Selecting the Optimal Thermal Insulation Material for a Residential Building Envelope in Cairo in Consideration of The Thermal Comfort and Energy Consumption


  • Youssef O. Elkhayat
  • Seham A. Elmozy Faculty of Engineering, Tanta University
  • Ingy I. El-Darwish



energy consumption, optimization, residential buildings, thermal comfort, thermal insulation, XPS


As a result of the current global energy crisis, there is a universal tendency towards energy-saving in the housing sector. In Egypt, mega housing projects such as "Dar Misr" are established to provide apartments for middle-income families. The envelopes of those buildings play a significant role in the increased heat gain of indoor spaces. Therefore, this study aims to assess the thermal performance and calculate the energy savings of five thermal insulation materials available in the market; (Vermiculite, Rockwool, Phenolic Foam, Extruded Polystyrene (XPS), and Polyethylene). The assessment is for those materials installed in the apartment's external walls to find the optimal material that achieves the most extended annual indoor thermal comfort hours and the highest annual energy-saving. An apartment in a typical floor was modeled by DesignBuilder software to calculate the indoor thermal comfort hours and energy consumption for the five alternatives. The results show that thermal insulation materials inside the external walls are pivotal in reducing heat gains and extending comfort hours. The optimal insulation material is XPS which achieved thermal comfort for 33% of the year compared to 28% and 29% by the Phenolic Foam and Rockwool, respectively. Moreover, the XPS saved 9.27% of the annual energy consumption, which is the highest energy-saving ratio compared to Polyethylene (6.21%) and Vermiculite (2.4%).