor
closet or utility area. |
| Downflow Furnace |
|
A furnace that pulls in cool return air from the top and blows/expels
warm air at the bottom - common where your furnace must be located in a
second-floor closet or utility area. |
| Drain Trap |
|
A dip in the drain pipe of sinks, toilets, floor drains, etc., which is
designed to stay filled with water, thereby preventing sewer gases from
escaping into the room. |
| Drier |
|
Sometimes called filter/drier, it removes moisture and keeps the
refrigerant clean. |
| Dry Bulb Temperature (DB) |
|
The temperature measured by a standard thermometer. A measure of the
sensible temperature of air. |
| Dual Fuel System |
|
A dual heating system, for example a heat pump and a fossil fuel
furnace. |
| Dual-Duct System |
|
A central plant heating , ventilation and air conditioning (HVAC )
system that produces conditioned air at two temperatures and humidity
levels. The air is then supplied through two independent duct systems to the
points of usage where mixing occurs. |
| Dual-Paned (Double-glazed) |
|
Two panes of glass or other transparent material, separated by a space. |
| Duct |
|
A pipe or closed conduit made of sheet metal, fiberglass board, or other
suitable material used for conducting air to and from an air handling unit.
A passageway made of sheet metal or other suitable material used for
conveying air or other gas at relatively low pressures. |
| Duct tape |
|
This (initially) sticky tape is unfortunately the most common material
used to seal duct connections. Care must be taken when it's applied. For
effective sealing, the surface it is applied to must be clean--free of dust,
dirt, oil, or other substances. Duct tape has a tendency to lose adhesion
with age, especially when used on ducts in unconditioned spaces. |
| Ductwork |
|
A pipe or closed conduit made of sheet metal, fiberglass board, or other
suitable material used for conducting air to and from an air handling unit.
Hollow pipes or channels that carry/transfer air from the Air Handler to the
air vents throughout your home. The delivery system through which warm air
from the furnace is brought to where it's needed. Ductwork is made of sheet
metal, fiberglass, or flexible plastic, and can be round or rectangular in
shape. Ductwork is one of the most important components of a home heating
and cooling system. |
| Dust |
|
Dust is comprised of particles in the air that settle on surfaces. Large
particles settle quickly and can be trapped by the body's defense
mechanisms. Small particles are more likely to be airborne and are capable
of passing through the body's defenses and entering the lungs. |
|
|
|
A
B C
D E
F G
H I
J K
L M
N O
P Q
R S
T U
V W
X Y
Z
|
| Economizer, Air |
|
A ducting arrangement and automatic control system that allows a
heating, ventilation and air conditioning (HVAC) system to supply up to 100
percent outside air to satisfy cooling demands, even if additional
mechanical cooling is required. |
| Economizer, Water |
|
A system which uses either direct evaporative cooling, or a secondary
evaporatively cooled water loop and cooling coil to satisfy cooling loads,
even if additional mechanical cooling is required. |
| EER - (Energy Efficiency Ratio) |
|
A ratio calculated by dividing the cooling capacity in Btu's per hour (Btuh)
by the power input in watts at any given set of rating conditions, expressed
in Btuh per watt (Btuh/watt). EER & SEER can not be compared equally. Air
source equipment is rated by SEER and geothermal equipment is rated by EER.
EER changes with the inside and outside conditions, falling as the
temperature difference between inside and outside gets larger. |
| Effective area (of an air terminal device) |
|
The smallest net area of an air terminal device used by the air stream
in passing through the air terminal device. |
| Efficiency |
|
A rating on comfort equipment is similar to the miles per gallon rating
on your car. The higher the rating number, the more efficient the system and
the lower your fuel consumption will be. You can save a lot of money with a
high efficiency unit. Depending on your local climate, lifestyle and
electricity rates, savings will vary. For furnaces. it is the rate at which
a furnace maximizes fuel use. This rate is numerically described as a ratio
called AFUE (see AFUE). As of January, 1991, no furnaces can be manufactured
with efficiencies lower than 78% afue. High efficiency furnaces will be
rated 85 to 95% afue. |
| Electric Radiant Heating |
|
A heating system in which electric resistance is used to produce heat
which radiates to nearby surfaces. There is no fan component to a radiant
heating system. |
| Electric Rate Schedule |
|
A statement of the electric rate and the terms and conditions governing
its application, including attendant contract terms and conditions that have
been accepted by a regulatory body with appropriate oversight authority. |
| Electric Resistance Heater |
|
A device that produces heat through electric resistance. For example, an
electric current is run through a wire coil with a relatively high electric
resistance, thereby converting the electric energy into heat which can be
transferred to the space by fans. |
| Electrostatic air cleaner |
|
A device that uses an electrical charge to trap particles traveling in
the air stream. |
| Emergency Heat (Supplementary Electric Heat) |
|
The back up electric heat built into a heat pump system. The same as an
auxiliary heater, except it is used exclusively as the heat source when the
heat pump needs repair. |
| Emission Standard |
|
A voluntary guideline or government regulation that specifies the
maximum rate at which a contaminant can be released from a source. |
| Encapsulate |
|
A mitigation technique that reduces or eliminates emissions from a
source by sealing with an impenetrable barrier. |
| Endotoxin |
|
A biological agent that is part of the outer membrane of some bacteria.
Endotoxins are highly toxic, capable of causing fever, malaise, respiratory
distress, even death. |
| Energy |
|
Broadly defined, is the capability of doing work. More specifically, it
is the capacity for doing work as measured by the capability of doing work
(potential energy) or the conversion of this capability to motion (kinetic
energy). Forms of energy include: thermal, mechanical, electrical and
chemical. Energy may be transformed from one form into another form useful
for work. Most of the worldıs convertible energy comes from fossil fuels
that are burned to produce heat that is then used as a transfer medium to
mechanical or other means in order to accomplish tasks. Electrical energy is
usually measured in kilowatt-hours, while heat energy may be measured in
British thermal units or other traditional non-metric speciallized units in
addition to metric units. In the electric power industry, energy is more
narrowly defined as electricity supplied over time, expressed in kilowatts. |
| Energy Efficiency |
|
Refers to programs that are aimed at reducing the energy used by
specific end-use devices and systems, typically without affecting the
services provided. These programs reduce overall electricity consumption
(reported in megawatthours), often without explicit consideration for the
timing of program-induced savings. Such savings are generally achieved by
substituting technically more advanced equipment to produce the same level
of end-use services (e.g. lighting, heating, motor drive) with less
electricity. Examples include high-efficiency appliances, efficient lighting
programs, high-efficiency heating, ventilating and air conditioning (HVAC)
systems or control modifications, efficient building design, advanced
electric motor drives, and heat recovery systems. |
| Energy Management System |
|
A control system (often computerized) designed to regulate the energy
consumption of a building by controlling the operation of energy consuming
systems, such as the heating, ventilation and air conditioning (HVAC),
lighting and water heating systems. |
| Enforcement |
|
The legal methods used to make polluters obey the CLEAN AIR ACT.
Enforcement methods include citations of polluters for violations of the law
(citations are much like traffic tickets), fines and even jail terms. EPA
and the state and local governments are responsible for enforcement of the
Clean Air Act, but if they don't enforce the law, members of the public can
sue EPA or the states to get action. Citizens can also sue violating
sources, apart from any action EPA or state or local governments have taken.
