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Installed faced fiberglass batt insulation with its R-value visible (R-21) [1]. The R-value (in K⋅m 2 /W) is a measure of how well a two-dimensional barrier, such as a layer of insulation, a window or a complete wall or ceiling, resists the conductive [2] flow of heat, in the context of construction. [3]
Thermal insulation is the reduction of heat transfer (i.e., the transfer of thermal energy between objects of differing temperature) between objects in thermal contact or in range of radiative influence. Thermal insulation can be achieved with specially engineered methods or processes, as well as with suitable object shapes and materials.
For a heat engine, thermal efficiency is the ratio of the net work output to the heat input; in the case of a heat pump, thermal efficiency (known as the coefficient of performance or COP) is the ratio of net heat output (for heating), or the net heat removed (for cooling) to the energy input (external work). The efficiency of a heat engine is ...
ISO 9869 describes how to measure the thermal transmittance of a structure experimentally. Choice of materials and quality of installation has a critical impact on the window insulation results. The frame and double sealing of the window system are the actual weak points in the window insulation.
Sheep's wool insulation is a very efficient thermal insulator with a similar performance to fiberglass, approximately R13-R16 for a 4-inch-thick layer. [22] Sheep's wool has no reduction in performance even when condensation is present, but its fire retarding treatment can deteriorate through repeated moisture. [ 23 ]
The above equation only takes into account the temperature differences and ignores two important parameters, being 1) solar radiative flux; and 2) infrared exchanges from the sky. The concept of T sol-air was thus introduced to enable these parameters to be included within an improved calculation. The following formula results:
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The House Energy Rating (HER) or House Energy Rating Scheme (HERS) are worldwide standard measures of comparison by which one can evaluate the energy efficiency of a new or an existing building. The comparison is generally done for energy requirements for heating and cooling of indoor space. The energy is the main criterion considered by any ...