I. Pollet, S. Germonpré, A. Vens
Bibliographic info:
35th AIVC Conference " Ventilation and airtightness in transforming the building stock to high performance", Poznań, Poland, 24-25 September 2014

Higher insulation and air tightness levels of buildings, increase the risk on overheating. Ventilative cooling as passive technique can limit overheating and decrease cooling energy consumption. The national energy performance regulations (EPBD) determine whether, how and under which requirements ventilative cooling can assist to reduce cooling demand and overheating. Therefore, those regulations are a key factor in the market uptake of ventilative cooling. Without a realistic and achievable approach, ventilative cooling will marginally be applied in buildings.

In this study, actual and possible requirements imposed on devices or systems for ventilative cooling are described. Besides, a sensitivity analysis is performed to assess the impact of parameter variation on the ventilative cooling effect. One reference dwelling is selected and introduced into the EP software of Belgium, The Netherlands and France. In that way, differences in buildings characteristics between countries on the output are ignored. Of course, the presented results are only valid for the selected reference dwelling.

In the three countries ventilative cooling by means of openable windows can be taken into account, in Belgium and France as a percentage of openable windows, in The Netherlands as present or not. Burglary resistance and water tightness of ventilative cooling devices are requirements (for The Netherlands) or have an impact on the performance of the ventilative cooling device (for Belgium). In France, openable windows are not allowed in case of active cooling. When there are openable windows in France, they are supposed to be opened during the heating season as well, resulting in an increased heating demand due to ventilative cooling.

As can be expected, ventilative cooling always decreases the cooling demand (26 to 96% in Belgium, 10 to 35% in The Netherlands), especially in combination with mobile solar shading.

Similar to the cooling demand, the risk on overheating in Belgium decreases by applying ventilative cooling. In France, summer indoor temperature can be strongly reduced by using openable windows, although the fraction  openable windows has no effect. Next to ventilative cooling, thermal capacity as well as solar shading can have a considerable impact on summer comfort and should be considered as complementary means.

The overall primary energy consumption of the reference dwelling is lower when ventilative cooling is applied (5 to 12% in Belgium, up to 4% in The Netherlands) except for France where openable windows remarkably increase the heating demand (up to 38%). The lowest primary energy consumption is achieved by applying ventilative cooling in combination with sun shading.