Glossary

All 0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Word Description
A
Absolute Humidity Air moisture content expressed in grains (or pounds) of water vapor per pound of dry air.
Absorptance The ratio of a solar energy absorbed to incident solar. Also called absorbtivity.
Absorption A solid material's ability to draw in and hold liquid or gas.
Accent Lighting Accent lighting illuminates walls, reduces brightness and contrast between walls and ceilings or windows.
Adsorption Adhesion of a thin layer of molecules to a surface they contact.
Air Barrier Any part of the building shell that offers resistance to air leakage. The air barrier is effective if it stops most air leakage. The primary air barrier is the most effective of a series of air barriers.
Air Changes per Hour at 50 Pascals The number of times the volume of air in a structure will change in one hour at the induced blower door house pressure of 50 pascals.
Air Exchange The total building air exchanged with the outdoors through air leakage and ventilation.
Air Handler A steel cabinet containing a blower with cooling and/or heating coils connected to ducts that transports indoor air to and from the air handler.
Air Infiltration Barrier A woven plastic sheet that stops almost all air traveling through a building cavity, while allowing moisture to pass through the cavity.
Air Sealing Also known as "house doctoring," air sealing is a systematic approach to "tightening" a dwelling unit's heated envelope (building shell) to reduce uncontrolled heat loss through air leakage points present in the shell. The prevalent technique is to perform this tightening from the interior of the home. Trained workers seal the air leakage points using a variety of materials, such as insulation, caulk, foam, vapor barriers, and weather-strip. Air leakage identification is usually aided by using diagnostic equipment like blower doors and infrared scanners, since many leakage point are not obvious to the naked eye. Part of the air sealing protocol includes testing to ensure that the building envelope is not sealed too tightly. Over-tightening can result in health and safety problems for the occupants, including back drafting of combustion equipment (furnaces, hot water heaters) and moisture condensation causing mold and mildew on surfaces.
Ambient Lighting Lighting spread throughout the lighted space for safety, security, and aesthetics.
Ampere A unit of measure for the flow of electric current
Annual Fuel Utilization Efficiency (AFUE) A laboratory-derived efficiency for heating appliances that accounts for chimney losses, jacket losses, and cycling losses, but not distribution losses or fan/pump energy.
Annual Return The yearly savings divided by the initial cost needed to achieve the savings, expressed as a percent.
Aquastat A heating control device that controls the burner or the circulator in a hydronic heating system
Asbestos A material made of sharp mineral fibers that damage lung and other bodily tissues.
ASHRAEAmerican Society of Heating, Refrigeration, and Air Conditioning Engineers
ASTMAmerican Society for Testing and Materials
Attic Insulation The installation of approved insulation products (rockwool, fiberglass, and cellulose) evenly across the unconditioned attic area to achieve desired levels of thermal resistance. Insulation products have manufacturer rated "R" levels (resistance to heat loss measurements). The more inches of insulation installed the higher the resistance level. The recommended "R" values vary by climatic regions of the country. It is common for weatherization programs to install a minimum of R-19 or as much as R-38 in colder regions. The cost-effective level of insulation to be added, if any, depends on the existing level of insulation in the attic. Auditors determined the amount of insulation to be added through prescriptive lists or energy audit programs that calculate the saving to investment ratio from increasing insulation levels.
Attic Preparation This refers to the protocol for inspecting and preparing an attic area for the installation of insulation. The preparatory work is directed primarily to air infiltration and safety issues. Some of the protocols include placing barriers around heat-producing sources in the attic (electrical junction boxes, recessed lights, etc.); placing chutes by the eaves to prevent the insulation from blocking needed air ventilation paths; and sealing bypasses and other penetrations between the heated space and the unconditioned attic area.
Audit The process of identifying energy conservation opportunities in buildings.
AWG American Wire Gauge
B
Back-drafting Continuous spillage of combustion gases from a combustion appliances
Back-draft Damper A damper, installed near a fan, that allows air to flow in only one direction.
Backer Rod Polyethylene foam rope used as a backer for caulking.
Baffle A plate or strip designed to retard or redirect the flow of flue gases.Balance point - The outdoor temperature at which no heating is needed.
Balance Heating This is the result of balancing the airflow of the central heating distribution system so that intake and output air exists at levels to maximize efficiency. The balancing of the distribution system assures that all areas of the home being served by the same heating or cooling system or any zone within the system receive approximately equal heated or cooled air.
Ballast A coil of wire or electronic device that provides a high starting voltage for a lamp and limits the current flowing through it
Band Joist See - Rim Joist
Batt A narrow blanket of fiberglass insulation, generally 14.5" or 22.5" wide.
Beam A strong horizontal building support used to carry the weight of a floor or roof.
Bimetal Element A metal spring, lever, or disc made of two dissimilar metals that expand and contract at different rates as the temperature around them changes. This movement operates a switch in the control circuit of a heating or cooling device.
Blower Door A blower door is a diagnostic tool used to locate the points of infiltration in the building envelope and help prioritize the air sealing protocols. This device can be mounted in an exterior door or window opening. The blower door uses a calibrated, powerful, variable speed fan to pressurize or depressurize the dwelling. Its adjustable frame allows the fan assembly to fit snugly in most frames. Air movement and pressure differentials are measured using a set of gauges attached to the frame and fan. These calculations of air movement allow technician to quantify the level of leakage. Such leakage measurements are usually expressed in terms of equivalent leakage area (ELA), air changes per hour (ACH), and cubic feet per minute of airflow (CFM). Any one or more of these measurements can help determine levels of air leakage, indoor air quality, and amount of sealing work to be performed. In addition to measuring air movement, the blower door will exaggerate the leakage points in the building shell for easy identification. This diagnostic tool, when used in conjunction with an infrared scanner, produces even more accurate results.
