Buildings which are too damp or too dry can be bad for occupants’ health. This fact has been well established by many reports including those of the World Health Organisation and the Institute of Medicine. Yet precisely how bad such buildings are to what kinds of occupants at what level of dampness or dryness is much more difficult to define, as are the agents of illness, such as the many types of mould, bacteria, other irritants and toxins that can result from imbalances of moisture in buildings.
This UK-based report seeks to identify the issues that prevent progress towards a better outcome for occupants, both now and in the future, and to suggest a constructive way forward.
The academic research into this project covered several hundred articles and books, and references almost 200 separate studies. From this research we can conclude not only that there is a significant link between moisture levels in buildings and occupant health, but that it is highly likely that we are increasing the risk of illness in this country through the current changes to building form, construction, occupation patterns and use.
However, as we show, the evidence necessary to provide proof of causality is not sufficiently strong to drive policy makers, industry or financial organisations to demand changes in legislation or practice, or to penalise wrongdoing. This is primarily because of the complexity of interactions between agents of illness, human health, and building condition. This complexity is compounded by a lack of robust methodologies and metrics, and by the fact that in each specific context there are multiple variables.
Consequently, it is difficult not only to identify causes with certainty, but also to calculate how much illness is caused by buildings which are too damp or too dry. For example, the Energy Savings Trust recently stated that around a third of the UK population report that they have mould in their homes3
ie, over 8 million properties and 20 million people—a figure which is wildly out of line with the English Housing Survey reports (of 4% of buildings with mould)4. Nonetheless, even using these most cautious estimates, there are over 1 million damp properties in the UK, with around 2.5 million people potentially affected by exposure to dampness in buildings5 in England alone, and the costs of this to the National Health Service and the economy may run into many tens, if not hundreds of millions of pounds each year6. It is therefore essential to be able to identify more clearly the actual level of this problem and to move forward towards robust evidence which will enable policy makers, industry and financial organisations,as well as building occupants, to act positively and promptly.
Our research makes the following recommendations for a way forward:
- 1 Where possible, within the current conventional knowledge framework in the UK, we shoulddevelop robust methodologies and metrics for the testing and collection of relevant data about moisture and health in buildings. In particular we need to have methods to assess more accurately the levels of dampness and mould in buildings, as well as building ventilation rates, and benchmarks for what is safe or unsafe.
- 2 We should develop a research methodology which integrates the complex interactions of health, moisture and buildings and takes full account of contextual conditions. We believe that this requires a new approach in research with an emphasis on multiple detailed holistic case studies, which, en masse and combined with quantitative data (as in point 1 above), will enable a new understanding of influential factors and of their causality.
- 3 A new way of thinking about moisture and health in buildings is required, based upon firstly, an informed understanding of the multiple factors which affect building performance and human health, and secondly, an understanding of the complex interactions of these factors in the context of specific buildings and their occupants. This would enable more accurate risk-based assessment, and the implementation of specific measures to address the moisture-based health risks of a particular building and occupancy, without the need to establish precise medical causality. We call this a balanced approach or model.
- 4 It is important to ensure that this approach gains acceptance by the medical establishment, and that medical, building science and building use researchers and experts work together.
The development of this knowledge base must happen before new policies and regulation in government, industry and the finance sector can be instituted. Therefore our short-term recommendations are that:
- i Moisture risks should become a priority of building safety and be fully integrated into regulations, and all building policy (including, especially, energy focused measures).
- ii A Whole Building approach to both new and existing building work must be taken, which integrates people, building fabric and services within the context of the building. In particular, ventilation and building use should be integrated with fabric measures such as airtightness and insulation.
- iii Additional attention should be given where there is particularly strong evidence of moisture risk. This applies to parts of the private rental sector, to temporary accommodation, and wherever there is overcrowding or high levels of poverty. Government should address these cases with urgency.
- iv All moisture safe design must also deal with unavoidable uncertainty and integrate sufficient capacity and caution into design, construction and use in order to mitigate unknown risks.
- v Engagement with the public in general and with building occupants during work is essential. More information and clearer communication about a balanced approach to moisture in buildings can help to reduce risk immediately.
- vi Funding for the research programme and for a public communication strategy should be forthcoming. This should become a priority for government and industry now.
The risks to health of excessive or too little moisture in buildings have been acknowledged and discussed for many years, but without identifying a clear way forward. We argue that this is no longer acceptable, given the increasing risks from ongoing changes to buildings and their use, and the well-known and better evidenced risks to the fabric and value of buildings from unbalanced moisture levels. We believe that we have identified a way forward for the study and assessment of health and moisture in buildings, and look forward to working collaboratively to develop it, and the solutions that will arise from it, for the health and benefit of buildings’ occupants and the UK.