Imagine getting into your car on a hot summer’s day after it has been sat in the sun. You open the door and feel the heat hit you, and your immediate reaction is to ramp the air conditioning thermostat down to low and the fans up to high. For a few minutes, it is sheer bliss.
However, once the temperature has reduced to “low” – normally 16°C – our ideal comfort level has been surpassed and the rest of the journey is spent alternating between turning the air conditioning on and off, never quite reaching a comfortable level.
The same is true of our homes during warm spells of weather, and with three major factors causing increases in overheating – including zero-carbon energy efficiency agendas, climate change and increased urbanisation – keeping residential dwellings comfortable for occupants is a fine balancing act; in fact, keeping individuals cooler is becoming more of an issue in cities than keeping them warm.
Have you heard of the urban heat island effect? In cities, unique microclimates are created because of excessive heat build-up from solar gain, mechanical services and community heating pipework within apartment blocks, as well as many other cumulative factors.
Thermal comfort levels are particularly important at night. Environmental Design, Guide A1 advises that bedrooms should be 23°C or lower to have no effect on quality of sleep. Research carried out by CIBSE and Arup tells us that a difference of 3°C is enough to change “comfortably warm” at 25°C to “uncomfortably hot” at 28°C. It seems amazing that such a small difference can have such an affect on our comfort levels.
The thing is, it is not just temperature that plays a major role in these comfort levels. In order to achieve comfort in homes, we also need to pay attention to the effect of humidity on perceived versus actual temperature – the additional 3°C may simply be perceived heat caused by high humidity levels.
Hurrying to specify air conditioning systems will not help achieve true year-round comfort in residential dwellings and will have huge energy impacts – which are definitely not needed.
In airtight and well-insulated dwellings, over-heating must be tackled in the most efficient and cost-effective way so as not to undo any of the important energy efficiency work already being used.
By reducing the humidity levels in the home you can also reduce the perceived air temperature and add to the comfort of the occupants.
The added benefit is that this will be felt throughout the entire home with none of the draughts or increased energy use associated with other cooling methods.
Comfort cooling technology integrated with your ventilation strategy means that you can get it right first time and maintain comfort throughout the year.
Michelle Sharp is the group communications manager at Zehnder Group UK