The Lab — Issue 41

The Private Room

The Seven Words

By Ivy Marlowe— July 16, 2026

Feature image for article: The Seven Words

In Maricopa County last year, 111 people died of heat indoors. In 94 percent of those cases, an air-conditioning unit was sitting right there in the home. The machine was present. The person still died. "The apartment has air conditioning" is seven words you see in leases and listings and housing inspections, and they sound like they're closing a question. But I keep turning them over, because between "has air conditioning" and "is safe from heat" there's a whole chain of silent conditions nobody mentions, and every single one of them can break.

The Private Room

The Seven Words

By Ivy Marlowe— July 16, 2026

In Maricopa County last year, 111 people died of heat indoors. In 94 percent of those cases, an air-conditioning unit was sitting right there in the home. The machine was present. The person still died. "The apartment has air conditioning" is seven words you see in leases and listings and housing inspections, and they sound like they're closing a question. But I keep turning them over, because between "has air conditioning" and "is safe from heat" there's a whole chain of silent conditions nobody mentions, and every single one of them can break.

The Public Room

The Building Behind the Pin

By Wren Castellano— July 16, 2026

Feature image for article: The Building Behind the Pin

Maricopa County's Heat Relief Network puts more than 200 cooling centers on an interactive map: name, address, hours, "air-conditioned." Clean enough to read on a phone screen while you're standing in 115-degree heat deciding where to go. Meanwhile, 11 percent of U.S. public libraries have HVAC in poor condition, 41 percent of school districts need updates in at least half their buildings, and nobody has published an audit that walks the line from a map pin to the compressor on the roof. The listing tells you the building exists. What the building can do when you walk through the door is a different system entirely, and it's the one nobody is inspecting.

The Public Room

The Building Behind the Pin

By Wren Castellano— July 16, 2026

Maricopa County's Heat Relief Network puts more than 200 cooling centers on an interactive map: name, address, hours, "air-conditioned." Clean enough to read on a phone screen while you're standing in 115-degree heat deciding where to go. Meanwhile, 11 percent of U.S. public libraries have HVAC in poor condition, 41 percent of school districts need updates in at least half their buildings, and nobody has published an audit that walks the line from a map pin to the compressor on the roof. The listing tells you the building exists. What the building can do when you walk through the door is a different system entirely, and it's the one nobody is inspecting.

The Dispatch Queue

Nine Trucks, 430 Deaths, and the Whiteboard in Between

The Dispatch Queue

Nine Trucks, 430 Deaths, and the Whiteboard in Between

Room Diagnostic

The Room You're Sitting In Right Now

In Maricopa County last year, 94% of people who died indoors from heat had an air conditioning unit present. Nearly three-quarters of those units weren't functioning. Another 23% were working fine but turned off. The room looked equipped. Nobody was cooled.

That distinction matters when you're looking at your own space. A room that protects against extreme heat needs to do one thing: stay below the mid-90s. The EPA is specific about this: once a room hits that range, a fan won't prevent heat illness. It moves air. It doesn't lower the temperature.

A room that protects against wildfire smoke needs to do the opposite: seal. Closed windows and doors alone cut indoor PM2.5 to roughly 55–60% of outdoor levels. Add a MERV 13 filter running continuously and you cut that roughly in half again.

The problem is when both hazards arrive together, which they increasingly do. Sealing against smoke traps heat. Ventilating against heat pulls smoke in. The EPA names this conflict directly. Without functioning AC, the two strategies cancel each other out. If you can't seal and cool simultaneously, the room doesn't protect you from either.]

Room Diagnostic

The Room You're Sitting In Right Now

In Maricopa County last year, 94% of people who died indoors from heat had an air conditioning unit present. Nearly three-quarters of those units weren't functioning. Another 23% were working fine but turned off. The room looked equipped. Nobody was cooled.

That distinction matters when you're looking at your own space. A room that protects against extreme heat needs to do one thing: stay below the mid-90s. The EPA is specific about this: once a room hits that range, a fan won't prevent heat illness. It moves air. It doesn't lower the temperature.

