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Knowledgebase : Materials and Constructions

1. For radiant barriers which are exposed to a thermal zone, such as an attic space, specify a reduced thermal absorptance for the innermost material layer. For example, an attic roof construction might be (outer to inner) Asphalt shingles, R-30 insu...
Emissivity is not the same as absorptance/absorptivity. Not even close. Emissivity is measured in Far IR range (thermal radiation), while asbortptivity is measured in Solar (UV, VIS, Near IR) range. Big difference, since solar radiation is at approximatel...
In the Engineering Reference, there is a section named "Outside Surface Heat Balance"... which contains a subsection named "External Longwave Radiation": External Longwave Radiation q"LWR is a standard radiation exchange formulation between the surface...
Q: I would like to know how E+ is calculating the emissivity of materials (not the glazing ones). I am guessing it is an indirect proceedure, as there is no specific input field for this subject. A: In EnergyPlus input there are three different waveleng...
Question: would you tell me please in which document or book or website i can find material's characteristic such as u value, density, and conductivity Answer: There's an entire database of materials and constructions (from ASHRAE and other sources) ...
Question: I am working with energy plus in sketchup on the quest for one model. What I am trying to do is to trace the external geometry from a 3d daylighting model and to build my energy plus model and then apply thicknesses internally afterwards to ...