Fully Glazed Office Building Façade Designs in Denmark

Abstract: The current trend in office building architecture includes large glazed areas that give transparent architecture. But these buildings have a challenging indoor climate and a higher energy use than required by current building regulations in Denmark. The limits for Building Class 2020 (BC2020) is 25 kWh/(m²·year) where an integrated Renewable Energy Source (RES) is used for lowering an actual building’s energy use. Now general building quality and sustainability are ensured by building certification systems. The German Sustainable Building Council (DGNB) certification fulfils the Danish building market needs and the Danish DGNB certification system was created in 2012. The combination between a fully glazed office building that reaches DGNB platinum level and fulfils the previously mentioned BC2020 energy use requirement seems impossible. The aim of the thesis is therefore to determine if a single-skin fully glazed office building façade can meet DGNB platinum level where the thermal and visual comforts, building envelope quality and the best economy are the main criteria. The BC2020 energy requirements should also be fulfilled. The office building called “Health Centre” was used as a reference case for a BC building. It was equipped with two types of offices: landscape and cell. They were facing all four cardinal directions. The thermal analyses for these cases were performed by simulations for operative and surface temperatures, while the visual comfort simulations output was a Daylight Factor (DF). The annual glare analyses as well as point-in-time glare simulations were created in further investigation for the visual comfort, as it was an issue. The building envelope quality was ensured by U-value calculations for external wall and the glazed part of the façade. The next considered element in this thesis was LCC calculations where the glazed part of the façade was analysed (various g-values, self-cleaning glass, two external shading types). And the annual energy use calculations summed the analyses up as they examined whole building performance. The study concluded that the office building, located in Denmark and equipped with the fully glazed façade, could meet the DGNB platinum level requirements for the thermal and visual comforts, the building envelope quality at the lowest price when the cell office layout was selected. For the landscape offices the DGNB visual comfort platinum requirement was not reached, as working planes were located too far from façades where daylight levels were low. The alternative that had the lowest LCC was selected to be the façade with the external screen shading combination with self-cleaning glass that had U-value of 0.6 W/(m²·K). In that case, the BC2020 energy use requirement was reached, but the building was not an energy-efficient office, as the RES implementation provided needed electricity power that reduced the building’s energy use to the BC2020 level. A larger amount of solar cells had to be integrated to compensate the building design issues. On the other hand, RES integration is more environmental-friendly solution than using other sources. Generally, the office building façade design with large glazed areas is a complex issue, as it requires detailed analyses of many parameters that influence the overall building quality.