Fenestration Glossary
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AAMA
American Architectural Manufacturers Association.
Above-Grade Wall
A wall that is not a below-grade wall.
Above-Grade Walls
Those walls (Section 802.2.1) on the exterior of the building and completely above
grade or the above-grade portion of a basement or first-story wall that is more
than 15 percent above grade.
AC
Alternate current.
ACH
Air changes per hour.
Addition
An extension or increase in the height, conditioned floor area, or conditioned volume
of a building. The code applies to additions to existing buildings.
Adopting Authority
The agency or agent that adopts a code or standard.
AFUE
Annual fuel utilization efficiency; combustion heating equipment efficiency is expressed
in terms of AFUE. New equipment typically ranges from about 78- to 96-percent AFUE.
Higher AFUE ratings indicate more efficient equipment.
AHAM
Association of Home Appliance Manufacturers.
Air Economizer
A duct and damper arrangement and automatic control system that together allow a
cooling system to supply outside air to reduce or eliminate the need for mechanical
cooling during mild or cold weather.
Air Economizer Systems
Ducting arrangements and automatic control systems that allow a cooling supply fan
system to supply outdoor (outside) air to reduce or eliminate the need for mechanical
refrigeration during mild or cold weather.
Alteration
Any construction, renovation, or change in a mechanical system that involves an
extension, addition, or change to the arrangement, type, or purpose of the original
installation.
ANSI
American National Standards Institute.
Application Part-Load Value (APLV)
A single number part-load efficiency figure of merit calculated in accordance with
the method described in ARI Standard 550 or 590 referenced with the method rating
conditions described in those standards.
AHRI
Air-Conditioning, Heating and Refrigeration Institute.
ASHRAE
American Society of Heating, Refrigerating and Air-Conditioning Engineers.
ASHRAE/IES
The American Society of Heating, Refrigerating and Air-Conditioning Engineers/Illuminating
Engineering Society Standard.
ASME
American Society of Mechanical Engineers.
ASTM
American Society for Testing and Materials.
Attic and Other Roofs
All other roofs, including roofs with insulation entirely below (inside of) the
roof structure (e.g., attics, cathedral ceilings, and single-rafter ceilings), roofs
with insulation both above and below the roof structure, and roofs without insulation
but excluding metal building roofs.
Authority Having Jurisdiction
The agency or agent responsible for enforcing the code or standard.
Auto Operated Control Damper
A damper which automatically opens and closes.
Automatic
Self-acting, operating by its own mechanism when actuated by some nonmanual influence,
such as a change in current strength, pressure, temperature, or mechanical configuration.
Automatic Control Device
A device capable of automatically turning loads off and on without manual intervention.
Automatic Time-Switch Controls
Controls that automatically switch lights or equipment on and off.
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Balancing, Air
Adjusting air flow rates through air distribution system devices, such as fans and
diffusers, by manually adjusting the position of dampers, splitter vanes, extractors,
etc., or by using automatic control devices, such as constant air volume or variable
air volume boxes.
Balancing, Hydronic
Adjusting water flow rates through hydronic distribution system devices, such as
pumps and coils, by manually adjusting the position valves, or by using automatic
control devices, such as automatic flow control valves.
Ballast
A device used in conjunction with an electric-discharge lamp to cause the lamp to
start and operate under the proper circuit conditions of voltage, current, wave
form, electrode heat, etc.
Basement Wall
Basement walls that enclose heated spaces are part of the building envelope. Basement
wall refers to the opaque portion of the wall (excluding windows and doors). To
be considered a basement wall, at least 50% of the wall''s total wall area (including
openings) must be below grade. Treat walls on each side of the basement individually
when determining if they are above-grade or basement walls. For any individual wall
less than 50% below grade, include the entire opaque wall area of that individual
wall as part of the above-grade walls.
Below-Grade Wall
That portion of a wall in the building envelope that is entirely below the finish
grade and in contact with the ground.
Below-Grade Walls
Basement or first-story walls (Section 802.2.8) associated with the exterior of
the building that are at least 85 percent below grade.
BOCA
Building Officials and Code Administrators International, Inc.
Boiler
A pressurized system in which water is vaporized to steam by heat transferred from
a source of higher temperature, usually the products of combustion from burning
fuels. Steam thus generated may be used directly as a heating medium or as the working
fluid in a prime mover to convert thermal energy to mechanical work, which in turn
may be converted to electrical energy.
Boiler, Packaged
A boiler that is shipped complete with heating equipment, mechanical draft equipment,
and automatic controls; usually shipped in one or more sections. A packaged boiler
includes factory-built boilers manufactured as a unit or system, disassembled for
shipment, and reassembled at the site.
Branch Circuit
The circuit conductors between the final overcurrent device protecting the circuit
and the outlet(s); the final wiring run to the load.
BSR
Board of Standards Review.
BTU
British thermal unit, which is the quantity of heat required to raise the temperature
of 1 pound (0.454 kg) of water 1°F.
Budget Building Design
A computer representation of a hypothetical design based on the actual proposed
building design. This representation is used as the basis for calculating the energy
cost budget.
Building
A structure wholly or partially enclosed within exterior walls, or within exterior
and party walls, and a roof, affording shelter to persons, animals, or property.
Building Entrance
Any doorway, set of doors, turnstiles, or other form of portal that is ordinarily
used to gain access to the building by its users and occupants.
Building Envelope
A building envelope includes all components of a building that enclose conditioned
space. Building envelope components separate conditioned spaces from unconditioned
spaces or from outside air. For example, walls and doors between an unheated garage
and a living area are part of the building envelope; walls separating an unheated
garage from the outside are not. Although floors of conditioned basements and conditioned
crawlspaces are technically part of the building envelope, the code does not specify
insulation requirements for these components.
Building Envelope Interior
The elements of a building that separate conditioned space from unconditioned space
or that enclose semiheated spaces through which thermal energy may be transferred
to or from the exterior, unconditioned spaces, or conditioned spaces.
Building Exit
Any doorway, set of doors, or other form of portal that is ordinarily used only
for emergency egress or convenience exit.
Building Grounds Lighting
Lighting provided through building''s electrical service for parking lot, site,
roadway, pedestrian pathway, loading dock, and security applications.
Building Information Model (BIM)
A digital representation of the building process. The BIM facilitates exchange and
interoperability of information in digital format.
Building Materials
Any element (other than air films and insulation) of the building envelope through
which heat flows and that is included in the component U-factor calculations.
Building Official
The officer or other designated representative authorized to act on behalf of the
authority having jurisdiction.
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C-Factor
Time rate of steady-state heat flow through the unit area of a material or construction
surfaces. Units of C-Factor are Btu/h x ft2 x degrees Fahrenheit. Note that the
C-factor does not include soil or air films.
CABO
The Council of American Building Officials.
Cavity Insulation
Insulation installed between structural members such as wood studs, metal framing,
and Z-clips.
