Central air conditioners are expensive. Installing them will cost you several thousand dollars, plus hundred of dollars on cooling bills per month during the cooling season.
But there are good alternatives to them.
If the SEER (energy coefficient) of your air conditioner is 10 or lower, you are wasting a lot of energy. You can reduce it in half by replacing it with a high-energy efficient AC.
But there are other features that you should care about, like variable speed motors.
Anyway, before installing a new central air conditioner you should ask yourself if you do need a central AC.
Stay away from unventilated portable air conditioners: they cool one part of the room while heating another.
Ductless and room air conditioners are a much better option for home energy improvement strategies. Ductless mini-splits are now an attractive choice for very energy efficient homes (to cool and to heat).
Before installing an AC system you should reduce as much as possible your home’s cooling needs. That may not be difficult, and you should try hard to know where the heat comes from.
Usually, the windows are the big source of unwanted heat gains. They may account for more than 50% of the heat gains, and if your windows are large and wrongly positioned and without low-energy glazing, you should install window films (that’s inexpensive) or replace your old windows.
Internal sources of heat (coming from laundry, food preparation, baths…) can also be very significant sources of unwanted heat. It's critical to reduce the heat that comes from them.
But there are other sources of unwanted heat gains, some involving air leaks and low levels of insulation.
Many central air conditioners are grossly oversized. AC with the double or the triple of the correct size are commonplace, and a cause of energy waste and drafts.
And that’s one of the reasons why it is so important to choose new multi-speed units, able to adjust their output; or to carry out improvements in the home’s shell – involving windows, sealing, insulation… - before buying new AC equipment.
Do not under-estimate AC maintenance. Air conditioners are like cars: their filters should be regularly changed, and they need to be regularly cleaned and checked; regular professional service is vital to avoid higher cooling bills.
Air conditioning costs vary dramatically from home to home. Some homes can consume $500 or more worth of electricity in the hot months, while others in the same neighborhood can spend $50 or less. It depends on the design of the house, the type and size of the windows, or elements like shade, insulation or cooling strategies.
Anyway, you can greatly reduce your cooling bills... Consider:
- proper window metallic films (or new windows);
- shading devices (overhangs, porches; awnings, blinds, shades, shutters) and the shade of trees.
- AC maintenance (remember: AC are like cars…)
- a smart use of thermostats: a 1-degree increase in the thermostat setting provides a 3-5% reduction in AC bills;
- reflective coating materials for your roof.
- to reduce internal sources of heat
- to replace old and inefficient AC equipment
- to seal and insulate your ducts
- using ceiling fans in conjunction with air conditioners.
See, for details: AC Savings
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Consider carefully the alternatives to central AC.
It’s not very difficult eliminate the use AC in new construction, or at least to reduce mechanical air conditioning to very small levels, even in the warmest climates. A well designed home, properly protected from the sun, with good ventilation and benefiting from high levels of shade, may not need mechanical AC.
There are some good alternatives to air conditioners. Even for existing homes.
See, for details: