This report is the result of over two years 'Phase 2' in-depth monitoring of the performance of Larch House and Lime House; two Passive House social housing prototypes built in Ebbw Vale, Wales, completed in 2011. The houses were built following an open competion held by the Building Research Establishment (BRE Wales). The houses were designed and procured in close collaboration with the BRE and with United Welsh, the social housing provider.

This report contains the full and detailed findings of the research team which looked at all aspects of the two houses, including comfort, performance and health. The research was led by bere:architects who employed Professor Dr Ian Ridley, formerly of University College London, now of RMIT Australia, to provide the independent technical evaluation of the building performance. The entire research and peer review team is credited at the front of the report.

The research project was made possible by funding from the Technology Strategy Board's Building Performance Evaluation (BPE) competition. The project methods and outputs were rigorously assessed at every stage by two leading building performance experts employed by the Technology Strategy Board; a Project Officer (Frank Ainscow) and a Project Evaluator (Ian Mawditt).

The Technology Strategy Board (now Innovate UK) has commended the quality of our research outputs.

The appendices to the report have not been uploaded at this stage due to the confidentiality implications of publishing the appendices in an entirely open forum. We may make this information available to academics at our discretion. However the main report anyway contains an immense amount of detail that we hope will be of interest to academics, professionals, policy makers and members of the public who may be considering whether to commission a Passive House.

Headline results:

  • Larch House has been found to perform very well and broadly in line with expectations. Socket electrical usage is higher than expected due to the large number of audio visual appliances in the house, the higher than usual level of home cooking when compared with the UK average, and the occupant's own kitchen appliances which are not A-rated, contrary to expectations. Summer temperatures were controlled by means of the external blinds which are manually controlled, and once insect mesh was installed outside a bedroom window, night purge ventilation could be used to help keep the building comfortable in summer.
  • Lime House has been found to perform very well considering that the occupants have the preference to leave at least one window open throughout the day during the winter months. Even though this habit has doubled the specific heat demand, this remains a very low energy building compared to what might be expected from a house designed to UK Building Regulations, and the performance results of this building would make it classified in Germany as a low energy building.