There are two factors behind the increased fuel consumption when running the air conditioning: first, the compressor that is powered by the engine. Second, the cooling fan requires energy to send air through the condenser. For instance, at low speeds and high temperatures consumption can quickly rise by 2 l/100 km. Various measures such as the integration of an internal heat exchanger into an on-board refrigeration circuit have improved the already very efficient air conditioning system from the Audi A5 to such an extent that the average increase in fuel consumption has been cut by approx. 0.2 l/100 km. At the same time the system weight of the refrigerant circuit has been reduced by about 10%.