Before the 1990 Clean Air Act, all enforcement actions had to be handled
through the courts. The 1990 Clean Air Act gave EPA authority so that, in
some cases, EPA can fine violators without going to court first. The purpose
of this new authority is to speed up violating sources' compliance with the
law and reduce court time and cost. |
| Enthalpy |
|
The quantity of heat necessary to raise the temperature of a substance
from one point to a higher temperature. The quantity of heat includes both
latent and sensible. |
| Envelope |
|
The geometrical surface of the points of an air jet, corresponding to a
determined value of the measured air velocity. This velocity is generally
called Ğterminal velocityğ. Also, the air barrier that separates the
conditioned space from the outside and from unconditioned spaces like attics
and garages. |
| Environmental Agents |
|
Conditions other than indoor air contaminants that cause stress,
comfort, and/or health problems (e.g., humidity extremes, drafts, lack of
air circulation, noise, and over-crowding). |
| Environmental Tobacco Smoke (ETS) |
|
The combination of sidestream and mainstream smoke that is emitted from
a burning cigarette; also called second-hand smoke. |
| Environmental Tobacco Smoke (ETS) |
|
Mixture of smoke from the burning end of a cigarette, pipe, or cigar and
smoke exhaled by the smoker. |
| EPA (Environmental Protection Agency) |
|
Environmental Protection Agency - http://www.epa.gov/ A federal agency
created in 1970 to permit coordinated governmental action for protection of
the environment by systematic abatement and control of pollution through
integration of research, monitoring, standards setting and enforcement
activities. EPA administers federal environmental policies, enforces
environmental laws and regulations, performs research, and provides
information on environmental subjects. The agency also acts as chief advisor
to the President on U.S. environmental policy and issues. |
| Epidemiological |
|
Dealing with the scientific study of the incidence, control, and spread
of disease in a population. |
| Ergonomics |
|
The science that investigates the impact of people's physical
environment on their health and comfort (e.g., chair design, monitor
location, desk configuration or height, etc.) |
| ERV (Energy Recovery Ventilator) |
|
This device preheats incoming outside air during the winter and
pre-cools incoming air during the summer to reduce the impact of heating and
or cooling the indoor air. This means that smaller capacity heating and
cooling systems can be used in homes, which results in lower installation
costs, lower peak demand for energy, and lower operating costs. |
| Evaporative Cooler |
|
A type of cooling equipment that turns air into moist, cool air by
saturating the air with water vapor. It does not cool air by use of a
refrigeration unit. This type of equipment is commonly used in warm, dry
climates. |
| Evaporative Cooling |
|
Cooling by exchange of latent heat from water sprays, jets of water, or
wetted material. |
| Evaporator Approach Temperature |
|
The temperature difference between the evaporatorıs refrigerant
temperature and the leaving chilled water temperature. |
| Evaporator Coil |
|
[Also see Indoor Coil] The evaporator coil is located inside your house
in a split system in the airhandler, or above the gas furnace. This will
produce cooling in the air conditioning mode and heating in a Heat Pump
mode. This coil section in the evaporator is where refrigerant evaporates
and absorbs heat from air passed over the coil.This is also very important
in removing humidity from your home. |
| Exfiltration |
|
Uncontrolled air leakage out of a building. |
| Exfiltration |
|
Air flow outward through a wall, building envelope, etc. |
| Exhaust |
|
Air removed deliberately from a space, by a fan or other means, usually
to remove contaminants from a location near their source. The air flow
leaving the treated space. Exhaust may be accomplished by one or more of the
following methods:
a. Extraction: exhaust in such a manner that the air is
discharged into the atmosphere.
b. Relief: exhaust in such a manner that the air is allowed to
escape from the treated space if the pressure in that space rises above a
specified level.
c. Recirculation: exhaust in which the air is returned to the air
treatment system.
d. Transfer: exhaust in which air passes from the treated space to
another treated space.
|
| Exhaust Air Flow Rate |
|
Volume of air leaving an exhaust air terminal device within a time unit. |
| Exhaust Air Terminal Device |
|
Air terminaI device through which air leaves the treated space. |
| Exhaust Ventilation |
|
Mechanical removal of air from a portion of a building (e.g., piece of
equipment, room, or general area). |
|
|
|
A
B C
D E
F G
H I
J K
L M
N O
P Q
R S
T U
V W
X Y
Z
|
| Fahrenheit (F) |
|
A temperature scale in which the boiling point of water is 212 degrees
and its freezing point is 32 degrees. To convert Fahrenheit to Celsius,
subtract 32, multiply by 5, and divide the product by 9. For example: 100
degrees Fahrenheit - 32 = 68; 68 x 5 = 340; 340 / 9 = 37.77 degrees Celsius. |
| Fan Coil |
|
An indoor component of a heat pump system used in place of a furnace, to
provide additional heating on cold days when the heat pump does not provide
adequate heating. A component of a heating, ventilation and air conditioning
(HVAC) system containing a fan and heating or cooling coil, used to
distribute heated or cooled air. |
| FAQ (Frequently Asked Questions) |
|
Used to mean a list of frequently asked questions. |
| Filter |
|
A device for removing dust particles from air or unwanted elements from
liquids. |
| Fire Valves (or Fire Dampers) |
|
Components which are installed in an air distribution system between two
fire separating compartments and are designed to prevent propagation of fire
and/or smoke. Generally are kept open by mechanical restraint, whose effect
is canceled under specific conditions. The valve is then closed
automatically. |
| Flame roll-out |
|
A dangerous situation that occurs when flame is pushed out of the bottom
of a combustion appliance. It can lead to fires. |
| Flex duct |
|
Usually installed in a single, continuous piece between the register and
plenum box, a flexible duct usually has an inner lining and an insulated
coating on the outside. |
| Flow Hood |
|
A diagnostic tool used to measure air flow through ducts, supply
registers, and return grilles. Device that easily measures airflow quantity,
typically up to 2,500 cfm. |
| Follow-Up Testing |
|
The testing designed to confirm the results of the initial testing using
identical testing devices and similar test conditions. |
| Forced Air |
|
This describes a type of heating system that uses a blower motor to move
air through the furnace and into the ductwork. Heating and or cooling system
that connects to the conditioned space with duct-work that uses air as the
moving fluid. The heating or cooling can come from any number of sources.
|
| Forced Air Unit (FAU) |
|
A central furnace equipped with a fan or blower that provides the
primary means for circulation of air. |
| Formaldehyde |
|
Formaldehyde is a colorless water-soluble gas. Due to its wide use, it
is frequently considered separately from other volatile organic compounds (VOCs) |
| Frequency |
|
The number of cycles which an alternating current moves through in each
second. Standard electric utility frequency in the United States is 60
cycles per second, or 60 Hertz. |
| Fungi |
|
A large group of organisms including molds, mildews, yeasts, mushrooms,
rusts, and smuts. Any of a group of parasitic lower plants that lack
chlorophyll. Most fungi produce spores, which are broadcast through the air
so that virtually all environmental surfaces will have some fungal material.
Most health effects are associated with allergic responses to antigenic
material or toxic effects from mycotoxins. Fungi also generate certain
volatile organic compounds. |
| Fungicide |
|
Substance or chemical that kills fungi. |
| Furnace |
|
That part of an environmental system which converts gas, oil,
electricity or other fuel into heat for distribution within a structure. |
| Furnace, Horizontal |
|
A furnace that lies on its side, pulling in return air from one side and
expelling warm air from the other. |
|
|
|
A
B C
D E
F G
H I
J K
L M
N O
P Q
R S
T U
V W
X Y
Z
|
| Gas Sorption |
|
Devices used to reduce levels of airborne gaseous compounds by passing
the air through materials that extract the gases. |
| Geothermal Energy |
|
Natural heat from within the earth, captured for production of electric
power, space heating or industrial steam. |
| Geothermal Equipment |
|
Heat pumps that uses the ground to transfer heat to and from the
refrigerant in the unit. The unit circulates water through a heat exchanger
in the to a closed loop buried in the ground or by pumping water from a well
through the unit. |
| Geothermal Gradient |
|
The change in the earth's temperature with depth. As one goes deeper,
the earth becomes hotter. |
| Global Climate Change |
|
Gradual changing of global climates due to buildup of carbon dioxide and
other greenhouse gases in the earth's atmosphere. Carbon dioxide produced by
burning fossil fuels has reached levels greater than what can be absorbed by
green plants and the seas. |
| Greenhouse Effect |
|
The presence of trace atmospheric gases make the earth warmer than would
direct sunlight alone. These gases (carbon dioxide [CO2], methane [CH4],
nitrous oxide [N2O], tropospheric ozone [O3], water vapor [H2O], and
chlorofluorocarbons) allow visible light and ultraviolet light (shortwave
radiation) to pass through the atmosphere and heat the earth's surface. This
heat is re-radiated from the earth in form of infrared energy (longwave
radiation). The greenhouse gases absorb part of that energy before it
escapes into space. Thus the greenhouse effect allows solar radiation to
penetrate but absorbs the infrared radiation returning to space. This
process of trapping the longwave radiation specifically is known as the
greenhouse effect. Scientists estimate that without the greenhouse effect,
the earth's surface would be roughly 54 degrees Fahrenheit colder than it is
today -- too cold to support life as we know it. See GLOBAL CLIMATE CHANGE. |
| Greenhouse Effect (Relating to Buildings) |
|
The characteristic tendency of some transparent materials (such as
glass) to transmit radiation with relatively short wavelengths (such as
sunlight) and block radiation of longer wavelengths (such as heat). This
tendency leads to a heat build-up within the space enclosed by such a
material. |
| Grille |
|
An air terminal device with multiple passages for the air. |
| Grilles |
|
Coverings for the ducts where they open to the conditioned space. (Same
as Registers) |
|
|
|
A
B C
D E
F G
H I
J K
L M
N O
P Q
R S
T U
V W
X Y
Z
|
| Half-Life |
|
The amount of time it takes for half of the existing amount of a
radioactive element to decay to non-radioactive products. |
| HCFC (Hydrochlorofluorocarbon) |
|
A class of refrigerants. Generally refers to Halogenated
Chlorofluorocarbon family of refrigerants. |
| Heat Balance |
|
The outdoor temperature at which a building's internal heat gain (from
people, lights and machines) is equal to the heat loss through windows, roof
and walls. |
| Heat Capacity |
|
The amount of heat necessary to raise the temperature of a given mass
one degree. Heat capacity may be calculated by multiplying the mass by the
specific heat. |
| Heat Engine |
|
An engine that converts heat to mechanical energy. |
| Heat Exchanger |
|
This is a device that enables furnaces to transfer heat from combustion
safely into breathable air. The primary heat exchanger transfers heat from
combustion gases to the air blowing through the ductwork. It's vital that
none of the combustion gas itself gets into the airstream. The primary heat
exchanger handles the hottest gases. This device transfers heat from
outgoing stale air to incoming cold air. In warm climates, this process can
be reversed. In high efficiency furnaces, secondary heat exchangers recover
heat that used to be vented up the chimney with the exhaust gases. By
recovering this heat, the furnace becomes more efficient. Part of the heat
recovered here causes the water and acid to condense out of the exhaust gas.
