Single and Double Skin Glazed Office Buildings - Analyses of Energy Use and Indoor Climate

University dissertation from Energy and Building Design, Lund University

Abstract: The energy efficiency and thermal performance of highly glazed office buildings are often questioned. However, nowadays glazed buildings are increasingly being built around the world, mainly due to an architectural trend, followed by the preference of companies to a distinctive image that a glazed office building can provide. Due to insufficient knowledge concerning the performance as to energy use and indoor environment of glazed office buildings, a project was initiated, in order study their possibilities and limitations for Scandinavian conditions. The aim of this PhD thesis is to (a) determine how the energy and indoor climate performance can be analysed, (b) clarify and quantify how highly glazed facades affect the energy use and thermal comfort and (c) determine how the design can be improved with regard to energy efficiency, thermal and visual comfort. The first part of this project involved establishing a reference building with different single skin glazed alternatives, choosing simulation tools and carrying out simulations for the determined alternatives. Results were obtained through varying the building’s orientation, the interior layout and the type of glazing and solar shading devices. In the second part, the performance of various double skin façade cavity alternatives was studied, in order to study the possibilities and limitations of the system’s performance. Simulations on an office zone and a building level were then carried out, in order to achieve optimal integration of the system. The results showed that, unless designed carefully, highly glazed buildings tend to perform poorly, resulting in increased energy use and poorer thermal environment. For Swedish climatic conditions during winter months, windows with low thermal transmittance are essential, in order to improve the building’s energy performance and thermal comfort, especially for highly glazed buildings. Low g and especially geffective values have a positive effect in lowering the cooling demand; externally placed shading or double skin facades can have this effect. In general, double skin façades result in improved energy and thermal performance of the building mainly when applied on the south façade, but their impact is limited since the cooling demand is usually rather limited, compared with the heating demand, for Scandinavian climatic conditions. Achieving improved building performance when using fully glazed façades can be a great challenge. Individual building design that takes into consideration the type of façade including the size and type of glazing, the position of shading devices, the temperature set points, the building occupancy and plan type can definitely lead to improved building performance. If this is established, even in highly glazed cases, the building performance may reach reasonable levels as to energy use and indoor climate. However, a building with low energy demand cannot be achieved by a highly glazed building in a Scandinavian climate.