A great source of information for planners, developers, and the construction supply chain has been published by Innovate UK as part of its Building Performance Evaluation (BPE) programme. Summary reports and case studies can be found at www.bdx.org.uk. The methods used in the case studies to assess performance provide a good overview of the techniques which can be employed. The construction of new housing developments, and the way people subsequently live in them, are by their nature diverse and complex. Identifying the underlying causes of the performance gap can be complex and require a mix of site investigation, monitoring, and detailed design assessment. Recourse to corrective action is not always straight forward, and best undertaken within the warranty period provided with the home.