Because this liquid is corrosive, secondary heat exchangers must be designed
to prevent deterioration. Usually this means they are made of stainless
steel or some derivative of it. |
| Heat Gain |
|
The amount of heat gained, measured in BTU's, from a space to be
conditioned, at the local summer outdoor design temperature and a specified
indoor design condition. An increase in the amount of heat contained in a
space, resulting from direct solar radiation, heat flow through walls,
windows, and other building surfaces, and the heat given off by people,
lights, equipment, and other sources. |
| Heat Loss |
|
The amount of heat lost, measured in BTU's from a space to be
conditioned, at the local winter outdoor design temperature and a specified
indoor design condition. A decrease in the amount of heat contained in a
space, resulting from heat flow through walls, windows, roof and other
building surfaces and from exfiltration of warm air. |
| Heat Pump |
|
A heating and air conditioning unit that heats or cools by moving heat.
A Heat Pump is a reverse cycle air conditioner. The Heat Pump uses a
compression cycle system to supply heat or remove heat remove a temperature
controlled space. An air-conditioning unit which is capable of heating by
refrigeration, transferring heat from one (often cooler) medium to another
(often warmer) medium, and which may or may not include a capability for
cooling. This reverse-cycle air conditioner usually provides cooling in
summer and heating in winter. When you run your air conditioner, your
outdoor unit will be blowing hot air, (in other words, removing the heat
from your home and sending it outside). When you run your heat pump, you
reverse the flow of refrigerant and remove the heat from the atmosphere
outside and blow it inside. When the temperature dips below 40 degrees
outside, the Heat Pump labors in producing heat so they install a back up or
auxiliary electric heat strip to supplement the Heat Pump. Electric Heat
strips are very expensive to operate. In southern climates where it rarely
dips below 40 degrees the heat pump is very efficient. A 3 to 1 savings in
heating compared to electric heat strips. |
| Heat Pump Cooling Mode |
|
In the cooling cycle of a Heat Pump , you are removing hot air from
inside the house and sending it outside. You can feel the hot air outside,
over the condenser fan motor. |
| Heat Pump Heating Mode |
|
In the heating mode of a Heat Pump the refrigerant cycle is reversed and
you are now removing the heat from the outside and sending it inside the
house. You can feel the cool air outside, over the condenser fan motor. When
temperatures go below 40 degrees Heat Pumps labor in producing heat and must
use back up electric heat strips. Heat strips cost 3 times as much to
operate as a Heat Pump when producing heat. |
| Heat Rate |
|
A number that tells how efficient a fuel-burning power plant is. The
heat rate equals the Btu content of the fuel input divided by the
kilowatt-hours of power output. |
| Heat Source |
|
A body of air or liquid from which heat is collected. In an air source
heat pump, the air outside the house is used as the heat source during the
heating cycle. |
| Heat Transfer |
|
Flow of heat energy induced by a temperature difference. Heat flow
through a building envelope typically flows from a heated, or hot area to a
cooled, or cold area. |
| Heating Degree Day |
|
A unit that measure the space heating needs during a given period of
time. |
| Heating Load |
|
The rate at which heat must be added to a space in order to maintain the
desired temperature within the space. |
| Heating System |
|
Energy Efficiency program promotion aimed at improving the efficiency of
the heating delivery system, including replacement, in the residential,
commercial, or industrial sectors. |
| Hertz |
|
A unit of electromagnetic wave frequency that is equal to one cycle per
second. -- It is named after Henrich R. Hertz. |
| HFC (Hydrofluorocarbon) |
|
A class of refrigerants. Generally refers to Hydrofluorocarbon family of
refrigerants |
| High-Efficiency Particulate Air (HEPA) Filter |
|
A specialized filter capable of removing 99.97% of particulates 0.3 µ in
diameter. High efficiency particulate arrestance (filters). |
| Home Energy Assistance Program (HEAP) |
|
A centrally operated direct payment program that assists eligible
households in offsetting the cost of heating and cooling their homes.
Payments are generally made in the form of dual party warrants (checks) made
payable to the applicant and their designated utility company. For example,
the program is administered in California by the California Department of
Economic Opportunity using federal and state funds. |
| Horsepower (HP) |
|
A unit for measuring the rate of doing work. One horsepower equals about
three-fourths of a kilowatt (745.7 watts). |
| House Dust Mite |
|
A common microscopic household arachnid, which feeds on shed skin
scales, and so tends to concentrate around mattresses and furniture.
Antigens present in the mite's excreta are implicated in cases of allergic
asthma and allergic rhinitis. |
| HRV (Heat Recovery Ventilator) |
|
This device bring fresh, outside air into a home while simultaneously
exhausting stale indoor air outside. In the process of doing this, an HRV
removes heat from the exhaust air and transfer it to the incoming air,
pre-heating it. This allows for the reclamation of much of the energy that
otherwise would simply be vented outside. The end result: home comfort
systems operate more efficiently. |
| HSPF (Heating Seasonal Performance Factor) |
|
Indicates how efficiently a Heat Pump is working. A higher number means
the unit works more efficiently. Heating Seasonal Performance Factor is
similar to SEER, but it measures the efficiency of the heating portion of
your heat pump. Like SEER, industry minimums have been raised recently, and
the minimum is now 6.80 HSPF. Most new units have ratings from 7.0 to 9.4. A
representation of the total heating output of a central air-conditioning
heat pump in Btus during its normal usage period for heating, divided byu
the total electrical energy input in watt-hours during the same period, as
determined using the specified test procedures. Efficiency is derived
according to federal test methods by using the total Btus during its normal
usage period for heating divided by the total electrical energy input in
watt-hours during the same period. The total heating output of a heat pump
during its normal annual usage period for heating divided by the total
electric power input in watt-hours during the same period. COP & HSPF can
not be compared equally. Air Source equipment is rated by HSPF or COP and
Geothermal equipment is rated by COP. ARI standards compares air source
equipment at two temperatures, 47 F and 17 F. Geothermal equipment is
compared at 32 F enter water temperature. |
| Humidifier |
|
A device that adds moisture to warm air being circulated or directed
into a space. This adds necessary moisture to protect your furnishings and
reduce static electricity. |
| Humidistat |
|
A device designed to regulate humidity input by reacting to changes in
the moisture content of the air. Much like a thermostat but turns the system
on & off by sensing the humidity level. |
| Humidity |
|
The amount of moisture in the air. Air conditioners remove moisture for
added comfort. |
| HVAC (Heating, Ventilating and Air Conditioning) |
|
Heating, Ventilating and Air Conditioning |
| HVAC/R (Heating, Ventilating, Air Conditioning, &
Refrigeration) |
|
Heating, Ventilating, Air Conditioning, & Refrigeration |
| Hydronic Heating |
|
A system that heats a space using hot water which may be circulated
through a convection or fan coil system or through a radiant baseboard or
floor system. |
|
|
|
A
B C
D E
F G
H I
J K
L M
N O
P Q
R S
T U
V W
X Y
Z
|
| IAQ Backgrounder |
|
A component of the IAQ Tools for Schools Action Packet that provides a
general introduction to IAQ issues in educational facilities. |
| IAQ Coordinator |
|
An individual (usually with facility management) who provides leadership
and coordination of all IAQ activities. |
| IAQ (Indoor Air Quality) |
|
Indoor Air Quality - characteristics of the indoor
climate of a building, including the gaseous composition, temperature,
relative humidity, and airborne contaminant levels. |
| IAQ Management Plan |
|
A set of flexible and specific steps for preventing and resolving IAQ
problems in any kind of commercial facility. |
| Indicator Compounds |
|
Chemical compounds, such as carbon dioxide, whose presence at certain
concentrations may be used to estimate certain building conditions (e.g.,
airflow, presence of sources). |
| Indoor Air Pollutant |
|
Particles and dust, fibers, mists, bioaerosols, and gases or vapors. |
| Indoor Coils |
|
[Also see Evaporator Coil] Refrigerant containing portion of a fan coil
unit similar to a car radiator, typically made of several rows of copper
tubing with aluminum fins. A homes comfort system consist of two components:
the outdoor unit (air conditioner or heat pump) and the indoor unit (coil or
blower coil). Combinations of various units will result in vastly different
efficiency ratings. Unreasonably high efficiency ratings can be created by
using unrealistic indoor and out door equipment combinations. The term "most
popular coil" indicates the actual tested combinations; other ratings may be
simulated and unrealistic. Be sure that the efficiency ratings you are
comparing are for "most popular coil." You'll know the ratings are
attainable and close to reality. |
| Indoor Unit |
|
This is usually located inside the house and contains the indoor coil,
fan, motor, and filtering device, sometimes called the air handler. |
| Induction |
|
Process by which the primary air sets into motion an air volume, called
secondary air, in the room. |
| Induction ratio (i) |
|
Ratio of the total air flow rate to the primary air flow rate. |
| Industrial |
|
The industrial sector is generally defined as manufacturing,
construction, mining, agriculture, fishing, and forestry establishments
(Standard Industrial Classification [SIC] codes 01-39). The utility may
classify industrial service using the SIC codes, or based on demand or
annual usage exceeding some specified limit. The limit may be set by the
utility based on the rate schedule of the utility. |
| Infiltration |
|
Air movement into an enclosed space through cracks and openings.
