Accent lighting: emphasizes a specific object or draws attention to a particular area, usually using lights with narrow beam control.

Active-solar heating system: the use of fans, pumps, and controls to distribute solar heat by moving air, water, or another fluid.

Air barrier: a continuous layer of materials that blocks the movement of air.

Air Conditioning Contractors of America (ACCA): certifies HVAC contractors, provides educational resources, and lists local air-conditioning contractors.

Air handler: the part of a forced-air heating or cooling system that moves the air through the conditioning and distribution components.

Air leakage: the uncontrolled movement of air in or out through the house structure. Air leakage carries heat with it by convection. Also called air infiltration, infiltration, and air exfiltration.

Airtight-drywall approach: an air-retarding technique that uses gaskets and caulk to seal drywall at its perimeter and penetrations.

Allowance: an amount of money set aside in a construction contract for items that are not specified explicitly in the original contract and therefore can’t be accurately bid.

Ambient lighting: lighting designed to provide uniform illumination.

American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE): a building technology organization that focuses on building systems, energy efficiency, IAQ, and sustainability.

Annual fuel utilization efficiency (AFUE): a laboratory-derived number for rating heating appliances; it accounts for chimney losses, jacket losses, and cycling losses, but does not include distribution losses or energy used to operate fans or pumps.

As-builts: architectural drawings that document the conditions of a home before renovations.

Assembly: a group of building materials that function as a system.

Assumable loan: a mortgage loan that allows a buyer to undertake the preexisting loan.

Backdraft damper: a damper installed in a duct that allows air to flow in only one direction.

Backdrafting: the pressure-induced spillage of exhaust gases from combustion appliances into the living space.

Backer rod: vinyl tube or foam rope placed in large cracks, so less caulk is needed.

Balanced pressure: see Neutral pressure.

Ballast: a device used with fluorescent or high-intensity discharge lights to provide the necessary circuit conditions for starting and operating the light. See Electronic ballast, Magnetic ballast.

Base load: the steady amount of energy or water consumed by a household year-round, not including peak use.

Batch water heater: a passive-solar water heater made of an insulated box with a glazed top exposed to sunlight.

Biocompatible: harmless to living tissue.

Blocking: horizontal framing (2 x 4 or 2 x 6) placed between wall studs to facilitate fastening items to the wall.

Blower door: a variable-speed fan mounted in an adjustable frame that fits snugly in a doorway; used to pressurize or depressurize a house to measure air leakage.

Blown-in blanket (BIB): loose-fill insulation installed in an exposed wall cavity and contained by a covering.

Blown insulation: any loose-fill insulation propelled into building cavities by air pressure.

Boiler: a device that heats water for use in heating the whole house; not usually intended to heat domestic hot water for consumption.

Borrowed light: a daylighting technique that transmits sunlight from brighter to darker rooms via an interior glazed opening.

Brass ball valve: a durable valve, operated with a lever, that opens or closes fully with a 90° turn.

British thermal unit (Btu): the amount of energy required to raise 1 lb of water 1°F at a specified temperature.

Building envelope: the boundary between conditioned and unconditioned spaces, consisting of the walls, roof, and floor, including air barrier and insulation material.

Building Performance Institute (BPI): certifies home energy professionals, specializing in assessments and energy retrofits of existing homes.

Building science: a body of knowledge about the physical phenomena that affect buildings. Includes analyses of building materials, building envelope systems, and mechanical systems for heating, cooling, and ventilating.

Can light: a cylindrical light fixture installed through a hole in the ceiling and providing downward-focusing lighting, either as a broad floodlight or as a narrow spotlight.

Carbon calculator: a tool for estimating the carbon footprint of a given activity.

Carbon footprint: the quantity of CO2 (and other greenhouse gases) emitted by a given activity, such as operating a home.

Cash-out refinance: a refinance of the first mortgage on a property that allows the borrower to take out additional cash.

Cathedral ceiling: a sloped or vaulted ceiling, usually with the rafters serving as the ceiling joists.

Caulk: sealer applied from a tube; dries to an airtight, flexible seal in cracks and holes.

