Control Strategies for Ventilative Cooling of Overheated Houses

Buildings constructed before 1979 in Denmark are responsible for 75% of the total energy consumption of the sector. However, many post-occupancy comfort studies of energy renovated dwellings have documented elevated temperatures not only during the summer period but also during the transition months. Ventilative cooling can be an energy-efficient solution to avoid overheating in energy renovated residences.

The aim of the research is to investigate the ability of a representative manual window use and different automated window control strategies in order to eliminate overheating under different opening positions, wind conditions and discharge coefficients. The study will also include examination of the ability of mechanical ventilation and shading systems regarding the overheating occurrence. The objectives are fulfilled through the simulation and analysis of a real representative single-family house from the 1970s. The case study is renovated deeply and high- efficient (nZEB) creating two different scenarios.

Mechanical ventilation system and manual control of the openings for both renovation scenarios cannot sufficiently eliminate the overheating risk indoors. The discharge coefficient of the windows, the presence of the wind and the opening position of the windows are critical parameters of the effectiveness of the ventilative cooling strategies. The fully all-day automated control strategy presents the best performance among the three strategies of the automated control (parallel use, automated during the occupied period and fully automated). In most of the cases of the parametric analysis the high-efficient renovation scenario presents lower values of overheating risk compared to the deep renovation scenario.