How to Analyze the Operating Cost of a Central A/C System in Warm Weather
Here’s a fun trivia fact: Willis Haviland Carrier was the first to design in 1902 something akin to what we now recognize as the air-conditioning unit. His design made it possible to set controls on temperature and humidity levels using the principles of refrigeration that removes moisture from an enclosed area while cooling the room at the same time.
Although over 80% of Americans use the air-conditioner in their homes in one form or another, many disregard the operating costs. This is tragic because it is entirely possible to lower costs and afford to run a/c units or systems in every room at any time of the year and not stress as much about electric bills.
That’s because air-conditioning of today, more than 100 years after Willis designed the first one, is far more advanced at controlling operating costs. Almost all of the new air-conditioning options on the market today have savings-friendly refrigerants, options for wireless thermostat and reduced cooling load while avoiding the ultimate complaint of ozone depletion.
How to Analyze Air Conditioning Operating Costs
You have to start with the space you need to cool down, the frequency that you will need to use the cooling system, and the number of rooms that will need cooling. If there’s just one room or a studio apartment, you will be saving if you stick to the mini-split, portable, or window-type. However, if the space is bigger than 550 square feet, the portable a/c is not going to do a good job and you will end up spending more energy cooling the space. That can outweigh the upside of portable a/c, since 1 it can be moved around and supplement other types of a/c.
You also have to take into consideration that some portable units tend to leak or drip on floors and a wood floor will not be able to take that kind of abuse. This will add to the cost of operating a portable. The window type a/c is good for one room with no dividers or walls unless you get the higher horsepower. Even so, it will struggle to be a good cooling system especially during the hot months if the room if divided.
For rooms that have dividers, the mini split air a/c works best but only up to 4 separate spaces. It is quieter than the window type because the cassette with the compressor is installed outside the house. You will need to make holes or opening on the wall for wiring and tubing. For bigger areas, the central a/c is more practical and with proper maintenance, plus it lasts up to 15 years. It also increases the value of the property which is an additional plus factor.
Cooling Capacity as an Operating Cost Factor
Another factor that affects your operating costs is the cooling capacity of the unit or system. Here is a general guideline on cooling capacity:
- 1.055 kilojoules (kj), the International System of Measurement unit for energy, can cool up to 550 square feet or consumes about 0.29 watts
- For areas over 1,000 square feet, you need over 24,270 kj and that consumes about 293.07 watts.
- If you install a portable a/c unit that covers space larger than 550 square feet, it will run for longer period but still not be able to do its job properly.
- Warm climates of over 90 degrees F increase joules by 32%
- If your home is not insulated properly, joule requirement also increases by 32%
- If the room has large glass windows that allows natural sunlight to come in, the kj requirement increases to slightly over 20%
- For every person who occupies a room, add 633 kj
- High ceilings (8 feet or higher) means 20% more kj
- An air-conditionws kitchen will require an extra 4,220 kj
Finally, you can reduce the kj by installing shades or tint on windows, planting trees in strategic areas, or by finding ways to reduce the heat inside a kitchen.