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Housing Perspectives

Research, trends, and perspective from the Harvard Joint Center for Housing Studies

Climate Change and Indoor Air Quality: Lessons from the Energy Crisis of the 1970s

Current discussions of climate change do not often focus on housing. Unless large numbers of homes are destroyed or damaged by extreme weather events such as hurricanes, tornadoes, or wildfires, we rarely scrutinize the effects of our warming planet on our homes. However, environmental health experts argue that this must change. In 2010, the US Environmental Protection Agency asked the Institute of Medicine to study the relationship between climate change and indoor environmental health. The Institute convened an expert committee of professionals from a range of fields, including earth sciences, public health, medicine, architecture, and engineering. Ultimately, they produced a thorough report – nearly 300 pages – arguing that climate change “may worsen existing indoor environmental problems and introduce new ones.” For example, extreme weather events and flooding could increase dampness and humidity, leading to mold growth and chemical emissions from decaying building materials. Or, extreme heat and cold could increase power outages, exposing already-vulnerable populations to dangerous temperatures or to carbon monoxide emissions from portable generators. Finally, well-intentioned attempts at energy conservation, such as weatherization, retrofitting, or excessively tight new construction, could reduce ventilation to dangerously low levels, exposing occupants to indoor air pollutants (radon, VOCs, and more).

This final example – tight, energy-efficient building – has an instructive history. The Arab Oil Embargo of 1973-1974, memorable to many Americans because of the gasoline shortages it caused, was a turning point in residential construction. Everyone from Sierra Club President Theodore Snyder, to President Gerald Ford, to energy expert Daniel Yergin endorsed residential energy conservation as a promising, if partial solution to America’s energy crisis. From rural homesteaders to large developers, American builders eagerly pursued energy-efficient housing designs. This was a time of great enthusiasm for underground and earth-sheltered homes, alternative power sources such as solar and wind, and other housing experiments. While some now seem outlandish, other innovations from this era are now standard, such as continuous polyethylene vapor barriers. If you’ve ever seen a half-built house cloaked in Tyvek Homewrap, this is an innovation that dates to the energy crisis of 1973-1974. The ideal of the nearly-airtight, highly energy-efficient house became increasingly attractive to builders and buyers alike; the lower a house’s “air changes per hour” (ACH), the more it could promise in energy and cost savings.

Above: a “zero energy” Habitat for Humanity house produced in collaboration with the National Renewable Energy Laboratory. Denver, Colorado. The home is tightly constructed, super insulated, and uses solar energy for space and water heating. It also has a mechanical ventilation system to conserve energy while preserving indoor air quality. Photo credit: National Renewable Energy Laboratory Image Gallery

As residential energy conservation became a political and popular priority by the mid-1970s, the Department of Energy funded the Lawrence Berkeley National Laboratory in Berkeley, California, to establish an energy-efficient buildings research program. Scientists studying residential energy efficiency began to investigate concentrations of indoor pollutants in these impressively-sealed homes. Focusing on nitrogen dioxide (a product of combustion from cooking and heating), formaldehyde (a common organic compound in building materials and furnishings), and radon (dependent more on the geology of a house’s site than the house itself), they found alarmingly high levels of indoor air pollution in some energy-efficient homes.

With these troubling findings as motivation, the Berkeley Lab pioneered scientific study of the complex relationship between residential energy efficiency and indoor air quality, and sought to balance these two necessities in cost-effective ways. In my recent working paper,I examine a crucial period in this history: during the early 1980s residential indoor air quality went from an obscure academic subject to a source of national anxiety. The Federal government, the popular media, and the public became increasingly concerned that America’s houses – especially its newly-popular energy-efficient ones – were full of insidious poisons. The media often oversimplified the situation by portraying energy-conservation as the enemy of healthy indoor air, when in reality the relationship between the two was complicated.

Above: Sources of Indoor Air Quality (IAQ) problems, Lawrence Berkeley National Laboratory, Indoor Environment Department. Conventional and energy efficient houses alike can contain harmful indoor air pollutants if not properly ventilated. Climate change is likely to exacerbate existing IAQ problems and introduce new ones. Photo credit: National Renewable Energy Laboratory Image Gallery

Knowledge of energy-efficient building, indoor air quality, and their relationship has increased exponentially since the energy crisis of 1973-1974. However, the continual proliferation of new building materials and household chemicals makes it difficult, if not impossible, for even the most ambitious indoor air experts to keep up. As the Institute of Medicine’s committee concluded, climate change adds even more variables to an already complicated set of equations.

The experience of the 1970s offers valuable lessons as we face the defining environmental problem of our time with an increasing sense of urgency. First, energy conservation in housing and other buildings is imperative, but can affect indoor environmental quality both negatively and positively. It might seem counterintuitive, but drafty old houses do not necessarily have better indoor air quality than tighter new ones: for example, well-insulated houses have the potential to burn less fossil fuel to maintain comfortable temperatures, thus releasing fewer combustion products and maintaining better indoor (and outdoor) air quality. Second, our homes are not isolated from the environments in which they are built: local, regional, and, increasingly, global conditions affect the longevity of housing and the quality of the indoor environment it envelops, which in turn affects the physical, mental, and financial health of occupants. Third, during the “environmental decade” of the 1970s, energy independence appealed to diverse sectors of American society for environmental, political, and financial reasons. This was a time of remarkable ingenuity in the residential energy sector. For example, the Federal government funded the Solar Energy Research Institute, the Department of Energy asked its National Laboratories to design energy-saving houses, major developers created conventional-looking homes that used thermal mass and solar power, and motivated Americans experimented with a variety of energy-saving strategies. Americans have a tradition of ingenuity in the face of energy crises, we have four decades worth of knowledge about indoor air quality and energy-efficient building, and we have a rapidly expanding knowledge of climate change. We can surely combine these advantages to ensure healthy homes on a healthy planet.