Climate-friendly housing cuts energy use in half

OPINION – In last month’s National Climate Assessment, America’s foremost climate scientists affirmed something that we Californians know first-hand—our state is getting hotter, smokier, and hit with more climate disasters. These trends are going to worsen in the future. You don’t need to be a climate expert to know our housing is woefully inadequate to deal with these problems; we experience it with every heat wave, every time wildfire smoke blankets our communities, and with each extreme weather event that threatens to knock out our power.

Our building codes haven’t kept pace with the growing scale and severity of these climate impacts. This poses an additional risk as legislative leaders, regulators, and Gov. Gavin Newsom seek to cut climate pollution, improve air quality, and achieve California’s climate goals by phasing out fossil fuels and switching homes and buildings to clean energy. Inefficient homes—even newly constructed ones under current or recent building codes—waste vital supplies of clean energy for space heating and cooling that can be used to decarbonize other sectors, like transportation or heavy industry.

These are the costs of constructing homes with leaky building envelopes, which are what protects our indoor living spaces. Passive House design solves this problem. It uses an airtight seal for the envelope and high-performance ventilation systems to provide filtered fresh air to keep us comfortable during extreme heat and cold. At a time when household energy costs are soaring in California, Passive House keeps heating and cooling bills far below average—and often eliminates them altogether. Building new homes to all-electric Passive House standards protects Californians’ health, safety, and comfort from the worsening impacts of climate changes, while also safeguarding power grids in the transition to clean energy.

New research published in late November by the Passive House Network and Emu Passive shows exactly why. It analyzed single-family homes built to Passive House standards in a variety of climate zones across California. Evaluating comfort, indoor air quality, heating and cooling loads, and energy efficiency, researchers revealed that Passive House single-family homes outperform counterparts built to California’s standard code. They concluded that the Passive House Institute (PHI) standard reduces heating and cooling energy use by over 50% compared with standard code.

Because its building envelope is so well-sealed, PHI’s Passive House standard design flattens heating loads. This has crucial ramifications for California, even with its mild year-round climate in many regions. While cooling demand typically peaks in daytime, when renewable generating resources like wind and solar are strongest, heating demand occurs at night, when renewable generation is scarcer. That requires storage systems like electric batteries. The research found PHI’s Passive House standard can drastically reduce the need to integrate battery storage into California’s electric grid.

When the power goes out in a winter cold snap, indoor temperatures in Passive House buildings won’t dip below critical safety thresholds for more than six days, whereas older homes will do so in as little as 8 hours. This principle works in reverse in a power outage during a heat wave—Passive House buildings are superior at keeping out hot air, experts have found.

In addition to saving lives and slashing climate pollution, Passive House design has the potential to save California billions of dollars through lower energy costs for households, and avoided investments in energy infrastructure. Based on years of research and real-world results in the U.S., Canada, and in other countries, Passive House Network has identified a series of successful policies that have led to mass-scale adoption of Passive House homes with little to no cost-premium compared with standard code. Once new incentives from the Inflation Reduction Act and other sources are factored in, Passive House can be cheaper.

In response, states such as New York and Massachusetts have become national leaders in policies spurring Passive House adoption. This includes allowing developers to choose Passive House design to achieve code compliance, adding incentives to overcome building industry inertia, starting competitive awards programs that reward high-performance buildings, and featuring Passive House in opt-in stretch codes. California has lagged in adopting these policies.

As California confronts cascading crises of climate change, housing supply and affordability, and household energy costs, Passive House design is barely scratching the surface of its potential. Our state’s policymakers and regulators must use a suite of proven tools to unlock the sweeping climate, health, resilience and affordability benefits that Passive House provides. This is how we must build the climate-ready housing California so desperately needs.

Bronwyn Barry is a California-based architect and Policy Director of the Passive House Network, a national education and advocacy organization that promotes Passive House building standards.