Why do more and more building owners always invest in eco-friendly energy saving technology? Apart from the good feeling, to leave an intact environment to the next Generation, the decision in between is also very attractive from economic viewpoint. Because he who heats or cools his buildings with regenerative energy, saves in long-term a lot of money and increases the value of his property. The costs for oil and power have multiplied alone in the last two decades. And the energy prices are – here all experts have agreed – also going to rise in future.