Taking the heat

Until now the peak electricity demand on Hydro Quebec, the quasi-governmental electricity utility here, has come during the winter. Montreal gets stinking hot in the summer, but a heat wave usually lasted only a few days. This meant that houses could cool off in between: residential air conditioning has hardly seemed worth it to most people.

That is changing. Summers are getting hotter, and air conditioning costs are going down. Walk around my neighborhood on a hot afternoon, and you hear more and more roar from cooling systems. And—a confession is in order—we put in a ductless mini-split system and ran it this week when temperatures topped 30 C (about 85 F.)

Air conditioning has three environmental costs: the energy to run it, the noise, and heat the systems pump back into the city. Residential solar air conditioners
are becoming available, and in Germany and Australia serious efforts are underway to shift a major portion of cooling to solar power. Since these are out of reach of most North Americans, though, it’s necessary for us to check out the Energy Efficient Ratio—the higher the better.

As for noise, split systems on roofs or under porches are much quieter than window units. We were delighted to discover this spring that neighbors across the street who have run window units non-stop in the past have switched to some other system: for the first time in a five or six years, it’s possible to sit outside on our front porch in the evening when it starts to cool off.

And taking advantage of natural cooling is essential. Plant trees, insulate, open houses to breezes in the morning when it’s cooler. Otherwise you contribute to actually making cities hotter since your system is pumping interior heat outside. (See some interesting research done in Japan.)

But I'm sorry, I’ve got to quit now, and go shut the windows and curtains because the sun has begun to fall on the front of the house...