Heavyweight homes will reduce impact of heatwaves

Compared with heavyweight homes built from concrete and masonry, lightweight homes are more likely to feel the full effects of summer heat during the day and feel even more uncomfortable at night.

The prediction from the Met Office of an increase in the number of heatwaves over the next two decades and of their becoming regular events after 2030 could mean uncomfortable living conditions for those in homes built using lightweight construction warns The Concrete Centre.

The Met Office's predictions have influenced the development of the Government's National Emergency Plan to deal with the rising risk of extreme hot weather linked to climate change which includes a 'siesta alert' system for instructing people to stay indoors during the middle of the day.

"This advice may not prove helpful for those living in homes built of lightweight construction", warned Joanne Turner, sustainability manager for The Concrete Centre.

"The thermal mass of heavyweight homes absorbs heat gains and so evens outs the internal temperature".

Research carried out by Arup for The Concrete Centre found that due to the predicted increase in summer temperatures a lightweight timber frame home with exterior brick and internal plasterboard finish would regularly overheat and occupants would need to retro-fit air-conditioning by 2021, in just 12 years time.

By comparison, a medium-weight house built with brick and block external walls or a heavyweight house, incorporating a precast concrete first floor and ground floor internal concrete block walls, would not over heat in such a way thanks to their inherent thermal mass.

The research, 'Embodied and operational carbon dioxide emissions from housing: a case study on the effects of thermal mass and climate change', also found that there was only a marginal additional embodied CO2 in the more heavyweight buildings.

This was offset in as little as 11 years due to superior thermal performance not only in summer but also during winter.

Thermal mass contributes to future proofing homes against a warming climate and can also save energy in modern homes by reducing heating bills in winter.

"The increased energy consumption resulting from the premature installation of air-conditioning in lightweight homes would significantly add to the energy burden of our homes which already account for some 27% of the UK's CO2 emissions", said Turner.

"The beneficial effects of thermal mass of homes built using concrete and masonry means that they will be much better equipped to offer comfortable living conditions during the hotter summers that the Met Office and others are predicting".

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