ENERGY / UTILITY GLOSSARY
speed drive (ASD) - An electronic device that controls the rotational speed
of a piece of motor-driven
equipment (e.g., a compressor, fan, or pump). Speed control is obtained by
adjusting the frequency of the
voltage applied to the motor. This approach usually saves energy for
Association of Energy Engineers, professional
society of the energy industry. AEE provides testing and
certification of energy engineers in several technical areas.
(AHU) - An equipment package that includes a fan or blower, heating and/or
air filtration, etc. for providing heating, ventilation, and air conditioning
(HVAC) to a building. Usually roof-top mounted
and sometimes abbreviated as a RTU. A candidate for efficiency
improvement through control improvement, variable
speed drive, leakage reduction, etc.
Acronym for American Society of Heating, Refrigerating and Air-Conditioning
sequencer - A control system that operates compressors in sequence according
to rules usually
developed to improve overall system efficiency.
Ballast - A device that provides starting voltage
and limits the current during normal operation for electrical
discharge lamps such as fluorescent lamps.
factor (BF) - The percentage of rated lamp lumens that will be produced by
the specific lamp/ballast combination.
BAS - Building Automation System
- A method of predicting heating and/or cooling
loads by doing load calculation at different outdoor
temperatures and then multiplying the result by the number of hours of
occurrence of each temperature.
- The removal of water from an evaporative system (e.g., cooling tower or
boiler) to reduce mineral
concentration that can cause scaling.
- A rate of steam production
equal to the evaporation of 34.5 pounds of water per hour at
a temperature of 212�F
into dry steam at 212�F.
One boiler horsepower is equal to 33,475 Btu per
hour of steam production.
horsepower (bhp) - Horsepower required at the blower, compressor, fan, or
pump shaft to
perform actual work. Often less than the electric motor nameplate rating, but
British thermal unit (Btu) -
A unit of heat energy approximately equal to the quantity of heat required
raise one pound of water by 1�F.
Certified Energy Manager, international professional designation available
through training and testing
by the Association of Energy Engineers (AEE)
CFC (chlorofluorocarbon) - A family of chemicals used as refrigerants that
is being tightly regulated
and phased out of production due to stratospheric ozone depletion potential.
Examples: R-11, R-12, R-113,
of Performance (COP) - A measure of
refrigeration efficiency. The ratio of the rate of heat removed
(cooling effect) to the rate of heat input required, expressed in the same
The generation of electricity and the concurrent use of rejected thermal energy
an auxiliary energy source (e.g., for heating or absorption cooling).
Also known as Combined Heat & Power (CHP)
(CRI) - The effect of a light source on color on a scale of 1 to 100 where
no color distortion. Lower CRI ratings produce more
COMMODITY - The actual energy provided
by a regulated or unregulated utility. For natural gas it is the natural gas
without LDC delivery charges. For electricity it is the 'generation" component
of the bill .. without EDC charges for
delivery and service.
compensation - A photocell-controlled dimming system that reduces lamp
output when daylight is present.
DDC - Direct
Digital Control, description of control method of some BAS / EMS
rate - An electric supply rate structure in which the unit price of
electricity decreases as the
amount of electricity used increases. Savings for energy conservation occurs at
the lowest (or "incremental"
or "marginal") rate, not the average rate.
DEMAND-SIDE ENERGY MANAGEMENT- Major element of Energy
Management dealing with energy efficiency
and control. Demand-Side EM deals with all cost savings opportunities inside
of the building.
Management (DSM) - The process of managing the
consumption of electrical energy,
generally to minimize demand and costs.
Electric Distribution Company, your local regulated
electric utility company
Electricity : I = AMPs, E = Voltage , KW = Kilowatts (real power), PF =
Measure (ECM) - An energy audit
EMS - Energy Management System,
computerized system for fully automatic control of HVAC, lighting,
refrigeration, etc. for temperature management, comfort and energy savings.
Contract (ESPC) - A
way to finance and implement a capital improvement
project by using utility cost savings to cover project costs. This service is
provided by an energy services
company (ESCO). The Federal Government has an accelerated
ESPC called Super ESPC
Services Company (ESCO) - A
company that offers to reduce a client's utility costs, often with the cost
savings being split with the client through an energy performance contract (EPC)
or a shared-savings agreement.