CFM50: cubic feet per minute of airflow with a 50 Pa pressure difference between indoors and out.

Change order: a client’s written order to the contractor, issued after execution of the construction contract, authorizing a change in contract terms.

Chase: an enclosed passageway, often used to carry ducts, plumbing, and telephone and electrical lines.

Clerestory window: a vertical window higher than eye level that can be used for lighting, ventilation, and collecting solar heat.

Closed-loop solar system: a solar hot-water system that uses an antifreeze heat transfer fluid (glycol, oil, alcohol) to heat the domestic hot water.

Cocoon: one or two rooms with increased insulation, where one spends most of one’s time during extremely cold or hot weather, shutting down heating or cooling to other rooms.

Coefficient of performance (COP): a measure of a heat pump’s efficiency; the amount of energy transferred to or from the space divided by the amount of energy used to make that transfer occur.

Coil: a heat exchanger in a heat pump or A/C that absorbs or rejects heat to transfer heat from indoors to outdoors (air conditioning) or from outdoors to indoors (heat pump in heating mode). The coil typically consists of copper tubing with aluminum fins; the tubing carries a refrigerant.

Color rendering index (CRI): indicates the effect of a light source on the color appearance of objects.

Color temperature: a measure of the color appearance of light as warm (reddish) or cool (blue-white). Color temperature is measured on the Kelvin scale; a lower temperature indicates a warmer color.

Combustion air: air that chemically combines with a fuel during combustion to produce heat and flue gases, mainly CO2 and water vapor.

Combustion chamber: the box where the fuel burns in fossil-fueled water heaters or furnaces.

Commissioning: verifying that all the building systems (e.g., HVAC, plumbing, electrical) function as designed.

Compact fluorescent light (CFL): a type of fluorescent light designed to replace an incandescent light.

Competitive bidding: soliciting bids from several contractors in order to get the lowest price for a project.

Composting toilet: uses no water and does not flush to a septic system or sanitary sewer system. It is self-contained and breaks down the waste using natural biological processes.

Compressor: a motorized pump in an A/C or heat pump that compresses the gaseous refrigerant and sends it to the condenser, where heat is released.

Condensation: the conversion of a fluid from a vapor to a liquid state, usually initiated by cooling.

Condenser: the outdoor coil in an A/C or heat pump where the refrigerant condenses and releases heat, which is carried away by air moving through the coil.

Condensing clothes dryer: uses a heat exchanger to cool the moisture-laden exhaust air from the dryer, condensing the water vapor into a drain and capturing the waste heat for reuse.

Condensing water heater: captures heat from flue gases to further heat the water; can exceed 80% fuel efficiency.

Conditioned space: the part of a house that is heated or cooled.

Conduction: heat transfer through a substance from one molecule to another.

Construction documents, Contract documents: drawings and specifications assembled by an architect that provide details of construction.

Contractor: a professional who contracts to perform labor and/or supply materials for construction work (see General contractor).

Controlled ventilation: mechanical ventilation for general IAQ improvement, controlled by a time, temperature, or humidity monitor.

Convection: circulatory motion in a fluid (gas or liquid) due to uneven distribution of heat in that fluid.

Convection oven: an oven that accelerates cooking time using convection currents.

Cool roof: a roof with a higher solar reflectance than a standard roof.

Cove lighting: indirect lighting built into ledges, recesses, or valances in a ceiling or high on the walls of a room; directs light up toward the ceiling and down adjacent walls.

Crawl space: space between the bottom floor and the ground, usually with very low vertical clearance.

Cross-ventilation: the passage of outdoor air from openings on one or more sides of a building through openings on the opposite sides.

Cubic feet per minute (CFM): unit of measurement for airflow.

Damper: a device in a duct or vent to limit or stop airflow.

Damp-spray insulation: see Wet-spray insulation.

Daylighting: illumination of indoor spaces by sunlight.

Deciduous: denotes plants that lose their leaves in cold seasons.

Deep energy retrofit: a home retrofit that aims to reduce energy use by 50–90%, which is more than is usually achieved by conventional energy retrofits.

Demand response programs: allow the utility or grid operator to remotely curtail an appliance’s energy use during periods of high demand.

