An intensive push to improve energy efficiency in buildings throughout the United States could prevent 1,800 to 3,600 premature deaths every year, according to a new modeling study. What’s more, combining this with efforts to achieve better indoor air quality in homes could prevent 2,900 to 5,100 deaths annually.
Building energy efficiency is important for fighting climate change because buildings represent 40% of total energy demand in the United States. Reducing that energy demand doesn’t just cut greenhouse gas emissions from fossil fuels though – it also reduces other air pollutants that can harm human health. So improving building energy efficiency could have health benefits as well as climate ones.
But here’s where it gets complicated: one of the main strategies to improve energy efficiency is to seal up buildings so that heated air stays inside in winter and cooled air stays inside in summer. Less exchange of air between inside and out can also lead to a buildup of air pollutants inside, with the potential for negative health effects.
The new study is the first to comprehensively examine how this all nets out by modeling the effects of increased building energy efficiency on both indoor and outdoor air quality across the entire United States.
The researchers used a well-known computer model of the U.S. energy system to analyze two scenarios of energy efficiency improvements across residential, commercial, and industrial buildings. Both scenarios are more ambitious than what has been studied before, yet technically feasible.
They also modeled how these changes would affect indoor air quality in U.S. homes – specifically exposure to fine particles known as PM2.5. People in the United States spend most of their time indoors, and most of that at home, “so residential exposures make up a large fraction of total exposures” to indoor air pollution, says Kenneth Gillingham, professor of economics at Yale University in New Haven, Connecticut and the paper’s lead author.
Energy efficiency improvements would lead to a 9% to 16% reduction in building energy use in 2050 compared to current policies, the Gillingham and his collaborators report in the journal Science Advances. This results in a 6% to 11% reduction in carbon dioxide emissions and an 18% to 25% reduction in PM2.5 emissions economy-wide, depending on the scenario.
Even after accounting for the potential for increased indoor air pollution from building “tightening,” these changes would have major health benefits, with 1,800 to 3,600 premature deaths avoided each year. That’s because PM2.5 concentrations are generally higher outside than inside, except in parts of the country where air pollution is lowest, and homes with the largest indoor emissions. (Indoor PM2.5 emissions come from a variety of sources, including stovetops, washing machines, and vacuuming.)
But there are also ways to improve indoor air quality in homes, such as with heating and cooling systems that exchange indoor and outdoor air (rather than just recirculating air indoors), and that have filters to remove fine particles. If such features were more widespread, the combination with building energy efficiency measures could prevent 2,900 to 5,100 premature deaths annually, the researchers calculated.
“Intensive energy efficiency improvements that are feasible and verified would save thousands of lives each year, but the gains could be even greater if they are coupled with improvements to indoor air recirculation and filtration,” Gillingham says.
“These findings broadly align with the efforts to improve air recirculation and filtration inspired by COVID-19,” he adds. “Ventilation is a little trickier because whether it helps depends on the outdoor air quality relative to the indoor air quality. We show that there are circumstances where improved ventilation alone may not be beneficial for indoor air exposures due to higher outdoor air pollutant levels than indoor levels” – emphasizing the need for comprehensive strategies that address multiple aspects of health.
Source: Gillingham K. et al. “The climate and health benefits from intensive building energy efficiency improvements.” Science Advances 2021.
Image: Robin Oberson via Flickr.