CC designations
A classification of light transmitting plastics under the Uniform Building Code
Standard 26-7. Under this standard, light transmitting plastics are tested to ASTM
D625-74 standard and are rated either CC1 or CC2. Plastics rated CC1 have a burning
extent of 1 inch (25mm) or less when tested in nominal 0.060 inch (1.5mm) thickness
(or in the thickness intended for use) by this test. Plastics rated CC2 have a burning
rate of 2.5 inches per minute (64nn/min) or less when tested in nominal 0.060 inch
(1.5mm) thickness (or in the thickness intended for use) by this test. Our Trituff
Copolyester, Energy Star Fiberlite and Tufflite Polycarbonate glazings all have
CC1 ratings.
CDD
Cooling degree day. See "Cooling Degree Days."
CDD50
Cooling degree days base 50 degrees F. See "Degree Day Base 50F."
CE
Combustion efficiency.
Ceiling
The ceiling requirements apply to portions of the roof and/or ceiling through which
heat flows. Ceiling components include the interior surface of flat ceilings below
attics, the interior surface of cathedral or vaulted ceilings, skylights, and sloped
building assemblies less than 60 degrees from horizontal, but excluding skylight
shafts.
CFM
Cubic feet per minute. A standard measurement of airflow.
Check Metering
Measurement instrumentation for the supplementary monitoring of equipment and tenant
energy use (electric, gas, oil, etc.) in addition to the revenue metering furnished
by the utility.
Circuit Breaker
A device designed to open and close circuit by non-automatic means and to open the
circuit automatically at a predetermined overcurrent without damage to itself when
properly applied within its rating.
Circulating Water Heater
Hot water continuously circulates through the distribution system.
Circulation Pumps
Pumps that are used to keep hot water circulating through the distribution system.
Class of Construction
For the building envelope, a subcategory of roof, above-grade wall, below-grade
wall, floor, slab-on-grade floor, opaque door, vertical fenestration, or skylight.
Clerestory
That part of a building that rises clear of the roofs or other parts and whose walls
contain windows for lighting the interior.
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Daylight Glazing
Exterior glazing over 6 feet above the finished floor.
DDC
Direct Digital Control.
Deadband
The temperature range in which no heating or cooling is used.
Decorative Lighting
Lighting that is purely ornamental and installed for aesthetic effect. Decorative
lighting shall not include general lighting.
Degree Day
See "Heating Degree Days."
Degree Day Base 50F, CDD50
For any one day, when the mean temperature is more than 50 degrees F, there are
as many degree days as degrees Fahrenheit temperature difference between the mean
temperature for the day and 50 degrees F. Annual cooling degree days (CDDs) are
the sum of the degree days over a calendar year.
Demand
The highest amount of power (average kw over an interval) recorded for a building
or facility in a selected time frame.
Design A
National Electrical Manufacturers Association (NEMA) design class designations for
standard general purpose polyphase squirrel-cage induction motors.
Design B
National Electrical Manufacturers Association (NEMA) design class designations for
standard general purpose polyphase squirrel-cage induction motors.
Design Capacity
Output capacity of a system or piece of equipment at design conditions.
Design Conditions
Specified environmental conditions, such as temperature and light intensity, required
to be produced and maintained by a system and under which the system must operate.
Design E
National Electrical Manufacturers Association (NEMA) design class designations for
standard general purpose polyphase squirrel-cage induction motors.
Design Energy Cost
The annual energy cost calculated for a proposed design.
Design Professional
An architect or engineer licensed to practice in accordance with applicable state
licensing laws.
Diffusion
The scattering of direct light from concentrated areas to less concentrated areas
by passing the light through a material or by bouncing it off a semi-reflective
surface. Highly diffused light creates "softer” more uniform light and does not
create shadows.
Direct Digital Control (DDC)
A type of control where controlled and monitored analog or binary data (e.g., temperature,
contact closures) are converted to digital format for manipulation and calculations
by a digital computer or microprocessor, then converted back to analog or binary
form to control physical devices.
Disconnect
A device or group of devices or other means by which the conductors of a circuit
can be disconnected from their source of supply.
Distribution System
Conveying means, such as ducts, pipes, and wires, to bring substances or energy
from a source to the point of use. The distribution system includes such auxilliary
equipment as fans, pumps and transformers.
DOE
U.S. Department of Energy.
Domestic Water Heating System
DWH systems may be circulating or non-circulating.
Door
Doors include all openable opaque assemblies (which are not fenestration) located
in exterior walls of the building envelope. Doors with glass can be treated as a
single door assembly, in which case an aggregate U-factor (a U-factor that includes
both the glass and the opaque area) must be used, or the glass area of the door
can be included with the other glazing, and an opaque door U-factor can be used
to determine compliance of the door.
Door Area
Total area of the door measured using the rough opening and including the door slab
and the frame. See "Fenestration Area."
Dry-Type Transformer
A transformer in which the core and coils are in a gaseous or dry compound.
DSM
Demand-side management.
Duct
A tube or conduit used for conveying air. The air passages of self-contained systems
should not be construed as air ducts.
Duct Furnace
A furnace normally installed in distribution ducts of air conditioning systems to
supply warm air for heating and which depends on a blower not furnished as part
of the duct furnace for air circulation.
Duct System
A continuous passageway for the transmission of air that, in addition to ducts,
includes duct fittings, dampers, plenums, fans, and accessory air-handling equipment
and appliances.
Dwelling Unit
A single housekeeping unit of one or more rooms providing complete, independent
living facilities, including permanent provisions for living, sleeping, eating,
cooking, and sanitation.
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Economizer
A duct and damper arrangement and automatic control system that allow a cooling
supply fan system to supply outdoor air to reduce or eliminate the need for mechanical
refrigeration during mild or cold weather.
Efficacy
A metric used to compare light output to energy consumption. Efficacy is measured
in lumens per watt. Efficacy is similar to efficiency but is expressed in dissimilar
units. For example, if a 100-watt source produces 9000 lumens, then the efficacy
is 90 lumens per watt.
Efficiency
Performance at specified rating conditions.
Electric Meter
A mechanical/electrical device that can measure electric power.
Electric Resistance
The property of an electric circuit or of any object used as part of an electric
circuit that determines for a given circuit the rate at which electric energy is
converted into heat or radiant energy and that has a value such that the product
of the resistance and the square of the current gives the rate of conversion of
energy.
Electric Supplier
An agency that sells and/or distributes electric power.
Electronic High Frequency Ballasts
Electronic ballasts improve fluorescent system efficacy by converting the standard
60 Hz input frequency to a higher frequency, usually 25,000 to 40,000 Hz. Lights
operating on these frequencies produce about the same amount of light while consuming
up to 30% less power than a standard magnetic ballast.
Emergency Power System (EPS)
A system that is required by codes or other laws to automatically supply illumination
or power or both in the event of failure of the normal supply or in the event of
accidents to such systems. Such systems may also include standby loads incidental
to system operations but shall not include systems for optional standby loads only.
Emittance
The ratio of the radiant heat flux emitted by a specimen to that emitted by a blackbody
at the same temperature and under the same conditions.
Enclosed Space
A volume substantially surrounded by solid surfaces such as walls, floors, roofs,
and openable devices such as doors and operable windows. Spaces not meeting these
criteria for enclosure are considered to be exterior to the building for purposes
of determining envelope requirements. For example, most parking garages do not qualify
as enclosed space.
Enclosure
The case or housing of an apparatus, or the fence or walls surrounding an installation,
designed to prevent personnel from accidentally contacting energized parts and to
protect equipment from physical damage.
Energy
The capacity for doing work. It takes a number of forms that may be transformed
from one into another such as thermal (heat), mechanical (work), electrical, and
chemical. Customary measurement units are British thermal units (Btu).
Energy Cost Budget
The annual energy cost for the budget building.
Energy Efficient Ratio (EER)
The ratio of net equipment cooling capacity in Btu/h to total rate of electric input
in watts under designated operating conditions. When consistent units are used,
this ratio becomes equal to the coefficient of performance.
Energy Factor (EF)
A measure of water heater overall efficiency.
Energy Performance Rating
The energy use of the proposed building under actual operating conditions. Projected
energy use targets can be used for buildings in the design or construction process.
Examples include kBtu/sf/yr, $/sf/yr, $/gross sales, Energy Performance Rating Score
(US EPA), or like expressions of energy performance.
Envelope Components
The building assemblies that provide a barrier between conditioned space and unconditioned
space. This includes the floors, walls, and ceiling/roof assemblies of the building.
Envelope Floor
That lower portion of the building envelope, including opaque area and fenestration,
that has conditioned or semiheated space above and is horizontal or tilted at an
angle of less than 60 degrees from horizontal but excluding slab-on-grade floors.
It is needed to determine building envelope requirements.
Equipment
Devices for comfort conditioning, electric power, lighting, transportation, or service
water heating including, but not limited to, furnaces, boilers, air conditioners,
heat pumps, chillers, water heaters, lamps, luminaires, ballasts, elevators, escalators,
or other devices or installations.
Equipment Efficiency
The measure of equipment efficiency varies with equipment type.
Exfiltration
Uncontrolled outward air leakage from inside a building including leakage through
cracks and interstices around windows and doors and through any other exterior partition
or penetration.
Existing Building
A building or portion thereof that was previously occupied or approved for occupancy
by the authority having jurisdiction.
Existing Equipment
Equipment previously installed in an existing building.
Existing System
A system or systems previously installed in an existing building.
Exterior Lighting Power Allowance
The maximum lighting power in watts allowed for the exterior of a building.
Exterior Wall
An above-grade wall enclosing conditioned space. Includes between-floor spandrels,
peripheral edges of floors, roof and basement knee walls, dormer walls, gable end
walls, walls enclosing a mansard roof, and basement walls with an average below
grade-wall area that is less than 50 percent of the total opaque and non-opaque
area of that enclosing side.
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F
Fahrenheit.
F-Factor
The perimeter heat loss factor for slab-on-grade floors, expressed in Btu/h x F.
Facade Area
Area of the facade, including overhanging soffits, cornices, and protruding columns,
measured in elevation in a vertical plane parallel to the plane of the face of the
building. Non-horizontal roof surfaces shall be included in the calculation of vertical
facade area by measuring the area in a plane parallel to the surface.
Fan Coil
A fan-coil terminal is essentially a small air-handling unit which serves a single
space without a ducted distribution system. One or more independent terminals are
typically located in each room connected to a supply of hot and/or chilled water.
At each terminal, a fan in the unit draws room air (sometimes mixed with outside
air) through a filter and blows it across a coil of hot water or chilled water and
back into the room.
Fan System Energy Demand
The sum of the nominal power demand (nameplate horsepower) of motors of all fans
that are required to operate at design conditions to supply air from the heating
or cooling source to the conditioned space(s) and return it to the source or exhaust
it to the outdoors.
Feeder Conductors
The wires that connect the service equipment to the branch circuit breaker panels.
Fenestration
All areas (including the frames) in the building envelope that let in light, including
windows, plastic panels, clerestories, skylights, glass doors that are more than
one-half glass, and glass block walls. A skylight is a fenestration surface having
a slope of less than 60 degrees from the horizontal plane. Other fenestration, even
if mounted on the roof of a building, is considered vertical fenestration.
Fenestration Area
Total area of the fenestration measured using the rough opening and including the
glazing, sash, and frame. For doors where the glazed vision area is less than 50%
of the door area, the fenestration area is the glazed vision area. For all other
doors, the fenestration area is the door area.
Fixture
The component of a luminaire that houses the lamp or lamps, positions the lamp,
shields it from view, and distributes the light. The fixture also provides for connection
to the power supply, which may require the use of a ballast.
Floor
A horizontal exterior partition, or a horizontal demising partition, under conditioned
space which separates conditioned space from unconditioned space.
Fluorescent Lamps
A light source consisting of a tube filled with argon, along with krypton or other
inert gas. When electrical current is applied, the resulting arc emits ultraviolet
radiation that excites the phosphors inside the lamp wall, causing them to radiate
visible light.
Flue Damper
A device in the flue outlet or in the inlet of or upstream of the draft control
device of an individual, automatically operated, and fossil fuel-fired appliance
that is designed to automatically open the flue outlet during appliance operation
and to automatically close the flue outlet when the appliance is in a standby condition.
Fossil Fuel
Fuel derived from a hydrocarbon deposit such as petroleum, coal, or natural gas
derived from living matter of a previous geologic time.
Fuel
A material that may be used to produce heat or generate power by combustion.
Fuel Fired Furnace
A self-contained, indirect-fired furnace that supplies heated air through ducts
to spaces that require it.
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General Lighting
Lighting that provides a substantially uniform level of illumination throughout
an area. General lighting shall not include decorative lighting or lighting that
provides a dissimilar level of illumination to serve a specialized application or
feature within an area.
General Service Lamp
A class of incandescent lamps that provide light in virtually all directions. General
service lamps are typically characterized by bulb shapes such as A, standard; S,
straight side; F, flame; G, globe; and PS, pear straight.
Generally Accepted Engineering Standard
A specification, rule, guide, or procedure in the field of engineering, or related
thereto, recognized and accepted as authoritative.
Glazed Wall System
A category of site-assembled fenestration products, which includes, but is not limited
to, curtain walls and solariums.
Glazing
Any translucent or transparent material in exterior openings of buildings, including
windows, skylights, sliding doors, the glass area of opaque doors, and glass block.
Glazing Area
The area of a glazing assembly is the interior surface area of the entire assembly,
including glazing, sash, curbing, and other framing elements. The nominal area or
rough opening is also acceptable for flat windows and doors.
Glazing U-Factor
Based on the interior-surface area of the entire assembly, including glazing, sash,
curbing, and other framing elements. Center-of-glass U-factors cannot be used.
Grade
The finished ground level adjoining a building at all exterior walls.
Gross Floor Area
The sum of the floor areas of the spaces within the building including basements,
mezzanine and intermediate-floored tiers, and penthouses with headroom height of
7.5 ft or greater. It is measured from the exterior faces of exterior walls or from
the centerline of walls separating buildings, but it excludes covered walkways,
open roofed-over areas, porches and similar spaces, pipe trenches, exterior terraces
or steps, chimneys, roof overhangs, and similar features.