Dense pack: a method of installing loose-fill insulation at a high density to improve its ability to slow air leakage.

Details: architectural drawings, usually large scale, that show construction of particular building elements.

Diffuser: supply grille that directs and speeds the flow of incoming air, mixing it with air already in the room.

Dimmer: a device used to vary the intensity of electric light.

Dip tube: the cold-water inlet that runs inside the hot-water tank, from the top to the base.

Directional lighting: the distribution of all or most of the light from a fixture in one direction.

Direct-vent: denotes a combustion appliance ducted to the exterior, with exterior air intake.

Distribution system: a system of pipes or ducts used to distribute energy or a fluid to and from a heating or cooling device, such as a furnace, boiler, or central A/C.

DIY: do-it-yourself.

Domestic hot water: the hot water that comes out of taps or appliances, as distinguished from the hot water circulated through the radiators and pipes of a hydronic heating system.

Downlight: see Can light.

Draft hood: a device built into an appliance, or made a part of the vent connector, that provides for the ready escape of the flue gases from the appliance and prevents backdrafting.

Drainback system: a solar water-heating system that allows fluid to drain out of the collector and into a tank when the pump to the collector shuts off.

Drain pan: a small basin under a water heater for catching minor spillage.

Drain valve: valve at the bottom of a water heater or other appliance, used to drain the appliance.

Drain water heat recovery (DWHR): a device that recovers heat from warm drain water (e.g., a shower or clothes washer) and uses it to preheat fresh water.

Drywall: a prefabricated panel with a gypsum plaster core sandwiched between layers of heavy paper, generally used to create finished surfaces on interior walls and ceilings. Also called wallboard, gypsum board, plasterboard, or Sheetrock.

Dual-flush: denotes a toilet with two flush volumes, one for liquid waste and one for solids.

Duct: a tube, often of sheet metal, that delivers air from the air-handling unit(s) throughout the home, and from the home back to the air-handling unit(s).

Ductless range hood: see Recirculating fan.

Electrical grid: an interconnected system of power plants, transmission and distribution lines, and other equipment through which electricity is produced and transmitted.

Electric-resistance heater: a device that heats water or air using electric- resistance elements (like those in electric stoves).

Electronically commutated motor (ECM): a highly energy-efficient, reliable electric motor used to power furnace and A/C blowers; the blower speed can be electronically varied; often called a variable-speed blower motor.

Electronic ballast: the electronic circuitry that provides the voltage and current needed to start and operate a fluorescent light.

Elevations: architectural drawings that show the vertical face of an interior or exterior wall.

Energy efficiency: a measure of how much useful work output results from a given energy input.

Energy efficiency ratio (EER): term used to rate efficiency of room A/Cs; equals capacity in Btu/h removed from indoor air divided by electrical input in watts.

Energy-efficient mortgage (EEM): an extension of a 30-year FHA first mortgage that provides an additional amount (up to 5% of appraised value as of this writing) to pay for specific energy-saving improvements. Requires a HERS audit.

EnergyGuide label: a large yellow sticker that appears, by law, on new appliances, making it possible to determine which model uses the least energy.

Energy modeling: process for calculating how much energy a building uses for heating, cooling, lights, appliances, water heating, and/or miscellaneous loads.

Energy recovery ventilator (ERV): a ventilation device that exchanges equal amounts of indoor air with outdoor air, transmitting heat and humidity from one airstream to the other for improved energy efficiency.

Energy vampire: see Phantom load.

Evaporative cooler: mechanical cooling equipment that forces dry outdoor air through moist pads, lowering its temperature and raising its humidity, and then delivers that air to the conditioned space.

Exfiltration: leakage of air from inside the conditioned space to outside.

Exterior insulation and finish system (EIFS): a system of rigid foam insulation and synthetic stucco finish that can be applied to the exterior of a building.

Federal Housing Administration (FHA): agency within the U.S. Department of Housing and Urban Development that administers loan programs, loan guarantee programs, and loan insurance programs designed to make more housing available.

FICO (Fair Isaac Corporation) credit score: a number by which lenders determine borrowers’ credit risk.

