It is the springtime, and our thoughts have turned to plowing, procreation and fertility. That's right, I'm talking about gardening. This is the time of year when we plant crops of homegrown vegetables or a new elm tree. You can use that green thumb of yours to save some money come the hot, treacherous summer by shading your air conditioner.
Shading your air conditioner will save you a little less than 5% on your cooling bills. That's not exactly a king's ransom, but the EERE claims that doing this will increase the energy efficiency of your AC unit by 10%. Your air conditioner will have reduced wear and tear, saving you in repairs and replacement. Trees and shrubs around the house also contribute to overall home cooling. In totality, this is not a bad little project to undertake.
The goal is to provide maximum shade while not interfering with air flow. Watch this video for examples of what not to do. Florida Solar Energy Center planted three eight-foot trees to create the greatest amount of shade with no air interference.
The alternative to this project is moving your air conditioner to the north side of the house, leave it unshaded but plant trees to reduce the heat in your yard microclimate. I think either idea is good, but you can only do one.