The Heat Is On..

Prompted by a call from BBC Radio Guernsey, my thoughts turned to building for hot weather. Our ancestors, of course, evolved methods over centuries of experimentation and failure, and in Guernsey the predominant forms that rose to common usage were thick granite walled buildings, small window openings and thatched roofs. This amalgamation of systems held back both the cold wet winters and the warm sunny summers, with high thermal mass, high ventilation and deep shade taking the edge off the hottest days over summer.

In the 1800's, as the population grew and extracted resources thinned, or, in Guernsey's case, became more valuable to export, the building types changed and we started building thinner walls, slate and tile roofs and, more recently, using a great deal of rubber, polymer and silicone sealant. Great for the cold, in the late 20th century central heating overtook open fires, and enjoying views out as part of our leisure time became more important than worrying about extreme weather and keeping care of the natural world around us. In this century, building costs have soared and old-fashioned, expensive details and materials have been designed out, particularly in low cost and affordable housing.

This summer has seen prolonged periods of intensely hot weather for our climate, with numerous days exceeding 30 degrees, and multiple days at a time, not just a quick peak above that threshold. In response, building users have sought respite through portable air conditioning units, using our electrical supply to cool the air in their homes and workplaces, but is this the answer?

That was part of the question Tim Hunter posed me this morning - what can we do in future to address the potential for a repeat of this kind of summer?

My answer - please don't initiate short-term measures that will exacerbate the potential for climate change, leading in turn to more of the intense heat we are experiencing.

Introducing solar shading to the external features of the building and encouraging more tree and shrub growth around our buildings are both key factors, reducing solar gain through glazing, and helping to create cool pockets of air externally that mitigate the overall air temperature. Those two measures will make natural ventilation more successful by encouraging movement of cooler air through and around a building.

Increasing natural heat-absorbing surfaces can be effective in reducing the 'urban heat-island' effect, where hard surfaces reflect heat and cause higher air temperatures in built up areas.

Fitting shutters to windows or applying solar reflective film to reduce heat transference through the glass will be better medium-long term solutions than fitting air conditioning systems that will be redundant for 90% of the year and will add demand to our already stretched power-supply infrastructure.

For those with more available capital, fitting whole-house ventilation systems with heat recovery can be a blessing all year round, and can capture the heat from the air and direct it to a secondary coil in a hot water cylinder, pre-heating domestic hot water services and reducing fuel consumption and costs from their boiler. Photovoltaic solar panels can generate localised electricity to run a cooling circuit within the same system, delivering chilled incoming air.

Recently, I've been looking into bioceramics as a construction material, which can be utlised to provide a low carbon structure and cladding that deal exceptionally well with extremes of both heat and cold. A client of mine is considering utilising the pioneering material in a series of new homes on Guernsey, and if permitted, could set a precedent for a paradigm shift in the way we look at building form and fabric, considering whole life environmental benefits alongside both construction costs and land value.

As with many things, Guernsey has the capacity as a small independent jurisdiction to pioneer new building forms and building materials. Our extreme exposure to Atlantic weather systems provides a perfect test-bed for innovative construction solutions. Europe and North America have seen an unprecedented summer in climate terms, and our island has an opportunity to be at the forefront of developing solutions for out future way of life.

If you agree, or disagree, please leave a comment - our future is in our hands, and we can all make a difference in our own way.