First-hour rating: the number of gallons of hot water a given tank-type water heater can deliver in an hour, starting with a full tank of hot water.

Flashing: thin, continuous sheet metal (or other impervious material) used to deflect water from an angle or joint on the outside of a building.

Flexible duct: air duct comprising a plastic inner core supported by a helical metal wire, surrounded by a layer of fiberglass insulation and an outer jacket that acts as a vapor barrier.

Flue: a channel or pipe through which combustion gases exit to the outdoors.

Fluorescent: an efficient electric light, usually in the form of a tube, in which illumination is produced by the action of ultraviolet rays on the inside fluorescent coating. See Compact fluorescent light (CFL).

Foam-in-place insulation: insulating material that is applied as a spray with a blowing agent under pressure; when cured, results in an airtight rigid foam insulation conforming to the shape of the assembly.

Foot-candle: a unit of measure of the intensity of light falling on a surface, equal to 1 lumen per square foot.

Fossil fuel: a natural fuel such as petroleum, coal, or natural gas, formed in the geological past from the remains of living organisms.

French drain: a trench or underground passage, filled with gravel or rock and sometimes incorporating perforated pipe, that redirects both surface water and groundwater away from a designated area, such as the exterior of a house.

Full-spectrum light: an electric light source (typically fluorescent) designed to simulate the appearance of noon sunlight.

Furring strip: a small slat or strip of wood used for spacing or nailing.

Gas fill: a gas (usually argon or krypton) sealed between the panes of an insulating glass unit to improve its insulating value.

Gasket: a rubber, plastic, or foam seal between two objects.

General contractor (GC): the contractor with primary responsibility for a construction project, who hires all of the subcontractors and suppliers.

General lighting: see Ambient lighting.

Glazing: the component of windows that allows for the direct transmission of radiant energy, often made of glass or plastic.

Gravity damper: a damper used to control the inflow of outside air down a chimney or exhaust flue. It naturally falls shut when the fan is off; when the fan is on, the air pressure blows the damper open.

Graywater: any wash water that has been used in the home, not including water from toilets.

Green building: the practice of creating buildings using environmentally responsible processes and products.

Grille: a louvered plate attached to either the entry point or the termination of an air duct to cover the hole, look attractive, and (sometimes) direct the airflow.

Gut rehab: a renovation in which finishes (such as drywall) are removed to expose the structural materials.

Halogen light: an incandescent light with a quartz bulb and a gas filling that includes halogen; provides a brilliant light from a compact unit.

Heat exchanger: a device that transfers heat from one medium to another, physically separate medium at a different temperature.

Heat pump: a mechanical device that removes heat from one medium, concentrates it, and distributes it in another medium to heat or cool indoor space.

Heat pump water heater: a heat pump that pulls heat from the air to heat water; about twice as efficient as a standard electric water heater.

Heating load: the amount of heat that must be provided in a given amount of time to maintain building temperature at a given level during the coldest weather.

Heating seasonal performance factor (hSPf): a rating for heat pumps that indicates the number of Btu transferred per kWh of electricity consumed during the heating season.

Heat recovery ventilator (HRV): a ventilation device that exchanges equal amounts of indoor air with outdoor air and exchanges the heat from one airstream to the other for improved energy efficiency.

High-performance window: a window that outperforms conventional windows by lowering energy consumption and increasing occupant comfort.

Home energy professional: a home energy auditor, rater, or contractor who takes a whole-house approach to providing diagnostic and performance testing, energy modeling, air sealing, insulation, and HVAC design.

Home Energy Rating System (HERS): a standard for evaluating a home’s energy efficiency and expected energy costs. HERS professionals are trained and certified by RESNET.

Home performance assessment: a professional evaluation of how your home uses energy.

Humidistat: a sensor used to control a device (such as an exhaust fan) based on the interior humidity level; it keeps the device running until the humidity level drops to an acceptable level.

HVAC: acronym for “heating, ventilation, and air conditioning.”

Hydronic: denotes a heating or cooling system that uses a fluid to transfer heat.

Hydropower: the use of flowing water to generate electrical power.