Blow-Down The act of removing water from a boiler to remove sediment and suspended particles.
Blower Fan The squirrel-cage fan in a furnace or air handler.
Boiler A fossil fuel appliance used for producing hot water or steam as the medium to distribute heat to the dwelling unit.
Boot A duct section that connects between a duct and a register or between round and square ducts
Branch Circuit An electrical circuit used to power outlets and lights within a home.
Brightness The intensity of the sensation derived from viewing a lit surface. Measured in footlamberts, it is also called luminance or luminous intensity.
British Thermal Unit (Btu) The quantity of heat required to raise the temperature of one pound of water one degree Fahrenheit.
Building Cavities The spaces inside walls, floors, and ceilings between the interior and exterior sheeting
Building Envelope The area of the building that encloses conditioned space. Only the exterior four walls to the ceiling under the attic and the floor above the unheated basement area are considered part of the building envelope. The floor of a unit that is built on stilts or is above an unheated crawl space is considered a part of the building envelope. The roof of a building that has no ceilings (or that is part of the ceiling) is considered part of the building envelope.
Building Science Branch of science dealing with construction, maintenance, safety, and energy efficiency of buildings.
Burner A device that facilitates the burning of a fossil fuel, like gas or oil.
C
Carbon Dioxide One of two main products of complete combustion of a hydrocarbon (the other is water vapor).
Carbon Monoxide (CO) Carbon Monoxide is a tasteless, odorless, colorless and poisonous gas that is a by-product of incomplete combustion of fossil fuels. It is usually caused by a lack of air to support combustion or impingement of the flame.
Casing Exposed molding or trim around a window or door.
Caulking Mastic compound for filling joints and cracks.
Cellulose Insulation Insulation, packaged in bags for blowing, made from newspaper or wood waste and treated with a fire retardant
Centigrade A temperature scale on which water freezes at 0 degrees and boils at 100 degrees
Central Heating System This refers to the primary heating system of the dwelling unit including the heat producing appliance, the return and supply system for heat distribution, and ducts or pipes for flue gas ventilation. Central heating systems usually do not include wood stoves, kerosene heaters, space heaters, and electric baseboard heating units.
CFM50 This term means the amount of cubic feet per minute of air moving through a structure and measured at 50-pascal pressure.
CFMn The cubic feet of air flowing through a house from indoors to outdoors during typical, natural conditions. This figure can be roughly estimated using a blower door.
CFM Per Person or Per Room An estimate of the cubic feet per minute of fresh air available or required per occupant or per room.
CFM - Cubic Feet per Minute. Usually seen as CFM 50, cubic feet per minute of air movement due to 50 pascal house/outdoor pressure differential.
Circuit Breaker A device found in a Circuit Panel Box that completes an electric circuit. This breaker disconnects the circuit from electricity when it senses an overload of current.
Clean and Tune (C&T) A procedure performed on a heating system by a licensed furnace service technician to maximize the appliance efficiency using existing hardware. The C&T is usually preceded by a combustion efficiency test to assess whether other conditions exist requiring extensive furnace work. The C&T can involve a variety of activities to upgrade the efficiency and safe operation of the heating system. These can include pilot and burner adjustment, adjustment of ventilation and combustion, check and reset controls, inspect filters, lubricate motors, flush low water cut-off, check operation of steam and water relief valves, check thermostat, check safety valve, and check thermocouple.
Co-efficient of Performance (COP) A heat pump or air conditioner's output in watt-hours of heat moved divided by watt-hours of electrical input.
Coil A snake-like piece of copper tubing surrounded by rows of aluminum fins that clamp tightly to the tubing and aid in heat transfer.
Color Rendering Index (CRI) A measurement of a light source's ability to render colors the same as sunlight. CRI has a scale of 0 to 100.
Color Temperature A measurement of the warmness or coolness of a light source in the Kelvin temperature scale.
Column A vertical building support usually made of wood or steel.
Combustible Means something will burn, although not necessarily readily.
Combustion Air Air that chemically combines with a fuel during the combustion process to produce heat and flue gases, mainly carbon dioxide and water vapor.
Combustion Analyzer A device used to measure steady-state efficiency of combustion heating units.
Combustion Chamber The area inside the heat exchanger where the flame burns
Combustion Test This test is performed to determine the efficiency at which a heating appliance is operating at steady state. The actual tests or sequence of tests may vary in conjunction with the type of testing equipment used or the type of heating appliance being tested. Persons performing these tests must be extremely familiar with the testing equipment being used and must be trained in conducting the tests. In some states, a license is required to perform such tests.
Compressor A motorized pump that compresses the gaseous refrigerant and sends it to the condenser where heat is released
Condense When a gas turns into a liquid as it cools, it condenses. Condensation is the opposite of evaporation. When a gas condenses into a liquid it releases heat.
Condenser The coil in an air conditioning system where the refrigerant condenses and releases heat, that is carried away by air moving through the coil.
Condensate Vapor condensed back to a liquid.
Condensate Receiver A tank for catching returning condensate water from a steam heating system.
Conditioned Intentionally heated or cooled areas of a building
Conductance The property of a material to conduct some energy form like heat or electricity.
Conduction Conduction is the transfer of heat through a material by molecular movement. Reducing heat loss through conduction can include the installation insulation in wall, ceiling, and floor cavities, insulation of hot water tanks, creating thermal breaks in window and door framing, and sealing of bypasses and other sources of air movement.
Contrast Difference in brightness measured by the relationship between an object's brightness and the brightness of its background.
Control Circuit A circuit whose work is switching a power circuit or opening an automatic valve
Convection The transfer of heat caused by the movement of a fluid like water or air. When a fluid becomes warmer it becomes lighter and rises.
