Influence of night ventilation on the cooling demand of typical residential buildings in Germany

The current type of construction preferred for new high energy efficient buildings in Germany, featuring highly insulated building components and an almost completely airtight building shell, raises several new challenges with regard to design, construction and use of these buildings. Cooling, in particular, is an issue that gains importance also in the residential sector, in connection with rising temperatures induced by the climate change.
Increased night ventilation is a cost-effective option to influence the indoor climate such that comfortable conditions are durably ensured, keeping technical expenditure within reasonable bounds. Though the functional principle of night ventilation is well known and its applications are manifold, it is not widely considered by building planners. One of the reasons for lacking attention might be that the potentials of night ventilation with regard to building cooling cannot be sufficiently estimated. The present study investigates the impact of night ventilation on the cooling demand of typical new residential buildings in Germany.
The potentials of night ventilation are examined for two exemplary cases, namely for a single-family home and a multi-family building. Thermal building simulation is used to perform numerical assessments and to discuss functionality and effects of natural ventilation. The study analyses several influences on the indoor thermal comfort including the impact of different types of construction, various designs, thermal insulation standards, ventilation strategies and the use of solar shading devices in combination with or without night ventilation.
The simulation results show that the problem of excess summer temperatures occurring under current climatic conditions in typical, new residential buildings in Germany can be controlled by appropriately adapting the building design and by using solar shading devices. Especially night ventilation can be a very efficient and effective measure to minimize the risk of overheating, irrespective of the type of construction, the use of solar shading systems, the standard of thermal insulation or the building design, thus making the use of an active cooling system superfluous. Even for a worst-case scenario, night ventilation can guarantee comfortable indoor temperatures to a large extent.