There are some effective ways of reducing your cooling bills, if you are using central air conditioning; consider them carefully; they can save you hundreds of dollars each year.
Windows can be responsible for more than 50% of unwanted heat gains, in the cooling season. Without proper glazing and shade, windows are an amazing source of unwanted heat, namely the east and west-facing windows.
If you have old windows, or windows without proper glazing, consider using window films. They are inexpensive and can reduce AC bills by a very significant percentage.
Trees and shrubs provide evapotranspiration and shade that can reduce temperatures by several degrees; tree-shaded windows, roofs and walls can greatly reduce AC consumption.
If you can’t benefit from the shade of trees, consider shading devices. They too are very effective at reducing cooling loads. In new construction consider overhangs and porches. And consider awnings, shades, shutters and other devices; they can make a big difference.
Many people assume that central air conditioners do not need maintenance once properly installed. But that’s terribly wrong; they are prone to many problems. They are like cars: filters have to be regularly replaced, and they need regular cleaning and professional service.
Without it, you will pay a lot more... through higher energy bills.
Use thermostats wisely, to reduce your air conditioning costs. Every Fahrenheit degree increase in your thermostat setting can reduce your cooling costs by 3% or more.
Consider the ideal standard summer temperature (78°F/26°C) and how much you want to turn the thermostat up while you are out or asleep. Why spending money with cooling when you are not at home?
Also consider variable speed features in your new AC, and zoning.
Pay attention to internal heating gains during the cooling season. They are typically the second source of unwanted heat gains (after gains through windows).
Avoid as much as possible hot baths and hot food preparation, and use exhaust fans.
Keep an eye on these issues, and do not undervalue their importance. They often account for more than 15% of the unwanted heat gains during the cooling season.
If you live in a hot climate and are going to re-roof your home, consider reflective coating materials.
Reflective coatings can be great for application over existing roofs. High reflective elastomeric coatings can provide big energy savings. They are relatively expensive (say, $20 per gallon), but can be cost-competitive if your roof is a major source of unwanted heat (these coatings will also extend the life of the roofing materials).
Also consider (in hot climates) radiant barriers for your attic. They too are very effective at reducing heat gains through roof.
See: Roof Coatings
If updating a central AC system, choose a new unit with a SEER (energy efficient coefficient) of at least 15. Compared to older units, with SEERs below 10, that means savings of 50% or more.
Just be sure that you do need a central AC. Central AC is expensive to buy, run and maintain. Room and ductless AC are a lot less expensive and cheaper to run and maintain.
Cooling losses through ducts can be huge. Potential savings are often estimated at 15% or more. Inspect your ducts, and seal and insulate them properly.
See: Guide to Home Ducts
Our video On How to Reduce Air Conditioning Costs: