Recommissioning
air
side systems
Equipment used to heat, cool, and transport air within building HVAC
systems.
ASHRAE
American Society of Heating, Refrigerating, and Air-Conditioning Engineers,
Inc.
balancing
Process of measuring and adjusting equipment to obtain desired flows.
Applies to both air side and water side systems.
boiler
Pressure vessel designed to transfer heat (produced by combustion)
or electric resistance to a fluid. In most boilers, the fluid is
water in the form of liquid or steam.
British thermal unit (Btu)
A unit of energy equivalent to the amount of heat required to raise
the temperature of 1 pound of water 1 degree Fahrenheit.
Btu
See British thermal unit.
calibration
Process of adjusting equipment to ensure that operation is within design
parameters.
carbon monoxide
Colorless, odorless, poisonous gas formed during incomplete combustion
of fuel.
central plant
Centrally located equipment that satisfies a building’s cooling
and heating loads.
CFCs
See chlorofluorocarbons.
cfm
Cubic feet per minute.
chiller
Mechanical device that generates cold liquid, which is circulated through
cooling coils to cool the air supplied to a building.
chlorofluorocarbons
Chemical compounds consisting of carbon, hydrogen, chlorine, and fluorine,
once used widely as aerosol propellants and refrigerants. Believed
to deplete the atmospheric ozone layer.
coil, condenser
A heat exchanger used to condense refrigerant from a gas to a liquid.
coil, cooling
Heat exchanger used to cool air under forced convection with or without
dehumidification. May consist of a single coil section or several
coil sections assembled into a bank.
coil, fan
A device that combines a heat exchanger and a fan in a single unit
that conditions air by forced convection.
coil, heating
Heat exchanger that heats air under forced convection. May consist
of a single coil section or several coil sections assembled into
a bank.
combustion air
Air that supplies the oxygen required to burn fuel.
commissioning
The quality assurance process that ensures design intent is met for
new facilities or major rehabilitation.
condenser
Heat exchanger in a refrigeration system that expels building heat
absorbed in the evaporator.
conditioned air
Air that serves a space and that has had its temperature and/or humidity
altered to meet design specifications.
controls
An instrument or set of instructions for operating or regulating building
systems.
control, pneumatic
A control that utilizes air pressure to vary equipment operation.
control, set back
The practice of reducing the thermostat setpoint during unoccupied
times.
cooling tower
Device that dissipates heat from water-cooled systems through a combination
of heat and mass transfer, whereby the water to be cooled is distributed
in the tower and exposed to circulated ambient air.
cycling
The noncontinuous operation of equipment.
dampers
Single- or multiple-blade devices, either manually or automatically
opened or closed, that control the flow of air.
demand charges
Fees levied by a utility company for electric demand.
demand, electric
Electrical power delivered to a system at a given time or averaged
over a designated period. Expressed in kilowatts.
diffuser, HVAC
A device that distributes conditioned air to a space.
diffuser, lighting
A device that distributes light produced by lamps into a space.
efficiency
Ratio of power output to input.
EMS
See energy management system.
energy management system (EMS)
The control system that monitors the environment and energy usage in
a building and alters equipment operation to conserve energy while
providing occupant comfort.
envelope, building
The outer shell of a building, including walls, roof, windows, and
doors.
evaporator
Heat exchanger in a refrigeration system that absorbs heat from chilled
water or building air, thus reducing the supply temperature.
fouling
The buildup of a film that reduces heat transfer.
heat exchanger
A device that transfers heat from one fluid to another.
humidistat
A device that responds to humidity changes and controls equipment by
seeking a setpoint.
HVAC
Heating, ventilating, and air-conditioning.
kilowatt (kW)
Unit of power equal to 1,000 watts.
kilowatt-hour (kWh)
Unit of electric consumption equal to the work done by 1 kilowatt acting
for 1 hour.
kW
See kilowatt.
kWh
See kilowatt-hour.
load
The demand upon the operating resources of a system. In the case of
energy loads in buildings, the word generally refers to heating,
cooling, and electrical (or demand) loads.
maintenance
An ongoing process to ensure equipment operates at peak performance.
occupancy sensor
A device that detects heat (passive infrared) or a shift in the frequency
of reflected ultrasonic sound waves, to control operation of lights
or equipment accordingly.
off-peak
Refers to a utility rate schedule that designates the time of day when
energy and demand costs are typically less expensive.