Unintentional movement of outdoor air into a house. Air flow inward into a
space through walls, leaks around doors and windows or through the building
materials used in the structure. It results from the forces of wind,
temperature difference, and HVAC operation. |
| ISO 9000 |
|
A family of international standards for quality management and assurance
by the ISO (International Standards Organization). |
| IWC (Inches of water column) |
|
Commonly used in the USA |
|
|
|
A
B C
D E
F G
H I
J K
L M
N O
P Q
R S
T U
V W
X Y
Z
|
| Joule |
|
A unit of work or energy. It takes ~ 1,000 joules to equal a British
thermal unit. It typically takes ~ 1 million joules to make a pot of coffee. |
|
|
|
A
B C
D E
F G
H I
J K
L M
N O
P Q
R S
T U
V W
X Y
Z
|
| KBTU (kBtu) |
|
One-thousand (1,000) Btus. |
|
|
|
A
B C
D E
F G
H I
J K
L M
N O
P Q
R S
T U
V W
X Y
Z
|
| Latent Cooling Load (or Latent Load) |
|
The cooling load caused by moisture in the air. The net amount of
moisture added to the inside air by plants, people, cooking, infiltration,
and any other moisture source. The amount of moisture in the air can be
calculated from a combination of dry-bulb and wet-bulb temperature
measurements. |
| Latent Heat |
|
Heat, that when added or removed, causes a change in state - but no
change in temperature. A change in the heat content that occurs without a
corresponding change in temperature, usually accompanied by a change of
state (as from liquid to vapor during evaporation). |
| Life Extension |
|
A term used to describe capital expenses which reduce operating and
maintenance costs associated with continued operation of electric utility
boilers and other equipment. Such boilers usually have a 40 year operating
life under normal circumstances. |
| Life-Cycle Cost |
|
Amount of money necessary to own, operate and maintain a building,
system, plant, piece of equipment, etc., over its useful life. |
| Load |
|
The amount of electric power supplied to meet one or more end user's
needs. The amount of electric power delivered or required at any specific
point or points on a system. The requirement originates at the energy
consuming equipment of the consumers. |
| Load Building |
|
Refers to programs that are aimed at increasing the usage of existing
electric equipment or the addition of electric equipment. Examples include
industrial technologies such as induction heating and melting, direct arc
furnaces and infrared drying; cooking for commercial establishments; and
heat pumps for residences. Load building should include programs that
promote electric fuel substitution. Load building effects should be reported
as a negative number, shown with a minus sign. |
| Load Estimate |
|
A series of studies performed to determine the heating or cooling
requirements of your home. An energy load analysis uses information such as
the square footage of your home, window and door areas, insulation quality
and local climate to determine the heating and cooling capacity needed by
your furnace, heat pump or air conditioner. When referring to heating, this
is often known as a Heat Loss Analysis, since a home's heating requirements
are determined by the amount of heat lost through the roof, entry ways and
walls. |
| Local Exhaust Ventilation |
|
An industrial ventilation system that captures and removes contaminants
emitted from nearby sources before dilution into ambient workplace air can
occur. |
|
|
|
A
B C
D E
F G
H I
J K
L M
N O
P Q
R S
T U
V W
X Y
Z
|
| Make-Up Air |
|
See "Outdoor Air Supply." |
| Man-Made Mineral Fibers (MMMF) |
|
Fiber insulation products including glass wool, fiberglass, rock wool,
slag wools, as well as refractory ceramic fibers, which are used for
fireproofing. |
| Manometer |
|
An instrument that measures air pressure differences between locations.
Tubes are usually attached to a manometer and run to the spaces where
pressures are measured. |
| Manual D |
|
Manual D is the ACCA method for designing duct systems. Contractors
often find it a laborious process and most duct systems are just installed,
not designed. The amount of time necessary to design a duct system is
certainly warranted in tract construction where the design is used
repeatedly and for custom homes where the total cost of the home warrants a
proper design. In short, designing a duct system is essential for proper
equipment performance and customer comfort. |
| Manual J |
|
Manual J is a widely accepted method of calculating the sensible and
latent cooling (and heating) loads under design conditions. It was jointly
developed by the Air Conditioning Contractors of America (ACCA) and the
Air-Conditioning and Refrigeration Institute (ARI). |
| Manual S |
|
Manual S is the ACCA method of selecting air conditioning equipment to
meet the design loads. It ensures that both the sensible capacity and the
latent capacity of the selected equipment will be adequate to meet the
cooling load. |
| Mastic |
|
An adhesive paste used in the fabrication and sealing of thermal
insulation on piping fittings, equipment, and duct work. It spreads easily
and dries permanently. Its applications include new ducts and old, sheet
metal seams, and ductboard. Not all mastics are created equal. Some are
toxic, some are water-based, and some take longer to cure, making them more
suitable for new construction than retrofit. |
| Matched System |
|
A heating and cooling system comprised of products that have been
certified to perform at promised comfort and efficiency levels when used
together, and used according to design and engineering specifications. |
| Material Safety Data Sheets (MSDS) |
|
Product safety information sheets prepared by manufacturers and
marketers of products containing toxic chemicals. These sheets can be
obtained by requesting them from the manufacturer or marketer. Some stores,
such as hardware stores, may have material safety data sheets on hand for
products they sell. |
| Mechanical System |
|
See HVAC. |
| Megawatt Hour (MWh) |
|
One thousand kilowatt-hours, or an amount of electricity that would
supply the monthly power needs of a typical home having an electric hot
water system. |
| Megawatt (MW) |
|
One thousand kilowatts (1,000 kW) or one million (1,000,000) watts. One
megawatt is enough energy to power 1,000 average California homes. |
| MHPU (Mobile Home Package Unit) |
|
The Mobile Home Package Unit is an air conditioner with electric or gas
heat or can be a Heat Pump. This unit has the condenser and air handler
all-in-one package. Commonly used in mobile homes and sits outside.
(Self-contained unit) |
| Microbiologicals |
|
See "Biological Contaminants." |
| Mildew |
|
A superficial covering of organic surfaces with fungi under damp
conditions. |
| Mitigation |
|
A procedure or strategy aimed at reducing or eliminating an indoor air
problem, either through source control, ventilation control, exposure
reduction, or air cleaning. |
| Mixing Ratio (Relative Humidity) |
|
Is often used in drying applications and is the ratio of the mass of
water vapor to the mass of dry air with which it is associated. Vaisala
products give this output as grams of water per kilogram of dry air (g/kg). |
| Mold |
|
A fungal infestation that causes disintegration of a substance. Molds
are a group of organisms that belong to the kingdom Fungi. In this document,
the terms fungi and mold are used interchangeably. There are over 20,000
species of mold. |
| Multiple Chemical Sensitivity (MCS) |
|
A condition in which a person reports sensitivity or intolerance (as
distinct from "allergic") to a number of chemicals and other irritants at
very low concentrations. |
| mVOC |
|
Microbial volatile organic compound, a chemical made by a mold which may
have a moldy or musty odor. |
| Mycotoxin |
|
A metabolic product generated by certain fungi; includes both useful
substances, such as penicillin, and harmful substances, such as aflatoxin.
|
|
|
|
A
B C
D E
F G
H I
J K
L M
N O
P Q
R S
T U
V W
X Y
Z
|
| National Ambient Air Quality Standar (NAAQS) |
|
The US outdoor air quality standard designed to protect public health.
