Low carbon straw house passes fire test

BaleHaus@Bath - built of pre-fabricated straw-bale and hemp panels - has fire resistance as good as houses built of conventional building materials according to new research.

Researchers at the University of Bath tested a pre-fabricated panel, as used in the construction of Balehaus@Bath, for fire safety by exposing it to temperatures over 1000°C. To reach the required standard the panel had to withstand the heat for more than 30 minutes. Over two hours later - four times as long as required - the panel had still not failed.

BaleHaus@Bath is part of a major new research project into how these renewable building materials can be used for homes of the future.

The research work on BaleHaus has been funded by Carbon Connections and the Technology Strategy Board. Researchers Dr Katharine Beadle and Christopher Gross, from the University's BRE Centre in Innovative Construction Materials, will be monitoring the house for a year for its insulating properties, humidity levels, air tightness and sound insulation qualities to assess the performance of straw and hemp as building materials.

The ModCell BaleHaus system consists of prefabricated panels made of a structural timber frame infilled with straw bales or hemp and rendered with a breathable lime-based system. It is the creation of White Design in Bristol and Integral Structural Design in Bath, and was used last year by Kevin McCloud to build an eco-friendly house in six days for the Grand Designs Live exhibition.

ModCell is carbon negative in manufacture. Due to the high insulating properties of the panels, the BaleHaus minimises additional heating requirements reducing heating bills in housing by up to 85 per cent, and CO2 emissions by 60 per cent.

Kevin McCloud officially opened the BaleHaus@Bath on 19 November. You can watch a film of it here.

Professor Pete Walker, Director of the University's BRE Centre in Innovative Construction Materials said: "Straw is an ideal environmentally-friendly building material because it is renewable and is a by-product of existing farming production.

"Whilst we've previously done tests on individual ModCell panels, this is the first time data have been collected from a complete house. We're hoping this will lead to these renewable materials being used more widely in the building industry for housing in the UK.

"The crop used for the straw can be grown locally, and because it absorbs carbon dioxide as it grows, buildings made from it have a very low carbon footprint."

Craig White, Director of ModCell, said: "It is unacceptable that 27 per cent of CO2 emissions currently come from the energy we use in our homes, it is just as unacceptable to continue to emit CO2 through the energy we use to make them.

"If we are completely serious about being "carbon free" we need to rethink the design of our buildings on a large scale. The ModCell BaleHaus system is designed to deliver just such a sustainable method of construction. These tests will offer proof that sustainable building materials are a realistic option for building on a large scale."

Kevin McCloud said: “The great problem across sustainable construction at the moment is the lack of data.

“There’s a whole raft of new technologies which have emerged in the past 10 years and nobody really knows how well they perform.

“There is an enormous paucity of good data, so any project which is as thorough in measuring the humidity, the environmental performance, the thermal conductivity, the temperatures - as this project is - is absolutely welcome.

“I think it’s essential.”

The project is already being followed by people across the world on the Balehaus website, where visitors watched the building of the house via "Strawcam".

The researchers at Bath have already started collecting data from the house, and have been posting online blogs on the progress of the project.

You can watch videos about the research project and the construction of the straw bale panels on the University's website.

Other industrial partners on the research project are Agrifibre Technologies, Lime Technology, Eurban, the Centre for Window & Cladding Technology, and Willmott Dixon.

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