Gross Wall Area
The gross wall area includes the opaque area of above-grade walls, the opaque area
of any individual wall of a conditioned basement less than 50% below grade (including
the below-grade portions), all windows and doors (including windows and doors of
conditioned basements), and the peripheral edges of floors.
Gross Window Area
Includes the rough-opening area of the window, not just the transparent-glass area.
Gutter
The space available for wiring inside panel boards and other electric panels; a
separate wireway used to supplement wiring spaces in electric panels.
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Harmonics
Voltages and currents at frequencies other than 60 Hz (or 50 Hz where applicable)
that cause heating and other detrimental effects in the power system.
Heat Capacity
The amount of heat necessary to raise the temperature of a given mass 1 degree F.
Numerically, the sum of the products of the mass per unit area of each individual
material in the roof, wall, or floor surface multiplied by its individual specific
heat.
Heat Pump
One or more factory-made assemblies which include an indoor conditioning coil, compressor(s)
and outdoor coil or refrigerant-to-water heat exchanger, including means to provide
both heating and cooling functions.
Heat Trace
A heating system where the externally applied heat source follows (traces) the object
to be heated, e.g., water piping.
Heat Traps
Devices or piping arrangements that effectively restrict the natural tendency of
hot water to rise in vertical pipes during standby periods. Examples are the U-shaped
arrangement of elbows or a 360-degree loop of tubing.
Heated Slab
Slab-on-grade construction in which the heating elements or hot air distribution
system is in contact with or placed within the slab or the subgrade.
Heated Space
Space within a building that is provided with a positive heat supply (see "Positive
Heat Supply"). Finished living space within a basement with registers or heating
devices designed to supply heat to a basement space shall automatically define that
space as heated space.
Heating Degree Days (HDD)
A unit, based upon temperature difference and time, used in estimating fuel consumption
and specifying nominal heating load of a building in winter. For any one day, when
the mean temperature is less than 65 degrees F (18 degrees C), there exists as many
degree days as there are Fahrenheit degrees difference in temperature between the
mean temperature for the day and 65 degrees F (18 degrees C).
Heating Degree Day Base 65F (HDD65)
For any one day, when the mean temperature is less than 65 degrees F, there are
as many degree days as degrees Fahrenheit temperature difference between the mean
temperature for the day and 65 degrees F. Annual heating degree days (HDDS) are
the sum of the degree days over a calendar year.
Heating Seasonal Performance Factor (HSPF)
The total heating output of a heat pump during its normal annual usage period for
heating, in Btu, divided by the total electric energy input during the same period,
in watt hours, as determined by DOE 10 CFR Part 430, Subpart B, Test Procedures,
and based on Region 4. Heat pump heating is expressed in terms of HSPF. New equipment
ranges from about 6.8 to 10.0 HSPF. Higher HSPF ratings indicate more efficient
equipment.
HID
High-intensity discharge.
High-Intensity Discharge Lamp (HID lamp)
An electric discharge lamp in that light is produced when an electric arc is discharged
through a vaporized metal such as mercury or sodium. Some HID lamps may also have
a phosphor coating that contributes to the light produced or enhances the light
color.
High-Rise Residential Building
Hotels, motels, apartments, condominiums, dormitories, and other residential-type
facilities that provide complete housekeeping or transient living quarters and are
over three stories in height above grade. Hotels, motels, and other buildings with
itinerant occupancies are covered by the "commercial" code regardless
of height.
Historic
A building or space that has been specifically designated as historically significant
by the adopting authority, is listed in "The National Register of Historic
Places," or has been determined to be eligible for listing by the U.S. Secretary
of the Interior.
Hot Water Supply Boiler
A boiler used to heat water for purposes other than space heating.
HUD
The U.S. Department of Housing and Urban Development.
Humidistat
A regulatory device, actuated by changes in humidity, used for automatic control
of relative humidity.
HVAC
Heating, ventilating, and air conditioning.
HVAC System
The equipment, distribution network, and terminals that provide either collectively
or individually the processes of heating, ventilating, or air conditioning to a
building.
HVAC Zone
A space or group of spaces within a building with heating and cooling requirements
that are sufficiently similar so that desired conditions (e.g., temperature) can
be maintained throughout using a single sensor (e.g., thermostat or temperature
sensor).
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ICAA
Insulation Contractors Association of America.
ICBO
The International Conference of Building Officials.
ICC
The International Code Council.
IECC
The International Energy Conservation Code formerly known as the MEC. The IECC was
published in 1998, 2000, 2003, 2006, and 2009.
IEEE
Institute of Electrical and Electronics Engineers, inc.
IESNA
Illuminating Engineering Society of North America.
IMC
International Mechanical Code.
Incandescent Lamp
A lamp in which light is produced by a filament heated to incandescence by an electric
current.
Indirectly Conditioned Space
An enclosed space within a building that is not a heated or cooled space, whose
area-weighted heat transfer coefficient to heated or cooled spaces exceeds that
to the outdoors or to unconditioned spaces; or through which air from heated or
cooled spaces is transferred at a rate exceeding three air changes per hour. (Also
see Heated Space, Cooled Space, and Unconditioned Space.)
Infiltration
The uncontrolled inward air leakage through cracks and interstices in any building
element and around windows and doors of a building caused by the pressure effects
of wind or the effect of differences in the indoor and outdoor air density or both.
Installed Interior Lighting Power
The power in watts of all permanently installed general, task, and furniture lighting
systems and luminaires.
Insulated Sheathing
An insulating board having a minimum thermal resistance of R-2 of the core material.
Insulation R-Values
R-values are used to rate insulation and are a measurement of the insulation''s
resistance to heat flow. The higher the R-value, the better the insulation.
Integrated-Control Economizers
Allows the cooling load of a building or space to be partially met by supplying
outside air while the rest of the load is met by the refrigeration equipment within
an HVAC system. Field- and factory-installed economizers supplied by major equipment
manufacturers include integrated controls.
Integrated Part Load Value (IPLV)
A single-number figure of merit based on part-load EER, COP, or kW/ton expressing
part-load efficiency for air-conditioning and heat pump equipment on the basis of
weighted operation at various load capacities for the equipment.
Interior Lighting Controls
Offer the ability for systems to be turned on and off either manually or automatically
and include switches, time clocks, occupancy sensors, and other devices that regulate
a lighting system.
Interior Lighting Power Allowance
The maximum lighting power in watts allowed for the interior of a building.
Interior Walls
Interior walls covered by Section 802.2.9 are those walls not on the exterior of
the building and that separate conditioned and unconditioned space.
International Foundation Class (IFC)
An object-oriented file format with a data model developed to facilitate interoperability
in the building industry.
Isolation Devices
Devices that isolate HVAC zones so that they can be operated independently of one
another. Isolation devices include, but are not limited to, separate systems, isolation
dampers, and controls providing shutoff at terminal boxes.
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K
Kelvin.
kg
Kilogram.
Kilovolt-Ampere (KVA)
Where the term "kilovolt-ampere" (KVA) is used, it is the product of the
line current (amperes) times the nominal system voltage (kilovolts) times 1.732
for three-phase currents. For single-phase applications, KVA is the product of the
line current (amperes) times the nominal system voltage (kilovolts).
