Fuel and car air conditioning
The air conditioning system compresses the cooling agent and in order to be able to do so, it uses the fuel. The harder it is for the system to compress the cooling agent, meaning that the hotter it is outside, the more fuel will be used by the air conditioning system. What many of the people might now know is the fact that even when the temperature in the car is higher than the one outside, the air conditioning system still uses fuel. The Federal Office for the Environment is currently working on the problem, as they try to identify solutions for the high fuel consumption caused by the air conditioning system.
In order to do so, the Federal Office for the Environment chose six modern cars for inspection. Three of the cars are diesel, whereas three are petrol. They tested the cars in different conditions; they used the air conditioning systems under certain temperatures and humidity levels, they turned them off under certain temperatures and humidity levels, and so on.
The results clearly showed that by using the air condition8ng systems on days with an air temperature of 27 degrees and a humidity of 60 percent will result in the increase of the total fuel consumption by 18 percent. They also reveled the fact that you can not rely too much on the air conditioning systems to turn themselves off at the proper time. They tested various cars with automatic transmissions, which are the most common cars nowadays, and they have noticed that in the case of those cars the air conditioning systems turns off when the external temperature is below 5 degrees.
This happens that the air conditioning must do various tasks in order to cool the car. First of all the air conditioning system cools the air and then dries it before sending it in to the car. They do this in order to avoid condensation which would occur on the widescreen otherwise. No one contests the fact that this is an excellent feature, however most of the people agree on the fact that the feature should not be used all the time, as it happens with the current air conditioning systems, but only when the air humidity is very high.
A car which was made according to the standards imposed by the Swiss Society of Engineers and Architects and which has the air conditioner on will consume with 5.4 percent more fuel than the cars which do not use the system. However this also depends on the type of conditions and roads on which the car is used. For example a car which is driven on an urban road will consume with 10 percent more fuel, one which runs on a suburban road with 2.8 percent, and one which runs on the highway with 1.3 percent more.
It is a proven fact that the drivers will feel the most comfortable in the cars when the temperature is around 23 degrees Celsius. Because of this, certain conditions will influence the comfort of the driver more than others. For example when the outside temperature is around 18 degrees Celsius, turning the air conditioning system off, should not result in a discomfort for the driver because inside the temperature would be optimum. If this would be applied, and the driver would turn off the air conditioning system when the exterior temperature would be 18 degrees Celsius or below, then in the case of the petrol based cars, the petrol savings would be of about 3.6 percent. Turning the air conditioning off when the exterior temperature is higher than 18 degrees Celsius might result in a discomfort for the driver, which might result in a loss of concentration, which could eventually lead to accidents.
In the case of the diesel based cars, running the air conditioning system on certain roads will result in different results as well. On an urban road, a diesel car will consume with 4.5 percent more fuel, on a suburban one with 2.3 percent, and on the highway with 1.2 percent. The interesting fact is that turning the air conditioning system off when the temperature is 18 degrees or lower will result in the same amount of fuel saving. The car will use with 3.1 percent less fuel with the air conditioning system off, than with it on.
If every driver in Switzerland would adopt this system, then the country would see a reduction on the total fuel usage in the country of about 2 percent. Experts believed that a lot has to do with common sense, as they believe that it is not very difficult to asses the situation and make the proper adjustments. Even so, they stated that they can not impose the drivers to make these changes, as the only thing they can hope for is for their test to be taken in consideration so maybe the following car models will be equipped with air conditioning systems which are based on this theory.11