Effect of energy-efficient homes on residents' health: evidence from a natural experiment in the Netherlands

Many governments around the world subsidise upgrades to poorly insulated homes, yet the extent to which these energy-efficiency improvements reduce health risks remains unclear. We aimed to provide the first large-scale evidence on whether such retrofits lower the use of respiratory health-care services, particularly for children and other vulnerable individuals.

We leveraged a large-scale natural experiment in which public housing units across the Netherlands were retrofitted between 2012 and 2021. Upgrades included insulation and mechanical ventilation and were implemented in homes eligible on the basis of poor energy efficiency and construction before the early 1990s. Treatment assignment was based on technical factors and was therefore shown to be unrelated to health outcomes, and opting out was not possible. We followed up 2 million individuals over 10 years, totalling approximately 12 million person-years-a sample size that provided high statistical power (95% CIs narrow enough to detect relative risk changes in medication use as small as 1%). Individual-level medication data were obtained from health insurers. Medication use and other health-care outcomes among 180 000 tenants in retrofitted homes were compared with those in not-yet-retrofitted homes using a staggered difference-in-differences design with individual fixed effects. The primary outcomes were the use of prescription respiratory-system medications: asthma or chronic obstructive pulmonary disease drugs, cough remedies, and antihistamines.

Antihistamine use declined by 1·87% (95% CI 0·19-3·55; p=0·029) after retrofits. Among children younger than 18 years, respiratory medication use fell by 3·76% (1·04-6·48; p=0·0067). Specifically, after 5 years, asthma medication use was reduced by 6·91% (-0·04 to 13·85; p=0·051). No statistically significant effects were found for non-respiratory medication outcomes and health-care costs.

Energy-efficiency upgrades led to measurable reductions in respiratory medication use, especially for children. These benefits probably reflect reduced exposure to indoor dampness and bad air quality. Childhood asthma reduction is a crucial co-benefit of energy-efficiency home upgrades.

NWO Dutch Research Council, RVO Netherlands Enterprise Agency, and Villum Fonden.