Here’s a piece written by Matt Golden and Jess Chamberlain for Sunset Magazine on best practices for keeping your house cool, the environmentally friendly way.

To keep a house cool, it’s really about either:

• Keeping the sun out, or
• Keeping the air cool/conditioned

In a retrofit situation, you have to first assess what your possibilities are:

• Is there an attic we can insulate?
• Are there eaves that are blocking some of the summer sun?
• Is there an existing cooling system?

This really affects what the best approach to take is.

For an average house in a cooling climate with an attic, we’d recommend reducing the cooling load as much as possible and utilizing passive cooling:
1. Air sealing
2. Adequate attic insulation (min. R-38) to create a thermal barrier
3. Radiant barrier, if there are ducts in attic; on roof decking or in attic
4. Low-E glazing on windows
5. Whole-house fan

This route is very cost-effective from a long-term standpoint; i.e. you’re not paying to condition the air, you just pay for the equipment and installation.
The other option is to actively cool the house, in which case you’d invest in the fundamentals (such as air sealing and insulation), then install a high SEER-rated AC unit (min. 16-18 SEER rating) designed to ACCA’s manuals J, S, D & T. If air handling equipment is located in the attic we would recommend encapsulating the attic with air-impermeable spray foam and bringing the attic into the building envelope. This prevents hot attic air (150˚F+) from infiltrating the duct system.

Easy Cooling Tips:

• Keep your AC unit in the shade
• Keep the coils clean
• Install high efficiency lighting (it keeps house cooler)
• Turn plug loads off
• Stop the sun before it gets into your house – use external shading, overhangs, and deciduous trees
• Low-E coating on windows