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Ways to improve roof insulation.

Des pistes d'amélioration de l'isolation des toitures.

Author(s) : HADDEDI I., DAOUAS N.

Type of article: Article

Summary

A model based on the Fourier complex transform method was developed in order to determine a precise solution for transient heat transfer across a multilayer roof subjected to the specific weather conditions encountered in Tunis. This method was applied to a typical roof structure subjected to the weather conditions during a representative summer day. The numerical calculations, performed using a MATLAB code, made it possible to study the effect of the thickness of the insulation and the location and number of layers of insulation on the thermal comfort inside. The results obtained demonstrated that roofing has better thermal inertia when the insulation is divided into two or three layers. The highest phase shift values and the lowest damping factor values (11.86h and 0.34% respectively, versus 6.24 h and 11.65% where there was no insulation) are obtained by placing half of the insulation in the middle of the roofing and the other half on the external surface of the roof. The best insulated roof performance is achieved when the insulation is divided into three layers. In poorly insulated old buildings, cool roofs are a good alternative to insulation. In this context, we studied the influence of solar reflectivity on infrared emissivity on the surface of the roof on energy consumption. The results demonstrate that an increase of 0.2 in the solar reflectance coefficient (for a traditional roof) to 0.89 (following application of cooling paint), reduced the maximum temperature of the roof by 18°C and the daily cooling load by 0.45 kWh/m, i.e. a 61% reduction.

Details

  • Original title: Des pistes d'amélioration de l'isolation des toitures.
  • Record ID : 30019820
  • Languages: French
  • Source: Revue générale du Froid & du Conditionnement d'air - n. 1157
  • Publication date: 2016/05

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