Kilowatt (KW)
The basic unit of electric power, equal to 1000 W.
kWh
Kilowatt-hour.
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Labeled
Devices, equipment, appliances, assemblies, or materials to which have been affixed
a label, seal, symbol, or other identifying mark of a nationally recognized testing
laboratory, inspection agency, or other organization concerned with product evaluation
that maintains periodic inspection of the production of the above-labeled items
and by whose label the manufacturer attests to compliance with applicable nationally
recognized standards.
Lamp
A generic term for a man-made light source often called a bulb or tube.
lb
Pound.
Lighting Power Density (LPD)
The maximum lighting power per unit area of a building classification or space function.
Lighting System
A group of luminaires circuited or controlled to perform a specific function.
Liquid-Immersed Transformer
A transformer in which the core and coils are immersed in an insulating liquid.
Listed
Equipment, appliances, assemblies, or materials included in a list published by
a nationally recognized testing laboratory, inspection agency, or other organization
concerned with product evaluation that maintains periodic inspection of production
of listed equipment, appliances, assemblies, or material, and whose listing states
either that the equipment, appliances, assemblies, or material meets nationally
recognized standards or has been tested and found suitable for use in a specified
manner.
Longitudinal Seam
A duct seam that is parallel to the direction of air flow.
Low Voltage Lighting
Lighting equipment that is powered through a transformer such as a cable conductor,
a rail conductor, or track lighting.
Low-Rise Residential
Single-family houses, multi-family structures with three stories or fewer above
grade and manufactured houses (modular and mobile homes).
Luminaire
A complete lighting unit consisting of a lamp or lamps, along with the parts designed
to distribute the light, hold the lamps, and connect the lamps to a power source.
Also called a fixture.
Luminous Light Transmission (LLT)
The measure of how much total light passes through a fenestration. Luminous light
transmission (LLT) measures a broader segment of the light spectrum than VLT. This
includes portions of the light spectrum that cannot be seen by the human eye. The
higher the LLT a skylight has, the greater its light transmission. LLT is expressed
as a number from 0 to 1
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Manual (nonautomatic)
Requiring personal intervention for control. Nonautomatic does not necessarily imply
a manual controller, only that personal intervention is necessary.
Manufacturer
The company engaged in the original production and assembly of products or equipment,
or a company that purchases such products and equipment manufactured in accordance
with company specifications.
Marked (nameplate) Rating
The design load operating conditions of a device as shown by the manufacturer on
the nameplate or otherwise marked on the device.
Mass Wall
A wall with a heat capacity exceeding (1) 7Btu/ft2 or (2) 5 Btu/ft2 x F provided
that the wall has a material unit weight not greater than 120 lb/ft3.
Mean Temperature
One-half the sum of the minimum daily temperature and maximum daily temperature.
Mechanical Cooling
Reducing the temperature of a gas or liquid by using vapor compression, absorption,
desiccant dehumidification combined with evaporative cooling, or another energy-driven
thermodynamic cycle. Indirect or direct evaporative cooling alone is not considered
mechanical cooling.
Mechanical System
The system and equipment used to provide heating, ventilating, and air conditioning
functions as well as additional functions not related to space conditioning, such
as, but not limited to, freeze protection in fire protection systems and water heating.
MEEA
Midwest Energy Efficiency Alliance
Metal Building
A complete, integrated set of mutually-dependent components and assemblies that
form a building consisting of a steel-framed superstructure and metal skin.
Metal Building Roof
A roof that (a) is constructed with a metal, structural, and weathering surface,
(b) has no ventilated cavity, and (c) has the insulation entirely below deck (i.e.,
includes neither a composite concrete and metal deck construction nor a roof framing
system that is separated from the superstructure by a wood substrate), and whose
structure consists of one or more of the following configurations: (1) metal roofing
in direct contact with the steel framing members, (2) insulation between the metal
roofing and the steel framing members, or (3) insulated metal roofing panels installed
as described in 1 or 2.
Metal Building Wall
A wall whose structure consists of metal spanning members supported by steel structural
members (i.e., does not include spandrel glass or metal panels in curtain wall systems).
Metal Halide Lamps
A type of high intensity discharge (HID) lamp in which most of the light is produced
by radiation of metal halide and mercury vapors in the arc tube. Available in clear
and phosphor-coated lamps.
Metering
Instruments that measure electric voltage, current, power, etc.
MICA
Midwest Insulation Contractors Association.
Model Energy Code (MEC)
The Model Energy Code. The MEC was first published in 1983, with subsequent full
editions published in 1986, 1989, 1992, 1993, and 1995. The MEC became the IECC,
first published in 1998.
Motor Power Rated
The rated output power from the motor.
Multifamily
A multifamily building is a residential building three stories or fewer in height
that contains three or more attached dwelling units. Multifamily buildings include
apartments, condominiums, townhouses, and rowhouses. Hotels and motels are considered
commercial rather than residential buildings.
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NAECA
The National Appliance Energy Conservation Act of 1987, 42 USC 6291 et seq., as
amended, Public Law 100-12.
NAGDM
National Association of Garage Door Manufacturers.
NCSBCS
The National Conference of States on Building Codes and Standards.
Net Wall Area
The net wall area includes the opaque wall area of all above-grade walls enclosing
conditioned spaces, the opaque area of conditioned basement walls less than 50%
below grade (including the below-grade portions), and peripheral edges of floors.
The net wall area does not include windows, doors, or other such openings, as they
are treated separately.
NEEA
Northwest Energy Efficiency Alliance.
NEEP
Northeast Energy Efficiency Partnerships.
NFPA
National Fire Protection Association.
NFRC
National Fenestration Rating Council.
Non-Standard Part Load Value (NPLV)
A single-number, part-load efficiency figure of merit calculated and referenced
to conditions other than IPLV conditions, for units that are not designed to operate
at ARI Standard Rating Conditions.
Non-Recirculating System
A domestic or service hot water distribution system that is not a recirculating
system.
Non-Renewable Energy
Energy derived from a fossil fuel source.
Non-Residential
All occupancies other than residential.
North-Oriented
Facing within 45 degrees of true north (northern hemisphere).
NPLV
Non-standard part load value.
NWWDA
National Wood Window and Door Association.
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Occupancy Type
The type of activity occurring within a building.
Occupant Sensing Device
A device that detects the presence or absence of people within an area and causes
any combination of lighting, equipment, or appliances to be adjusted accordingly.
Occupant Sensor
A device that detects the presence or absence of people within an area and causes
lighting, equipment, or appliances to be regulated accordingly.
Opaque
All areas in the building envelope, except fenestration and building service openings
such as vents and grilles.
Opaque Areas
Opaque areas include all areas of the building envelope except openings for windows,
skylights, doors, and building service systems. For example, although solid wood
and metal doors are opaque, they should not be included as part of the opaque wall
area (also referred to as the net wall area).
Operational Performance Requirements
A written document that details the functional requirements of a project and the
expectations of how it will be used and operated. This includes project and design
goals, measurable performance criteria, budgets, schedules, success criteria, and
supporting information.