on-peak
Refers to a utility rate schedule that designates the time of day when
energy and demand costs are typically more expensive.
packaged unit
A self-contained HVAC unit that provides heating and/or cooling to
a building space.
part-load
Condition when equipment operates at less than full capacity to meet
the demand placed upon it.
part-load performance
Equipment efficiency at less than full capacity.
pressure drop
The loss in pressure experienced by flowing water or air due to friction
and obstructions.
radiator
Device that provides warmth to a space through radiant or convective
heat provided by either steam or hot water.
recommissioning
Recommissioning ensures system functionality. It is an inclusive and
systematic process intended not only to optimize how equipment and
systems operate, but also to optimize how the systems function together.
refrigerant
Substance, such as CFCs, HCFCs, HFCs, air, ammonia, water, or carbon
dioxide, used to provide cooling by evaporation and condensation.
reset, chilled water
The practice of increasing chilled water temperature to obtain higher
chiller efficiency.
reset, condenser water
The practice of decreasing condenser water temperature to obtain higher
chiller efficiency.
rooftop unit
Air-handling equipment such as packaged units located on the roof.
schedule
A control sequence that turns equipment on and off.
setpoint
Desired temperature, humidity, or pressure in a space, duct, etc.
shell, building
See envelope, building.
space
The distinct area to which conditioned air is delivered.
steam trap
A device that separates air and condensed water from steam.
TAB
See testing, adjusting, and balancing.
testing, adjusting, and balancing (TAB)
The process of adjusting HVAC system components to supply air and water
flows at design or revised specifications.
thermostat
A device that responds to temperature changes and controls equipment
by seeking a setpoint accordingly.
ton
Unit of cooling capacity equal to 12,000 Btu/hr.
tubes, condenser
Heat exchanger tubes through which condenser water is pumped to allow
heat transfer between the condenser water and the refrigerant.
tubes, evaporator
Heat exchanger tubes through which chilled water is pumped to allow
heat transfer between the chilled water and the refrigerant.
tune-up, building
The purposeful sequence of maintenance and operational improvements,
undertaken at a specific point in time, designed to reduce energy
use, heating loads, and cooling loads of existing facilities.
variable air volume (VAV)
A type of air-handling system that provides air at a constant temperature
and varies the air quantity to each zone to match the variation in
room load.
water side systems
Equipment used to heat, cool, and transport water to building HVAC
systems.
Lighting
ballast
Power-regulating device that modifies input voltage and controls current
to provide the electrical conditions necessary to start and operate
gaseous discharge lamps.
carbon dioxide
Colorless, odorless, incombustible gas formed during respiration, combustion,
and organic decomposition. Increasing amounts of carbon dioxide in
the atmosphere are believed to contribute to the global warming phenomenon.
CERCLA
Comprehensive Environmental Response, Compensation and Liability Act
(1980) an EPA regulation. Also known as the Superfund law.
color rendering index (CRI)
A measure ranging from 0 to 100 of the accuracy with which a light
source renders different colors in comparison to natural light, which
has a measure of 100.
controls
An instrument or set of instructions for operating or regulating building
systems.
CRI
See color rendering index.
cycling
The noncontinuous operation of equipment.
deadband
A setting in the lighting control that provides a time delay, signaling
the lights to switch off only if the light level is somewhat above
the setting, or on only if the level is somewhat below the setting.
DEHP
Di (2-ethylhexyl) phthalate, an insulator used to replace PCBs in ballast
capacitors starting in 1979. DEHP is listed as a hazardous waste
in its pure form, but, according to RCRA, it is no longer considered
hazardous once used in a lighting ballast.
demand charges
Fees levied by a utility company for electric demand.
demand, electric
Electrical power delivered to a system at a given time or averaged
over a designated period. Expressed in kilowatts.
diffuser, HVAC
A device that distributes conditioned air to a space.
diffuser, lighting
A device that distributes light produced by lamps into a space.
efficacy
The ratio of lamp lumen output to total lamp power input expressed
in lumens per watt.
efficiency
Ratio of power output to power input.
EMS
See energy management system.
energy management system (EMS)
The control system that monitors the environment and energy usage in
a building and alters equipment operation to conserve energy while
providing occupant comfort.
footcandle (fc)
Unit of illuminance equal to 1 lumen per square foot.
heat gain
The rate at which heat enters or is generated within a space at a given
instant.
HID
High-intensity discharge.
HVAC
Heating, ventilating, and air-conditioning.
