- There has been a progressive decline in the annual burden of cold-related deaths since the mid-1970s, which probably reflects the continuation of a trend of reducing winter-/cold-related mortality going back over many decades – a trend that has occurred despite the gradual rise in the proportion of people aged > 65 years who are known to be more vulnerable to the effects of low temperatures. The factors contributing to this decline are not understood in detail but are likely to include a wide range of factors associated with improving socioeconomic conditions, including improving population health and health care and more effective health protection measures.
- There is evidence that since the introduction of WFPs in 1997 the gradient of association between winter cold and mortality is somewhat weaker than in earlier years. This is consistent with WFPs having had a beneficial effect in helping to reduce cold mortality, but interpretation must also recognise that many other potentially relevant factors have changed over a similar period. These include improvements in housing quality and winter indoor temperatures, and advances in the clinical management and prevention of disease, especially ‘temperature-sensitive’ diseases such as ischaemic heart disease, whose rates have declined rapidly in recent years. Therefore, it is not possible to conclude with certainty that the contribution of WFPs to the cost of heating the home has been the primary, or indeed even a contributory, factor in this decline, although it seems likely that it has had at least some moderate benefit for health and well-being, particularly for families in FP. There is also evidence that years with higher than average domestic fuel prices have shown a somewhat stronger relationship between low outdoor temperatures and mortality than years of below-average fuel prices, a result compatible with high fuel prices having a negative impact with regard to cold-related deaths.
- HEE measures installed across the English housing stock during the first decade of this century have had a relatively modest impact in improving the indoor environment, specifically with respect to winter indoor temperatures and air quality. The small gains in winter temperatures (estimated to be around 0.1 °C) arise because most of the energy efficiency interventions have been relatively modest and because of the shape of the empirical relationship between energy efficiency and indoor temperature (as reflected by the SIT). This relationship suggests a relatively shallow increase in SIT as energy efficiency is improved and, importantly, a plateau effect at around 300 watts/K E-value, a value that is close to the average energy efficiency of the English stock. Further improvement of energy efficiency beyond this point appears to result in little or no change in average winter indoor temperatures and hence, on average, in little or no reduction in exposure to cold in the home.
- As a consequence of the small average improvements in indoor temperatures from energy efficiency interventions, the impact that has been had on reducing the burden of cold-related deaths appears to be correspondingly limited. Our best estimate is a reduction of around 300 cold-related deaths per year attributable to the energy efficiency improvements installed between 2002 and 2007. This figure is broadly consistent with our own and other published evidence on the change in annual burden of cold-related deaths based on seasonal or daily time-series analyses of mortality data over the longer term.
- Energy efficiency-related changes in the ventilation characteristics of dwellings may be more important for health risks than the direct effect of temperature. The actual changes in indoor air quality resulting from typical energy efficiency interventions in the English stock cannot be defined with precision because of the lack of direct empirical data. Nonetheless, building physics models of expected changes in ventilation characteristics associated with such interventions suggest that the impacts had on health could be positive or negative and potentially greater, by as much as an order of magnitude, than those related to the improvement in indoor temperatures. The balance of harms and benefits from ventilation changes (protection against the ingress of pollution, especially PM2.5 from the outdoor environment and potential increase of pollutants, including PM2.5, radon and STS of indoor origin) depend on many assumptions and vary by area, dwelling type and occupants. Ventilation can be controlled with appropriate design, implementation and maintenance of control measures (including, for some, mechanical ventilation with heat recovery), but in formulating policies it would be prudent to assume substantial failure/suboptimal operation as the norm.
- Although heat is currently less important than cold, there is evidence that energy efficiency characteristics of dwellings determine indoor temperatures during hot weather and may, thus, affect heat risks to health. This may become increasingly important to take into account, particularly in the context of rising global temperatures with climate change. For many homes, energy efficiency improvement appears to act to increase indoor temperatures during hot weather.
- Energy efficiency retrofits, although not clearly loft insulation or double glazing, result in observable reductions in space-heating energy demand (with resultant cost savings for the householders). On average, the presence of an installed dwelling fabric energy efficiency retrofit is associated with a reduction of 790 kWh/year in gas energy use, or a 3.9% reduction from the stock mean gas demand in 2006, and the presence of a heating energy efficiency retrofit is associated with a reduction of 1950 kWh/year (10.4% reduction). These savings are part of the gain from energy efficiency measures that are taken instead of increases in temperature. These savings may have indirect (but unquantified) benefits for the health of householders, especially those on low incomes, because of the improvement to disposable income.
- Evaluating the full range of impacts of HEE interventions on health necessarily involves some element of health modelling, given the relatively modest impact that most forms of intervention have and the need to take into account the long-time course for their evolution, such as changes in the risk of radon-related lung cancer and the progression of cardiopulmonary diseases related to changes in long-term exposure to indoor pollutants. Modelling methods now allow the estimation of most such impacts, both physical and mental, relating to changes to the indoor environment (including impacts relating to cold and heat risks and those of a range of air pollutants and mould risk) and would be useful to guide policy development. An example assessment suggests that HEE improvements of similar annualised cost to current WFPs achieve greater improvements in health and that they reduce, rather than increase, CO2 emissions. Replacing policies that incentivise additional fuel consumption for home heating with a rapid full-scale programme of energy efficiency could help transform the UK stock, which is important for health and essential for climate change mitigation, without substantial financial burdens to government.
- The MCDA provides a useful framework for comparing policy options relating to HEE programmes using a suite of criteria, which potentially includes health, health inequalities, environmental and cost parameters. Critical to any such assessment is the transparency and robustness of evidence relating in particular to impacts that result from changes in ventilation characteristics. The use of the MCDA is most helpful as a tool for iteratively explorating the reasons that stakeholders support specific policy choices, rather than as a method to identify optimal choices based on predefined criteria.
- Much larger-scale changes are required to the housing stock in England if the full potential benefits for improving health and for reaching increasingly important climate change mitigation targets are to be realised. This will require efforts to dovetail national and local policy objectives with those of householders. Householders consider HEE technologies as subsidiary artefacts within broader framings of home improvement, home maintenance, subsidised public goods and environmental sustainability. Promoting the first two framings might foster installation rates in the short term but this puts at risk the relational, common goods engendered by the last two framings.
- Given the relevance of housing to several key strategic objectives (winter- and cold-related mortality/morbidity, climate change mitigation, energy security), it would be prudent to seek the greater integration of policy development across all relevant policy domains. This may be important not only for efficiency of actions, but also to ensure that specific policy initiatives are aligned towards the same strategic goals and do not, in part, act against each other.
- There remain important areas of uncertainty with regard to the impact that housing and housing improvement has on health, particularly with respect to cold-related illness. These uncertainties, in part, reflect the complexity of the causal linkages and the methodological challenges of bringing together data and research methods from across different sources and disciplinary domains. There is a need to strengthen empirical evidence on basic relationships between dwelling characteristics, interventions, the indoor environment and human exposures, to improve models of exposure and impact, and to explore record linkage and primary intervention studies. Although many research questions remain, a key uncertainty that has potentially very important bearing on health is the impact that HEE changes have on the ventilation characteristics of dwellings, which could have either positive or negative effects depending on context and the specific forms of intervention. This is an area that merits further research as a matter of priority given the scale of housing improvements planned for the coming decades. Specifically, there is need for further empirical research to understand the impact that energy efficiency interventions have on indoor air quality, and the consequences for health. Such research should include a large-scale programme of monitoring to record changes to the indoor environment following the installation of routine energy efficiency measures. This would provide a very important input to help improve current health impact models of HEE interventions as a guide for policy development.
The impact of home energy efficiency interventions and winter fuel payments on winter- and cold-related mortality and morbidity in England: a natural equipment mixed-methods study · Conclusions and recommendations
Conclusions and recommendations
Attribution. Ben Armstrong; Oliver Bonnington; Zaid Chalabi; Michael Davies; Yvonne Doyle; James Goodwin et al. (2018). The impact of home energy efficiency interventions and winter fuel payments on winter- and cold-related mortality and morbidity in England: a natural equipment mixed-methods study. NIHR Journals Library. Copyright © Queen’s Printer and Controller of HMSO 2018. This work was produced by Armstrong et al. under the terms of a commissioning contract issued by the Secretary of State for Health and Social Care. This issue may be freely reproduced for the purposes of private research and study and extracts (or indeed, the full report) may be included in professional journals provided that suitable acknowledgement is made and the reproduction is not associated with any form of advertising. Applications for commercial reproduction should be addressed to: NIHR Journals Library, National Institute for Health Research, Evaluation, Trials and Studies Coordinating Centre, Alpha House, University of Southampton Science Park, Southampton SO16 7NS, UK. Licensed under CC BY 4.0. NCBI Bookshelf NBK532137. CC BY 4.0. Original source ↗. Text reproduced from the Bookshelf XML without changing wording; figures, images and supplements are not reproduced.