NATURAL MATERIALS
Picture of fresh mix of hempcrete (hemp concrete) being cast into a cube mould.
in other European countries, but when we build with hempcrete, for instance, we are using hemp from Yorkshire and a lime binder from Northern Ireland or Shropshire. Some hempcrete materials are imported from France and Belgium but it is better to use local materials. We can keep the cost of houses and renovation schemes using ecological materials close to conventional products’. BENEFITS In order to understand the benefits of natural ecological materials it is necessary to look at the negative aspects of current forms of building and renovating. Using petrochemical synthetic materials such as polyurethane, poly-isocyanurate, expanded polystyrene, spray foam and many more buildings can introduce an unnecessary amount of hazardous chemicals into the building and the lives of the inhabitants. The manufacturers of these insulation materials will tell you that they are more effective, efficient and not dangerous, but doubts have been cast during the Grenfell enquiry, following the fire that
killed 72 people. Sealing houses up with air-tight membranes can lead to a range of unintended consequences such as increased mould and poor air quality. We are now able to use affordable scientific tests to check the indoor air pollutants in houses, and it is not unusual to find that these are well over the safe levels set by the World Health Organisation and other bodies. The UK Government Agency DEFRA has just issued a 142-page report on the importance of indoor air quality problems. The hempcrete cottage that we built in County Down 12 years ago has been a useful test bed. The house needs very little energy to keep warm and we
have tested it for air tightness and cold bridging. Over the past year, it has been monitored by University of Ulster and so we have data showing how relative humidity stayed the same all year round, whatever the weather conditions or occupancy. People who stay in the house – as it is let as a holiday cottage – comment on the beneficial air quality and some have even gone on to build their own hempcrete houses. If you want to know more details about all the natural building options that are available, my book, Natural Building Techniques, (Crowood Press), explains all the different materials and techniques and also lists suppliers. E: tom.woolley@btconnect.com
Tom Woolley is an Architect working for Rachel Bevan Architects in County Down. He was Professor of Architecture at Queens University from 1991 -2007 and has been a visiting Professor in England, Wales, Sweden and Malaysia. He was chair of the Northern Ireland Building Regulations Advisory Committee and also a member of the NI Ministerial Advisory Group for Architecture. He is chair of the UK Clean Air Steering Committee and the All Party Parliamentary Forum on Carbon Monoxide. The Author:
www.northernbuilder.co.uk
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