Optimum Start Controls
Controls that are designed to automatically adjust the start time of an HVAC system
each day with the intention of bringing the space to desired occupied temperature
levels immediately before scheduled occupancy.
Orientation
The direction an envelope element faces, i.e., the direction of a vector perpendicular
to and pointing away from the surface outside of the element.
Outdoor Air
Air taken from the outdoors and, therefore, not previously circulated through the
system.
Overcurrent
Any current in excess of the rated current of equipment or the ampacity of a conductor.
It may result from overload, short circuit, or ground fault.
Overhead Glazing Area
The area whose horizontal dimension, in each direction, is equal to the overhead
glazing dimension plus either the floor to ceiling height or the dimension to the
nearest 66" or higher opaque partition, or one-half the distance to the adjacent
overhead or vertical glazing.
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Packaged Terminal Air Conditioner (PTAC)
A factory-selected wall sleeve and separate unencased combination of heating and
cooling components, assemblies, or sections. It may include heating capability by
hot water, steam, or electricity and is intended for mounting through the wall to
serve a single room or zone.
Packaged Terminal Heat Pump (PTHP)
A PTAC capable of using the refrigerating system in a reverse cycle or heat pump
mode to provide heat.
Party Wall
A fire wall on an interior lot line used or adapted for joint service between two
buildings.
Performance Approach
A performance approach (also known as a systems performance approach) compares a
proposed design with a baseline or reference design and demonstrates that the proposed
design is at least as efficient as the baseline in terms of annual energy use. This
approach allows the greatest flexibility but may require considerably more effort.
A performance approach is often necessary to obtain credit for special features
such as a passive solar design, photovoltaic cells, thermal energy storage, fuel
cells, and other nontraditional building components. This approach requires an annual
energy use value. There are several commercially available software tools that perform
this analysis.
Perm Rating
The amount of water vapor that passes through an area in a certain period of time.
Permanantly Wired Luminaires
Light fixtures physically attached to a surface (e.g. ceiling or wall) using a permanent
mounting system and wired directly to a power source. Examples include fluorescent
fixtures located in a ceiling grid and wall sconces.
Permanently Installed
Equipment that is fixed in place and is not portable or movable.
Photo Cell
A light-sensing device used to control luminaires and dimmers in response to detected
light levels.
Plenum
An enclosure that is part of the air-handling system and is distinguished by having
a very low air velocity. A plenum often is formed in part or in total by portions
of the building.
Pool
Any structure, basin, or tank containing an artificial body of water for swimming,
diving, or recreational bathing. The term includes, but is not limited to, swimming
pool, whirlpool, spa, and hot tub.
Positive Cooling Supply
Mechanical cooling deliberately supplied to a space, such as through a supply register.
Also, mechanical cooling indirectly supplied to a space through uninsulated surfaces
of space-cooling components, such as evaporator coil cases and cooling distribution
systems that continually maintain air temperatures within the space of 85 degrees
F (29 degrees C) or lower during normal operation.
Positive Heat Supply
Heat deliberately supplied to a space by design, such as a supply register, radiator,
or heating element. Also, heat indirectly supplied to a space through uninsulated
surfaces of service water heaters and space-heating components, such as furnaces,
boilers, and heating and cooling distribution systems that continually maintain
air temperature within the space of 50 degrees F (10 degrees C) or higher during
normal operation.
Power Factor
The ratio of total real power in watts to the apparent power (root-mean-square volt
amperes).
Prescriptive Approach
A prescriptive approach lists the minimum R-value or maximum U-factor requirements
for each building component such as windows, walls, and roofs. For lighting systems
in commercial buildings, a prescriptive approach would simply list the allowable
watts per square foot for various building types. For mechanical systems and equipment,
a prescriptive approach would list the minimum required equipment efficiencies.
Primary Air System
The central, air-moving, heating, and cooling equipment that serves multiple zones
through mixing boxes, VAV boxes, or reheat coils.
Process Energy
Energy consumed in support of a manufacturing, industrial, or commercial process
other than conditioning spaces and maintaining comfort and amenities for the occupants
of a building.
Process Load
The load on a building resulting from the consumption or release of process energy.
Projection Factor (PF)
The ratio of the distance the overhang projects from the window surface to its height
above the sill of the window it shades.
Proposed Design
A computer representation of the actual proposed building design or portion thereof
used as the basis for calculating the design energy cost.
psi (g)
Pounds per square inch gauge.
Pump System Energy Demand (Pump System Power)
The sum of the nominal power demand (nameplate horsepower) of motors of all pumps
that are required to operate at design conditions to supply fluid from the heating
or cooling source to all heat transfer devices (e.g., coils, heat exchanger) and
return it to the source.
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R-Value
A measure (h ft2 °F/Btu) of thermal resistance, or how well a material or series
of materials resists the flow of heat. The R-value is the reciprocal of the U-factor.
An expression of insulating value. R Value is the reciprocal of U Factor a measure
of the rate of heat loss of a fenestration. The higher the R Value the greater the
skylight’s resistance to heat flow and the greater its insulating value.
Radiant Heating System
A heating system that transfers heat to objects and surfaces within the heated space
primarily (greater than 50%) by infrared radiation.
Raised Truss
Raised truss refers to any roof/ceiling construction that allows the insulation
to achieve its full thickness over the plate line of exterior walls. Several constructions
allow for this, including elevating the heel (sometimes referred to as an energy
truss, raised-heel truss, or Arkansas truss), use of cantilevered or oversized trusses,
lowering the ceiling joists, or framing with a raised rafter plate.
Rated Lamp Wattage
The power consumption of a lamp as published in manufacturers'' literature.
Readily Accessible
Capable of being reached quickly for operation, renewal, or inspections without
requiring those to whom ready access is requisite to climb over or remove obstacles
or resort to portable ladders, chairs, etc. In public facilities, accessibility
may be limited to certified personnel through locking covers or by placing equipment
in locked rooms.
RECD
The Rural Economic and Community Development, formerly the Farmer''s Home Administration.
Recirculating System
A domestic or service hot water distribution system that includes a closed circulation
circuit designed to maintain usage temperatures in hot water pipes near terminal
devices (e.g., lavatory faucets, shower heads) in order to reduce the time required
to obtain hot water when the terminal device valve is opened. The motive force for
circulation is either natural (due to water density variations with temperature)
or mechanical (recirculation pump).
Recooling
Lowering the temperature of air that has been previously heated by a mechanical
heating system.
Record Drawings
Drawings that record the conditions of the project as constructed. These include
any refinements of the construction or bid documents.
Reflectance
The ratio of the light reflected by a surface to the light incident upon it.
Reflector Lamp
A class of incandescent lamps that have an internal reflector to direct the light.
Reflector lamps are typically characterized by reflector shapes such as R (reflector),
ER (elipsodial reflector), PAR (parabolic aluminized reflector), MR (multi-faceted
reflector), and others.
Reheating
Raising the temperature of air that has been previously cooled either by mechanical
refrigeration or an economizer system.
Reset
Automatic adjustment of the controller set point to a higher or lower value.
