Wall insulation measures for residential villas in Dubai: A case study in energy efficiency

Over the past decade Dubai's energy demand has increased in sync with the rapid urban development and population growth of the UAE. In particular the residential villa stock has grown by more than 300% from 20,000 villas in 2000 to over 60,000 villas in 2009. In order to limit energy consumption, the local authorities introduced building legislation (2001 and 2003) that prescribes minimum insulation levels for external walls and roofs. The resulting constructive solutions focus on the use of a mid-plane insulated prefabricated block to attain the prescribed maximum wall U value (0.57 W/m2 K), however the reinforced concrete frame typically remains non-insulated, and thus introduces significant thermal bridges in the building envelope. This work investigates the impact of this thermal bridging effect on the building's energy consumption by modeling (hourly simulation using DesignBuilder/EnergyPlus) the energetic performance of a series of typically applied insulation strategies, both for buildings in the initial design stage, and in retrofit mode. The simulation model is calibrated against collected consumption data and experimental infiltration measurements of the actual building. Simulation results show that with appropriate external wall insulation strategies alone, energy savings of up to 30% are realized.

► We study wall insulation strategies that evolved from emerging local energy codes.
► An energy model is constructed and benchmarked with an as-built villa.
► The effect of thermal bridging on the energy efficiency of the villa is modeled.
► Results indicate significant thermal bridging, and can be decreased by over 25%.
► Full perimeter external insulation measures prove highly effective.