A room that protects against wildfire smoke needs to do the opposite: seal. Closed windows and doors alone cut indoor PM2.5 to roughly 55–60% of outdoor levels. Add a MERV 13 filter running continuously and you cut that roughly in half again.

The problem is when both hazards arrive together, which they increasingly do. Sealing against smoke traps heat. Ventilating against heat pulls smoke in. The EPA names this conflict directly. Without functioning AC, the two strategies cancel each other out. If you can't seal and cool simultaneously, the room doesn't protect you from either.]

Check for heat:

AC runs, not just exists. Turn it on now, before a heat event. Is it actually cooling?
Serviced this season? Technician availability drops once heat arrives.
Electricity reliable? No power, no cooling. Know your grid's outage history.
Windows shaded? Morning and afternoon sun drives indoor temps up fast.
Fan your only option? It stops helping in the mid-90s. Have a backup plan.

Check for smoke:

Fresh air intake closed? HVAC, window units, and especially evaporative coolers can pull smoke in. Set to recirculate.
MERV 13 filter compatible? Not all systems can handle it. Check before smoke season, not during.
Fan set to "On," not "Auto"? Continuous filtration matters.
Indoor sources eliminated? Candles, frying, gas stoves, vacuuming all add particles.

When both hit at once:

Can you seal AND cool? If not, the room fails for both hazards.
Night ventilation possible? Only if outdoor air is cooler and air quality is acceptable.
Shelter elsewhere an option? Know your cooling center before you need it.]

Room Conditions by Hazard

Most climate safety advice operates at the scale of cities, regions, policy. The unit that matters when conditions get dangerous is smaller. It's the room you're sitting in, and whether the chain between your equipment and your actual protection holds.

Six cards follow, each naming a hazard, the minimum conditions a room needs during it, and the most common failure point. A pattern connects them. People tend to check for the equipment (the AC unit, the sealed window, the house above the flood line) and stop there. But the equipment depends on conditions far less visible: power, filtration, road access, water supply. Those are what break first.

Room Conditions by Hazard

Most climate safety advice operates at the scale of cities, regions, policy. The unit that matters when conditions get dangerous is smaller. It's the room you're sitting in, and whether the chain between your equipment and your actual protection holds.

Six cards follow, each naming a hazard, the minimum conditions a room needs during it, and the most common failure point. A pattern connects them. People tend to check for the equipment (the AC unit, the sealed window, the house above the flood line) and stop there. But the equipment depends on conditions far less visible: power, filtration, road access, water supply. Those are what break first.

Extreme Heat

Your AC Being Present Doesn't Mean You're Safe

Minimum conditions: a cooling unit that functions, electricity, and a space the unit can actually cool to safe temperatures. In Maricopa County's 2025 indoor heat deaths, AC was physically present in 94% of cases. In 72% of those, the unit wasn't working.

Wildfire Smoke

Closed Windows Reduce Smoke but Don't Stop It

Without active filtration, sealed rooms still reach 55–60% of outdoor PM2.5 levels, per EPA data. MERV-13 or higher filtration in the HVAC system, or a portable HEPA cleaner, substantially changes that ratio. Sealing gaps is a start. Filtration is what gets indoor air to protective levels.

Power Outage

Without Electricity, Indoor Heat Rises Dangerously Fast

Upper floors of AC-dependent homes can reach body-temperature thresholds within two hours at 95°F outside. Modeling of Austin homes found 85% posed significant death risk to elderly residents during a three-day outage above 110°F. The relevant variables: battery backup, passive cooling features, evacuation access.

Tidal Flooding

A Dry Room Can Still Be Cut Off

High-tide flooding doesn't need to reach your floor to compromise safety. NOAA projects some Gulf Coast locations will see 38–60 high-tide flood days this year. Road closures sever access to medical care, groceries, and emergency response while the room itself stays perfectly dry.