IES
Illuminating Engineering Society.
illuminance
Commonly called light level, the light intensity arriving on a surface
measured in footcandles.
internal rate of return (IRR)
Compound interest rate at which the total discounted benefits equal
total discounted costs for a particular investment.
IRR
See internal rate of return.
kilowatt (kW)
Unit of power equal to 1,000 watts.
kilowatt-hour (kWh)
Unit of electric consumption equal to the work done by 1 kilowatt acting
for 1 hour.
kW
See kilowatt.
kWh
See kilowatt-hour.
load
The demand upon the operating resources of a system. In the case of
energy loads in buildings, the word generally refers to heating,
cooling, and electrical (or demand) loads.
lumen
Unit measurement of the rate at which a light source produces light
per unit time.
luminaire
Complete lighting unit, consisting of one or more lamps together with
a housing, the optical components to distribute the light from the
lamps, and the electrical components (ballast, starters, etc.) necessary
to operate the lamps.
luminance
Commonly referred to as brightness, the light leaving a surface measured
in footlamberts. It considers both illuminance on the surface and
reflectance of the surface.
luminance ratio
The ratio between the luminances of any two areas in the visual field.
This is a measure of the uniformity of luminance.
maintenance
An ongoing process to ensure equipment operates at peak performance.
nitrogen oxides
Chemical compounds that contain nitrogen and oxygen. They react with
volatile organic compounds in the presence of heat and sunlight to
form ozone and are a major precursor to acid rain.
occupancy sensor
A device that detects heat (passive infrared) or a shift in the frequency
of reflected ultrasonic sound waves, to control operation of lights
or equipment accordingly.
packaged unit
A self-contained HVAC unit that provides heating and/or cooling to
a building space.
payback
See payback, simple.
payback, simple
Also known as payback. Measurement of the elapsed time between an initial
investment and the point at which accumulated savings are sufficient
to offset the initial investment.
PCB
Polychlorinated biphenyl. A substance used as an insulator in the capacitor
of fluorescent and HID magnetic ballasts prior to 1970. PCBs have
been labeled as carcinogenic and can cause skin, liver, and reproductive
disorders.
photocell
A device that responds electrically to the presence of light.
power factor
Ratio of real power to total apparent power.
power quality
The degree to which voltage and current wave forms conform to a sinusoidal
shape and are in synchronous phase with one another. Poor power quality
can have negative impacts on electrical equipment.
RCRA
Resource Conservation and Recovery Act, an EPA Regulation.
reflector
A device installed in luminaires used to direct light from a source
via specular or diffuse reflection.
rightsizing
The process of correctly sizing equipment to the peak load.
rooftop unit
Air-handling equipment such as packaged units located on the roof.
schedule
A control sequence that turns equipment on and off.
sulfur dioxide
A heavy, colorless, pungent air pollutant formed primarily by the combustion
of fossil fuels such as coal. It is a respiratory irritant and a
precursor to the formation of acid rain.
VCP
See visual comfort probability.
visual comfort probability (VCP)
A rating given to lighting systems expressed as the percentage of people
who will find light output acceptable in terms of glare due to direct
light from luminaires.
voltage, volts
International system unit of electric potential or the amount of electrical
flow, also referred to as electromotive force.
Supplemental Load Reductions
air-handling unit (AHU)
Equipment used to distribute conditioned air to a space. Includes heating
and cooling coils, fans, ducts, and filters.
air side systems
Equipment used to heat, cool, and transport air within building HVAC
systems.
ASHRAE
American Society of Heating, Refrigerating, and Air-Conditioning Engineers,
Inc.
balancing
Process of measuring and adjusting equipment to obtain desired flows.
Applies to both air side and water side systems.
ballast
Power-regulating device that modifies input voltage and controls current
to provide the electrical conditions necessary to start and operate
gaseous discharge lamps.
British thermal unit (Btu)
A unit of energy equivalent to the amount of heat required to raise
the temperature of 1pound of water 1 degree Fahrenheit.
Btu
See British thermal unit.
calibration
Process of adjusting equipment to ensure that operation is within design
parameters.
carbon dioxide
Colorless, odorless, incombustible gas formed during respiration, combustion,
and organic decomposition. Increasing amounts of carbon dioxide in
the atmosphere are believed to contribute to the global warming phenomenon.