Heat Pump - A heat pump
that uses the ground, ground water, or pond water as a heat source or
heat sink, rather than using outside air. Ground or water temperatures are more
stable and are warmer in winter
and cooler in summer than air temperatures. Geothermal heat pumps can operate
more efficiently than other
types of heat pumps.
- The amount of dissolved calcium salts and/or magnesium present in water.
Hardness is measured
in units of parts per million (ppm) or grains per gallon (gpg). [gpg x 17.1 =
ppm] Poor water treatment can
result in excessive scale that provides excessive resistance to heat transfer
and thus inefficiency and higher costs.
Heat pipe - A device that transfers heat by the
evaporation and condensation of an internal fluid.
Heat recovery ventilator
- A device that captures
heat from exhaust air from a building and transfers it to
the fresh air entering the building to preheat the air and thus reduce energy
consumption and cost.
(HID) - A generic term used to describe metal halide, sodium, and mercury
(HP) - (Electrical/mechanical horsepower, not
boiler horsepower.) A shaft energy output rate of
550 foot-pounds per second, usually specified for electric motors as the maximum
output. One electrical HP is
equal to 0.7457 kW or 2,545 Btu/hour. The actual kW required will be higher due
to motor inefficiency.
Hours Use -
electric utility calculation, normally used outside of electricity tarriffs,
determined by dividing
monthly kWh (consumption) by Kw (demand peak), resulting in 'hours' use
HVAC systems - Heating, ventilation, and air conditioning
systems. Common systems capable of providing
tremendous amounts of comfort and tremendous amounts of waste, sometimes
simultaneously. Variation of
this term is HVACR (with Refrigeration included)
IESNA - Illuminating
Engineering Society of North America.
- true cost of purchasing an
additional energy unit or saving energy based on the last
step in a electricity or natural gas tarriff ( based on volume of consumption
during a monthly billing period).
The incremental value of an energy unit is often lower than the 'average' cost
per energy unit.
Interruptible service - Utility service (electric
or natural gas) supplied under agreements that allow the supplier
to curtail or stop service at times in return for a discounted rate at other
(kW) - A unit of electric power or capacity equal to 1,000 watts. �Demand�
or �capacity� charges for
electricity are usually based on the peak kW occurring during the billing
period, often only as measured during
times defined as �on peak� hours. KW peaks are normally
measured every 15 or 30 minutes. The highest KW
period during the month sets KW demand peak billed for the entire month. Some
rates index KWH consumption
rates based on the KW demand peak ( Rate tariffs used the term KWH per KW)
(kWh) - A unit of electric energy consumption equal to that consumed in
using a power level
of one kilowatt (1,000 watts) for a duration of one hour. Example:
Illuminating ten 100-watt bulbs for one
hour consumes 1 kWh. 1 KWh = 3,413 BTU.
LDC - Local Distribution Company - Your
local regulated natural gas utility company
- The average percentage of capacity of a utility
that is used over a given period of time such as
a month or year. Deregulated electricity sellers prefer clients with high load
factors (i.e., stable and predictable
loads) and sometimes offer them preferred rates.
Low-E coating (for windows)
- A coating applied to
the surface of window glazing to reduce heat transfer
through the glazing by reducing
Lumen - A
measurement of light . The official
definition of the lumen, the unit of luminous flux, is:
The luminous flux dF of a source of
luminous intensity I (cd)
in an element of solid angle dR is given by
dF = IdR In plain English: The flux from a
light source is equal to the intensity in candela multiplied
by the solid angle over which the light is emitted,
taking account of the varying intensity in different directions.
Lumens Per Watt
- Method to compare the energy
efficiency of various types of lighting. Higher lumens per
watt indicates more light for less KWH consumption.
Luminaire - A complete lighting unit consisting of lamp(s),
lamp protector(s), ballast(s), and components
to direct and control the light.
Rate - The rate that has to be paid for the last
increment of service. For example, with a declining block
electric rate, the marginal rate is the rate in the last rate block used and is
lower than the average rate.
Savings from reducing consumption will occur at the marginal rate, not the
1,000 cubic feet of natural gas, having an
energy value of approximately one million Btu.
and Verification ( M&V
) - A process capable of keeping an Energy
Contract fair to all parties.