Ice dam: accumulation of ice at the eaves of a sloped roof, formed as snow is melted by heat leaking from the attic and refreezes at the overhang; allows water to penetrate under shingles.

Incandescent lightbulb: a glass bulb in which a metal filament is heated until it glows to produce electric light; generally less energy efficient than fluorescent or LED lighting.

Indirect lighting: lighting in which the light source is reflected diffusely off the ceiling or walls.

Indoor air quality (IAQ): the quality of air inside a space, especially as it relates to health and comfort.

Induction cooktop: an electric cooktop with an element that produces an oscillating magnetic field, which transfers energy to a cooking vessel without heating up the cooktop itself.

Infiltration: air leakage from outside to inside a conditioned space.

Infrared (IR): the portion of the invisible electromagnetic spectrum that has wavelengths slightly longer than the light human beings see as red.

Insulating concrete forms (ICFs): assemblies of rigid insulation that serve as forms for poured concrete, and remain as permanent insulation.

Insulating glass unit (IGU): a window configuration consisting of two or more glazings separated by a space. Insulation is achieved by thin coatings of metal oxides on the glazing, and by dead air space or inert gases between glazings.

Insulation: material that slows heat conduction.

Integrated control motor (ICM): see Electronically commutated motor (ECM).

Interest: money charged for the use of money.

Interest rate: the percentage of a borrowed amount of money that is charged for the use of that money for a specified time.

Joists: the horizontal structural framing for floors and ceilings.

Jumper duct: a duct connecting grilles in two rooms, allowing air to move between the rooms to prevent pressure imbalances within the conditioned space.

Kelvin (K): temperature scale used to describe the correlated color temperature of a light source.

Kill-a-Watt® meter: a portable meter used to measure electrical energy use of appliances.

Kilowatt: 1,000 watts.

Knee wall: a short wall, generally erected to separate a living space from an attic or to join two rooms with different ceiling heights.

Laundry-to-landscape system: a simple graywater system that reuses laundry water for irrigation.

Lien: a charge against property making it security for the payment of a debt.

Light-emitting diode (LED): an energy-efficient semiconductor device that emits visible light when an electric current passes through it.

Light tube: see Tubular skylight.

Load: the amount of heat that must be provided or removed by an HVAC system to maintain a desired temperature within a building.

Loan: a sum of money lent to one who promises to repay the sum plus interest.

Loan-to-value ratio (LTV): the ratio between the amount of money borrowed and the appraised value of the property.

Loose-fill insulation: fibrous or granular insulation that can be poured or blown into place.

Low-e: low-emissivity; for example, a coating fixed to one of the surfaces of a multipane window that allows short-wavelength visible and near-infrared solar radiation through the window, but reflects back inside longer wavelengths of infrared heat.

Lumen: the unit for measuring light output.

Magnetic ballast: a ballast that uses a magnetic core and coil to provide the voltage and current needed to start and operate fluorescent and high-intensity discharge lights.

Makeup air: air supplied to replace air removed by an exhaust appliance, such as a kitchen range hood.

Manifold: a central branching unit that splits one stream of air or liquid into several channels.

Manual D: industry manual that describes the code-required ACCA method of designing duct systems.

Manual J: industry manual that describes the code-required ACCA method of calculating cooling and heating loads.

Manual S: industry manual that describes the code-required ACCA method of selecting air-conditioning equipment to meet design loads.

Mastic: a thick, creamy, latex-based sealer for ducts and cracks; dries to form a permanent, flexible seal.

Mechanical damper: a damper in a duct, chimney, or flue used to control airflow, operated by a motor that opens or closes the damper on command.

Microclimate: a small, local area with climate characteristics that differ somewhat from those of the average surrounding climate.

Micro-hydropower: hydropower from a generator small enough to be used in a creek.

Mil: a unit of length equal to 0.001 inch.

Mini-split: a heat pump with refrigerant loops connecting an air handler in each room or zone to an outdoor compressor/evaporator; pipes carrying refrigerant thus replace ducts carrying air.

Moist-spray insulation: see Wet-spray insulation.

Moisture barrier: waterproof material, such as polyethylene or house wrap, used to prevent the passage of moisture.

