Wall/roof thermal performance differences between air-conditioned and non air-conditioned rooms

摘要

A one dimensional heat transfer model for periodic outdoor conditions is presented and used to evaluate the thermal performance of a monolayered and multilayered envelope wall/roof in an air-conditioned and in a non air-conditioned room. Three materials are tested for a monolayered wall/roof: high density concrete (HDC), aerated concrete (AeC), and expanded polystyrene foam (EPS). Three multilayered walls/roofs of width 0.10 m composed of a sheet of 0.02 m of EPS and the rest of HDC are considered. The EPS can be on the outside, middle or inside of the wall/roof. The main conclusion is that an appropriate wall/roof for an air-conditioned room may not be suitable for a non air-conditioned one. For the monolayered wall/roof and conditions under study, it is found that in an air-conditioned room the most important physical property of the wall/roof is its thermal conductivity, which has to be as small as possible, while for the non air-conditioned room the most important physical property is the thermal diffusivity, which also has to be as small as possible. In this case the position of the insulation in a multilayered wall/roof is important.