NEC - National Electrical Code
control device that senses the presence of a person in a given space and is
used to control lighting. Occupancy sensors are sometimes used to control
HVAC in some building types.
- Fresh air taken from
outside that has not previously circulated through the HVAC system.
air often requires substantial heating and air conditioning and should be
- The time rate of doing work or consuming energy, usually measured in
Btu/hour, horsepower, or kW.
Power use is often billed in addition to energy use (e.g., an electric bill will
have both kW and kWh charges).
Factor (PF) -
The ratio of power actually
being used in an electric circuit, expressed in kW, to the
power that is apparently being drawn from the power source, expressed in
In other words,
the ratio of "active" or "real" power (that
actually turns the motor shaft) to "apparent power." The apparent power
includes "reactive power" strictly used to develop the magnetic field. Reactive
power creates no useful work,
results when current is not in phase with voltage, and can be corrected using
capacitors or other devices.
- A measure of thermal resistance used to compare insulating values. The
higher the R-value number
of a material, the better its insulating properties and the slower the heat
flows through it.
Electrical power strictly used to develop magnetic field. Reactive power is
never converted to
useful power such as shaft power, but it often gets billed anyway. Power factor
correction can reduce
reactive power costs. See "power factor."
Pricing (RTP) -
The instantaneous pricing of
electricity based on the cost of the electricity at the
time it is used by the customer. RTP rates can vary over a wide range and are
typically very high when system
demand is high (e.g., on a hot, summer, weekday afternoon). Real-time rates
differ from time-of-use (TOU) rates
in that they are based on actual (rather than forecasted) prices that may
fluctuate frequently during a day and
are weather-sensitive rather than varying with a set schedule.
Tax Exemption - An
opportunity to reduce utility costs that is available to manufacturers and
in many states. Regulations vary by State.
Agreement - An agreement to share utility cost
savings in return for providing the studies, designs,
systems, and/or support necessary to create the savings. Or, sometimes, an
agreement to surrender more than
a fair share of the actual savings to an outside firm that does the calculations
and inflates the savings estimates.
Special Contract - A
contract that provides utility service under terms and conditions other than
in the utility tariff. For example, an electric utility may enter into a special
contract with a large customer
to provide electricity at a lower-than-tariff rate in order to prevent the
customer from taking advantage of other
options (e.g., deregulated competition or on-site cogeneration) that would
result in the loss of the customer's load.
SUPPLY-SIDE ENERGY MANAGEMENT - Major element of
Energy Management dealing with the cost of the energy
based on regulated tariffs or the cost of the 'commodity' in deregulated States.
Supply-Side EM deals with the utility
meter and everything outside of the building.
- Industry nomenclature for a fluorescent lamp that is 8 one-eighths of an
inch in diameter
(i.e., one inch diameter). A T12 lamp is 12 one-eighths or 1.5 inches in
- 100,000 Btu. A common unit for quantifying the energy content of natural
1 therm = 100 CF or .1 MCF
(TOU) rate - Pricing of electricity based on several time blocks per 24-hour
(e.g., on-peak, mid-peak, off-peak, etc.) and on seasons of the year (e.g.,
summer and winter).
Not the same as real-time pricing (RTP). See " real-time pricing (RTP)."
Also called Time-of-Day demand metering.
of Refrigeration - 12,000 Btu/hour of
cooling capacity. One
ton of capacity is equal to the heat required to
melt 2,000 pounds of ice in 24 hours.
(or U-value) - A measure
of how well heat is transferred by a window, thus affecting heating and air
conditioning costs. U-factor is the inverse of R-value. The lower the U-factor,
the better the window will
retain heat on a cold day or cooling on a hot day.
(VSD) - An electronic device that controls the rotational speed of a piece
Frequency Drive (VFD)
equipment (e.g., a blower, compressor, fan, or pump). Speed control is obtained
by adjusting the frequency
of the voltage applied to the motor. This approach usually saves energy for
Also known as
VAV System (Variable
Air Volume) -
An HVAC system serving multiple zones that controls the
temperature in each zone by controlling the amount of heated or cooled air
supplied to the zone.
Lean and Green Glossary
of the California Energy Commission)