10. Plug up holes
To keep cool air from escaping, fault around leaky windows and doorways, or if you’re feeling particularly ambitious, install weatherstripping.
11. Keep your vents clear
Working up a sweat to ensure your AC vents are clear of dust will pay off in the long run, since even a slightly clogged up vent will affect how much harder your system needs to work to cool things down. You also shouldn’t be blocking any vents with furniture, but if you can’t get around it, invest in one of these.
Joe McGauley is a senior editor at Supercompressor who grew up without air conditioning.