overheating

Major and deep energy renovations of single-family houses (more than 60% of the building stock) are expected in Europe over the next several years (Psomas et al., 2016a). A number of research projects have documented and verified overheating risk during the design and operation phase in nearly zero energy or existing renovated single-family houses without mechanical cooling systems in temperate climates. Post occupancy surveys and comfort studies have also monitored high indoor temperatures over 27oC and 28oC even in Northern countries (Psomas et al., 2016a).

Overheating in domestic homes, specifically in built up urban areas, has become a pressing problem throughout the UK. It is likely to become a costly energy problem in years to come if passive design strategies are not fully understood and integrated. This research looks to investigate how internal and external solar shading systems impact on operative temperatures when differing blinds together with a night time natural ventilation strategy are adopted within a renovated block of flats in North London.

According to the 2016 Household Projections report, England’s housing stock could reach 28 million households by 2039 with approximately one fifth being new constructions. A significant proportion of these newly built dwellings may face a high risk of overheating as a result of the combined effects of climate change and more stringent building thermal efficiency standards, if not appropriately designed.

Where residential developments rely on opening windows to control overheating, there can be a compromise between allowing excessive noise ingress with windows open, or excessive temperatures with windows closed. This problem is exacerbated by the move towards better insulated, more airtight buildings and the need, particularly in urban areas, to consider development on noisier sites. A working group has been formed by the Association of Noise Consultants to provide guidance on acoustic conditions and design when considering both the provision of ventilation and prevention of overheating.

In response to the European Energy Performance Buildings Directive 2010/31/EU and the Energy Efficiency Directive 2012/27/EU, buildings have increasingly become more insulated in order to reduce the heating losses to a minimum. However, this could also lead to the problem of indoor high temperatures during warm and transition seasons. Furthermore, the Intergovernmental Panel on Climate Change (IPCC) warns about increases in temperature of more than 4 ºC by the end of the century.

The most representative typology of residential buildings of Catalonia has been simulated in TRNSYS to evaluate the impact of both infiltration and natural ventilation. The typology is a block of apartments constructed during 1950-1980. 

The new initiatives and regulations towards nearly zero energy buildings forces designers to exploit the cooling potential of the climate to reduce the overheating occurrence and to improve thermal comfort indoors. Climate analysis is particularly useful at early design stages to support decision making towards cost-effective passive cooling solution e.g. ventilative cooling.

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.