Paper Conference

Proceedings of BauSim Conference 2008: 2nd Conference of IBPSA-Germany and Austria


Bewertung von Nachtlüftungskonzepten in der Praxis

Christoph Kempkes

Abstract: A comparative study on thermal behaviour in summer with special regard to a nightcooling concept for a building at Kassel University is described. The thermal impact of natural ventilation during nighttime is shown and the question is answered, if mechanical cooling is necessary or not. For the evaluation of the façade concept regarding nightcooling, the actual ventilation rate across the openings depending on pressure- and temperature differences is the essential impact. Quantifying ventilation rates regarding both influences means a high effort in calculation and usually is not possible within the frame of “normal” consultancy. In this case a simplified approach developed by (Maas, 1995) is being used and – on the safe side – only the temperature influence is taken into account. In the present study a dynamic simulation tool is being used, which carries out these calculations during runtime. The simulations were done using the valid test reference year on the one hand and measured local climate data – the weather station of the department of building physics is very close - for ten years period on the other hand. Thus the impact of realistic (local) weather could be shown as well. Without nightcooling temperatures in summer normally are above the outdoor temperature and with peak values above 32 °C far beyond the comfort criteria. Regarding the concept for night cooling, the temperature level can be reduced by app. 4-5 K.
Pages: 55 - 56