Motion detector: a device that is sensitive to movement; can be used to conserve electricity.

Mudsill: the horizontal framing member that sits on the foundation in a wood-framed house.

Mulch: a protective cover placed over soil to retain moisture, reduce erosion, provide nutrients, and suppress weed growth.

Native plants: plants indigenous or naturalized to a given area.

Negative pressure: a condition in which air is exhausted from a space faster than it is replaced; the resulting drop in pressure can pull in pollutants and cause backdrafting.

Net zero energy (NZE): denotes a home that produces as much energy on-site as it uses over the course of a year.

Neutral pressure: a condition in which the airflow into and out of an area is balanced in volume, and the air pressure differential is zero.

Optimum-value engineering (OVE): a method of framing houses that minimizes the use of wood while improving the builder’s ability to insulate effectively.

Oriented strand board (OSB): engineered wood made of chips or flakes of wood fiber pressed and glued together.

Outgas, off-gas: the process whereby a solid material releases volatile gases as it ages, decomposes, or cures.

Pascal: a metric measure of pressure used by home energy pros to measure air leakage, duct leakage, and other air-related diagnostics.

Passive House standard: a voluntary standard that promotes extreme levels of energy efficiency through a superinsulated, supertight, well-ventilated building envelope, so that the heating-and-cooling system can be radically downsized.

Passive-solar heating: the direct use of solar energy to heat a building.

Peak demand, Peak load, Peak power: a period when power use on the electric grid spikes above normal levels.

Peak-hour demand: the demand on a water heater during the one hour of the day when the most hot water is used.

Perimeter drain: a French drain that collects and drains water away from a building’s foundation.

Permanent-magnet motor: an electrical motor that uses permanent magnets instead of field windings to create torque; far more energy efficient and longer-lasting than older, capacitor-driven motors.

Phantom load: a plug load that uses energy even when nominally turned off or in standby mode. Also called standby load or vampire load.

Photosensor: a device that converts light to electrical current.

Photovoltaic (PV): denotes solar cells that convert the sun’s energy into electricity.

Plug load: the energy used by a product that is powered via an ordinary electrical plug.

Positive pressure: a condition in which air pressure in one area is higher than air pressure in another area, causing the air to migrate from the first area to the second one.

Power strip: a block of electrical sockets that attaches to the end of a flexible cable.

Pressure drop: the decrease in pressure from one point in a pipe or tube to another point downstream.

Programmable timer: a device that allows the user to program when and for how long a given function will occur.

Radiant barrier: a layer of metallic foil, reflective paint, or other material that reflects or reduces the emission of radiant energy.

Radiation: heat transfer in the form of electromagnetic waves from one surface to an unconnected colder surface.

Radon: a colorless, odorless, radioactive, naturally occurring gas that is present in soils and groundwater in varying amounts.

Rebate: a predetermined sum of money returned to the homeowner after purchase of an appliance or building component.

Recessed light: see Can light.

Recirculating fan: a fan, usually over a cooking surface, that does not exhaust the contaminants to the outside, but rather concentrates them and blows them back into the room.

Recirculation system: a distribution system that keeps hot water in the pipes to provide immediate hot water at the taps; generally saves water, but consumes energy to do so.

Register: a grille covering a duct outlet, usually containing a damper to control airflow.

Renewable energy: energy from sources that will last indefinitely, such as the sun, wind, tides, and the earth’s heat.

Residential Energy Services Network (RESNET): a recognized national standards-making body for building energy efficiency rating and certification systems.

Return ducts: the ducts in a forced-air heating or cooling system that bring house air to the furnace or A/C to be heated or cooled.

Rim joist: the outermost joist around the perimeter of the floor framing.

R-value: the resistance of a material to heat transfer by conduction; a higher R-value indicates better insulation.

Sacrificial anode: a replaceable magnesium or aluminum rod that corrodes before steel can rust, preventing damage to the water heater tank.

Sconce: a wall-mounted electric light fixture that washes the wall with light in an upward and/or downward direction.

Sealed-combustion: denotes a fossil-fuel heater that provides outside air directly to the burner, rather than using household air.

