Reconciling retrofitting with IEQ to maintain energy, environmental and economic performance: A methodological approach for generic office buildings

Office building retrofitting may instigate significant reductions in energy consumption and there is growing recognition that buildings' energy, economic and environmental performances (the 3Es) must be considered in tandem. This study aims at maintaining the 3Es when retrofitting office buildings towards nZEB standards. A simulation-based methodology was designed consisting of three generic building forms describing common office building geometries constructed between 1952 and 1980 in Egypt; linear, square with courtyard and L-shaped. Each accommodated for open, closed and semi-closed office layouts as recommended in architectural manuals, and was oriented in four directions, giving 36 base cases. A combined retrofitting strategy was applied and both base cases and retrofitted cases were simulated in DesignBuilder using Cairo weather data, which was validated indirectly through real measurements using preliminary simulations that retrieved statistical significance. Results were analyzed for each of the 3Es by comparing base cases to post-retrofitting performances. Results revealed that not all retrofitted cases that demonstrate acceptable environmental performance and/or energy- efficiency are cost-optimal. However, the following patterns were deduced. Square courtyard buildings yield superior performances, and L-shapes tend to perform outside acceptable ranges. Closed plans demonstrate superior energy and environmental performance but poorer economic performance. 17 out of 36 retrofitted cases achieved nZEB, illustrating the potential of implementing nZEB in Egypt. This work may be considered prototypical, encouraging a national office building retrofitting process toward nZEB. However, implications extend beyond the national level, as results may be used to support a kick-off retrofitting programme based on basic office building geometries.