Door thermal performance speaks to door thermal specifications and door thermal regulations.
They are considerations of the designer’s task in selecting doors, windows and skylights using testing programs that allow objective comparisons of the structural, thermals and other requirements of products of different types and from different manufacturers.
Thermal energy is the part of the total potential energy and kinetic energy of an object or sample of matter that results in the system temperature. This quantity may be difficult to determine or even meaningless unless the system has attained its temperature only through cooling, and not been subjected to work input or output, or any other energy-changing processes.
The internal energy of a system, also often called the thermodynamic energy, includes other forms of energy in a thermodynamic system in addition to thermal energy, namely forms of potential energy that do not influence temperature, such as the chemical energy stored in its molecular structure and electronic configuration, intermolecular interactions associated with phase changes that do not influence temperature (i.e., latent energy), and the nuclear binding energy that binds the sub-atomic particles of matter.
The first of these standards is the Standard/Specification for Windows, Doors and Unit Skylights, jointly published by the American Architectural Association (AAMA), the Window and Door Manufacturers Association (WDMA) and the Canadian Standards Association (CSA) officially designated as AAMA/WDMA/CSA 101/I.S.2/A440.
Thermal performance speaks with regard to energy efficiency, the National Fenestration Rating Council (NFRC) sponsors a program of testing and labeling based on the standards Procedure for Determining Fenestration Product U Factors, NFRC 100 and Procedure for Determining Fenestration Product Solar Heat Gain Coefficient and Visible transmittance at Normal Incidence, NFRC 200.
The two most important properties included in these standards are thermal transmittance (U Factor) and solar heat gain coefficient,, both of which directly impact building energy consumption and are regulated by energy codes. Importantly U Factors represent the overall thermal transmittance or whole product heat loss, of complete window, door and skylight products.
That is, they account for the combined contributions to thermal transmittance of the center of glass, edge of glass, framing and other components. Visible light transmittance air leakage and condensation resistance ratings may also be included in NFRC ratings. An example of a standard label that is affixed to each NFRC rate door may be viewed online.
Both AAMA/WDMA/CSA and NFRC standards are referenced by the International Building Code, making them the de facto standards for the selection of most building fenestration products sold in the United States and Canada.