Convective Air Flow Air movement where less dense (warmer) air is displaced by more dense (cooler) air. Often expressed by the phrase "hot air rises." Convective air flow can be useful if controlled, as in gravity hot air heating systems, but is more often a contributor to heat loss.
Convective Loop A structural heat loss resulting from temperature differences between the inside and outside wall surfaces causing an air movement loop within the wall cavity. This condition can be present when a stud cavity has no insulation. Air in the cavity is heated near the interior surface of the wall, rises, circulates back toward the exterior siding, falls, re-circulates back to the warm side, is re-heated, and so on.
Cooling Load The maximum rate of heat removal required of an air conditioner when the outdoor temperature and humidity are at the highest expected level.
Cost Effective Having an acceptable payback, return-on-investment, or savings-to-investment ratio.
Cross Section A view of a building component drawn or imagined by cutting through the component.
CSBG - Community Services Block Grant The Community Services Block Grant (CSBG) is federal, anti-poverty block grant which funds the operations of a state-administered network of local agencies. This CSBG network consists of more than 1,100 agencies that create, coordinate and deliver programs and services to low-income Americans in 96% of the nation's counties. Most agencies in the CSBG network are Community Action Agencies (CAAs), created through the Economic Opportunity Act, a predecessor of the CSBG. Community representation and accountability are hallmarks of the CSBG network, where agencies are governed by a tri-partite board. This structure consists of elected public officials, representatives of the low-income community, and appointed leaders from the private sector. Because the CSBG funds the central management and core activities of these agencies, the CSBG network is able to mobilize additional resources to combat the central causes of poverty.
Cubic Foot Per Minute (CFM) A measurement of air movement past a certain point or through a certain structure
Curtain Wall A wall between columns and beams that supports no weight but its own
Customer Certification A final determination concerning program eligibility based on income and ownership, resulting in the customer's receipt or denial of WAP benefits.
D
Dado A rectangular groove cut into wood.
Decking The wood material installed under roofing material to support the roofing.
Demand for Energy The peak need for electrical energy. Some utilities levy a monthly charge for demand.
Demand Side Management (DSM) The planning and implementation of those utility sponsored activities designed to influence customer use of electricity or gas in ways that will produce desired changes in the utility's load shape, such as changes in the pattern and magnitude of the utility's load. DSM study has resulted in a variety of utility-sponsored programs to redirect their customer's usage patterns, especially in the peak load periods. While mainly an electric utility applied concept, there is some application to gas utilities as well. The ultimate goal for most utilities is to avoid the need to invest in new power plants or distribution due to excessive demands on current capacity.
Density The weight of a material divided by its volume, usually measured in pounds per cubic foot.
Degree Days A measure of the temperature element of climate produced by multiplying temperature difference by time.
Depressurize Cause to have a lower pressure or vacuum with respect to a reference of a higher pressure.
Desiccant A liquid or solid material used to absorb water or water vapor.
Design Temperature A high or low temperature used for designing heating and cooling systems.
Dew Point The warmest temperature of an object in an environment where water condensation from the surrounding air would form on that object
Dilution Air Air that enters through the dilution device-an opening where the chimney joins to an atmospheric-draft combustion appliance
Dilution Device A draft diverter or barometric draft control on an atmospheric-draft combustion appliance.
Distribution System This term refers to that part of a central heating system used to deliver heated transfer media to the living space, and return the cooled transfer media to the appliance for re-heating. In a forced air system this includes the blower, ducts, registers, dampers, and cold air returns. In a hot water system this includes circulators, supply lines, radiators, and return lines.
Domestic Hot Water (DHW) Refers to a separate, closed system to heat potable (drinkable) water and supply it to the dwelling unit for washing, bathing, etc.
Dormer A vertical window projecting from a roof.
Draft Diverter A device located in gas appliance flue pipe. Used to moderate or divert draft that could extinguish the pilot or interfere with combustion
Drywall Gypsum interior wallboard used to produce a smooth and level interior wall surface and to resist fire. Also called gypsum wall board or sheetrock.
Dry Bulb Temperature Normal ambient air temperature measured by a thermometer.
Duct Blower A blower-door-like device used for testing duct leakiness and air flow.
Duplex Any structure which consists of two separate dwelling units in one building.
Dwelling Unit A house, including a stationary mobile home, an apartment, a group of rooms, or a single room occupied as separate living quarters.
E
Eaves The edges of a roof system (See - Soffit)
Efficiency The ratio of output divided by input
Efficacy The number of lumens produced by a watt used for lighting a lamp. Used to describe lighting efficiency.
Eligible Multi-Family Dwelling Units A multi-family building qualifies to be weatherized in its entirety when 66% (50% for 2 and 4 unit buildings) or more of the total dwelling units in the building are determined to be eligible as per DOE rules.
Eligible Unit A unit occupied by a household that is categorically eligible or income eligible by DOE and/or LIHEAP standards.
Emittance The ability of a material to emit radiant energy from its surface. Also called emissivity.
Energy A quantity of heat or work
Energy Consumption The conversion or transformation of potential energy into kinetic energy for heat, light, electricity, etc.
Energy Education The process used by WAP staff to inform customers of the ways they can further reduce energy consumption through altering their behavioral patterns. The most effective protocol includes multiple interaction and reinforcement with the household residents and use of a negotiated and written action plan.
Energy Efficiency Term used to describe how efficiently a building component uses energy.
Energy Efficiency Ratio (EER) A measurement of energy efficiency for room air conditioners. The EER is computed by dividing cooling capacity, measured in British Thermal Units per hour (Btuh), by the watts of power. (See - Seasonal Energy Efficiency Rating or SEER)
Enthalpy The internal heat of a material measured in Btus per pound.