Pollutants covered by the NAAQS include ozone, sulfur dioxide, lead,
nitrogen dioxide, respirable particulates, and carbon monoxide. |
| National Institute for Occupational Safety and Health (NIOSH)
|
|
The US government agency authorized to research and develop exposure
criteria for toxic substances and recommend these standards to OSHA. NIOSH
is also authorized to investigate unsafe working conditions. |
| Natural Ventilation |
|
The supply of outdoor air through passive flow from windows, chimneys,
doors, and other infiltration. |
| Negative Ion Generator |
|
An air cleaning device that uses static charges to remove particulates
from indoor air. |
| Negative Pressure |
|
Condition that exists when less air is supplied to a space than is
exhausted from the space, so the air pressure within that space is less than
that in surrounding areas. Under this condition, if an opening exists, air
will flow from surrounding areas into the negatively pressurized space. |
| NESHAP |
|
National Emissions Standard for Hazardous Pollutants |
| New Construction |
|
Energy efficiency program promotion to encourage the building of new
homes, buildings, and plants to exceed standard government-mandated energy
efficiency codes; it may include major renovations of existing facilities. |
| Nitrogen dioxide (N02) |
|
A pollutant associated with combustion; a deep lung irritant. The two
most prevalent oxides of nitrogen are nitrogen dioxide (NO2) and nitric
oxide (NO). Both are toxic gases with NO2 being a highly reactive oxidant,
and corrosive. NO gradually reacts with the oxygen in the air to form NO2. |
| Nozzle |
|
An air terminal device designed to generate a low energy loss and thus
produce a maximum throw by minimum entertainment. |
|
|
|
A
B C
D E
F G
H I
J K
L M
N O
P Q
R S
T U
V W
X Y
Z
|
| Occupational Safety and Health Administration (OSHA)
|
|
The regulatory arm of the US Department of Labor, which promulgates
safety and health standards, facilitates training programs, and enforces
regulations on work sites. OSHA has developed permissible exposure limits
for over 600 contaminants present in the industrial workplace. |
| Ohm |
|
A unit of measure of electrical resistance. One volt can produce a
current of one ampere through a resistance of one ohm. |
| Organic Compounds |
|
Chemicals that contain carbon. Volatile organic compounds vaporize at
room temperature and pressure. They are found in many indoor sources,
including many common household products and building materials. |
| Original Equipment Manufacturer (OEM) |
|
Refers to the manufacturers of complete vehicles or heavyduty engines,
as contrasted with remanufacturers, converters, retrofitters, up-fitters,
and repowering or rebuilding contractors who are overhauling engines,
adapting or converting vehicles or engines obtained from the OEMs, or
exchanging or rebuilding engines in existing vehicles. |
| Outdoor Air Supply |
|
Air brought into a building from the outdoors (often through the
ventilation system) that has not been previously circulated through the
system. Also known as "Make-Up Air." |
| Outdoor Coil |
|
[Also see Condenser Coil] Refrigerant containing portion of a fan coil
unit similar to a car radiator, typically made of several rows of copper
tubing with aluminum fins. |
| Outside Air |
|
Air taken from outdoors and not previously circulated through the HVAC
system. |
| Ozone (03) |
|
A kind of oxygen that has three atoms per molecule instead of the usual
two. Ozone is a poisonous gas, but the ozone layer in the upper atmosphere
shields life on earth from deadly ultraviolet radiation from space. The
molecule contains three oxygen atoms (O3). a highly reactive form of oxygen.
Ozone exposure an result in mucous membrane irritation and potential
pulmonary damage. Some copier machines and laser printers emit noticeable
levels. |
| Ozone Generator |
|
An air cleaning device that produces highly reactive ozone, which reacts
with volatile organic compounds to form non hazardous products, remove
particulates, and reduce the number of biocontaminants. These devices are
controversial because their touted benefits may only be accomplished at
ozone levels above recommended exposure levels. |
| Ozone Hole |
|
Thin place in the ozone layer located in the stratosphere high above the
Earth. Stratospheric ozone thinning has been linked to destruction of
stratospheric ozone by CFCs and related chemicals. The 1990 CLEAN AIR ACT
has provisions to reduce and eliminate ozonedestroying chemicals' production
and use. Ozone holes have been found above Antarctica and above Canada and
northern parts of the United States, as well as above northern Europe. |
|
|
|
A
B C
D E
F G
H I
J K
L M
N O
P Q
R S
T U
V W
X Y
Z
|
| Package Unit or Package System |
|
A self-contained unit or system that has the Air Handler & Condenser in
same unit. Normally placed outside the home and connected to a duct system
by a penetration through the homes foundation. Except for geothermal which
is a self-contained indoor unit that is place in a closet, attached garage,
basement, or mechanical room. |
| PAPR |
|
Powered air purifying respirator. |
| Particulates |
|
Small airborne particles found in indoor environments which include
fibrous materials, solid-state semi-volatile organic compounds, and
biological materials. |
| Pascals (Pa) |
|
A small unit of air pressure. One pound per square inch equals 6,895
pascals. |
| Passive Smoking |
|
The inhalation of environmental tobacco smoke; also called involuntary
smoking. |
| Pathogen |
|
Any microorganism or substance that causes disease. |
| PELs |
|
Permissible Exposure Limits (standards set by the Occupational, Saftey
and Health Administration). |
| Permeable |
|
Porous, allowing the passage of air. |
| Personal Protective Equipment (PPE) |
|
|
| Pesticides |
|
Pesticides are chemicals that are used to kill or control pests which
include bacteria, fungi, weeds, and other organisms, in addition to insects
and rodents. Most pesticides are inherently toxic. Most contain volatile
organic compounds. |
| Picocurie |
|
A unit of measurement used to describe radon concentration. |
| Plenum |
|
Air compartment connected to a duct or ducts. Air flow passage made of
duct board, metal, drywall, or wood. Joins supply and return ducts with HVAC
equipment. The portions of the air distribution system that makes use of the
building structure, and the sheet meal that connects distribution ductwork
to an air handling unit. Many buildings use the space above a dropped
ceiling as a plenum. |
| Pollutant Pathways |
|
Avenues for distribution of pollutants in a building. HVAC systems are
the primary pathways in most buildings; however all building components
interact to affect how air movement distributes pollutants. |
| Positive Pressure |
|
Condition that exists when more air is supplied to a space than is
exhausted, so the air pressure within that space is greater than that in
surrounding areas. Under this condition, if an opening exists, air will flow
from the positively pressurized space, outward to surrounding areas. |
| Power |
|
The rate at which energy is transferred. Electricity for use as energy
is also referred to as power. Electrical power is usually measured in watts.
Also used for a measurement of capacity. |
| PPM (Parts Per Million) |
|
A unit, which may be mass/mass, and hence represents a direct measure of
fractional mass, or volume/volume, and represents in this case, a molar
fraction at low pressures and high temperatures, commonly used to represent
the degree of pollutant concentration where the concentrations are small.
|
| Pressed Wood Products |
|
A group of materials used in building and furniture construction that
are made from wood veneers, particles, or fibers bonded together with an
adhesive under heat and pressure. |
| Pressure balancing |
|
The process of neutralizing pressure differences within a home. |
| Preventive Maintenance (PM) |
|
A program of building maintenance implemented to reduce the possibility
of problems, usually through periodic inspection, cleaning, adjustment.
calibration. and replacement of functioning, parts of the HVAC system, as
well as housekeeping practices to reduce the buildup of potential
contaminants. Primarily done on a building's mechanical systems, this
involves a regular and systematic inspection, cleaning, and replacement of
worn parts, materials, and systems. Preventive maintenance helps to prevent
parts, material, and systems failure by ensuring that parts, materials and
systems are in good working order. |
| Price of Quality, The |
|
There is more to buying a heat pump or air conditioner than ratings. The
quality of construction and materials used as well as the reliability of the
manufacturer and installing contractor can all affect your long-term
satisfaction and comfort. Top quality, high efficiency equipment will cost
more initially, but it will save you money on utility bills and service
calls for years to come. Be sure to weigh all the factors before choosing
your new system. |
| Primary Air Flow Rate |
|
Volume of air entering a supply air terminal device within a time unit.
|
| Process Heating |
|
Energy Efficiency program promotion of increased electric energy
efficiency applications in industrial process heating. |
| Programmable Controller |
|
A device that controls the operation of electrical equipment (such as
air conditioning units and lights) according to a preset time schedule. |
| Psychosocial Factors |
|
Psychological, organizational, and personal stressors that could produce
symptoms similar to those caused by poor indoor air quality. |
|
|
|
A
B C
D E
F G
H I
J K
L M
N O
P Q
R S
T U
V W
X Y
Z
|
| |
|
|
A
B C
D E
F G
H I
J K
L M
N O
P Q
R S
T U
V W
X Y
Z
|
| R-Value |
|
A measure, in Btu/(ft2 F), of the resistance to transmission of heat by
an insulating material. The higher the R-value of a material, the greater is
its insulating properties and the slower the heat flow through it. The
specific value needed to insulate a home depends on climate, type of heating
system and other factors. |
| Radiant |
|
System that uses hot surfaces to radiate or convect heat into the
environment. Without the use of fans or blowers |
| Radiant Barrier |
|
A device designed to reduce or stop the flow of radiant energy. |
| Radiation |
|
The transfer of heat directly from one surface to another (without
heating the intermediate air acting as a transfer mechanism). |
| Radioactive Decay |
|
The disintegration of the nuclei of the atoms of radioactive (charged)
elements with the concomitant release of alpha, beta, or gamma rays. |
| Radon (Rn) and Radon Decay Products |
|
Radon is a radioactive gas formed and emitted by the decay of radium and
uranium in rock. The radon decay products (also called radon daughters or
progeny) can be breathed into the lung where they continue to release
radiation as they further decay. |
| Re-Entrainment |
|
Situation that occurs when the air being exhausted from a building is
immediately brought back into the system through the air intake and other
openings in the building envelope. |
| Receiver |
|
Tank on the liquid side of a system that holds excess refrigerant in the
system that needs to be there for proper operation. |
| Reclaiming |
|
Processing or returning used refrigerant to the manufacturer or
processor for disposal or reuse. |
| Recool |
|
The sensible cooling of air that has been previously heated by HVAC
systems serving the same building. |
| Refrigerant |
|
Substance used in refrigerating mechanism. A substance that produces a
refrigerating effect while expanding or vaporizing. Air conditioning systems
use Refrigerant in the Evaporator Coil to cool air as it passes by.
