Energy
When compared to the common household fan the amount of electricity required to run an air conditioner is enormous. Air conditioners literally devour electricity. The energy an average air conditioner uses in on 3 hours is enough to power a fridge for a week. A large electricity bill may affect you in the short term, but high-energy consumption is likely to affect the environment in the long term.
Tables from Sustainability Victoria - Running Costs brochure
External Conditioning
On top of massive energy consumption, the use of many air conditioners can and does affect the local temperature. As the cool air is created inside, intense hot air is pumped outside via the condensers. This creates heat zones, multiply these zones in a city and you have what the science world call an urban heat island. This is the name given to describe the characteristic warmth of both the atmosphere and surfaces in cities (urban areas) compared to their (non-urbanized) surroundings.
Take for example blocks of apartments, office blocks or large commercial buildings, pumping out 40C to 60c per unit to the already hot external air temperature. When you add up a city’s worth of air conditioners, you can understand why it is that cities are hotter than the countryside in summer. This additional heat also creates a microclimate convection system whereby the hot air rises swiftly in pocketed areas, creating many new abnormal localized weather patterns.
Refrigerants
Another environmental concern is the use of refrigerants in air conditioners. Hydro Fluro Carbons (HFCs) such as R410A or R407C are the most commonly used refrigerant type found in domestic air conditioners. While HFCs don’t damage the ozone layer like CFCs do, they are a much more potent greenhouse gas than carbon dioxide, with profound consequences.
Greener alternatives
The latest wave of green alternatives for cooling and heating your house are geothermal pumps, solar ventilation or solar fans, and HRV (heat recovery ventilation) systems.
Ground cooling/heating systems, solar (Solarventi) or geothermal pumps can provide adequate comfortable natural air conditioning to any building. The obvious advantages being initial minimal running costs with minute carbon emissions. The added benefits being that fresh filtered air is ventilating the property thereby creating a fresher cleaner and healthier internal environment.
Solar ventilation systems will run cost free and most are maintenance free.
Electric fans
Fans use a fraction of the power of that of air conditioners, as they only have to rotate blades, but as such they only move the air around - they don’t cool it.
Ceiling fans cool by creating a low-level “wind chill” effect. This windchill effect makes you feel cooler by accelerating the evaporation of moisture on your skin. As long as indoor humidity isn’t stifling, they can be quite effective.
Insulation
Insulation, in its many forms, helps stop the transfer of heat from one place to another. A good example of this is the insulation in the attic. A thick layer of insulation helps to stop heat flow from the house to the attic during the winter. In the summer, that same insulation helps stop heat transfer.
Tips – if you do feel the need to use your air conditioner
- Keep filters clean. Filters blocked (with dust) make the machine work harder and use more electricity.
- Each degree you are able to raise the thermostat, you will save 3–5% on air conditioning costs.
- Keep the air in the room moving – use a fan. A little breeze will make it feel even cooler.
- Using a timer to automatically switch air conditioners on and off. If your model doesn’t have a timer function, use a separate plug timer between the air conditioner and the plug socket.
- Reduce heat gain by pulling drapes or shades, and use shelters to prevent direct sunlight from streaming in through windows on the south and west-facing sides of the house. Overhangs, patio overheads, latticework, awnings work well.
- Always keep all doors and windows closed when operating an air conditioner.
- Don’t cool unoccupied rooms (but don’t shut off too many vents either, or it will put pressure on the system).
- Install inexpensive heat-reflecting film on windows that face the sun. This will keep the house cooler and reduce glare and ultraviolet rays that damage furniture and floors.
- Hire a professional technician to inspect, clean, and tune your system every 2-3 years.
- One of the most important principles of an energy-efficient home is to keep the house or building air sealed. Air sealing prevents the flow of heat from outside to inside and outside. Weather-strip all windows and doorways.
Useful links:
www.sustainabilityvictoria.com.au
Image credit:OakleyOriginals via Flickr Creative Commons
Written by Eamon Corless
Comments
On all models there will be a star rating. Those that cool only, have one row of blue stars, while the reverse cycle air conditioners have two rows, one of blue and one of red. They also have two rows of energy consumption figures.
They can reduce energy consumption on Commercial Air Conditioning systems by approx 16% and also reduce water use by approx 30%.
Maybe you should mention some of these business's also.
[Ed: This comment has been edited. Also note - this article is aimed at residential use of air-conditioners.]