Today's inverter air conditioning systems are a highly efficient and cost-effective way to heat and cool your home, typically with a 'Coefficient Of Performance' (COP) value of around 4.0. This means, in effect, that for every euro of electricity a heating unit consumes, it generates four euros' worth of heat energy.
A similar system can be used to heat water instead of air. A heat pump, similar in appearance to the external unit of an air-con system, takes the outside ambient air and raises or 'upgrades' its temperature, transferring this heat to water pipes for radiators or underfloor heating. Such highly efficient systems are nowadays readily available – the Ecodan system from Mitsubishi, for example, produces heated water even if the outdoor temperature is 15 degrees below zero – anyway an impossibility in the Algarve's mild winter climate.
Penguin has installed a number of Ecodan systems, with home owners reporting highly satisfactory results, low heating bills and an excellent return on investment.