Cooling demand in commercial buildings-The influence of building design

Licentiate thesis, 2005

Large window areas and glass façades have become popular by architects. As the glass architecture has become fashionable in quite a short time it seems that the architects are not always aware of the energy consuming consequences that the highly glazed buildings, sometimes in combination with special room plans might cause. In order to avoid overheating problems high cooling capacities are needed for removing the surplus heat from the room. It often makes the first investment cost for an office building’s cooling system high. In some cases the overheating problem has not been fully considered and it has brought along high room temperatures as result. The objective of the thesis is to show how the façade design and the room design influence the peak cooling load and the need of cooling energy. The size and the cost of the HVAC system strongly depended on the peak load. Therewith the architectural design is decisive for the HVAC solutions needed. The influence of the building design on the need of energy and the choice of different solar factors are discussed. Some economic viewpoints in connection with the choice of different solar shadings are discussed as well. Measurements have been carried through in a couple of new office buildings in Tallinn. Comparison between established simulation programs for indoor temperature, heat loads and cooling needs has been carried out. The observation of office buildings in operation indicated that in three office rooms out of four totally monitored; the need of cooling capacity exceeded 100 W/m . Two power simulation programs, TeknoSim and WinDon have been tested and compared. Also two energy calculation programs, IDA and BV2 have been compared in a similar way. The comparisons indicate that there is a quite a good similarity between the results obtained in the comparisons, presupposed that the room design is not close to a greenhouse. Outgoing from the comparisons, one power program and one energy program have been chosen for a comprehensive analysis of the influence of different building designs on the cooling capacities needed.