Non repeating thermal bridges and the impact on overall heating energy consumption in a typical UK home

Abstract

A non-repeating thermal bridge occurs at junctions when building components such as a metal lintel crossing from the buildings’ interior to exterior with a little or no intervening insulation, creating a ‘bridge’ for heat losses through the external wall. In the UK, when considering a domestic building with standards of the building regulation 2006, the proportion of heat losses due to non-repeating thermal bridges is typically 10-15 %. This can rise up to 30 % in highly insulated low energy buildings. Limiting thermal bridging will therefore become increasingly important as more energy efficient buildings are being built due to more stringent requirements by the current and future building regulations, and the endorsements of higher levels by the Code for Sustainable Homes (CfSH) standard. The study has undertaken dynamic computer simulations to calculate the impact on heating energy consumption and to provide both cost and CO2 benefit analysis for a typical four bedroom terraced house with installation of Glass Reinforced Plastic (GRP) lintels and conventional use of Steel lintels under London climate. Furthermore, two-dimensional temperature and relative humidity distribution study has been carried out to investigate the condensation risks, and the results are presented in this paper based on energy performance where a better insulated home with GRP lintels showed better performance levels in heating energy consumption, CO2 emissions and overall energy bills. However, the most significant result of the reductions was achieved by improving the building fabric. Moreover, the reduction achieved from installation of GRP lintels has provided a further 10 % energy demand reduction compared with the conventional Steel lintel use in the case study home. With regard to the condensation risk and the two-dimensional study, the paper has shown that the GRP lintel use would reduce non-repeating thermal bridges significantly, particularly around junctions, and at the same time can help keeping dry the area around the junctions. On the other hand, the Steel lintel use would have high risks for condensation and again can cause further health implications with mould growth on surfaces.