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Projects: Projects for Investigator
Reference Number 38/19/228
Title Improved thermal and moisture performance of pitched roofs
Status Completed
Energy Categories Energy Efficiency(Residential and commercial) 100%;
Research Types Applied Research and Development 100%
Science and Technology Fields ENGINEERING AND TECHNOLOGY (Architecture and the Built Environment) 100%
UKERC Cross Cutting Characterisation Not Cross-cutting 50%;
Sociological economical and environmental impact of energy (Policy and regulation) 50%;
Principal Investigator Project Contact
No email address given
Building Research Establishment (BRE) Ltd
Award Type Standard
Funding Source DCLG
Start Date 10 August 2001
End Date 31 May 2003
Duration 21 months
Total Grant Value £60,000
Industrial Sectors Manufacturing
Region East of England
Programme DCLG Building regulations research and technical support
 
Investigators Principal Investigator Project Contact , Building Research Establishment (BRE) Ltd (100.000%)
Web Site
Objectives (BD2171) The objectives of the project are - To establish the factors that determine the successful performance of cold and warm pitched roofs with high levels of thermal insulation and roofs that have been converted with a 'room in the roof'. To produce design guidance for optimum design of pitched roofs, both warm (insulated at rafter line) and cold (insulated at flat ceiling line). To demonstrate novel designs of pitched roof that are more energy efficient with fewer condens ationproblems and withstand the more severe climate over the next century.
Abstract This project falls directly into Priority Area 22 - Evaluation of risks to safety and health of the DETR Construction Research and Innovation Programme. They are concerned with the durability, reliability and maintainability of highly insulated roofs, particularly those that have been converted and refurbished. Although of secondary importance, the effects of the impacts of climate change on safety and health will also be included. In the short term the major impacts of the project will be a)the design and construction of pitched roofs that achieve higher insulation levels with fewer thermal bridging problems at eaves, ridge and around dormer windows or rooflights and b) the possibility of energy efficient loft conversions in a greater proportion of houses. In the medium and long term there will be a reduction in the risk of damaging condensation within highly insulated roofs. These impacts will be achieved by providing a clear understanding of the roles of heat, air and moisture movement through roofs and the effects of ventilation, vapour control layers and breather membranes and disseminating these concepts through a series of Good Practice Guides. Summary of results: Pitched roofs in some European countries provide roof ventilation via a vapour permeable membrane fixed under the tiling but with no eaves ventilation. This project investigated a range of roof ventilation strategies. The results indicate that there is little difference in moisture performance between theUK or European ventilation methods. However using the vapour permeable membrane in place of eaves ventilation may reduce heat losses. The project was part funded by the construction industry under the PII scheme and will benefit the development of construction procedures. The guidance on ?new? means of ventilating roofs should prove useful for industry specialists. The project has apparently aroused some arguments within the pitched roofing industry on the benefits and otherwiseof using semi permeable roof membranes. This is a healthy start to the development of new practice that may bring some energy efficiency benefits for pitched roofs.
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Added to Database 19/11/07