Double Skin Building Envelopes and their impact on the HVAC Systems and energy efficiency of Buildings

Case studies were used in order to examine the impact on designing and dimensioning of building service systems as well as the overall energy efficiency of buildings. The essential outcome of this research was the understanding that the energy efficiency of buildings with double skins depends on whether the double skin faade allows the elimination of building services i.e. mechanical ventilation. If this is not the case, it can take up to 25 years for the initial manufacturing energy of the second skin to redeem through operation energy savings. However, if a complete building service system can be eliminated by constructing a second building skin, the payback time can be reduced to a reasonable time frame, in some cases even within two years. The investigated case studies clearly show, a highly efficient double skin faade not only can improve the energetic building behavior but also help reduce investment costs of building services significantly. That is why the economic efficiency of such a measurement should not only be evaluated towards the potential to reduce costs for energy but also in correlation of a possible reduction of investment costs for HVAC- systems in the building. A mere reduction in size of building services more often than not have not happened on a noteworthy scale in terms of savings.