AC expert Allison Bailes has a few suggestions; we add a few of our own.
We used to make the case on TreeHugger that you could live without air conditioning, but for most people these days it's hard. More people live in the south (thanks to air conditioning), our homes are no longer designed for cross-ventilation, our summers have got hotter and we have become acclimatized to it. But air conditioning uses a lot of electricity. As William Saletan wrote a dozen years ago:
The United States now uses more electricity for air conditioning than a billion people in Africa use for everything. So really, we have to do everything we can to reduce the amount of air conditioning required, make it as efficient as it can be, and then reduce the non-renewable resources needed to run it.
Air conditioning takes indoor heat and pushes it outdoors. To do this, it uses energy, which increases production of greenhouse gases, which warm the atmosphere. From a cooling standpoint, the first transaction is a wash, and the second is a loss. We're cooking our planet to refrigerate the diminishing part that's still habitable.
Over at Energy Vanguard, physicist Allison Bailes has some suggestions to improve air conditioner performance and making them more efficient in our homes right now. My favourite is his first: instead of adding more cooling you should be reducing heat gain.
1. Seal the leaksWherever you live, whether an apartment or house, the first and simplest thing to do is to seal the air leaks. "If you have an older house that's never been air-sealed, this may be a big part of your heat gain problem, especially if you have leaks from the attic. If you haven't had a blower door test, get one."
2. Keep the sun and the heat out in the first place.
3. Get efficient lighting and appliancesThis is getting old but people still have incandescent bulbs that put out a lot of heat. Turn them off or get rid of them.
4. Insulate if you canIf you have access to an attic, make sure that the insulation is spread evenly and add more if you can. Allison notes that bumpy insulation is not as good as smooth.
5. Make some minor lifestyle changes.
6. Keep the vents clear
I've seen dressers, piles of clothes, and dog beds completely or partially covering supply or return vents in homes. Choking off air flow at the vents increases the pressure in the duct system and reduces air flow.
7. Look for duct air flow problemsYou should look to Allison's site for this; I have never lived in a house with ducts and he shows a lot of photos that scare me and make me wonder why anyone would. He writes that "Most ducts are bad. Some are really bad. Some are really, really bad." He also gives recommendations for checking, fixing and sealing your ducts, and keeping the outdoor unit clear of obstructions, covers and vegetation.
All of Allison's suggestions are good, but in the end we need a mix of lifestyle changes and better buildings. Some things that he doesn't mention that reduce the impact of air conditioning:
8. Get a smart thermostatTreeHugger Sami has achieved significant savings in energy in his leaky house with smart thermostats. He talks mainly about heating in his post, but energy savings on cooling are supposed to be about 15 percent.
10. Add some rooftop solar panelsIt is hottest when the sun is shining, so it makes some sense to try and offset electricity consumption with rooftop solar if you can. It is not perfect, because we are often not home when the panels are generating most of the power and need it later in the day (hence the famous duck curve) but it is a help.
11. Get outside and cool with culture, not contraptions.
12. In summary: go for a mix of lifestyle, technology and good design
We need a balance between the old and the new, an understanding of how people lived before the thermostat age along with a real understanding of building science today. To minimize our heating and air conditioning loads and maximize comfort, we have to design our homes right in the first place.
There are things we can do to reduce our need for AC, from adding fans, dressing properly or changing what and when we eat. But in the end, we need radical building efficiency to reduce the amount of air conditioning required.