Seasonal energy efficiency ratio (SEER): a rating for central A/Cs and heat pumps representing the cooling output for a season in Btu divided by the electrical input in kWh required to achieve that cooling.

Section: an architectural drawing of a vertical slice through the building, depicting spatial, structural, and finish features.

Secured loan: a loan backed by property in case of default.

Sensible heat ratio (SHR): an A/C rating that indicates the fraction of the evaporating coil’s capacity used for reducing temperature, as opposed to condensing moisture from the air. The higher the SHR, the smaller the fraction of capacity used to remove moisture from the air.

Setback thermostat: combines a clock and a thermostat so that heating and cooling can be reduced during periods when less is needed—for example, at night.

Shaded-pole motor: an old-fashioned, inefficient blower motor.

Shaving the peak: reducing peak demand by reducing energy use.

Simple solar water heating: an uninsulated water storage tank placed in a warm environment to preheat the water simply and inexpensively.

Smart energy devices: digital gadgets and tools, often Internet enabled and wireless, that measure, manage, or control consumer energy use.

Smart meter: a digital meter that records household energy consumption in or near real time, and transfers the data to the utility through a communications network; also called advanced metering.

Smart power strip: one that can shut down power to devices when they go into standby mode.

Smoke pencil: a tool that releases a smoke-like substance used to detect air leaks.

Smooth metal duct: air duct constructed of either rigid round or rectangular sheet metal; the smooth surface allows air to move through with little frictional resistance.

Solar heat gain coefficient (SHGC): the fraction of solar radiation falling on a window, glazed door, or skylight that is admitted into the house as heat; the lower a window’s SHGC, the less solar heat it admits into the house.

Solar radiation: radiant energy from the sun, including ultraviolet, visible, and infrared wavelengths.

Solar-thermal: denotes a system that converts sunlight into heat, typically by using the sun to heat water or air.

Solar tube: see Tubular skylight.

Solar water heating: uses energy from the sun to heat water directly.

Sone: a sound rating; fans rated at 1.5 sones and below are considered very quiet.

Split-capacitor motor: an older type of blower motor; not very energy efficient.

Spot ventilation: ventilation provided in a limited area to remove contaminants produced in that area, such as smoke in the kitchen or steam in the bathroom.

Sprayed foam: see Foam-in-place insulation.

Stack effect: the upward movement of air in a building or chimney due to the tendency of warm air to rise.

Standby load: see Phantom load.

Steam oven: a midsize oven that cooks via steam, reducing cooking time in comparison to that of a standard oven.

Stem wall: the vertical portion of a foundation wall or retaining wall, designed to carry a structural load above it without lateral support at the top or bottom.

Structural insulated panel (SIP): a composite building material consisting of rigid insulation sandwiched between two layers of structural board.

Subcontractor: a trade professional who specializes in a particular aspect of a construction project, such as electrical, plumbing, or painting.

Subfloor: a rough floor (typically plywood) over which finished flooring is laid.

Sun pipe: see Tubular skylight.

Sun space: a glazed room designed to collect solar heat, which is used to heat the rest of the house.

Supply ducts: the ducts in a forced-air system that supply heated or cooled air from the furnace or A/C to the house.

Swamp cooler: see Evaporative cooler.

Tankless water heater: a water heater with no storage tank that heats water as needed, using large electric elements or gas burners.

Task lighting: light directed to a specific work area or surface.

Tax credit: an amount that is subtracted from the tax due.

Temperature and pressure relief valve: a safety device on storage water heaters that reduces dangerously high temperatures or pressures if they build up inside the tank.

Tempered glass: glass that has undergone a heat treatment that strengthens it and decreases likelihood of breakage.

Termite barrier: a continuous material between the foundation and the structure of a building through which termites cannot tunnel.

Thermal boundary: the border between conditioned and unconditioned space where insulation is placed.

Thermal break: a relatively less conductive material used as part of an assembly to reduce thermal transmittance through more conductive materials.

Thermal bridge: a break in the continuity of insulation in a wall, ceiling, or floor that allows heat to flow more readily between inside and outside.

Thermal mass: materials inside the building envelope (e.g., masonry, stone, tile, concrete, or water) that absorb heat during the day and release the heat as the space cools at night.

