Post occupancy evaluation of social housing designed and built to Code for Sustainable Homes levels 3, 4 and 5

• Seven social dwellings are evaluated to assess water, energy and carbon performance.
• Differing levels of the Code for Sustainable Homes are tested against performance.
• Unintended consequences arise through both system complexity and occupant behaviour.
• Increasing levels of the code lead to better carbon performance.
• Increasing levels of the code lead to an increased risk of system failure.

In the housing sector, carbon emissions arise primarily through the consumption of energy to heat, light and ventilate our homes. Significant improvements in UK housing energy performance have been driven both by changes in legislation, and by the introduction of the Code for Sustainable Homes in 2007. Compliance with certain levels of this Code has been adopted as policy by Local and Regional Authorities, and social housing providers. The evaluation of the performance of low carbon housing requires the assessment of increasingly complex building services technology, and occupant behaviour. This added services complexity, and the expectation that tenants understand how to use it, has led to a number of unintended consequences which have resulted in a higher risk of performance failure. This study comprises the detailed evaluation of seven new social housing dwellings, designed and built to Code levels 3, 4 and 5, including comprehensive environmental monitoring, measurements of the consumption and generation of resources, and social surveys of the occupants. The results show that as the Code levels increase there is a reducing energy and water consumption rate, and an increasing energy generation rate, but only at the expense of a significantly increased risk of services system failure.