Evaluating the 'as-built' Performance of an Exemplar Eco-Housing Development

Session 17, Paper 3, CIBSE ASHRAE Technical Symposium, Dublin, Ireland 3-4 April 2014

This paper uses an empirical building performance evaluation (BPE) approach to forensically and systematically evaluate the ‘as built’ performance of an eco-housing development in UK, during the post-construction and early occupation stage, focusing on two case studies. Undertaken as part of Technology Strategy Board’s national BPE programme, the 12-month study captures the ‘as built’ performance of the building envelope and installed equipment; and how occupants react to it including the effectiveness of the handover process. The actual performance is compared with the design intent to reveal a growing performance gap, which has the potential to undermine Government’s zero carbon housing policy.
Air permeability test, infra-red thermography and in-situ u-value measurements reveal thermal anomalies, leakage paths and cold bridges within the building fabric arising from construction quality. Installation and commissioning checks of services and systems show under-performance of MVHR systems due to inadequate commissioning and maintenance, and complex control interfaces and room thermostats resulting in poor occupant control. Evaluation of the handover process and occupant satisfaction raises the urgent need for clear and succinct guidance to occupants on how to operate and manage their homes. Lessons are drawn for policy makers, developers, designers and equipment suppliers to reduce the gap between ‘as designed’ and ‘as built’ performance of future eco-housing developments.