The Cost of Staying Cool

There is a particular sound to an Indian summer evening now, and it is not cicadas. It is the compressor hum of several thousand outdoor units, a flat mechanical drone that starts in the afternoon and does not really stop.

I want to be careful how I write about this, because there is a strand of environmental commentary that treats air conditioning as a moral failing, and that strand is generally written by people who are not doing physical work in forty-degree heat. Heat kills. It kills outdoor workers, the elderly, infants, and people with conditions that heat makes worse, and it does that quietly enough that the deaths are usually attributed to something else. Cooling is not a luxury in that context. Access to it is closer to a public health question than a lifestyle one.

The difficulty is that the way we currently deliver cooling has a structural perversity built into it. An air conditioner does not destroy heat. It moves heat — out of your room and into the street. Multiply that across a dense neighbourhood and the street gets measurably hotter, which makes everyone's unit work harder, which moves more heat into the street. The people most exposed to that added heat are, reliably, the people without a unit of their own.

Add the refrigerants, many of which are potent greenhouse gases when they leak, and the electricity, which in most of the country still means burning something. A device that keeps one room survivable contributes to the conditions that make the next summer hotter. This is not a reason to give up cooling. It is a reason to be precise about what kind of cooling we build.

The precision is mostly architectural, and it is not new. Buildings in this country used to be designed by people who assumed there would be no machine. Thick walls that absorb heat during the day and release it at night. Deep shading so sunlight never reaches the glass. Cross-ventilation that actually connects two sides of a room. Courtyards, jaalis, high ceilings, light-coloured roofs. None of this is nostalgia — it is thermal mass and airflow, and it works for the same reasons it always worked.

We stopped doing it largely because sealed glass buildings are faster to build, cheaper per floor, and read as modern. Then we installed machinery to compensate for the thermal properties we had just designed out, and passed the running cost to the occupant and the waste heat to the street.

What would change it is unglamorous: building codes that treat cooling demand as something you design down before you install equipment, shading and insulation standards that are enforced rather than notional, cool roofs at scale, and shade trees treated as infrastructure rather than decoration. A street with a continuous canopy is several degrees cooler than the same street without one, and the tree does not need an electricity connection.

On the balcony I have learned this at a tiny scale. The plants on the shaded side survive May. The ones in direct afternoon sun need water twice a day and still look punished. The difference is not care. It is shade — which is the one cooling technology that costs nothing to run and improves the street for everybody who walks down it.

We are going to need the machines. We should stop designing buildings that make them mandatory.