Heat waves and power shutoffs: what you owe your ADU tenant this summer

The first 95-degree stretch of the year hit the South Bay this week, and PG&E has already floated its first Public Safety Power Shutoff warnings of the season. Both land on a question most ADU owners have never thought through: when the heat climbs or the lights go out, what do you actually owe the person living in your backyard?

I've managed ADUs across the South Bay for 12 years, 200-plus tenancies. Summer is when the habitability questions show up, and the honest answer surprises most owners, because what the law requires and what keeps a good tenant are two different lists.

What habitability legally covers in California

California's implied warranty of habitability (Civil Code Section 1941.1) sets the floor every rental has to meet: working plumbing, hot and cold water, working heat, safe wiring, weatherproofing, no pests, and so on. A unit that fails these isn't legally habitable, and the tenant has real remedies.

Here's the part that catches owners off guard: the list requires working heating. It does not require air conditioning. Under California law, an ADU with no AC is still a legally habitable unit, even in a July heat wave. There's no statewide maximum-temperature rule for rentals the way there's a minimum-heat rule.

That's the legal floor. It is not where I'd stop, and I'll explain why.

Heat: required vs. smart

Two things change the AC calculus even though the state doesn't mandate cooling.

If your ADU already has AC or a heat pump, you have to keep it working. Once cooling is part of the unit you rented, it falls under the "good working order" umbrella. A broken AC in a unit advertised with AC is a repair obligation, not an optional one. Most newer ADUs built under the 2025 Energy Code have heat pumps, which means they have cooling, which means you're now responsible for it.

If your ADU has no AC, you're legally clear but practically exposed. A 700-square-foot unit with western exposure and no cooling can hit the mid-90s indoors during a heat dome. The tenant won't file a habitability claim, but they will leave at renewal, and a turnover costs far more than a window AC unit. I keep a couple of portable AC units in storage and drop one off when a heat wave is forecast for an un-airconditioned unit. It's goodwill, not obligation, and it pays for itself in retention.

Power shutoffs: the shared-meter problem

A PSPS is the utility cutting power to reduce wildfire risk. You didn't cause it and you're generally not liable for the outage itself. But the consequences can still land on you.

The wrinkle specific to ADUs is the shared meter. Most ADUs sit on the main house's electrical service, so when a PSPS hits, the ADU goes dark exactly when your own house does. If the property is on a well or a pump, water goes too, and no water crosses back into actual habitability territory. The shared-utility setup I covered separately is the thing to understand before fire season, not during it.

What I do before and during a shutoff: give the tenant PG&E's PSPS notification link at move-in so they get their own alerts, confirm at lease signing whether anyone in the unit relies on power for medical equipment (that changes the plan entirely, and PG&E has a Medical Baseline program for it), and keep a couple of portable power stations on hand for the medical-need cases. For a standard tenant, clear communication and a realistic timeline is most of the job. For a tenant on a CPAP or a medication fridge, a backup plan isn't optional.

Wildfire smoke: the gray zone

Smoke is the murkiest of the three. California doesn't have a clean-indoor-air habitability mandate the way it has a heat mandate, so a smoky week generally isn't a habitability violation on its own. But weatherproofing and working windows are on the 1941.1 list, so a unit that can't seal out smoke because of a broken window or a gap under the door is a different story.

The practical version: I put a decent MERV-13 filter in any unit with central HVAC and hand tenants a portable HEPA purifier during a heavy smoke event. An air purifier for a small ADU runs $120 to $200. Set against a tenant who decides the unit is unlivable every September, it's a rounding error.

What I provide vs. what's goodwill

The line I draw, after a dozen summers of this:

Obligations: working heat, working AC if the unit has it, weatherproofing that seals, safe wiring, water. These are the law, full stop.

Goodwill that retains tenants: a portable AC unit during heat waves for un-airconditioned ADUs, a HEPA purifier during smoke events, a power station for medical-need tenants during a PSPS, and proactive communication before a forecasted event. None of it is required. All of it is cheaper than a vacancy.

What to put in the lease

A few clauses save a lot of mid-summer friction. Specify who maintains the AC or heat pump and the filter-change schedule. Include a clause noting that utility interruptions outside the landlord's control (including PSPS events) aren't landlord-caused, while preserving the habitability obligations that do apply. Disclose the shared-meter arrangement per the rules covered in the utility separation guide. And capture, at signing, whether any occupant has a medical power dependency.

What to do this week

With heat already here and PSPS season starting, the short list:

• Confirm the AC or heat pump in every cooled unit actually works before the next heat wave, not during it
• Drop a portable AC at any un-airconditioned unit with a vulnerable tenant or bad sun exposure
• Send tenants the PG&E PSPS alert sign-up and confirm any medical power needs
• Swap in a fresh MERV-13 filter and stage a HEPA purifier for smoke season
• Re-read your lease's utility-interruption and AC-maintenance language before you need it

The law sets a floor that's lower than most owners assume. The tenants who stay three and four years stay because their landlord did the goodwill list without being asked. In a market where a turnover eats months of rent, that math isn't close.

Want help getting an ADU tenancy set up so the summer surprises don't become disputes? Request a free ADU rental analysis and I'll walk through the lease, the utility setup, and what's worth providing for your specific unit. Or call me at (408) 813-8001.

Sources

• California Civil Code Section 1941.1 (Habitability) — California Legislative Information
• PG&E Public Safety Power Shutoffs — Pacific Gas and Electric Company
• PG&E Medical Baseline Program — Pacific Gas and Electric Company
• AirNow Air Quality Index — U.S. EPA
• California Department of Consumer Affairs — Landlord/Tenant — California Department of Consumer Affairs
• CARB Wildfire Smoke and Indoor Air — California Air Resources Board