Residential
Spaces in buildings used primarily for living and sleeping. Residential spaces include,
but are not limited to, dwelling units, hotel/motel guest rooms, dormitories, nursing
homes, patient rooms in hospitals, lodging houses, fraternity/sorority houses, hotels,
prisons, and fire stations.
Residential Building, Group R-2
Residential occupancies containing more than two dwelling units where the occupants
are primarily permanent in nature such as apartment houses, boarding houses (not
transient), convents, monasteries, rectories, fraternities and sororities, dormitories
and rooming houses. For the purpose of this code, reference to Group R-2 occupancies
shall refer to buildings that are three stories or less in height above grade.
Residential Building, Group R-4
Residential occupancies shall include buildings arranged for occupancies as Residential
Care/Assisted Living Facilities including more than five but not more than 16 occupants,
excluding staff. For the purpose of this code, reference to Group R-4 occupancies
shall refer to buildings which are three stories or less in height above grade.
Roof
The upper portion of the building envelope, including opaque areas and fenestration,
that is horizontal or tilted at an angle of less than 60 degrees from horizontal.
Roof Assembly
A roof assembly shall be considered to be all roof/ceiling components of the building
envelope through which heat flows, thus creating a building transmission heat loss
or gain, where such assembly is exposed to outdoor air and encloses conditioned
space. The gross area of a roof assembly consists of the total interior surface
of all roof/ceiling components, including opaque surfaces, dormer and bay window
roofs, treyed ceilings, overhead portions of an interior stairway to an unconditioned
attic, doors and hatches, glazing, and skylights exposed to conditioned space that
are horizontal or sloped at an angle less than 60° from the horizontal.
Roofing With Insulation Entirely Above Deck
A roof with all insulation (1) installed above (outside of) the roof structure and
(2) continuous (i.e., uninterrupted by framing members).
Room Air Conditioner
An encased assembly designed as a unit to be mounted in a window or through a wall,
or as a console. It is meant to provide direct delivery of conditioned air to an
enclosed space, room, or zone. It includes a prime source of refrigeration for cooling
and dehumidification and a means for circulating and cleaning air. It may also include
a means for ventilating and heating.
Room Cavity Ratio
A factor that characterizes room configuration as a ratio between the walls and
veiling and is based upon room dimensions.
rpm
Revolutions per minute.
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SBCCI
The Southern Building Code Congress International, Inc.
Screw Lamp Holders
A lamp base that requires a screw-in-type light such as an incandescent or tungsten-halogen
bulb.
Seasonal Coefficient of Performance (cooling)
The total cooling output of an air conditioner during its normal annual usage period
for cooling divided by the total electric energy input during the same period in
consistent units (analogous to the HSPF but for IP or other consistent units).
Seasonal Coefficient of Performance (heating)
The total heating output of a heat pump during its normal annual usage period for
heating divided by the total electric energy input during the same period in consistent
units (analogous to the HSPF but for IP or other consistent units.)
Seasonal Energy Efficiency Ratio (SEER)
The total cooling output of an air conditioner during its normal annual usage period
for cooling, in Btu/h (W), divided by the total electric energy input during the
same period, in watt-hours, as determined by DOE 10 CFR Part 430, Subpart B, Test
Procedures. New equipment ranges from about 10 to 16 SEER. Higher SEER ratings indicate
more efficient equipment.
Semiheated Space
An enclosed space within a building that is heated by a heating system whose output
capacity is greater than or equal to 3.4 Btu/Ft2 of floor area but is not a conditioned
space.
Service Agency
An agency capable of providing calibration, testing, or manufacture of equipment,
instrumentation, metering, or control apparatus, such as a contractor, laboratory
or manufacturer.
Service Equipment
The necessary equipment, usually consisting of a circuit breaker or switch and fuses
and accessories, located near the point of entrance of supply conductors to a building
or other structure (or an otherwise defined area) and intended to constitute the
main control and means of cutoff of the supply. Service equipment may consist of
circuit breakers or fused switches provided to disconnect all underground conductors
in a building or other structure from the service-entrance conductors.
Service Water Heating
Heating water for domestic or commercial purposes other than space heating and process
requirements.
Set Point
Point at which the desired temperature (degrees Fahrenheit) of the heated or cooled
space is set.
Setback
Reduction of heating (by reducing the set point) or cooling (by increasing the set
point) during hours when a building is unoccupied or during periods when lesser
demand is acceptable.
Shading Coefficient (SC)
The ratio of solar heat gain through fenestration, with or without integral shading
devices, to that occurring through unshaded 1/8-in.-thick double-strength glass.
A measure of the solar heat transmission of a fenestration in comparison to the
solar heat transmission of 1/8” clear glass. Shading coefficient is being phased
out in favor of the newer solar heat gain coefficient (SHGC) measurement, and is
approximately equal to the SHGC multiplied by 1.15. The shading coefficient is expressed
as a number from 0 to 1. The lower a skylight’s shading coefficient, the less solar
heat it transmits, and the greater its shading ability. A low shading coefficient
in combination with a high LT% and high diffusion is the key to optimal skylight
performance.
Simulation Program
A computer program that is capable of simulating the energy performance of building
systems.
Single Family
A detached residential building, irrespective of height, including duplexes.
Single Zone Units
Unitary HVAC systems that serve a single zone. Single zone systems can provide either
heating or cooling, but they provide supply air at the same volume and temperature
to the entire zone which they serve.
Single-Rafter Roof
A subcategory of attic roofs where the roof above and the ceiling below are both
attached to the same wood rafter and where insulation is located in the space between
these wood rafters.
Single-Zone System
An HVAC system serving a single HVAC zone.
Site-Recovered Energy
Waste energy recovered at the building site that is used to offset consumption of
purchased fuel or electrical energy supplies.
Site-Solar Energy
Thermal, chemical, or electrical energy derived from direct conversion of incident
solar radiation at the building site and used to offset consumption of purchased
fuel or electrical energy supplies. For the purposes of applying this standard,
site-solar energy shall not include passive heat gain through fenestration systems.
Skylight
A fenestration surface having a slope of less than 60 degrees from the horizontal
plane. Other fenestration, even if mounted on the roof of a building, is considered
vertical fenestration.
Skylight Well
The shaft from the skylight to the ceiling.
Solar Heat Gain Coefficient (SHGC)
A measure of the solar heat transmission of a fenestration in comparison to the
solar heat transmission of 1/8” clear glass. Solar Heat Gain Coefficient is now
favored over Shading Coefficient. SHGC measurements include both the radiant solar
heat as well as a calculation of the conductive heat from the fenestration. SHGC
is expressed as a number between 0 and 0.87. The relationship between SHGC and SC
is SHGC = SC x 0.87. The lower the SHGC the less solar heat the skylight transmits,
and the greater it’s shading ability. A low solar heat gain coefficient in combination
with a high LT% and high diffusion is the key to optimal skylight performance.
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Tandem Wiring
A wiring option in which a ballast is shared by two or more luminaires. This reduces
labor, materials, and energy costs.
TE
Thermal efficiency.
Temperature Reset Controllers
Controls that automatically reset supply water temperatures by representative building
loads (including return water temperature) or by outside air temperature.
Thermal Block
A collection of one or more HVAC zones grouped together for simulation purposes.
