Air Duct and Dryer Vent Cleaning for California's Varied Climates

One state, many climates

California doesn't have a single heating and cooling pattern. NOAA's climate summary notes that coastal locations have mild year-round temperatures, inland locations see a wider range, the southern deserts are among the nation's hottest and driest areas, and higher elevations can bring low temperatures and heavy snowfall. The California Energy Commission accounts for that diversity with sixteen climate zones in the state Energy Code.

The federal county-by-county climate guide tells a similar story: hot-dry counties such as Los Angeles, San Diego, Sacramento, and Fresno; marine counties around San Francisco Bay; a warmer hot-dry zone in Imperial County; and cold zones in Alpine and Mono counties.

For ductwork, the practical difference is how long and how hard a system runs. An inland home may run its air conditioning for long stretches every summer, while a mild coastal home may barely use its system. That's one reason EPA recommends cleaning ducts only as needed rather than on a fixed schedule — the condition of your own system matters more than the calendar.

Sources: California Energy Commission — Climate zone tool, maps, and information supporting the California Energy Code; PNNL for U.S. DOE Building America — Guide to Determining Climate Zones by County (IECC 2021 updates); NOAA State Climate Summaries 2022 — California; U.S. EPA — Should You Have the Air Ducts in Your Home Cleaned?

Wildfire smoke puts the focus on your filter

NOAA's climate summary for California notes that summer is the dry season and that wildfires are common, particularly toward the end of summer. When smoke arrives, both the California Air Resources Board (CARB) and the U.S. EPA point first to filtration: use a MERV 13 filter, or the highest rating your system can handle, and keep the system from pulling in outdoor air.

CARB also suggests setting the fan to "on" instead of "auto" during smoke events so air is filtered continuously. EPA advises checking HVAC filters frequently and changing them when they appear dirty, and keeping spare filters on hand, because during heavy smoke they may need replacing more often than the manufacturer recommends.

A smoky season doesn't automatically mean your ducts need cleaning. EPA suggests considering duct cleaning when ducts are clogged with excessive dust and debris, or when particles are actually released into the home from supply registers.

Sources: NOAA State Climate Summaries 2022 — California; California Air Resources Board — Smoke Ready California; U.S. EPA — Wildfires and Indoor Air Quality; U.S. EPA — Should You Have the Air Ducts in Your Home Cleaned?

Duct cleaning is not Title 24 duct testing

California's Energy Code includes field verification and diagnostic testing that can come into play when a home's heating or cooling system is changed. The California Energy Commission explains that a HERS rater inspects features such as the HVAC equipment, air ducts, and vents, and that a homeowner who changes an HVAC system can ask to see the completed HERS forms — and can hire a rater who is independent of the contractor. As of January 1, 2026, the Commission says those field verification and diagnostic testing provisions sit in Title 24, Part 6, under its Energy Code Compliance (ECC) Program.

That testing, and any duct sealing or replacement it leads to, is HVAC contractor work. A cleaning visit removes dust and debris; it doesn't replace equipment, seal leaks, or satisfy an Energy Code requirement. The current 2025 edition of California's building standards took effect on January 1, 2026.

Sources: California Energy Commission — Home Energy Rating System (HERS) Program; California Building Standards Commission — Codes (Title 24)