Metal, usually galvanized sheet metal, used to provide protection against infiltration of precipitation into a roof or exterior wall; usually placed around roof penetrations such as chimneys.

A column of gas at standard conditions of temperature and pressure (32 degrees Fahrenheit and one atmosphere).

A slightly sloped roof, usually with a tar and gravel cover. Most commercial buildings use this kind of roof.

Materials that prevent or slow down the movement of heat.

Pounds/force per square inch gauge.

The push or pull that alters the motion of a moving body or moves a stationairy body; the unit of force is the dyne or poundal; force is equal to mass time velocity divided by time.

The relative extent that energy is required for a process.

A high-efficiency photovoltaic device containing two or more cell junctions, each of which is optimized for a particular part of the solar spectrum.

A measure of the efficacy (efficiency) of lamps. It indicates the amount of light (lumens) emitted by the lamp for each unit of electrical power (Watts) used.

The water content of a substance (a solid fuel) as measured under specified conditions being the: Dry Basis, which equals the weight of the wet sample minus the weight of a (bone) dry sample divided by the weight of the dry sample times 100 (to get percen ...

A particle of light that acts as an individual unit of energy.

A type of heating appliance that performs more than one function, for example space and water heating.

One millionth of a meter (10-6 m).

A thermodynamic property of a substance, defined as the sum of its internal energy plus the pressure of the substance times its volume, divided by the mechanical equivalent of heat. The total heat content of air; the sum of the enthalpies of dry air and w ...

The amount of energy absorbed (or converted) by a solar collector (or photovoltaic cell or module) over a 15 minute period.

The lowest wind speed at which a wind turbine begins producing useable power.

A system of astronomical time in which the sun crosses the true north-south meridian at 12 noon, and which differs from local time according to longitude, time zone, and equation of time.

A general term for the visible and near visible (ultraviolet and near-infrared) electromagnetic radiation that is emitted by the sun. It has a spectral, or wavelength, distribution that corresponds to different energy levels; short wavelength radiation ha ...

A photovoltaic device where incident sunlight is split into different spectral regions, with an optical apparatus, that are directed to individual photovoltaic cells that are optimized for converting that spectrum to electricity.

A toilet that uses less water than a standard one during flushing, for the purpose of conserving water resources.