Spaces need not be contiguous to be combined within a single thermal block.
Thermal Bridge
A component, or assembly of components, in a building envelope through which heat
is transferred at a substantially higher rate than through the surrounding envelope
area.
Thermal Conductance
Time rate of heat flow through a body (frequently per unit area) from one of its
bounding surfaces to the other for a unit temperature difference between the two
surfaces, under steady conditions (Btu/h x ft² x °F) [W/(m² x K)].
Thermal Resistance (R)
The reciprocal of the time rate of heat flow through a unit area induced by a unit
temperature difference between two defined surfaces of material or construction
under steady-state conditions.
Thermal Transmittance
The coefficient of heat transmission (air to air). It is the time rate of heat flow
per unit area and unit temperature difference between the warm-side and cold-side
air films (Btu/h x ft² x °F) [W/(m² x K)]. The U-factor applies to combinations
of different materials used in series along the heat flowpath, single materials
that comprise a building section, cavity airspaces and surface air films on both
sides of a building element.
Thermostat
An automatic control device responsive to temperature.
Thermostat Set Back
Usually done at night to reduce the amount of conditioning provided at night by
allowing the interior temperature to drift naturally to a marginal temperature during
the night and then to recondition it to normal conditions in the morning.
Tinted
(As applied to fenestration) bronze, green, blue, or gray coloring that is integral
with the glazing material. Tinting does not include surface applied films such as
reflective coatings, applied either in the field or during the manufacturing process.
Trade-Off Approach
A trade-off approach involves trading enhanced energy efficiency in one component
against decreased energy efficiency in another component. These trade-offs typically
occur within major building systems (e.g. envelope, mechanical) or in commercial
lighting.
Transformer
A piece of electrical equipment used to convert electric power from one voltage
to another voltage.
Transverse Seam
All duct seams other than the longitudinal seam (which runs parallel to the direction
of air flow).
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U-Factor
A measure (Btu/h ft2 °F) of how well a material or series of materials conducts
heat. U-factors for window and door assemblies are the reciprocal of the assembly
R-value. The smaller the number, the less the heat flow. A measure of the rate of
heat loss of a fenestration. U Factor ratings are expressed as a number between
.20 and 1.20. In the US this number represents Btu/h ft² F. The metric equivalent
is W/m²K. Insulating value is indicated by the R Value, which is the inverse of
the U Factor. The lower a skylight’s U Factor the greater its resistance to heat
flow and the greater its insulating value.
UA
U-factor X area; REScheck performs a simple UA calculation for each building assembly
to determine the overall UA of your building. The UA that would result from a building
conforming to the code requirements is compared against the UA for your building.
If the total heat loss (represented as a UA) through the envelope of your building
does not exceed the total heat loss from the same building conforming to the code,
then the software declares that you pass. A high-efficiency equipment trade-off
can also be performed under certain codes.
UL
Underwriters Laboratories Inc.
UL 181A/B
A test procedure for tapes and mastics used to seal ductwork.
Unconditioned Space
An enclosed space within a building that is not a conditioned space.
Unenclosed Space
A space that is not an enclosed space.
Unit Energy Costs
Costs for units of energy or power purchased at the building site. These costs may
include energy costs as well as costs for power demand as determined by the adopting
authority.
Unitary Cooling Equipment
One or more factory-made assemblies that normally include an evaporator or cooling
coil and a compressor and condenser combination. Units that perform a heating function
are also included.
Unitary Heat Pump
One or more factory-made assemblies that include an indoor conditioning coil, compressor(s)
and outdoor coil or refrigerant-to-water heat exchanger, including means to provide
both heating and cooling functions. When heat pump equipment is provided in more
than one assembly, the separate assemblies shall be designed to be used together.
Unitary Heating and Cooling
One or more factory-made assemblies that include an evaporator or cooling coil,
a compressor and condenser combination, and that shall be permitted to include a
heating function as well. When heating and cooling equipment is provided in more
than one assembly, the separate assemblies shall be designed to be used together.
Unitary Packaged
Each package is a standalone system which provides all of the heating and cooling
requirements for the area of the building that it serves.
UV
Ultraviolet.
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Vapor Retarder
A component that retards water vapor diffusion but does not totally prevent its
transmission. Vapor retarder material is usually a thin sheet or coating. However,
a construction of several materials, some perhaps of substantial thickness, could
also constitute a vapor retarder system.
Variable Air Volume (VAV)
HVAC system that controls the dry-bulb temperature within a space by varying the
volumetric flow of heated or cooled supply air to the space.
Variable Frequency Drive
Changes the speed of the motor by changing the voltage and frequency of the electricity
supplied to the motor based upon system requirements.
Vent Damper
A device intended for installation in the venting system of an individual, automatically
operated, fossil fuel-fired appliance in the outlet or downstream of the appliance
draft control device, which is designed to automatically open the venting system
when the appliance is in operation and to automatically close off the venting system
when the appliance is in a standby or shutdown condition.
Ventilated Mechanically
The process of supplying or removing air by mechanical means to or from any space.
Such air may or may not have been conditioned.
Ventilated Naturally
The process of supplying or removing air by natural means to or from any space.
Ventilation
The process of supplying or removing air by natural or mechanical means to or from
any space. Such air shall be permitted to be conditioned or unconditioned.
Ventilation Air
That portion of supply air that comes from outside (outdoors) plus any recirculated
air that has been treated to maintain the desired quality of air within a designated
space. See ASHRAE 62 and definition of "Outdoor Air."
Vertical Fenestration
All fenestration other than skylights.
Visible Light Transmittance (VLT)
The fraction of solar radiation in the visible light spectrum that passes through
the fenestration. The measure of how much visible light passes through a fenestration.
Visible light transmission or simply visible transmission (VT) measures the segment
of the light spectrum from 380 to 740 nanometers. This is the portion of the light
spectrum that can be seen by the human eye. The higher the VLT or VT a skylight
has, the greater its light transmission. VLT is expressed as a number from 0 to
1.
Voltage Drop
A decrease in voltage caused by losses in the lines connecting the power source
to the load.
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W
Watt.
Wall
Opaque portion of the building envelope.
Warm-Up
Increase in space temperature to occupied set point after a period of shutdown or
setback.
Water Economizer
A system by which the supply air of a cooling system is cooled indirectly with water
that is itself cooled by heat or mass transfer to the environment without the use
of mechanical cooling.
Water Heater
Vessel in which water is heated and is withdrawn for use external to the system.
Water Heating
The process or system used to heat service water.
WH
Watt-hour.
Window
The terms "fenestration", "window", and "glazing"
are often used interchangeably. However, window actually describes a system of several
components. Window is the term given to an entire assembly comprised of the sash,
glazing, and frame.
Window Projection Factor
A measure of the portion of glazing that is shaded by an eave or overhang.
Window-Wall Ratio
The window-wall ratio is the percentage that results from dividing the total glazed
area of the building by the total wall area.
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Zone
A space or group of spaces within a building with any combination of heating, cooling,
or lighting requirements sufficiently similar so that desired conditions can be
maintained throughout by a single controlling device.