Refrigerants absorb heat in evaporator by change of state from a liquid to a
gas, and releases its heat in a condenser as the substance returns from the
gaseous state back to a liquid state. |
| Refrigerant Charge |
|
The amount of refrigerant contained within the airc conditioning
equipment and required for proper operation. |
| Refrigerant Lines |
|
Two copper lines that connect the Condenser (Outdoor) Coil to the
Evaporator (Indoor) Coil. |
| Registers |
|
Combination grille and damper assembly covering an air opening or end of
an air duct. Coverings for the ducts where they open to the conditioned
space. (Same as Grilles) |
| Reheat |
|
The heating of air that has been previously cooled either by mechanical
refrigeration or economizer cooling systems. |
| Relative Humidity (RH) |
|
Relative humidity is defined as the ratio of the water vapor pressure to
the saturation vapor pressure (over water) at the temperature of the gas. RH
= Pw/Pws * 100 |
| Relative Risk |
|
The ratio of health impact incidence among exposed individuals to
incidence among unexposed individuals. |
| RELs |
|
Recommended Exposure Limits (recommendations made by the National
Institute for Occupational Safety and Health (NIOSH)). |
| Remediate |
|
Fix |
| Reservoir |
|
The environmental substrate, or source, of a particular organism.
Reservoirs for indoor biocontaminants include stagnant water, moist
surfaces, and dust collection sites. |
| Residential |
|
The residential sector is defined as private household establishments
which consume energy primarily for space heating, water heating, air
conditioning, lighting, refrigeration, cooking, and clothes drying. The
classification of an individual consumerıs account, where the use is both
residential and commercial, is based on principal use. |
| Resistance (Electrical) |
|
The ability of all conductors of electricity to resist the flow of
current, turning some of it into heat. Resistance depends on the cross
section of the conductor (the smaller the cross section, the greater the
resistance), the material, the length of the flow path, and its temperature
(the hotter the cross section, the greater its resistance). |
| Resistance (Thermal) |
|
The reciprocal of thermal conductance. See R-VALUE. |
| Respirable Suspended Particulates |
|
Particulates less than 10 µm in diameter that can enter the respiratory
tract. |
| Retrofit |
|
Broad term that applies to any change after the original purchase, such
as adding equipment not a part of the original purchase. As applied to
alternative fuel vehicles, it refers to conversion devices or kits for
conventional fuel vehicles. (Same as 3aftermarket2.) |
| Return |
|
The ductwork that carries air from the house to the air handler. |
| Return Air |
|
Air drawn into a heating unit after having been circulated from the
heater's output supply to a room. The air removed from an occupied space and
returned to the air handler to be exhausted or recirculated. |
| RSES |
|
A leading HVAC/R Association - Refrigeration Service Engineers Society -
http://www.rses.org/ |
|
|
|
A
B C
D E
F G
H I
J K
L M
N O
P Q
R S
T U
V W
X Y
Z
|
| Saturation Temperature |
|
Also referred to as the boiling point or the condensing temperature.
This is the temperature at which a refrigerant will change state from a
liquid to a vapor or visa versa. |
| SEER (Seasonal Energy Efficiency Ratio) |
|
An efficiency measurement that is similar to Miles Per Gallon for cars.
The higher this number, the more energy efficient they system is. The amount
of cooling your equipment delivers per every dollar spent on electricity.
The higher the number the lower the operating cost (not more cooling.) SEER
applies to air conditioners and heat pumps. In the past, a unit with a SEER
of 8.00 was considered standard efficiency, and a unit with a 10.00 SEER was
considered high efficiency. After January 1, 1992, the minimum SEER required
by the DOE is 10.00 and 15.00+ SEER is considered high efficiency. EER &
SEER can not be compared equally. Air source equipment is rated by SEER and
geothermal equipment is rated by EER. New units have SEER ratings from 10 to
17 BTUs per watt. The total cooling of a central unitary air conditioner or
unitary heat pump in Btu's during its normal annual usage period for cooling
divided by the total electric energy input in watt-hours during the same
period. The Seasonal Energy Efficiency Ratio is a standard method of rating
air conditioners based on three tests. All three tests are run at 80 degrees
Fahrenheit inside and 82 degrees Fahrenheit outside. The first test is run
with humid indoor conditions, the second with dry indoor conditions, and the
third with dry conditions cycling the air conditioner on for 6 minutes and
off for 24 minutes. The published SEER may not represent the actual seasonal
energy efficiency of an air conditioner in your climate. The total cooling
output of a central air conditioning unit in Btus during its normal usage
period for cooling divided by the total electrical energy input in
watt-hours during the same period, as determined using specified federal
test procedures. [Title 20, Section 2-1602(c)(11)]. |
| Sensible Cooling Load |
|
The heat gain of the home due to conduction, solar radiation,
infiltration, appliances, people, and pets. Burning a light bulb, for
example, adds only sensible load to the house. This sensible load raises the
dry-bulb temperature. |
| Sensible Heat |
|
Heat, that when added or removed, causes a change in temperature but not
in state. Heat that results in a temperature change. |
| Sensitization |
|
Repeated or single exposure to an allergen that results in the exposed
individual becoming hypersensitive to the allergen. |
| Setback |
|
A reduction of climate control energy demand in HVAC controls when a
building is unoccupied. |
| Setpoint |
|
The temperature to which a thermostat is set to result in a desired
heated space temperature. |
| Short-Circuiting |
|
Situation that occurs when the supply air flows to return or exhaust
grilles before entering the breathing zone (area of a room where people
are). To avoid short-circuiting, the supply air must be delivered at a
temperature and velocity that results in mixing throughout the space. |
| Sick building |
|
A building in which the indoor air quality is considered to be
unacceptable to a substantial majority of occupants. |
| Sick Building Syndrome (SBS) |
|
A phenomenon in which building occupants experience a variety of health
and/or comfort effects linked to time spent in a particular building, but
where no specific illness or causative agent can be identified. Symptoms in
sufferers often include headaches, eye irritation, and respiratory
irritation. Term that refers to a set of symptoms that affect some number of
building occupants during the time they spend in the building and diminish
or go away altogether during periods when they leave the building. (Contrast
with Building Related Illness.) |
| Single Package |
|
A year 'round heating and air conditioning system that has all the
components completely encased in one unit outside the home. |
| Sizing |
|
Refers to the procedure a heating contractor goes through to determine
how large a furnace (measured in btuh) is needed to heat a house
efficiently. Too small a furnace won't deliver enough heating; too large a
furnace increases energy costs and can have an adverse effect on comfort.
