Civil and Built Environment
Partners: Nottingham University and Roger Bullivant Ltd
Ask anyone in the construction industry about foundations, and they will tell you that they are the most important part of a building. Yet when it comes to reducing energy in the built environment, foundations have, up until now, been overlooked.
‘The majority of people don’t think about foundations because they are hidden in the ground,’ said Prof Saffa Riffat, head of the Institute of Building Technology at Nottingham University. ‘So when they talk about low carbon buildings, people talk about the buildings themselves, the windows and the doors…but in fact energy use of foundations is massive.’
Riffat, who is also president for the World Society of Sustainable Energy Technologies, has worked with construction company Roger Bullivant Ltd to develop a modular house foundation system known as ‘System First’. The process is designed to replace traditional trench-fill foundations using prefabricated steel beams that lay across concrete piles. These piles are covered with polystyrene slabs which are then covered with a layer of concrete screed to create a lightweight and insulated floor slab.
‘System First provides a floor which is suitable for use in homes of the highest sustainability standards due to its exceptionally low heat loss through the floor,’ explained Riffat. ‘It uses significantly less concrete and raw materials than traditional flooring construction and has lower embodied CO2. The floor slabs also have minimal heat transmittance which reduces the building’s energy requirements and CO2 emissions.’
The System First technique is claimed to achieve an 88 per cent saving in water, a 75 per cent reduction in construction time and a 92 per cent saving in raw materials; foundation which would conventionally use 233 tonnes of cement can be reduced to 18 tonnes. The concept has already been demonstrated in a wide range of projects including in the BASF House, the Mark Group House, and the Solar Decathlon House at the Nottingham University Institute, in the Llanelli School extension, and in Buckshaw village in Lancashire.
But the team has gone one step further and combined System First with a ‘Thermafoundation’ process to turn the foundation piles into heat exchangers for a ground source heat pump. This provides a cost effective method to install ground loops for heat collection from the ground and could overcome barriers in rolling out ground-source heat pumps in the UK. According to Riffat, a home with a 80m2 footprint using this system could cut its carbon emissions from 45 tonnes to 11 tonnes.
‘Thermafoundation can be used alongside solar roof panels which captures summer heat for storage in the ground below the building,’ said Riffat. ‘This heat can be extracted in the winter months and allows the heat pump to operate at a high coefficient of performance. Compared to a gas boiler, it could save around 50 per cent in carbon dioxide emissions.’
Nottingham University estimates that energy generated in the operation of buildings currently contributes to over 50 per cent of the UK’s total CO2 emissions. Domestic buildings alone generate around 28 per cent, while an average household in the UK produces around six tonnes of carbon dioxide each year. Around 4/5 of energy generated is used for heating purposes.
The UK government is attempting to slash these figures and wants all new housing in the UK to have zero carbon emissions by 2016. At the same time, it is predicted that of the necessary housing stock required by 2050, one third is yet to be built. Based upon the current carbon intensity of grid electricity the heat pump can save around 50 per cent of carbon emissions against gas boiler installations. Overall introducing System First to only 30 per cent of the UK construction market would save approximately 11 million tonnes of quarried aggregate annually.
‘The project has the potential to change building practice in foundation structures,’ explained Riffat. ‘Embodied carbon is now a important issue affecting decision making in the construction sector and the technology developed under this project not only complies with future requirements in this area but extends the role of foundation structures from their traditional function as a passive element of building design to a working component of building occupancy.’
Nottingham has contributed to the project in terms through design work for the heat pump and solar roof. Roger Bullivant has provided significant expertise in developing the System First and pile technology in a partnership with the University that has spanned over 12 years. As a result of the collaboration, students have had the opportunity to be at the forefront of innovative commercial activities and the practical application of sustainable technologies in the built environment.
The technology, claims Riffat, showcases the best in British engineering talent. ‘I feel quite sad about the situation in the UK, because when I exhibit in various places I look around and all the technology seems to made in Germany or in China and unfortunately very few UK companies are making things. So this is a very good example of how the UK can make things, and we’re proud of that achievement.’
It is anticipated that tens of thousands of these foundation systems could be installed each year and the resultant wide scale use of ground source heat will lead to a dramatic reduction in heating supplied by gas boilers. The electrical energy required to operate the ground source heat pump would be offset by local renewable electricity generation. The processes involved are simple to replicate and the technology could be utilised anywhere in the world.
‘We have completed the foundation system testing and have several demonstration,’ said Riffat. ‘Bullivant has tried to use the technology abroad, we don’t want to constrain it to just the UK, we’re talking about a world wide roll out…Roger is 72 years old now, and I know for him this project is a dream come true. After all this time working in foundations, and focusing on sustainability, this is a major thing.’
Roger Bullivant has invested over £1.5m in the project which has received further funding of two EPSRC grants each of £120,000, a Knowledge Transfer Partnerships grant of £128,009 and an East Midlands Development agency grant £18,000 have been awarded for this research. Other companies involved include Metrotile, Rehau, Ice Energy and Hydratech.
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