In this century, the world has already witnessed the biggest increasein its population in human history, which led to the increase of theuse of the land and shrinking green areas. The main concern of thepresent thesis is the city which is characterized by higher nighttimetemperature compared to rural areas. This phenomenon is known asan urban heat island (UHI). UHI leads to degraded comfortconditions both outdoor and indoor, and as a result, higher energyconsumption for cooling.One of the main reasons for the UHI is the materials used forbuilding envelope and urban areas. Many attempts have been madeto avoid UHI by using a new type of materials such as usingmaterials with high solar reflectance. In addition, these types ofmaterials help minimize energy consumption if used on an urbanscale. In our research, we address the building envelope designwith respect to its main types of construction materials as well as itslayer design and its shape to mitigate the urban heat island andachieve energy consumption reduction. The work is applied on oneof the important residential complexes in Mosul city – Iraq, which willbe constructed in many cities in Iraq. The weather of the Mosul cityis characterized by hot semi-arid climate. In summer, the climate isdry and extremely hot, whereas it is very cold and the temperaturesare down to below zero in winter. The main objective of this researchis to propose an appropriate building envelope design and designstrategy which provides high thermal performance regarding theexterior and interior surface temperature, high-level of indoor thermalcomfort with minimum energy needed, reduce the air temperaturedifference between the city and its surrounding rural area. It tacklessome important questions that are related to the case study: What isthe relation between the building envelope design and the followingaspects: 1. The external surfaces temperature of buildings andurban surfaces which lead to raise the air temperature, and finallycontribute to the UHI phenomenon, 2. The indoor surfacestemperature of buildings which influence the indoor thermal comfortand the energy needed to maintain this level of comfort?To answer the research questions, simulations have been achievedby using Solene-microclimat. From simulation results, it is shownthat it is possible to find different combinations of materials, formsand surface coatings to both to reduce the interior and exteriorsurfaces temperature and consequently, maintain indoor andoutdoor thermal comfort. We also show that the strategy can bedifferent depending on the surface exposure to the sun and theinteraction between surfaces. We propose a methodology to find thebest combination depending on the case study.