8. Avoid Using Air Conditioning
Most houses in Portola Valley can avoid the need for air conditioning. You can use fans to cool a house. You can pull down shades to block out sunlight.
San Mateo City Library uses water on the roof to cool it. You might consider using water, if your house gets very hot. Insulating your roof can also keep your home cool.
You may also want to ensure trees shade your property - but be careful that they are not a fire hazard.