CFCs
See chlorofluorocarbons.
cfm
Cubic feet per minute.
chiller
Mechanical device that generates cold liquid, which is circulated through
cooling coils to cool the air supplied to a building.
chlorofluorocarbons
Chemical compounds consisting of carbon, hydrogen, chlorine, and fluorine,
once used widely as aerosol propellants and refrigerants. Believed
to cause depletion of the atmospheric ozone layer.
coil, condenser
A heat exchanger used to condense refrigerant from a gas to a liquid.
coil, cooling
Heat exchanger used to cool air under forced convection, with or without
dehumidification. May consist of a single coil section or several
coil sections assembled into a bank.
coil, fan
A device that combines a heat exchanger and a fan in a single unit
that conditions air by forced convection.
coil, heating
Heat exchanger that heats air under forced convection. May consist
of a single coil section or several coil sections assembled into
a bank.
controls
An instrument or set of instructions for operating or regulating building
systems.
dampers
Single- or multiple-blade devices, either manually or automatically
opened or closed, that control the flow of air.
DEHP
Di (2-ethylhexyl) phthalate, an insulator used to replace PCBs in ballast
capacitors starting in 1979. DEHP is listed as a hazardous waste
in its pure form, but, according to RCRA, it is no longer considered
hazardous once used in a lighting ballast.
demand charges
Fees levied by a utility company for electric demand.
demand, electric
Electrical power delivered to a system at a given time or averaged
over a designated period. Expressed in kilowatts.
demand ventilation
Method of controlling the amount of outdoor air intake based on carbon
dioxide levels in a space.
desiccant
A material that absorbs moisture from its surrounding environment.
domestic hot water
All hot water consumed in a building that is used for purposes other
than heating a space.
efficacy
The ratio of lamp lumen output to total lamp power input expressed
in lumens per watt.
efficiency
Ratio of power output to power input.
ENERGY STAR label
EPA’s trademark symbolizing excellence in energy efficiency.
envelope, building
The outer shell of a building, including walls, roof, windows, and
doors.
exhaust air
Air removed from a building and not reused.
glazing
Glass set or made to be set in frames.
glazing system
A configuration of materials with a transparent or translucent element
designed to admit sunlight.
GPM
Gallons per minute. A measure of water flow rate.
heat exchanger
A device that transfers heat from one fluid to another.
heat, latent
The heat required to change the state of matter from a liquid to gas
or gas to liquid.
heat pump
Heat pump utilize the vapor compression refrigeration cycle the same
that a DX unit or chiller does. The difference is that a heat pump
can reverse the direction of heat flow which naturally flows from
warmer to cooler areas.
heat, sensible
The heat required to change temperature without changing state of matter.
This temperature change can occur by exposure to radiation, friction
between two objects, chemical reaction, or contact with a hotter
object.
hp
Horsepower. A unit of mechanical power.
HVAC
Heating, ventilating, and air-conditioning.
infiltration
Air that leaks into a building through the building shell.
kilowatt (kW)
Unit of power equal to 1,000 watts.
kilowatt-hour (kWh)
Unit of electric consumption equal to the work done by 1 kilowatt acting
for 1 hour.
kW
See kilowatt.
kWh
See kilowatt-hour.
load
The demand upon the operating resources of a system. In the case of
energy loads in buildings, the word generally refers to heating,
cooling, and electrical (or demand) loads.
maintenance
An ongoing process to ensure equipment operates at peak performance.
nitrogen oxides
Chemical compounds that contain nitrogen and oxygen. They react with
volatile organic compounds in the presence of heat and sunlight to
form ozone and are a major precursor to acid rain.
occupancy sensor
A device that detects heat (passive infrared) or a shift in the frequency
of reflected
ultrasonic sound waves, to control operation of lights or equipment
accordingly.
payback, simple
Also known as payback. Measurement of the elapsed time between an initial
investment and the point at which accumulated savings are sufficient
to offset the initial investment.
PPM
Parts per million. A unit of concentration.
roof curb
A raised and reinforced area on a roof for mounting equipment.
setpoint
Desired temperature, humidity, or pressure in a space, duct, etc.
shell, building
See envelope, building.
space
The distinct area to which conditioned air is delivered.
timeclock
The control device used to turn equipment on and off at set times of
the day.
ton
Unit of cooling capacity equal to 12,000 Btu/hr.
transformer
A device that reduces the incoming line voltage, usually to a standard
level, so that it may be used to operate electrical equipment in
a building.
tune-up, building
The purposeful sequence of maintenance and operational improvements,
undertaken at a specific point in time, designed to reduce energy
use, heating loads, and cooling loads of existing facilities.
