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Benefits from intensive building energy efficiency improvements

Intensive building energy efficiency improvements can reduce emissions from energy use, improving outdoor air quality and human health, but may also affect ventilation and indoor air quality. 

This study examines the effects of highly ambitious, yet feasible, building energy efficiency upgrades in the United States. Our energy efficiency scenarios, derived from the literature, lead to a 6 to 11% reduction in carbon dioxide emissions and 18 to 25% reductions in particulate matter (PM2.5) emissions in 2050.

These reductions are complementary with a carbon pricing policy on electricity. However, our results also point to the importance of mitigating indoor PM2.5 emissions, improving PM2.5 filtration, and evaluating ventilation-related policies. Even with no further ventilation improvements, we estimate that intensive energy efficiency scenarios could prevent 1800 to 3600 premature deaths per year across the United States in 2050. With further investments in indoor air quality, this can rise to 2900 to 5100.

Global energy consumption is expected to rise by 27% by 2040, which underscores serious challenges for mitigating climate change. In the United States, building energy use alone accounts for 40% of total energy demand. Investments in building energy efficiency hold promise to reduce energy demand and thus curb emissions from fossil fuel combustion, including emissions of both greenhouse gases and non-greenhouse gas pollutants, the latter of which are hereafter referred to as “local” air pollutants.

These reductions in local air pollutant emissions would improve outdoor air quality, potentially providing substantial benefits to human health. However, people in the United States spend 87% of their time indoors. This raises a potential concern of increased exposure to indoor pollutants for some homes due to decreased air exchange rates via infiltration that result from the tightening of the building shell for energy efficiency improvements.

Thus, some intensive energy efficiency measures could also negatively affect human health, potentially offsetting the gains from improved outdoor air quality, unless additional measures are taken, including reductions in indoor emissions and/or investments in indoor air recirculation with pollutant filtration or increased outdoor air ventilation, such as those available as part of heating, ventilation, and air conditioning (HVAC) systems.

This study examines the long-run impacts of intensive energy efficiency improvements in buildings that go far beyond the current utility energy efficiency programs but align with calls for concentrated efforts to deeply improve energy efficiency. We explore the impacts on energy consumption and emissions, outdoor air quality health impacts, and indoor air quality effects (both with and without improvements in recirculation with filtration or emission reductions).

To examine a range of potential impacts, we develop two scenarios of energy efficiency improvements in a comprehensive set of building services, such as space heating, space cooling, water heating, and lighting. These carefully designed scenarios are more ambitious than those in previous work and deeply grounded in the literature on potential energy efficiency improvements. We also implement an example carbon pricing scenario to better understand the effects of intensive energy efficiency in a world with carbon pricing on electricity generation.

This is an extract from the paper. The full version is available here