ICC Res Energy key terms

The range of work covered by the residential energy code, typically new dwellings, additions, alterations, repairs, and changes of occupancy, plus the systems and equipment installed as part of that work.

The authority having jurisdiction who reviews plans, issues permits, conducts inspections, and determines whether a building complies with the adopted energy code.

Plans, calculations, product listings, and certificates submitted with a permit application that show how the project meets each applicable energy code requirement.

A geographic category, numbered 1 through 8, that groups locations with similar weather so the code can set insulation and efficiency requirements matched to local conditions.

The boundary separating conditioned interior space from unconditioned or exterior space, made up of walls, roofs, floors, windows, doors, and the seals between them.

A combination of materials and assemblies that are sealed and joined to limit air movement through the building thermal envelope without gaps or breaks.

Unintended movement of air through cracks, joints, and penetrations in the building envelope, which wastes energy and can bring in moisture or pollutants.

A measure of a material's resistance to heat flow; higher numbers mean better insulating performance. Insulation levels in the code are usually stated as R-values.

The rate of heat flow through an assembly or product, equal to the inverse of its R-value; lower U-factors mean better performance and are used for windows and doors.

Windows, skylights, glazed doors, and similar transparent or translucent openings in the building envelope, which are regulated for U-factor and solar heat gain.

The fraction of solar radiation entering through a window or skylight as heat. Lower values reduce cooling loads in sunny climates.

A material, such as a membrane or coated facing, installed to slow the movement of water vapor through building assemblies and reduce condensation risk.

Insulation, such as fiberglass batts or loose fill, that air can pass through easily, so the code requires a separate air barrier and often a protective cover.

A room-by-room engineering calculation of heat loss and gain used to size heating and cooling equipment properly, so units are not oversized or undersized.

Thermal insulation applied to ductwork, with a required R-value that depends on duct location and climate, to limit heat gain or loss through the duct walls.

Air escaping from or entering ducts through joints and seams, measured by a pressure test and limited by the code when ducts run outside conditioned space.

Duct runs located inside the insulated, conditioned envelope. The code strongly favors this arrangement because it avoids the large energy losses of ducts in attics or crawlspaces.

A control that automatically adjusts heating and cooling setpoints on a daily schedule so the home uses less energy when occupants are asleep or away.

Deliberately supplied outdoor air, delivered by fans and ducts, to maintain indoor air quality in a tightly built dwelling that leaks little on its own.

A balanced ventilation device that transfers heat between outgoing stale air and incoming fresh air to reduce the energy penalty of ventilating a home.

A fan and duct system that removes moisture, odors, and pollutants at their source, such as in bathrooms and kitchens, and discharges them outdoors.

The rated efficiency of heating and cooling units, expressed as SEER, HSPF, or AFUE, which must meet minimum values in the code for the equipment type.

The energy used to heat water for domestic purposes such as bathing, cleaning, and cooking, covered by rules on equipment efficiency, piping, and controls.

A standardized rating of water heater efficiency that accounts for both standby losses and the energy delivered, used to compare models and set code minimums.

Insulation wrapped around hot water pipes, required on specified runs to reduce heat loss between the water heater and the fixtures.

A device that preheats incoming cold water using heat from warm water going down the drain, reducing the energy the water heater must supply.

A light fixture that meets the code's minimum efficiency, typically using LED or fluorescent lamps, counted to satisfy the requirement for energy-efficient lighting.

Devices such as dimmers, occupancy sensors, or timers that turn lights off or reduce their output when light is not needed.

A designated unobstructed area of roof, plus reserved conduit and equipment space, kept available so photovoltaic or solar thermal panels can be added later.

A compliance method in which each building component must meet preset table values, such as minimum R-values and U-factors, without trade-offs between components.

A compliance method that compares the proposed home's annual energy use with a reference home of the same shape and size, allowing trade-offs among components.

A prescriptive-based method that sums the U-factor times area of all envelope components and allows trade-offs as long as the total does not exceed the code baseline.

A score comparing a home's energy performance to a standard reference home, produced by accredited rating software, that a code may accept as an alternative compliance path.

Requirements that apply to every project no matter which compliance path is chosen, such as air sealing, thermostat controls, and insulation installation criteria.

A published technical document, such as an ASHRAE, ACCA, ASTM, or RESNET standard, that the code adopts by citation and thereby makes part of its requirements.

A referenced standard for ventilation and indoor air quality in low-rise residential buildings, defining required outdoor air rates and exhaust capacities.

A diagnostic test that pressurizes or depressurizes a home with a calibrated fan to measure whole-house air leakage, often required to show envelope tightness.

Construction work that changes an existing building's components or systems without adding floor area; the code applies specific, sometimes limited, requirements to it.

New floor area or volume added to an existing dwelling, which must generally comply with the code as if it were new construction.

A building officially designated as historically significant, which may be exempted from some energy code requirements in order to preserve its character.