Thermal resistance: the ability to retard heat flow, expressed as R-value.

Thermal traps: the curved pipes or check valves that prevent hot water from rising into the cold-water inlet pipe (also known as heat traps).

Thermosyphon: a system in which a heat-storing liquid is circulated by convection, not requiring a mechanical pump.

Tint: a mineral coloring incorporated into the glass pane of a window to reduce solar heat gain.

Title insurance: a policy that protects the property owner from loss sustained by defects in the title to the property.

Tons of cooling: a measure of A/C capacity; one ton of air conditioning is 12,000 Btu/h.

Torchiere: a floor lamp that provides indirect light by sending most of its light upward.

Track lighting: a lighting system with an electrically fed linear track that accepts one or more track heads.

Trade contractor: see Subcontractor.

Transfer grille: see Jumper duct.

Transformer: a small electronic pack that plugs into an electrical outlet to transform house electrical current to the form required by a computer, phone, or rechargeable device.

Tubular skylight: a cylindrical skylight with a small diameter that fits between existing roof framing members. The walls of the cylinder are highly reflective, bouncing a strong beam of sunlight into the living space.

U-factor: a measure of how much heat is conducted through a window. U-factor is the inverse of R-value; the lower the U-factor, the better the window insulates.

Ultraviolet (UV): describes radiation beyond the violet end of the visible spectrum, with wavelengths shorter than those of visible light and longer than those of X-rays.

Unconditioned space: any space that is enclosed by the walls, roof, and foundation of a house and that is not heated or cooled. Examples include an unfinished basement, attic, garage, or crawl space.

Underwriting: the part of the loan approval process that entails guaranteeing or assuming liability for the loan amount.

Unsecured loan: a loan backed only by the consumer in case of default, with no real property asset as security.

Unvented crawl space: one that does not provide vents to the outside.

Vampire load: see Phantom load.

Vapor barrier: a material that is impermeable to water vapor.

Vapor retarder: a continuous layer of materials that resists the passage of water vapor by diffusion (e.g., polyethylene, aluminum foil, low-permeability paints, vinyl wall covers, impermeable rigid insulations, sheet metal, plywood, or waferboard).

Variable speed: an electromechanical feature that allows pump or fan speeds to be changed, either continuously or in increments, thereby increasing efficiency, comfort, or both. See Electronically commutated motor (ECM), Integrated control motor (ICM).

Vented crawl space: an unconditioned crawl space that allows outside air to bring in heat and/or moisture.

Ventilation: the controlled movement of air into and out of a house.

Visible transmittance (VT): the fraction of visible light falling on a window, glazed door, or skylight that is transmitted through it.

Wall cavity: the space between the studs of a wall.

Wall sheathing: a structural component, such as plywood or OSB, installed as part of the wall assembly. Sometimes rigid insulation board is also called nonstructural wall sheathing.

Waterless urinal: a urinal that uses no water to flush; minimizes odors using a sealant cartridge or deodorant block.

Watt-hour: the work done by 1 watt in one hour.

Watt (W): a unit of power.

Weather shell: the outer layer of a home that keeps rain, wind, and snow from getting into building assemblies or conditioned space.

Weather strip: foam, bronze, or vinyl strips or gaskets attached around the moving parts of doors and windows to reduce air leaks.

Wet-spray insulation: loose-fill fiber insulation mixed with water and sometimes adhesives that can be blown into open cavities or on irregularly shaped areas. Damp-spray and moist-spray insulation are mixed with less water and dry faster.

Whole-house fan: a large fan, commonly installed high in a wall or in the opening to an unconditioned and ventilated attic. It flushes the house by pulling outdoor air in through open windows as it exhausts hot air to the outside.

Wind power: the conversion of wind into electricity via a generator called a wind turbine.

Work triangle: an arrangement of stove, refrigerator, and kitchen sink that provides adequate work space, with no more than two of the three appliances along the same wall.

Zero peak: denotes a home designed to draw no electricity from the power grid during peak hours.

Zoning (zoned): designing the HVAC system so that different areas of the house can be set to different temperature levels.

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