When record heat hit the Midwest last summer, most of us didn’t sweat it out.

We just made our air conditioners work a little harder.

Stan Cox worries our year-round preference for cool, dry air is creating an unsustainable feedback loop. Our reliance on air conditioning contributes to global warming, which increases our reliance on air conditioning, which increases our reliance on air conditioning, and so on.

Cox is author of Losing Our Cool: Uncomfortable Truths About Our Air-Conditioned World. The 2010 book traces how air conditioning has reshaped the country and lowered our ability to adapt to climate change.

I spoke briefly with Cox last month about the challenge we’d face in resetting our collective thermostat.

“We’ve built ourselves into a corner,” Cox said. “We’ve built countless square feet of interior space that are uninhabitable without air conditioning.”

Offices built before the 1950s often had H-, T-, and L-shaped footprints so inhabitants were never far from a window. Air conditioning allowed architects to do away with that constraint, designing buildings instead as giant cubes.

Opening windows for a cross breeze just isn’t possible in most large, modern office buildings.

With homes, the introduction of air conditioning prompted builders to cut out extra insulation and other energy saving features that helped make pre-AC homes more comfortable.

Recent building code updates improve energy efficiency, but they don’t address the most important factor: size. We’re building more efficient homes today, but for decades we also moved into larger and larger homes (a trend that only slowed after the housing market tanked in 2007.)

Cox describes a 2005 study from the Journal of Industrial Ecology that compared three homes: a large, energy efficient home, a small efficient home, and a small inefficient home.

“The authors concluded that a 1,500-square-foot house with mediocre energy-performance standards will use far less energy for heating and cooling than a 3,000-square-foot house of comparable geometry with much better energy detailing.”

And that’s the problem with efficiency:

“Efficiency first tends to make frugality seems less necessary,” says Cox.

There is no single solution. Cooling ourselves more sustainably will probably require a combination of broadening our comfort zone, increasing efficiency and improved building design.

“It’s not going to be that easy because air conditioning is kind of an all or nothing thing,” says Cox. “It’s not easy to build a building that can run part of the time really efficiently with air conditioning, and another part of the time be comfortable with natural ventilation.”