Sizing depends on the square-footage of the home, the amount of ceiling and
wall insulation, the window area, use of storm doors, storm windows, and
more. |
| Smoke stick |
|
A diagnostic tool used to observe air flow. Usually it consists of a
chemical in a squeezable container. When squeezed it emits smoke which
visibly follows air flow currents. |
| Sound Attenuators |
|
Components which are inserted into the air distribution system and
designed to reduce airborne noise which is propagated along the ducts. |
| Sound Rating Number (SRN) |
|
Sound is measured in bels (a bel equals 10 decibels). The SRN of a unit
is based on ARI test, performed at ARI standard rating conditions. Average
sound rating range from 7.0 to 8.0 decibels. The lower the SRN rating, the
quieter the unit. |
| Sound Ratings |
|
Although sound does not affect the efficiency of a unit, it will
certainly affect your comfort. If your unit has a low sound level, you will
hardly notice it is operating. But if it has a higher sound level, it may
mean your good night's sleep is disturbed every time it runs! |
| Source Control |
|
A preventive strategy for reducing airborne contaminant levels through
removal of the material or activity generating the pollutants. |
| Sources |
|
Sources of indoor air pollutants. Indoor air pollutants can originate
within the building or be drawn in from outdoors. Common sources include
people, fixtures and furnishings, photocopiers, plants, food, etc. |
| Specific Heat |
|
In English units, the quantity of heat, in Btu, needed to raise the
temperature of one pound of material one degree Fahrenheit. |
| Split System |
|
Refrigeration or air conditioning installation, which places condensing
unit outside or away from evaporator. These unit are connected together by a
supply and return refrigerant lines. Also applicable to heat pump
installations. A combination heat pump or air conditioner with indoor
components such as a furnace or blower coil. To maximize effectiveness,
Split Systems should be matched. |
| Spore |
|
Molds reproduce by means of spores. Spores are microscopic; they vary in
shape and size (2-100 micrometers). Spores may travel in several ways--they
may be passively moved (by a breeze or waterdrop), mechanically disturbed
(by a person or animal passing by), or actively discharged by the mold
(usually under moist conditions or high humidity). |
| Spread (LS) (for a supply air terminal device)
|
|
Maximum distance between two vertical planes tangent to a specified
envelope and perpendicular to a plane through the core center. The spread
are generally referred to the envelope corresponding to 0.25 m/s for zero
supply temperature differential (i.e., under isothermal conditions). |
| SRN (Sound Rating Number) |
|
Sound is measured in bels (a bel equals 10 decibels). The SRN of a unit
is based on ARI test, performed at ARI standard rating conditions. Average
sound rating range from 7.0 to 8.0 decibels. The lower the SRN rating, the
quieter the unit. |
| SRN (Sound Rating Number ) |
|
Sound is measured in bels (a bel equals 10 decibels). The SRN of a unit
is based on ARI test, performed at ARI standard rating conditions. Average
sound rating range from 7.0 to 8.0 decibels. The lower the SRN rating, the
quieter the unit. |
| Stack effect |
|
A condition resulting from the rise of heated air, which creates
positive pressure near the top of the building and negative pressure toward
the bottom. Stack effect pressures have been known to overpower mechanical
ventilation systems, disrupting proper circulation and contributing to the
infiltration and stagnation of pollutants. |
| Stack Effect |
|
The overall upward movement of air inside a building that results from
heated air rising and escaping through openings in the building super
structure, thus causing an indoor pressure level lower than that in the soil
gas beneath or surrounding the building foundation. |
| Standard Industrial Classification (SIC) |
|
A set of codes developed by the Office of Management and Budget, which
categorizes business into groups with similar economic activities. |
| Static Pressure |
|
Condition that exists when an equal amount of air is supplied to and
exhausted from a space. At static pressure, equilibrium has been reached. |
| Statistical Significance |
|
The probability that and degree to which the results of an experimental
study describe an actual relationship between two factors beyond that which
might be expected by pure coincidence. |
| Straight Cool |
|
This is an air conditioner that uses different forms of heating such as
Natural Gas, LP Gas, Electric Resistance heat and oil. |
| Stratosphere |
|
Part of the atmosphere, the gases that encircle the Earth. The
stratosphere is a layer of the atmosphere 9-31 miles above the Earth. Ozone
in the stratosphere filters out harmful sun rays, including a type of
sunlight called ultraviolet B, which has been linked to health and
environmental damage. |
| Subcooled Liquid |
|
Liquid refrigerant which is cooled below its saturation temperature.
|
| Superheated Vapor |
|
Refrigerant vapor which is heated above its saturation temperature. If a
refrigerant is superheated, there is no liquid present. |
| Supplementary Heat (Emergency Heat) |
|
The auxiliary or emergency heat provided at temperatures below a heat
pump's balance point. It is usually electrical resistance heat. |
| Supply |
|
The ductwork that carries air from the air handler to the rooms in the
house. |
| Supply Air |
|
The air flow entering the treated space. |
| Swamp Cooler |
|
See Evaporative Cooler. |
| Switchover Valve |
|
A device in a heat pump that reverses the flow of refrigerant as the
system is switched from cooling to heating. Also called a reversing valve or
four-way valve. |
| System |
|
A combination of equipment and/or controls, accessories, interconnecting
means and terminal elements by which energy is transformed to perform a
specific function, such as climate control, service water heating, or
lighting. |
| Systems Control |
|
The control of indoor air pollutants through the use of mechanical means
such as ventilation control or air cleaning. |
|
|
|
A
B C
D E
F G
H I
J K
L M
N O
P Q
R S
T U
V W
X Y
Z
|
| Temperature |
|
Degree of hotness or coldness measured on one of several arbitrary
scales based on some observable phenomenon (such as the expansion). |
| Temperature Differential |
|
The difference between the entering and leaving temperature for a given
fluid. For example, a 10-degree evaporator temperature differential for a
chiller would describe an operating condition where the entering water
temperature is 54 degrees and the leaving is 44 degrees. |
| Testing, Adjusting, And Balancing (TAB) |
|
The diagnostic and corrective procedures for HVAC controls and operating
components to ensure provision of specified airflow rates and environmental
conditions. |
| Therm |
|
Another measurement of heat. One therm equals One hundred thousand
(100,000) British thermal units (1 therm = 100,000 Btu). |
| Thermal (Energy) Storage |
|
A technology that lowers the amount of electricity needed for comfort
conditioning during utility peak load periods. A buildings thermal energy
storage system might, for example, use off-peak power to make ice or to
chill water at night, later using the ice or chilled water in a power saving
process for cooling during the day. See THERMAL MASS. |
| Thermal Mass |
|
A material used to store heat, thereby slowing the temperature variation
within a space. Typical thermal mass materials include concrete, brick,
masonry, tile and mortar, water, and rock or other materials with high heat
capacity. |
| Thermodynamics |
|
The study of the transformation of energy into other manifested forms
and of their practical applications. Commonly encountered forms of the
statements of the three principal laws of thermodynamics are: (0) The heat
capacity and entropy of every crystalline solid becomes zero at absolute
zero (0 degrees Kelvin). (1) The Law of the Conservation of Energy -- energy
may be transformed in an isolated system, but its total is constant. (2)
Heat from a reservoir at a constant temperature cannot be changed completely
into work by a cyclic process. |
| Thermostat |
|
A temperature sensitive switch for controlling the operation of a heater
or furnace. Typically found on a wall inside the home, that consists of a
series of sensors and relays that monitor and control the functions of a
heating and cooling system. A device that allows you to control the
temperature inside your home by telling the heating or cooling system how
much air to produce. An automatic control device designed to be responsive
to temperature and typically used to maintain set temperatures by cycling
the HVAC system. |
| Thermostat, Air-Sensing |
|
Thermostat unit in which sensing element is located in refrigerated
space. |
| Thermostat, Setback (Programmable Thermostat) |
|
A state-of-the-art electronic thermostat with a built-in memory that can
be programmed for different temperature settings at different times of the
day. A device, containing a clock mechanism, which can automatically change
the inside temperature maintained by the HVAC system according to a preset
schedule. The heating or cooling requirements can be reduced when a building
is unoccupied or when occupants are asleep. |
| Threshold (IAQ) |
|
The contaminant dose or exposure level below which there is no expected
significant effect. |
| Threshold Limit Value (TLV) |
|
The American Conference of Governmental Industrial Hygienists
recommended guideline for exposure limit represented in terms of exposure
over a work day (8 hours) or a work week (40 hours). |
| Threshold Limit Values (TLVs) |
|
Threshold Limit Values (guidelines recommended by the American
Conference of Governmental Industrial Hygenists). |
| Throw (Lt) |
|
The maximum distance between the center of the core and a plane which is
tangent to a specified envelope and perpendicular to the intended direction
of flow The throw is generally referred to as the envelope corresponding to
0.25 m/s for zero supply temperature differential (i.e., under isothermal
conditions). |
| Tight Building Syndrome (TBS) |
|
A condition in which a building is very tightly insulated against
infiltration, its ventilation is reduced for energy conservation, and
airborne contaminants are sufficiently elevated to cause health effects in
occupants; often used synonymously with sick building syndrome (SBS). |
| Time Delay |
|
Usually refers to a device that will not allow the condenser to restart
for an average of 5 minutes. |
| Ton or "Ton of Cooling" |
|
A cooling unit of measure. Each ton equals the cooling effect of 12,000
Btuh. Heat pumps and air conditioners are generally sized in tons. Typical
sizes for single family residences are between two and five tons. It is
important to note that actual capacity is not constant and will change based
on outdoor or indoor temperatures. The published capacity rating of air
conditioners and heat pumps is based on performance at the ARI standard
temperature levels of 95 F outside, 80 F inside, and 50% relative humidity.