Fans
air-handling unit (AHU)
Equipment used to distribute conditioned air to a space. Includes heating
and cooling coils, fans, ducts, and filters.
air side systems
Equipment used to heat, cool, and transport air within building HVAC
systems.
ASHRAE
American Society of Heating, Refrigerating, and Air-Conditioning Engineers,
Inc.
balancing
Process of measuring and adjusting equipment to obtain desired flows.
Applies to both air side and water side systems.
boiler
Pressure vessel designed to transfer heat produced by combustion or
electric resistance to a fluid. In most boilers, the fluid is water
in the form of liquid or steam.
British thermal unit (Btu)
A unit of energy equivalent to the amount of heat required to raise
the temperature of 1 pound of water 1 degree Fahrenheit.
Btu
See British thermal unit.
CFCs
See chlorofluorocarbons.
cfm
Cubic feet per minute.
chiller
Mechanical device that generates cold liquid, which is circulated through
cooling coils to cool the air supplied to a building.
chlorofluorocarbons
Chemical compounds consisting of carbon, hydrogen, chlorine, and fluorine,
once used widely as aerosol propellants and refrigerants. Believed
to cause depletion of the atmospheric ozone layer.
coefficient of performance (COP)
A measure of efficiency in which a higher value designates a more efficient
system.
coil, condenser
A heat exchanger used to condense refrigerant from a gas to a liquid.
coil, cooling
Heat exchanger used to cool air under forced convection, with or without
dehumidification. May consist of a single coil section or several
coil sections assembled into a bank.
coil, fan
A device that combines a heat exchanger and a fan in a single unit
that conditions air by forced convection.
coil, heating
Heat exchanger that heats air under forced convection. May consist
of a single coil section or several coil sections assembled into
a bank.
condenser
Heat exchanger used to expel building heat absorbed in the evaporator
of a refrigeration system.
conditioned air
Air that serves a space that has had its temperature and/or humidity
altered to meet design specifications.
constant volume (CAV, constant air volume)
Type of air-handling system that supplies the conditioned space at
a constant air flow and modulate heating and cooling by varying the
air temperature.
controls
An instrument or set of instructions for operating or regulating building
systems.
cooling tower
Device that dissipates heat from water-cooled systems through a combination
of heat and mass transfer, whereby the water to be cooled is distributed
in the tower and exposed to circulated ambient air.
COP
See coefficient of performance.
cycling
The noncontinuous operation of equipment.
demand charges
Fees levied by a utility company for electric demand.
demand, electric
Electrical power delivered to a system at a given time or averaged
over a designated period. Expressed in kilowatts.
downsizing
Process of reducing the size (capacity) of equipment so that it operates
efficiently at design load conditions.
ductwork
The distribution system for air in HVAC systems. It is usually made
of sheet metal
or fiberglass.
efficiency
Ratio of power output to power input.
EMS
See energy management system.
energy management system (EMS)
The control system that monitors the environment and energy usage in
a building and alters equipment operation to conserve energy while
providing occupant comfort.
evaporator
Heat exchanger in a refrigeration system that absorbs heat from chilled
water or building air, thus reducing the supply temperature.
fouling
The buildup of a film that reduces heat transfer.
gasket
Material used to seal a joint against leakage.
GPM
Gallons per minute. A measure of water flow rate.
heat exchanger
A device that transfers heat from one fluid to another.
heat, latent
The heat required to change the state of matter from a liquid to gas
or gas to liquid.
heat pump
Heat pump utilize the vapor compression refrigeration cycle the same
that a DX unit or chiller does. The difference is that a heat pump
can reverse the direction of heat flow which naturally flows from
warmer to cooler areas.
heat, sensible
The heat required to change temperature without changing state of matter.
This temperature change can occur by exposure to radiation, friction
between two objects, chemical reaction, or contact with a hotter
object.
hp
Horsepower. A unit of mechanical power.
HVAC
Heating, ventilating, and air-conditioning.
impeller
The rotating element of a fan or pump used to circulate the air or
water.
internal rate of return (IRR)
Compound interest rate at which the total discounted benefits become
equal to total discounted costs for a particular investment.