Entropy Heat unavailable to a closed thermodynamic system during a heat transfer process.
EPA - U.S. Environmental Protection Agency EPA's mission is to protect human health and to safeguard the natural environment - air, water, and land - upon which life depends. For 30 years, EPA has been working for a cleaner, healthier environment for the American people.
Equivalent Leakage Area (ELA) Calculation, in square inches, of the total area of all holes and cracks in a structure. The leakage area is then accumulated to represent one total leakage point.
Evaporation The change that occurs when a liquid becomes a gas. Evaporation is the key process in the operation of air conditioners and evaporative coolers.
Evaporative Cooler A device for cooling homes in dry climates by humidifying and cooling incoming air.
Evaporator The heat transfer coil of an air conditioner or heat pump that cools the surrounding air as the refrigerant inside the coil evaporates and absorbs heat.
Exfiltration This term describes the movement of air out of a building. Often refers to warm air leaving a building due to pressurization, infiltration, wind, stack effect, and/or convective flow.
F
Fahrenheit A temperature scale used in the United States and a few other countries. On the Fahrenheit scale, water boils at 212 degrees and freezes at 32 degrees.
Family Unit All persons living together in a dwelling unit
Fan Control A bimetal thermostat that turns the furnace blower on and off as it senses the presence of heat.
FEMP - Federal Energy Management Program A program of DOE that implements energy legislation and presidential directives. FEMP provides project financing, technical guidance and assistance, coordination and reporting, and new initiatives for the federal government. It also helps federal agencies identify the best technologies and technology demonstrations for their use.
Fenestration Window and door openings in a building's wall.
Fiberglass A fibrous material made by spinning molten glass used as an insulator and heat loss retardant
Fill Tube A plastic or metal tube used for its stiffness to blow insulation inside a building cavity.
Fin Comb A comb-like tool used to straighten bent fins in air conditioning coils.
Fire Stop Framing member designed to stop the spread of fire within a wall cavity.
Flame Safety Control A control device used to stop the flow of fuel to the burner assembly in the event of no ignition.
Flashing Waterproof material used to prevent leakage at intersections between the roof surface at walls or penetrations.
Floor Joists The framing members that support the floor area.
Flue The channel of pipe used to control air flow of combustion gases.
Foam Board Plastic foam insulation manufactured most commonly in 4'x8' sheets in thickness of 1/4" to 3".
Foot Candle A measure of light striking a surface
Footer The part of a foundation system that actually transfers the weight of the building to the ground
Frost Line The maximum depth of the soil where water will freeze during the coldest weather
Furnace An appliance for heating a medium to distribute heat throughout the dwelling unit.
G
Gable The triangular section of an end wall formed by the pitch of the roof.
Gas Heating System A heating system that uses natural gas or bottled liquid propane gas as fuel.
Gasket Elastic strip that seals a joint between two materials.
Glazing Glass installation. Pertaining to glass assemblies or windows
Glass Load Factor A number combining glass's solar heat transmission and its heat conduction. Used for cooling load calculations.
Gravity Furnace A central heating system that uses natural gravity to distribute heat throughout the dwelling unit as opposed to forced circulation, pumps, or circulation blowers.
Gusset A metal or wood plate added to the surface of a joint to strengthen the connection.
Gypsum Board A common interior sheeting material for walls and ceilings made of gypsum rock powder packaged between two sheets of heavy building paper. Also called sheetrock, gyprock, or gypboard.
H
Handicapped Person Any individual who is: 1) handicapped as defined in Section 7 (6) of the Rehabilitation Act of 1973; 2) under a disability as defined in Section 1614 (1) (3) (A) or 223 (d) (i) of the Developmental Disabilities Services and Facilities Construction Act; or 3) who is receiving benefits under Chapter 11 or 15 of Title 38, U.S.C. Other conditions may apply state to state, which can deem an individual as handicapped for the purposes of the WAP.
HDD - Heating Degree Day(s) The number of degrees per day that the daily average temperature (the mean of the maximum and minimum recorded temperatures) is below a base temperature, usually 65 degrees Fahrenheit, unless otherwise specified; used to determine indoor space heating requirements and heating system sizing. Total HDD is the cumulative total for the year/heating season. The higher the HDD for a location, the colder the daily average temperature(s).
Heat Anticipator A very small electric heater in a thermostat that causes the thermostat to turn off before room temperature reaches the thermostat setting, so that the house does not overheat from heat remaining in the furnace and ducts after the burner shuts off.
Heat Capacity The quantity of heat required to raise the temperature of 1 cubic foot of a material 1 degree F.
Heat Gains Term used to mean unwanted heat that accumulates in homes, making mechanical cooling desirable or necessary.
Heat Loss The amount of heat escaping through the building shell as measured for a specific period of time (month, year, etc.)
Heat Rise The number of degrees of temperature increase that air is heated as it is blown over the heat exchanger. Heat Rise equals supply temperature minus return temperature.
Heat Transmission Heat flow through the walls, floor, and ceiling of a building, not including air leakage.
Heat Transfer Coefficient See U-value.
Heating Degree Day Each degree that the average daily temperature is below the base temperature (usually 65 degrees F) constitutes one heating degree day.
Heating Load The maximum rate of heat conversion needed by a building during the very coldest weather.
Heating Seasonal Performance Factor (HSPF) Rating for heat pumps describing how many Btus they transfer per kilowatt-hour of electricity consumed.
HERS - Home Energy Rating Systems A nationally recognized energy rating program that give builders, mortgage lenders, secondary lending markets, homeowners, sellers, and buyers a precise evaluation of energy losing deficiencies in homes. Builders can use this system to gauge the energy quality in their home and also to have a star rating on their home to compare to other similarly built homes.
