Kim B. Wittchen, Ejvind Løgberg, Søren Pedersen, Rolf Djurtoft, Jesper Thiesen
Bibliographic info:
Building Simulation, 2005, Montreal, Canada, 8 p

Traditional night cooling control strategies relies on the knowledge of the current situation – indoor and outdoor. The building is ventilated – passive or as free cooling via a mechanical ventilation system - with cool night air, hoping that the building  will warm up the  following day due to excess of free gains. In cool or moderate climates this often results in a thermal discomfort the next morning due to un- der-cooled constructions. As a consequence the sys- tem is often turned off. Alternatively the control sys- tem is modified to provide a hot air boost in the morning to compensate for the cold constructions. The latter is the best solution as the boost only heats the air and leaves the stored cooling energy inside the constructions for subsequent release to the room. No matter which solution, the result is increased energy consumption for space cooling or heating compared to an optimal situation where heating and cooling is minimised for the next day. This paper focus on a method taking advantage of forecasts issued by the local meteorological office as back- ground for making an intelligent decision about how to control night ventilation – set-point and air flow