IRR
See internal rate of return.
kilowatt (kW)
Unit of power equal to 1,000 watts.
kilowatt-hour (kWh)
Unit of electric consumption equal to the work done by 1 kilowatt acting
for 1 hour.
kW
See kilowatt.
kWh
See kilowatt-hour.
load
The demand upon the operating resources of a system. In the case of
energy loads in buildings, the word generally refers to heating,
cooling, and electrical (or demand) loads.
maintenance
An ongoing process to ensure equipment operates at peak performance.
meter
A device used to measure and display or record data.
nitrogen oxides
Chemical compounds that contain nitrogen and oxygen. They react with
volatile organic compounds in the presence of heat and sunlight to
form ozone and are a major precursor to acid rain.
off-peak
Refers to a utility rate schedule that designates the time of day when
energy and demand costs are typically less expensive.
on-peak
Refers to a utility rate schedule that designates the time of day when
energy and demand costs are typically more expensive.
packaged unit
A self-contained HVAC unit that provides heating and/or cooling to
a building space.
part-load
Condition when equipment operates at less than full capacity to meet
the demand placed upon it.
payback,
payback
See payback, simple.
payback, simple
Also known as payback. Measurement of the elapsed time between an initial
investment and the point at which accumulated savings are sufficient
to offset the initial investment.
power factor
Ratio of real power to total apparent power.
pressure drop
The loss in pressure experienced by flowing water or air due to friction
and obstructions.
refrigerant
Substance, such as CFCs, HCFCs, HFCs, air, ammonia, water, or carbon
dioxide, used to provide cooling by evaporation and condensation.
reset, chilled water
The practice of increasing chilled water temperature to obtain higher
chiller efficiency.
reset, condenser water
The practice of decreasing condenser water temperature to obtain higher
chiller efficiency.
rightsizing
The process of correctly sizing equipment to operate efficiently at
design load conditions.
rooftop unit
Air-handling equipment such as packaged units located on the roof.
schedule
A control sequence that turns equipment on and off.
seasonal energy-efficiency ratio (SEER)
Cooling capacity (Btu/hr) divided by total input power (watts) requirement
where both are seasonal averages.
SEER
See seasonal energy-efficiency ratio.
sheave
(Pronounced shiv.) Pulley.
space
The distinct area to which conditioned air is delivered.
thermostat
A device that responds to temperature changes and controls equipment
by seeking a setpoint accordingly.
timeclock
The control device used to turn equipment on and off at set times of
the day.
ton
Unit of cooling capacity equal to 12,000 Btu/hr.
tune-up, building
The purposeful sequence of maintenance and operational improvements,
undertaken at a specific point in time, designed to reduce energy
use, heating loads, and cooling loads of existing facilities.
variable air volume (VAV)
A type of air-handling system that provides air at a constant temperature
and varies the air quantity to each zone to match the variation in
room load.
VAV
See variable air volume.
VSD
See variable-speed drive.
variable-speed drive (VSD)
A device used to adjust the speed of an AC motor to match load requirements.
Heating and Cooling
air-handling unit (AHU)
Equipment used to distribute conditioned air to a space. Includes heating
and cooling coils, fans, ducts, and filters.
air side systems
Equipment used to heat, cool, and transport air within building HVAC
systems.
ARI
Air-Conditioning and Refrigeration Institute.
ASHRAE
American Society of Heating, Refrigerating, and Air-Conditioning Engineers,
Inc.
ASME
American Society of Mechanical Engineers.
boiler
Pressure vessel designed to transfer heat produced by combustion or
electric resistance to a fluid. In most boilers, the fluid is usually
water in the form of liquid or steam.
calibration
Process of adjusting equipment to ensure that operation is within design
parameters.
carbon dioxide
Colorless, odorless, incombustible gas formed during respiration, combustion,
and organic decomposition. Increasing amounts of carbon dioxide in
the atmosphere are believed to contribute to the global warming phenomenon.
CAV
See constant volume.
CFCs
See chlorofluorocarbons.
chiller
Mechanical device that generates cold liquid, which is circulated through
cooling coils to cool the air supplied to a building.
chlorofluorocarbons
Chemical compounds consisting of carbon, hydrogen, chlorine, and fluorine,
once used widely as aerosol propellants and refrigerants. Believed
to cause depletion of the atmospheric ozone layer.
coefficient of performance (COP)
A measure of efficiency in which a higher value designates a more efficient
system. For example, Chiller efficiency measured in Btu output (cooling)
divided by Btu input (electric power), measured at full or part load.
coil, condenser
A heat exchanger used to condense refrigerant from a gas to a liquid.
coil, cooling
Heat exchanger used to cool air under forced convection, with or without
dehumidification. May consist of a single coil section or several
coil sections assembled into a bank.
coil, heating
Heat exchanger that heats air under forced convection. May consist
of a single coil section or several coil sections assembled into
a bank.
condenser
Heat exchanger used to expel building heat absorbed in the evaporator
of a refrigeration system.
constant volume (CAV, constant air volume).
