Air District Signals Critical Move Toward Zero-Emission Appliances

By Melissa Yu

California prides itself as a leader on climate action, with commitments in place to slash emissions in coming decades and reach carbon neutrality by 2045. But recent studies indicate the state is far off course to meeting these goals, in part because emissions from buildings are going in the wrong direction — up 17.8 percent in the residential sector since 2014. Air agencies nationwide have authority under the Clean Air Act to set zero-emission standards for appliances, and the Bay Area Air Quality Management District (Air District) is poised to become the first public agency to set a deadline requiring new appliances to be zero-emission.

Our Air District has announced its intention to amend the current residential furnace and water heater rules, 9-4 and 9-6. The existing rules already limit nitrogen oxide (or NOx) emissions from residential water heaters and furnaces, but current standards are not low enough to require fuel switching (away from gas) and still allow pollution to persist, with impacts to both indoor and outdoor air quality. Zero-NOx appliance standards, on the other hand, will ensure a transition from polluting fossil fuel appliances to clean, healthy alternatives. 

The emissions under review here, NOx, are toxic, highly reactive gasses that are emitted when a fuel is burned, such as when operating cars, trucks, power plants, and household appliances. NOx also reacts with the sun and atmosphere to become harmful smog (ozone) and particulate matter (PM2.5). 

Most household appliances in California run on gas and emit NOx in and near our homes. In the Bay Area, appliances release nearly three times as much NOx as passenger vehicles, and over eight times as much NOx as power plants. As a result of this appliance pollution, buildings in California are responsible for over 1,500 premature deaths and over $17 billion dollars of health impact costs.

To address this major source of deadly pollution, the Air District is proposing that all newly purchased space and water heaters will be zero-emission as soon as 2027, though implementation dates vary by appliance:

  • 2027 = all new home water heaters will be zero-emission
  • 2029 = new home and commercial furnaces will be zero-emission
  • 2031 = new commercial water heaters will be zero-emission

These regulations apply to manufacturers, installers, retailers, and sellers. They are “point of sale” regulations, which means all appliances being sold or installed in the nine-county area after the specified date must comply with the zero-emission requirement. The rules will not require proactive retrofits, but rather will only impact appliance replacements and new construction. All major gas appliances in our homes already have zero-emission counterparts on the market: heat pump water heaters, air source heat pumps, induction cooktops, and electric dryers. 

Regulating NOx in appliances will promote electrification of new and existing buildings in a way that prioritizes environmental justice communities. Low-income communities are disproportionately impacted as they are already located near sources of pollution such as power plants and major highways. Growing up in homes with NOx-emitting appliances has been found to be a precursor for childhood asthma. Eliminating gas appliances reduces NOx pollution in these households. 

In making this move, the Air District is in step with State policy and funding priorities: Governor Newsom recently set a target of three million climate-ready and climate-friendly homes by 2030 and seven million homes by 2035, to be achieved through the deployment of six million heat pumps by 2030. At least half of the funding to achieve this policy goal will be directed toward disadvantaged communities. 

There will likely be an Air District Board hearing on the way to rule adoption towards the end of this year or early next year. If your organization wants to get involved, they could become a participant in the formal Air District Stakeholder Working Group. Additionally, as an individual, you can join a group of advocates for informal biweekly meetings to hear the latest updates on the rulemaking process and weigh in on how you want to see the Air District move forward. To get involved or learn more, email Melissa Yu at

Melissa Yu is the Chapter's Senior Energy Campaigns Representative.