Unit of heat equal to 100,000 British thermal units (Btus); commonly used for natural gas.

Heat flow that occurs across more conductive components in an otherwise well-insulated material, resulting in disproportionately significant heat loss. For example, steel studs in an insulated wall dramatically reduce the overall energy performance of the wall, because of thermal bridging through the steel.

A camera that provides an image showing radiation in the infrared range of the electromagnetic spectrum. Since the amount of infrared radiation emitted from a surface varies with temperature, a thermal imaging camera is a useful tool for detecting hot or cold areas on walls, ceilings, roofs, and duct systems. When used to scan a building envelope, a thermal imaging camera can detect missing insulation or locations with high levels of infiltration. Thermal imaging cameras can provide useful information when the difference in temperature (delta T) between the indoors and the outdoors is as low as 18F°; however, the higher the delta T, the easier it is to see building defects.

Heavy, high-heat-capacity material that can absorb and store a significant amount of heat; used in passive solar heating to keep the house warm at night.

In wood-frame construction, the framing member that forms the top of a wall. In advanced framing, a single top plate is often used in place of the more typical double top plate.

Round skylight that transmits sunlight down through a tube with internally reflective walls, even through an attic space; it delivers daylighting through a ceiling light diffuser. Most tubular skylights are 12 to 16 inches in diameter and deliver daytime lighting comparable to several 100-watt incandescent light bulbs.