The number of tons a system has is the total BTU capacity of the system. The
size of the area to be cooled will determine the correct size of the system
in tons. While an air conditioner may be called a three ton unit, it may not
produce 36,000 Btu/h in cooling. There is a wide variety of actual
capacities that are called "three tons." |
| Total air flow rate (QL) |
|
Sum of the primary and secondary air flow rates which are moved in the
treated space. |
| Total Home Comfort System |
|
The ultimate solution to providing you with consistent, customized home
comfort, despite the ever-changing weather. |
| Total Volatile Organic Compounds (TVOCs) |
|
A measure representing the sum of all VOCs present in the air to provide
an approximate indication of pollutant levels. Indoor air typically contains
hundreds of different VOCs in very low concentrations, some of which can
have additive effects. |
| Total Volatile Organic Compounds (TVOCs) |
|
Total volatile organic compounds. See "Volatile Organic Compounds (VOCs)" |
| Toxicant |
|
A substance that can cause tissue damage or otherwise affect organs or
systems within the body. |
| Tracer Gas |
|
An inert compound that is a rare constituent of indoor air which is
released into building air and monitored qualitatively and/or quantitatively
to characterize airflow characteristics to determine air pathways,
infiltration, and ventilation efficiency measurements. |
| Tracer Gases |
|
Compounds, such as sulfur hexaflouride, which are used to identify
suspected pollutant pathways and to quantify ventilation rates. Trace gases
may be detected qualitivatively by their odor or quantitatively by air
monitoring equipment. |
| Transformer |
|
A device, which through electromagnetic induction but without the use of
moving parts, transforms alternating or intermittent electric energy in one
circuit into energy of similar type in another circuit, commonly with
altered values of voltage and current. |
| Transmittance |
|
The time rate of heat flow per unit area under steady conditions from
the air (or other fluid) on the warm side of a barrier to the air (or fluid)
on the cool side, per unit temperature difference between the two sides.
|
|
|
|
A
B C
D E
F G
H I
J K
L M
N O
P Q
R S
T U
V W
X Y
Z
|
| UA |
|
A measure of the amount of heat that would be transferred through a
given surface or enclosure (such as a building envelope) with a one degree
temperature difference between the two sides. The UA is calculated by
multiplying the U-Value, or overall heat transfer coefficient U, by the area
A of the surface (or surfaces). |
| Unconditioned Space |
|
A space that is neither directly nor indirectly conditioned space, which
can be isolated from conditioned space by partitions and/or closeable doors. |
| Upflow |
|
See "Upflow Furnace" |
| Upflow Furnace |
|
A furnace that pulls cool return air in from the bottom and blows/expels
warm air out the top into the duct work. This type of furnace is usually
installed in a basement or an out-of-the-way closet. |
| Urea Formaldehyde Foam Insulation (UFFI) |
|
A form of insulation no longer in use because of excessive formaldehyde
emissions and documented associated health impacts. |
| Useful Thermal Output |
|
The thermal energy made available for use in any industrial or
commercial process, or used in any heating or cooling application, i.e.,
total thermal energy made available for processes and applications other
than electrical generation. |
|
|
|
A
B C
D E
F G
H I
J K
L M
N O
P Q
R S
T U
V W
X Y
Z
|
| Valves |
|
Components inserted into air ducts or devices which permit modification
of the air resistance of the system and consequently a complete shut-off of
the air flow (control valves). |
| VAV System (Variable Air Volume System) |
|
A mechanical HVAC system capable of serving multiple zones which
controls the temperature maintained in a zone by controlling the amount of
heated or cooled air supplied to the zone. |
| VAV (Variable Air Volume) |
|
Variable Air Volume. |
| Ventilation |
|
The process of supplying or removing air by natural or mechanical means
to or from any space. Such air may or may not have been conditioned or
treated. |
| Ventilation Air |
|
Defined as the total air, which is a combination of the air brought
inside from outdoors and the air that is being recirculated within the
building. |
| Ventilation effectiveness |
|
A measure of the fraction or percentage of outdoor air that reaches the
occupied zone of a specified area; an evaluation of air delivery to
occupants, regardless of the effectiveness of contaminant removal. |
| Ventilation efficiency |
|
An evaluation of the pollutant removal capacity of a ventilation system.
|
| Ventilation Rate |
|
The rate at which indoor air enters and leaves a building. Expressed in
one of two ways: the number of changes of outdoor air per unit of time (air
changes per hour, or "ach") or the rate at which a volume of outdoor air
enters per unit of time (cubic feet per minute, or "cfm"). |
| Ventilation standard |
|
A specification for the minimum rate of input of outdoor air into indoor
spaces. |
| VFD (Variable Frequency Drive) |
|
Electronic speed control for motors. |
| Volatile Organic Compounds (VOCs) |
|
One of a class of chemical compounds; indoor sources include tobacco
smoke, building products, furnishings, cleaning materials, solvents, and
office supplies. In sufficient quantities, VOCs can cause eye, nose, and
throat irritations; dizziness; and headaches. Some VOCs are suspected
carcinogens. Data for health effects resulting, from exposure to the
characteristically low levels of VOCs in the indoor environment are scarce.
Compounds that vaporize (become a gas) at room temperature. Common sources
which may emit VOCs into indoor air include housekeeping and maintenance
products, and building and furnishing materials. In sufficient quantities,
VOCs can cause eye, nose, and throat irritations, headaches, dizziness,
visual disorders, memory impairment; some are known to cause cancer in
animals; some are suspected of causing, or are known to cause, cancer in
humans. |
| Volt |
|
A unit of electromotive force. It is the amount of force required to
drive a steady current of one ampere through a resistance of one ohm.
Electrical systems of most homes and office have 120 volts. |
|
|
|
A
B C
D E
F G
H I
J K
L M
N O
P Q
R S
T U
V W
X Y
Z
|
| W (Watt) |
|
A watt is a unit of electricity. A unit of measure of electric power at
a point in time, as capacity or demand. It is the rate of energy transfer
equivalent to 1 ampere flowing under a pressure of 1 volt at unity power
factor. One watt of power maintained over time is equal to one joule per
second. Some Christmas tree lights use one watt. The watt is named after
Scottish inventor James Watt and is capitalized when shortened to w and used
with other abbreviations, as in kWh. |
| Water vapor |
|
Water vapor can be treated as a gas. At a particular temperature air for
example can only hold so much water vapor. The higher the temperature the
more water vapor it can hold. When saturated the relative humidity would be
100 % RH, so relative humidity describes how close to saturation the air is.
It is important to remember that in a process with a high relative humidity
a small drop in temperature will cause the humidity to rise and the
environment to saturate. Rapid temperature changes in a an environmental
chamber for example could also cause condensation. |
| Watt-Hour (W-hr) |
|
One watt of power expended for one hour. An electrical energy unit of
measure equal to 1 watt of power supplied to, or taken from, an electric
circuit steadily for 1 hour. One thousandth of a kilowatt-hour. |
| WB |
|
Wet Bulb |
| WC (Water Column) |
|
Common measure of air pressure used in HVAC systems. |
| Weather Stripping |
|
Specially designed strips, seals and gaskets installed around doors and
windows to limit air leakage. |
| Wet Bulb Temperature |
|
The temperature at which water, by evaporating into air, can bring the
air to saturation at the same temperature. Wet-bulb temperature is measured
by a wet-bulb psychrometer. Traditionally this was the temperature indicated
by a thermometer whose bulb is wrapped in a wet sheath. The wet bulb
temperature and the dry bulb temperature (i.e air temperature) would then be
used to calculate relative humidity or dewpoint. Alternatively charts or
tables can be used. |
| Wet-bulb Temperature |
|
When a wet wick is placed over a standard thermometer and air is blown
across the surface, the water evaporates and cools the thermometer below the
dry-bulb temperature. This cooler temperature (called the wet-bulb
temperature) depends on how much moisture is in the air. |
| Whole House Fan |
|
A system capable of cooling a house by exhausting a large volume of warm
air when the outside air is cool. |
|
|
|
A
B C
D E
F G
H I
J K
L M
N O
P Q
R S
T U
V W
X Y
Z
|
| |
|
|
A
B C
D E
F G
H I
J K
L M
N O
P Q
R S
T U
V W
X Y
Z
|
| |
|
|
A
B C
D E
F G
H I
J K
L M
N O
P Q
R S
T U
V W
X Y
Z
|
| Zonal Control |
|
A method of designing and controlling the HVAC system of a residence so
that living areas can be maintained at a different temperature than sleeping
areas using independent setback thermostats. If specific requirements are
met, zonal control may earn a credit towards compliance with whatever
building energy efficiency standards are applicable. |
| Zone |
|
1) Conditioned space in a house under the control of a thermostat. 2) A
space within a house with a distinct pressure compared to other pressure
zones. Also see Buffer zone. or 1) In the context of an HVAC system: a space
or group of spaces served by an HVAC system or portion of an HVAC system
controlled by a single thermostat or other control device; 2) A space or
group of spaces within a building with sufficiently similar comfort
conditioning requirements so that comfort conditions can be maintained
throughout by a single control device. |
| Zone Heat |
|
A central heating system in a building, designed to allow different
temperatures to be maintained in two or more parts of the building. |
| Zoning |
|
A system in which living areas or groups of rooms are divided into
separate spaces and each space's heating/air conditioning is controlled
independently. This can be accomplished by using either multiple independent
systems, or a single system using electronic controls and motorized dampers
(see Damper). For example, you might prefer to have the kitchen area of your
home be slightly cool, while at the same time keeping the temperature in the
bedrooms warmer. |
|
|
