Having a pleasant temperature in the house, even when the thermometer exceeds 40�C in the street, is no longer a pipe dream for 12 in every 100 Spanish homes thanks to air conditioning. But these machines, the unmistakable symbol of a high standard of living, have negative effects on the environment that must be considered before buying.

In the mid-1980s scientists confirmed that a chlorine derivative called chlorofluorocarbon (CFC) - much used in the refrigerating apparatus of air conditioning systems - was responsible for destroying the earth's ozone layer. Hence, in 1987, the Montreal Accord prohibited the use of CFC from 1 January 1996. This treaty also called for the gradual elimination of hydrochlorofluorocarbons (HCFC), the temporary substitute of CFCs, that are also harmful to the ozone layer, albeit to a lesser extent (5% compared to CFCs).

In Spain, most domestic air conditioning systems continue to work with the HCFC R22 refrigerant, although the situation is changing. Some brands - Bosch, Carrier, Daikin, Panasonic or Samsung, to name a few - have already substituted R22 for hydrofluorocarbons (HFC), such as R407 or R410, chlorine-free coolants that do not harm the ozone layer.

Another of the problems associated with air conditioning is the excessive energy consumption of these machines. An average 1.5W air conditioning system connected for 10 hours on a very hot day consumes as much energy as illuminating a four person property during 10 days. And energy consumption leads to the emission of contaminating gases such as CO2, the main cause of the greenhouse effect. This is why ecologists never tire in reminding us that the more we cool down our house, the more we heat up the planet.

To ease some of this impact on the environment, we must choose a system that consumes less energy.� According to IDAE, there are air conditioning systems that consume up to 50% less energy to produce a cooling unit, the measure of refrigerating power. The so-called split and multisplit are systems that are divided into an exterior unit and a single (split) or several (multisplit) interior units, connected via a flexible tube. These tend to be energy efficient as well as silent due to the compressor, the noisiest component, being included in the exterior unit. The noise and acoustic contamination are thus left outside the home.

Multisplit systems also allow you to regulate the temperature in every room, so that you can save energy. Most manufacturers now use Inverter technology that saves up to 30% in energy. It works with night storage so that programming the system to switch on and off at certain times does not waste energy.

Calculating the refrigerating power needed is another thing to take into account. Such factors as the climatic zone (temperature and humidity), the property's location (the higher, the greater the power), its orientation (more power if south facing), the number of people in the home and, of course, its size must all be considered. Hence, to cool down a square metre of space, around 100 cooling units are needed.

The Spanish Consumer's Association (OCU) has reference tables that can be requested to clear any doubts. If the system is more powerful than we need, we will be wasting energy and money. Also, an apparatus that is too powerful for our needs will cool down the house so rapidly that it only has time to eliminate part of the air's humidity, resulting less effective.

When trying to save energy, the best option is clearly to switch on the air conditioning only when it is needed and at the correct temperature. Neither every day of the summer nor every hour of the day are equally hot, so it is not necessary to have the system switched on 24 hours a day. Sometimes, it is advisable to have the machine's dial switched on to ventilation, something that most of the models allow. Simply moving the air about helps temperatures drop around 3 to 5�C. Further advice to making better use of air conditioning systems are:
- Do not cool down the house to an exaggerated extent. The correct temperature should be around 25�C. Each degree less means increasing energy consumption around 8%. For this reason, installing a thermostat is recommended if the system does not tell you the temperature.
- Switch off the machine when the house or a room are empty. You only need a few minutes to reach the desired temperature and it is far more economic to cool down a room again rather than keeping it cold all day long.
- Install the compressor in an area that has good air circulation and is protected from the rays of the sun. Regularly clean the filters, keep the thermostat away from heat sources, such as lamps and direct sunlight, and avoid putting furniture near to the ventilation grille.

DID YOU KNOW?
- During the three months of summer, North Americans will consume as much energy in air conditioning than 2,000 million Chinese in a year.
- From January 2003 air conditioning systems that are sold in the EU must carry an energy label that categorises the most efficient machines with an A, and the least efficient with a G. Currently 14 suppliers are taking part in the American-style labelling programme. Energy Star, Carrier, Electrolux, LG, Panasonic, Samsung, Sharp and Whirlpool are just some of them.
- If you need heating as well as air conditioning, install a heat pump. In summer it consumes as much energy as the air conditioning system. In winter it consumes up to 60% less energy than an electric radiator.
- HFCs, as opposed to CFCs and HCFCs do not harm the ozone layer, but they contribute to climatic change. Natural coolants, such as ammonia and water, exist that do not affect the environment, but they are still not used in domestic air conditioning systems.