High Limit A bimetal thermostat that turns the heating element of a furnace off if it senses a dangerously high temperature.
Home Heating Index The number of Btus of energy used by a home divided by its area in square feet, then divided by the number of heating degree days during the time period.
HOME Program A program created under Title II (the Home Investment Partnership Act) of the National Affordable Housing Act of 1990. Provides funds for states to expand the supply of decent and affordable housing for low-income people. This program can be easily coordinated with a state's WAP efforts.
Household Any individual or group of individuals who are living together as one economic unit for whom residential energy is customarily purchased in common or who make undesignated payments for energy in the form of rent.
House Pressure The difference in pressure between the indoors and outdoors measured by a manometer.
HUD U.S. Department of Urban Housing and Development
Humidistat An automatic control that switches a fan, humidifier, or dehumidifier on and off to control relative humidity.
Humidity Ratio Same as "absolute humidity." The absolute amount of air's humidity measured in pounds of water vapor per pound of dry air.
HVACHeating, Ventilation, and Air-Conditioning System All components of the appliances used to condition interior air of a building.
Hydronic A heating system that uses hot water or steam as the heat-transfer fluid.
I
IAQIndoor Air Quality The quality of indoor air relative to its acceptability for healthful human habitation. Assessing and ameliorating, when necessary, the quality of indoor air is a major concern of the weatherization process. In particular, all by-products of major combustion appliances must be directly evacuated to the outdoors under all operating conditions.
Illumination The light level measured on a horizontal plane in Foot Candles
Inch of Water Small air pressure differences caused by wind, blower doors, furnace fans, and chimneys are measured in inches of water (in.-H2O) in the American measurement system.
Incidental Repairs Under DOE rules, this term refers to the repairs on a dwelling unit necessary for the effective performance or preservation of the allowable energy conservation measures to be installed. Usually, a specific dollar amount is set by a state to limit such incidental repairs.
Indoor Air Quality (IAQ) Refers to the measurement of air quality in the living space of the home. Pollutants can exist within a home, and WAP staff must be aware of the impact their work has on the quality of the atmosphere within the living space. The presence of pollutants, combined with inadequate ventilation factors, can contribute to a variety of occupant health and safety problems. Therefore, IAQ is a primary concern when workers seal or "tighten" homes.
In-Kind Contributions In-kind contributions represent the value of non-cash contributions provided by the grantee, and non-Federal parties. In-kind contributions may be in the form of charges for real property and non-expendable personal property and the value of goods and services directly benefiting and specifically identifiable to the project or program.
Infiltration Infiltration refers to the movement of air into a building through cracks and penetrations in the building envelope. Cold air often enters the structure due to depressurization, exfiltration, wind, stack effect, and/or convective airflow.
Infrared Thermography The science of using infrared imaging to detect radiant energy or heat loss characteristics of a building. The infrared camera or scanner electronically senses heat radiated by objects and converts that thermal energy into images visible to the human eye. The camera or scanner, similar to a camcorder in appearance, produces varying shades of black and white images of the building structure. The darker the image, the colder the corresponding surface; the lighter areas are the hotter surfaces. Some scanners can automatically record these images on video, as well as allow the operator to record audio commentary as he/she scans the building. A certain degree of interpretation skill is required to properly assess the images being recorded. Used in conjunction with a blower door, the scanner can provide valuable data, since the pressurization or depressurization can magnify air leakage sites and thermal bypasses.
Input Rating The measured and assigned rating indicating the level at which an energy-using device consumes electricity or fossil fuel.
Insolation The amount of solar radiation striking a surface
Insulated Glass Two or more glass panes installed in windows and doors, spaced apart and sealed in a factory.
Internal Gains The heat generated by bathing, cooking, and operating appliances, that must be removed during the summer to promote comfort.
Intermittent Ignition Device A device that lights the pilot on a gas appliance when the control system calls for heat, thus saving the energy wasted by a standing pilot.
Intermediate Zone A zone located between the building's conditioned space and the outdoors, like a crawl space or attic.
J
Jamb The side or top piece of a window or door frame.
Joist A horizontal wood framing member that supports a floor or ceiling.
K
Kilowatt A unit of electric power equal to 1000 joules per second or 3412 Btus per hour.
Kilowatt-hour A unit of electric energy equal to 3600 kilojoules.
L
Landlord/Tenant Agreement Document required for completed application when applicant is a renter. The Agreement is legally binding contract, signed by the tenant, the landlord (or property owner), and the local agency specifying the role and responsibilities of each party. The basic goal of the WAP is to ensure that the benefits of the program accrue to the low-income family. A variety of standard clauses can be incorporated into the Agreement, including clauses on landlord's inability to raise rents for specified period of time, eviction prohibition, and landlord required "participation." Participation can take the form of actual cash, provided labor, and/or in-kind contributions.
Leakage Ratio Measurement of total square inches of infiltration area per 100 feet of building envelope surface area.
Leverage Activity The actions of the state and local agencies to obtain and account for resources provided to supplement or supplant federal funding being used to weatherize dwelling units.
Local Agency Also referred to as the subgrantee, contractor, service delivery network member, or local service provider, a local agency is a nonprofit organization or unit of local government responsible for providing WAP services in a specified political subdivision.
Low-E Short for "low emissivity", which means the characteristic of a metallic glass coating to resist the flow of radiant heat.
Low Water Cutoff A float-operated control for turning the burner off if a steam boiler is low on water.
Lumen A unit of light output from a lamp.
M
Make-up Air Air supplied to a space to replace exhausted air.
Manometer Measuring device for small gas pressures.
Mastic A thick creamy substance used to seal seams and cracks in building materials.
MHEA - Mobile Home Energy Audit A software tool that predicts manufactured home energy consumption and recommends weatherization retrofit measures.
Mitigate To make less severe or to mollify.
Mortar A mixture of sand, water, and cement used to bond bricks, stones, or blocks together.
Mortise A recessed area cut into the wood framing member where a hinge or wood tongue fits.
N
NASCSP - National Association for State Community Services Programs NASCSP's mission is to assist state in responding to poverty issues. NASCSP members are state administrators of the Community Services Block Grant (CSBG) and U.S. Department of Energy's Weatherization Assistance Program (DOE/WAP). The CSBG, administered by the states, provides core funding to local agencies to reduce poverty, revitalize low-income communities and to empower low-income families to become self-sufficient. The DOE/WAP helps low-income families reduce their energy costs by making homes more energy efficient. The local agencies funded by these programs provide a wide range of services such as weatherization, energy assistance, child care, job training, and housing. NASCSP keeps its members, the federal government, and other interested parties informed about issues related to CSBG and DOE/WAP through its publications.
Natural Ventilation Ventilation using only natural air movement without fans or other mechanical devices.
NEAT - National Energy Audit Created by Oak Ridge National Laboratories as a DOE approved audit qualifying for the 40% materials waiver. It is a computerized auditing tool for prioritizing energy conservation measures for houses.
Net Free Area The area of a vent after that area has been adjusted for insect screen, louvers, and weather covering. The free area is always less than the actual area.
Nozzle An orifice for spraying a liquid like fuel oil.
O
Oil Heating System Refers to a central heating system that uses #2 fuel oil, kerosene, or residual oil as the primary fuel for heat generation.
Open-Combustion Heater A heating device that takes its combustion air from the surrounding room air.
Orifice A hole in a gas pipe or nozzle fitting where gas or fuel oil exits to be mixed with air before combustion occurs in the heating chamber.
Oscillating Fan A fan, usually portable, that moves back and forth as it operates, changing the direction of the air movement.
Output Capacity The conversion rate of useful heat that a heating unit produces after accounting for any waste caused by the conversion of energy into heat.
Oxygen Depletion Sensor A safety device on a heating unit that shuts off the fuel supply to the combustion chamber when oxygen is depleted.
P
Packaged Air Conditioner An air conditioner that contains the compressor, evaporator, and condenser in a single cabinet.
PA - Pascal A unit of measurement of air pressure. One column inch of water equals 247 pascals. Atmospheric pressure (29.92 inches of mercury) is equivalent to 102,000 PA.
Payback Period The number of years that an investment in energy conservation will take to repay its cost through energy savings.
Perlite A heat-expanded mineral used for insulation.
Perm A measurement of how much water vapor a material will let pass through it per unit of time.
Plaster A plastic mixture of sand, lime, and Portland cement spread over wood or metal lath to form the interior surfaces of walls and ceilings.
Plate A piece of lumber installed horizontally to which the vertical studs in a wall frame are attached.
Plenum The piece of ductwork, usually found above the heat exchanger of a hot air furnace, that connects the air handler to the main supply duct.
Plumb Absolutely vertical at a right angle to the earth's surface.
Plywood Laminated wood sheeting with layers cross-grained to each other.
Polyethylene Polymer plastic used for vapor barriers, air barriers, and foam backer rod.
Polyisocyanurate A plastic foam insulation sold in sheets, similar in composition to polyurethane.
Polystyrene Insulation A rigid plastic foam insulation, usually white or blue in color.
Polyurethane A versatile plastic foam insulation, usually yellow in color.
Potential Energy Energy in a stored or packaged form, like fuel oil, coal, wood, etc.
Pressure A force encouraging movement by virtue of a difference in some condition between two areas.
Pressure Diagnostics The practice of measuring pressures and flows in buildings to control air leakage, and also to ensure adequate heating and cooling air flows and ventilation.
Pressure Pan A device used to block a duct register while measuring the static pressure behind it.
Pressuretrol A control that turns a steam boiler's burner on and off as steam pressure changes.
Prime Window The main window installed on the outside wall consisting of fixed or moveable lights that slide on permanently fixed tracks (not to be confused with a storm window).
Priority List The list or ranking of installation measures developed by a program to produce the most cost effective energy savings results based on a savings to investment ratio calculation.
Program Income Income earned by the grantee from grant-supported activities, including but not limited to, income from service fees, sale of commodities, usage or rental fees, and royalties on patents and copyrights.
Psychrometrics The study of the relationship between air, water vapor, and heat.
Purlins Framing members that sit on top of rafters, perpendicular to them, designed to spread support to roofing materials.
PV - Photovoltaic A solid-state elctrical device that converts light directly into direct current electricity of voltage-current characteristics that are a function of the characteristics of the light source and the materials in and design of the device. Solar photovoltaic devices are made of various semi-conductor materials including silicon, cadmium sulfide, cadmium telluride, and gallium arsenide, and in single crystalline, multi-crystalline, or amorphous forms.
R
R-Value A measurement of thermal resistance for materials and related surfaces.
Radiant Barrier A foil sheet or coating designed to reflect heat producing sun rays.
Radiant Temperature The average reflective temperature of objects in a home, like walls, ceiling, floor, and furniture.
Radiation Heat energy originating on a hot body like the sun and traveling from place to place through the air.
Radon A radioactive gas that decomposes into radioactive particles.Rafter - A roof beam that follows the roof's slope.
Reflectance Also called reflectivity, it is the ability of a material's surface to reflect radiant heat.
Recovery Efficiency A water heater's efficiency at actually heating water to capacity level without regard to standby or distribution losses.
Reflective Glass Glass that has a mirror-like coating on its exterior surface to reflect solar heat. The solar heat gain coefficient of reflective glass ranges from 0.10 to 0.40.
Refrigerant A special fluid used in air conditioners and heat pumps that heats air when it condenses from a gas to a liquid and cools air when it evaporates from a liquid to a gas.
Register The grille cover over a duct outlet for warm air distribution or cold air return.
Relamping The replacement of an existing, standard light bulbs with lower wattage energy efficient bulbs like compact fluorescent lamps.
Relative Humidity The percent of moisture absorbed in the air compared to the maximum amount possible. For instance, air that is completely saturated has 100% relative humidity.
Relay An automatic, electrically-operated switch.
Reset Controller Adjusts fluid temperature or pressure in a central heating system according to outdoor air temperature.
Resistance The property of a material resisting the flow of electrical energy or heat energy.
Retrofit An energy conservation measure applied to an existing building or the action of improving the thermal performance or maintenance of a building.
Return Air Air circulation back to the furnace from the house to be heated by the furnace and supplied to the rooms.
Re-Weatherized Unit Any unit that received weatherization services prior to September 30, 1985 and has received additional services under subsequent grants or allowed by current DOE regulations.
Rim Joist The outermost joist around the perimeter of the floor framing.
S
Savings-to-Investment Ratio (SIR) They are computed over the lifetimes of the retrofit measures installed and expressed in terms of the net present value of the retail cost of the dwelling's fuel. Under some methodologies, other benefits, etc. Investment usally takes into account materials, labor, and support costs. SIRs of greater than one are counted as cost effective under this DOE WAP method of determining cost-effectiveness.
Sealed Combustion Heater A heater that draws air for combustion from outdoors and has a sealed exhaust system.
Seasonal Efficiency Refers to the overall efficiency of the central heating system including on and off cycle fuel utilization and heat loss. The calculation of these factors is represented in the Annual Fuel Utilization Efficiency (AFUE) rating for the appliance. Distribution system loss is not factored into the AFUE.
Seasonal Energy Efficiency Ratio (SEER) A measure of seasonal or annual efficiency of a central air conditioner or air conditioning heat pump. It takes into account the variations in temperature that can occur within a season and is the average number of Btu of cooling delivered for every watt-hour of electicity used by the heat pump over a cooling season.
Seasonal Performance Factor (SPF) Ratio of useful energy output of a device to the energy input, averaged over an entire heating season.
Separate Living Quarters Living quarters in which the occupants do not live and eat with any other persons in the structure and that have either a direct access from the outside of the building or through a common hall or complete kitchen facilities for the exclusive use of the occupants. The occupants maybe a single family, one person living alone, two or more families living together, or any other group of related or unrelated persons who share living arrangements.
Sequencer A bimetal switch that turns on the elements of an electric furnace in sequence.
Settling This term refers to the effect of insulation depressing over time and, thereby, reducing the overall energy efficiency of the materials. This process is primarily the result of using too much air when installing the blown-in insulation - commonly called "fluffing," or the effect of long periods of time on the materials. One reason to re-inspect some work several months after installation to assess the settling factor. Settling can also occur during the installation of sidewall insulation when the cavity is not completely filled. This is usually avoided if "dense pack" protocols are followed during the installation.
Shading Coefficient (SC) A decimal describing how much solar energy is transmitted through a window opening compared to clear single glass having an SC of 1.0. For example, reflective glass has an SC of .20 to .45.
Sheathing A structural sheeting, attached on top of the framing, underneath siding, or on the roof of a building.
Sheeting Common term for any building material used for covering a building surface.
Shell The building's exterior envelope including walls, floor, and roof.
Shingle A modular roofing material, usually asphalt, that is installed in overlapping rows to cover the entire roof.
Short Circuit A dangerous malfunction in an electrical circuit where electricity is flowing through conductors and into the ground without going through an electric load, like a light or motor.
Sidewall Insulation The process of installing insulation material, usually blown cellulose, into the non-insulated wall stud cavities of a structure to reduce heat loss. Installation is achieved by drilling one or more rows of holes into the wall, one in each stud cavity. To achieve the most effective results, a dense pack protocol is used to install "high density" insulation materials. The "packing" of the materials should be tight enough that the installer cannot move the insulation when complete. It is common to install materials at 3.5 pounds per square foot.
Sill The bottom of a window or door frame.
Sill Box The outer area of the floor bound by the rim joist, floor joist, sill plate, and floor.
Sling Psychrometer A device holding two thermometers that is slung through the air to measure relative humidity.
Soffit The underside of a roof overhang or a small lowered ceiling, as above cabinets or a bathtub.
Solar Gain Heat from the sun that is absorbed by a building's materials and contributes to the heating and cooling requirements of the dwelling.
Solar Heat Radiant energy from the sun with wavelengths between 0.7 and 1 micrometers.
Solar Heat Gain Coefficient (SHGC) The ratio of solar heat gain through a window to incident solar heat, including both transmitted heat and absorbed/radiated heat.
Solar Heat Gain Factor (SHGF) Solar heat gain amount on a surface with a particular angle and orientation expressed in Btus per square foot per hour.
Solar Transmittance The percent of total solar energy transmitted by a material.
Solenoid A magnetic device that moves a switch or valve stem.
Space Heating Heating the living spaces of the home with a room heater or central heating system.
Span Horizontal distance between supports.
Specific Heat The ratio of the heat storage capacity of a particular material to the heat storage capacity of water.
Spillage Temporary flow of combustion gases from a dilution device.
Spline A strip of vinyl, rubber, or plastic that, when inserted into a groove, holds a screen or plastic film in place on a frame.
Split-System Air Conditioner An air conditioner having the condenser and compressor outdoors and the evaporator indoors.
