Using the methodology developed for the study, it was estimated that it was costing the NHS some £600m per annum in first-year treatment costs to leave people living in the poorest housing in England. The research was very well received and the figure of £600m pa has been widely quoted. It has also been questioned. Some have re-worked the assumptions from the original research to come up with alternative figures. Others have taken a different approach to measurement, in particular by examining the reasons why people had been treated by the NHS and making assumptions about how much of this was caused by the home, without actually having any information on the design and condition of the dwellings themselves. One such study suggested that the cost to the NHS was some £2.5bn per annum (NHF). However, it should be pointed out that the £600m and £2.5bn figures are not contradictory but are measuring different things. The BRE Trust figure only considers the worst housing stock in England (that which has an HHSRS Category 1 hazard) and then calculates the initial treatment costs if the hazards are not dealt with. The NHF estimate is based on all NHS treatment costs applied to the total UK housing stock.

The BRE Trust figure represents the cost of preventative action it calculates the statistical risk and associated costs of a health incident occurring before it does. Of course, such an approach will inevitably lead to investment in situations where an incident is never going to happen. A number of intervention studies have looked at the impact of housing improvements as a cure to pre-existing problems and come up with even more encouraging benefits, particularly in the area of energy efficiency improvements. However, few would argue that preventing the development of respiratory and circulatory diseases through living in a warm, dry home should only happen when we have improved all the homes of people who already have such problems. Certainly, the fitting of handrails on the stairs of a vulnerable person’s home to prevent a fall will be far more cost-effective (and humane) than waiting for an accident to happen before intervening. Various advocates have picked up on the BRE Trust research, seeing the value of using the methodology to promote their own agendas. For example, Shelter Wales co-sponsored a report which applied the methodology to the cost of poor housing in Wales . The Northern Ireland Housing Executive co-sponsored a report which applied the methodology to Northern Ireland , and the Chartered Institute of Environmental Health promoted a report on the cost of poor housing in London. A BRE Trust report even extrapolated the results to the whole of the United Kingdom, by modelling data for Scotland and combining it with results from the other national reports.