Apparently this is the root of my predicament:

Heat is mean molecular kinetic energy, meaning that the hotter something gets, the faster its little molecules are vibrating or bouncing around. As air gets hotter, the combined gas law dictates that it will expand if it can. (Those molecules bounce against each other more furiously, causing an increase in pressure.) Since you then have the same amount of air taking up more space, its density is lower and it tends to rise above the surrounding, unheated air.

A nice demonstration of this phenomenon can be found in the airshaft of the apartment where I live. It’s a vertical space about seven feet long by three feet wide that runs more than three stories up the interior of our building. Two bedrooms and a bathroom on each floor have windows that open into the airshaft. At the top, the shaft is capped by a pyramidal steel frame holding panels of wired glass, with a tiny vent on the very top that lets out a negligible amount of air while keeping any rainwater out.

So when heat is added to the system — say, by someone running an air conditioner that vents into the shaft — the heated air starts traveling upwards, just as a physicist would predict. It goes up and up and up until it hits the steel and glass cap at the top of the shaft. And then it stops.

It can’t escape, or at least not enough of it can escape from the aforementioned tiny vent to make much of a difference. And as more and more hot air rises up the shaft to join it, the air at the very top gets hotter and hotter. Depending on how much heat is being pumped into the airshaft, the air at the top can get very hot indeed.

That hot air, increasing in pressure just as the gas law says it will, tries to escape the confines of the shaft. One convenient escape route is through the windows that open into the top-floor apartment. One of those windows, unfortunately, is mine.

My bedroom, then, can get ridiculously hot without intervention. So I intervene — I have a window unit air conditioner which I run when I need to. It was there when I moved in, and I don’t think it’s the most efficient thing on the market, and it’s probably missing some freon, but it cools the room if you give it long enough. Of course, that’s at the cost of pumping more hot air out into the shaft, which then comes rushing back in through the air conditioner. It’s a thermodynamic hamster wheel.

This week we have temperatures in the 90s in New York City, so everybody with a window on the airshaft is running their coolers, as am I. My room stays livable, but I know a fair amount of the time I’m running my air conditioner just to get rid of the excess heat from everyone else’s air conditioners that spills into my room.

When it’s not so hot I don’t have to run the AC as often, but I still have to run it more than I’d like. And besides being frustrated by the pocket of superheated air at the top of the airshaft, I get wistful for the cooling natural breezes that could blow through my room if the airshaft weren’t capped.

Is it even an airshaft if it has a cap on it that keeps the air from leaving it? I’ve been up to the roof; almost all the neighboring buildings have the exact same arrangement. I wonder if some guy came and installed all those caps at once. A couple of neighbors have those spinning, wind-powered attic exhaust fans, which seem ideal. And one building a couple of doors down has a great setup that lets the the top-floor residents open and close a glass panel from inside, letting them vent the air when it’s hot and close up the vent when it’s raining.

So to quote John Lennon, what is to be done? I’m sure my landlord wouldn’t lift a finger or spend a dime on improvements. Tenants pay their own electric bills, so better ventilation wouldn’t help him at all. What would happen if I smashed or merely removed a pane of glass from the cap? Would the water damage be that bad? Should I resign myself to living with a superheated column of air just outside my bedroom window that forces me to run an air conditioner all the time?* Should I be looking for a new apartment with an outside window? Or should I take a sledgehammer to the thing?

*Why don’t I like running the air conditioner? Many reasons. It’s loud, and the compressor kicking on or off disturbs me when I’m trying to fall asleep. I find air-conditioned air to be antiseptic and strange; it’s an unpleasantness I only accept when the alternative is very hot air. Running the AC runs up the electric bill. But I’m also bothered by the unsustainability of the whole thing, an unsustainability that my airshaft problem illustrates in microcosm. Air conditioning is basically taking heat from somewhere and putting it somewhere else, in the process generating more heat and consuming energy. When I run the AC in my room, I heat the air in the airshaft, which eventually spills back into my room. When people in New York City run air conditioners, they pump the heat out of their buildings, cars, and subway trains out into the streets and subway tunnels, making it that much more miserable to walk somewhere or wait for a train. And the energy that runs air conditioners is usually produced by processes that create greenhouse gases. So in general, I avoid air conditioning if I can, though I’m grateful for it when I need it.