Stack Effect The term describes the effect of higher pressure at the top of a structure, lower pressure at the bottom of a structure, and neutral pressure somewhere in between, relative to the ambient (surrounding) air pressure. It is usually the result of different densities of warmer and cooler air (convective airflow).
Standing Loss Heat loss from a hot water storage tank through its shell.
Steady State Efficiency The measurement of heat system balance in the on-cycle when heat into system equals heat out. Generally provided as a percentage of the maximum available heat generation capacity (100%) against the amount of usable heat being sent to the distribution system. This figure can also represent the percentage of heat being used within the system as compared to the heat lost through the flue. The reading is most valid when the stack temperature becomes constant and the distribution pumps or blowers are operating.
Steam Trap An automatic valve that closes to trap steam in a radiator until it condenses.
Steam Vent A bimetal-operated air vent that allows air to leave steam piping and radiators, but closes when steam strikes the surface.
Stop A thin, trim board for windows and doors to close against or slide against.
Strike Plate The metal plate attached to the door jamb that the latch inserts into upon closing.
Stud A vertical wood or metal framing member used to build a wall.
Sub-Floor The sheathing over the floor joists and under the floor covering.
Supply Air Air that has been heated or cooled and is moved through the ducts and to the supply registers of a home.
Suspended Ceiling Modular ceiling panels supported by a hanging frame.
T
Taped Duct Test (TDT) A procedure using the blower door to measure the "potential" for leakage reduction of the duct system. All supply registers and return grills are taped shut following the initial blower door reading and a subsequent air leakage test taken. if closing off the duct system in this manner causes an appreciable reduction in the air leakage rate, this is an indication that there are significant duct leaks.
Therm A unit of energy equal to 100,000 Btus or 29.3 kilowatt-hours.
Thermal Break A relatively low heat/cold conductive material separating two highly conductive materials.
Thermal Bridging Rapid heat conduction resulting from direct contact between very thermally conductive materials like metal and glass.
Thermal Bypass Similar to a convection loop, this structural heat loss is characterized by heated air traveling up exterior or interior stud cavities and leaking out the top of that cavity to the attic through joints and cracks in the framing, wiring and plumbing holes, etc. These types of heat loss sources are sometimes the most difficult to locate.
Thermal Conductance General term applied to both K-value and U-value, meaning heat flow rate.
Thermocouple A bimetal-junction electric generator used to keep the safety valve of an automatic gas valve open.
Thermodynamics The science of heat.
Title XVI Term to be used interchangeably with those income groups known as SSI (Supplemental Security Income) recipients.
Tracer Gas A harmless gas used to measure air leakage in a building.
Transformer A double coil of wire that increases or decreases voltage from a primary circuit to a secondary circuit.
Trim Decorative wood that covers cracks around window and door openings and at the corners where walls meet floors and ceilings. Sometimes called molding.
Truss A lightweight, rigid framework designed to be stronger than a solid beam of the same weight.
U
U-Value The amount of heat flowing through a square foot of building materials.
Ultraviolet Radiation Solar radiation having wavelengths just shorter than visible light.
Unconditioned Space Ant area within the building envelope not intentionally or unintentionally heated.
V
Vapor Barrier A material that retards the passage of water vapor.
Vapor Diffusion The flow of water vapor through a solid material.
Veiling Reflection Light reflection from an object or task that obscures details.
Veneer The outer layer of a building component (e.g., interior doors often have a wood veneer; some wood-frame houses have brick veneer walls, etc.).
Vent Connector The vent pipe carrying combustion gases from the appliance to the chimney.
Vent Damper An automatic damper powered by heat or electricity that closes the chimney while a heating device is off.
Venting The removal of combustion gases by a chimney.
Ventilation Refers to the controlled air exchange within a structure. All dwellings must "breathe" and proper ventilation rates must be determined. If the structure requires more interior/exterior air exchanges, there are mechanical and non-mechanical options for increasing those rates. The most common option is passive ventilation through the installation of roof, soffit, or gable vents.
Vermiculite A heat-expanded mineral used for insulation.
Visible Transmittance The percent of visible light transmitted by a glass assembly.
Visqueen Polyethylene film vapor barrier.
W
Watt A unit electrical power equivalent to one joule per second or 3.4 Btuh Watt-Hour A unit of electrical energy equivalent to 3600 joules or 3.4 Btus.
Weatherization Assistance Program (WAP) DOE's Weatherization Assistance (Wx) Program is the nation's largest residential energy efficiency program. Its mission is to increase the energy efficiency of dwellings occupied by low-income Americans, therby reducing their energy costs, while safeguarding their health and safety. DOE works directly with the states, the District of Columbia, and Native American Tribal Governments to carry out these goals. These agencies, in turn, contract with approximately 1,000 local governmental or non-profit agencies to deliver weatherization services to our low-income clients.
Weatherstripping Flexible gaskets, often mounted in rigid metal strips, for limiting air leak age at opening in the shell like doors and windows.
Webbing A reinforcing fabric used with mastics and coatings to prevent patches from cracking.
Weep Holes Holes drilled for the purpose of allowing water to drain out of an area in a building where it has accumulated.
Wet-Bulb Temperature The temperature of a dampened thermometer of a Sling Psychrometer used to determine relative humidity, dew point, and enthalpy.
Window Films Plastic films, coated with a metallic reflective surface, that are adhered to window glass to reflect heat rays from the sun.
Window Frame The sides, top, and sill of the window forming a box around window sashes and other components.
Worst-Case Depressurization Test A safety test, performed by specific procedures, designed to assess the probability of chimney back-drafting.
Z
Zone A room or portion of a building separated from other rooms by an air barrier.