Type of air-handling system that supplies the conditioned space at
a constant air flow and modulate heating and cooling by varying the
air temperature.
controls
An instrument or set of instructions for operating or regulating building
systems.
cooling tower
Device that dissipates heat from water-cooled systems through a combination
of heat and mass transfer, whereby the water to be cooled is distributed
in the tower and exposed to circulated ambient air.
COP
See coefficient of performance.
dampers
Single- or multiple-blade devices, either manually or automatically
opened or closed, that control the flow of air.
demand charges
Fees levied by a utility company for electric demand.
direct expansion system
Cooling system in which the refrigerant runs in the cooling coil to
cool the air directly; that is, there is no water loop between the
refrigerant and the air to be cooled.
downsizing
Process of reducing the size (capacity) of equipment so that it operates
efficiently at design load conditions.
EER
Energy Efficiency Ratio. Cooling capacity (Btu/hr) divided by total
input power (watts) requirement.
efficiency
Ratio of power output to power input.
EMS
See energy management system.
energy management system (EMS)
The control system that monitors the environment and energy usage in
a building and alters equipment operation to conserve energy while
providing occupant comfort.
fan, cooling tower
Fans that are used to draw air through the cooling tower to carry away
water vapor.
gasket
Material used to seal a joint against leakage.
GPM
Gallons per minute. A measure of water flow rate.
heat-exchange area
Area where heat is transferred from one medium to another.
heat pump
Heat pump utilize the vapor compression refrigeration cycle the same
that a DX unit or chiller does. The difference is that a heat pump
can reverse the direction of heat flow which naturally flows from
warmer to cooler areas.
HVAC
Heating, ventilating, and air-conditioning.
IEEE
Institute of Electrical and Electronic Engineers.
internal rate of return (IRR)
Compound interest rate at which the total discounted benefits become
equal to total discounted costs for a particular investment.
IRR
See internal rate of return.
kilowatt (kW)
Unit of power equal to 1,000 watts.
kilowatt-hour (kWh)
Unit of electric consumption equal to the work done by one kilowatt
acting for one hour.
kW
See kilowatt.
KWh
See kilowatt-hour.
load, cooling
Cooling (typically measured in Btu/hr or tons) required to maintain
an indoor design temperature.
part-load conditions
Time when equipment is operating at less than design loads; represents
the majority of the time equipment is operating.
payback
See payback, simple.
payback, simple
Also known as payback. Measurement of the elapsed time between an initial
investment and the point at which accumulated savings are sufficient
to offset the initial investment.
peak (cooling) load
Maximum cooling required to maintain an indoor design temperature under
the most adverse summertime outdoor air conditions.
pump, chilled-water
Device that circulates chilled water.
pump, condenser-water
Device that circulates condenser water.
refrigerant
Substance, such as CFCs, HCFCs, HFCs, air, ammonia, water, or carbon
dioxide, used to provide cooling by evaporation and condensation.
seasonal energy-efficiency ratio (SEER)
Cooling capacity (Btu/hr) divided by total input power (watts) requirement
where both are seasonal averages.
SEER
See seasonal energy-efficiency ratio.
setpoint
Desired temperature, humidity, or pressure in a space, duct, etc.
space
The distinct area to which conditioned air is delivered.
strainer screen
Filtering device used in water side systems to protect equipment from
dirt, rust, and other particles.
TAB
See testing, adjusting, and balancing.
ton
Unit of cooling capacity equal to 12,000 Btu/hr.
variable air volume (VAV)
A type of air-handling system that provides air at a constant temperature
and varies the air quantity to each zone to match the variation in
room load.
variable-speed drive (VSD)
A device used to adjust the speed of an AC motor to match load requirements.
VAV
See variable air volume.
VSD
See variable speed drive.
water side systems
Equipment used to supply heating and cooling for air side systems.
Includes pumps, chillers, boilers, and other devices.
Energy terms can be confusing. We have compiled some definitions to energy terms to help.
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