Renewable energy sources
"Renewable" means that the source of energy is always replaced. That means we don't have to worry that the source of energy will run out at some point. Renewable energy sources do not contribute to climate change either. Consequently, they are subsidised by the state in many countries.
Wood from trees can always grow back and draw in the CO2 released during combustion. This results in a continuous cycle, allowing logs, pellets and the like to be considered renewable energy sources.
Air, water, ground
Heat pumps give you the means to draw free, usable energy from the air, ground or groundwater. This technology requires electricity to generate heat. In purely mathematical terms, the environment supplies an average of three quarters of the heat that a modern heat pump provides to your home.
The sun delivers 8000 times as much energy to the earth as humans need – every day. Installing a solar heat system on your roof or façade allows you to collect free solar energy. The heat provided by a system like this can be used for domestic hot water and heating.
Oil, gas and coal are fossil fuels. They are called fossil fuels because they were formed from fossils – the remains of animals and plants – millions of years ago. Extracting and mining these fuels depletes natural deposits and is causing these resources to run out. In addition, burning them releases CO2 – one of the main drivers of climate change.
Gas is a particularly cheap source of energy. Natural gas is considered the cleanest fossil fuel. Modern wall-mounted gas-condensing boilers can utilise practically all of the heat contained in the fuel and achieve energy efficiency class A.
In many countries, oil is the uncontested leading source for heating. Although reserves are limited, supply is guaranteed for a number of years. Oil can be burned efficiently using condensing technology, as demonstrated by the fact that modern condensing boilers are rated energy efficiency class A.
Coal or coke can also be used as a reliable and cheap heat source. Efficient solid fuel boilers ensure high-efficiency combustion as well. Many people find the heat provided by fireplaces and tiled stoves particularly pleasant.