What modern types of heating and energy-efficient heating systems are available?

Gas heating is the classic among heating systems and currently the most widely used type of heating in Germany. It is convenient for the consumer, as natural gas is supplied directly to the household via the gas grid. This saves space because there is no need to store fuel. If you want to save money and take advantage of seasonal price differences, you can run your gas heating system on liquid gas and store it in your own tank. Depending on the region, the use of biogas is a future-proof alternative, especially if it is produced locally. In Germany, energy suppliers mostly only supply a mixture of biogas and natural gas. Another environmentally friendly and energy-efficient measure is to combine gas heating with renewable energies such as solar thermal energy. This combination is eligible for state subsidies. This means that in addition to the purchase price of a gas heating system, which can be between 5,000 and 10,000 euros, there are also the costs of solar thermal energy. Policymakers want to ban the installation of conventional gas heating systems in new buildings that do not use renewable energies from 2025 onwards.

Oil heating can be used independently of the energy supplier. Homeowners need their own oil tank for this, which they can have filled at any time. In contrast to a gas connection, there is no minimum price, so you can control your consumption yourself. Nevertheless, most oil heating systems use heating oil, which is one of the limited fossil fuels available. Similar to biogas, there is bio heating oil, which so far, however, only makes up 5.9 percent of the heating oil. Even older heating systems can be operated with this share of biofuel. In order to use a higher share of the oil, which is mostly produced from rapeseed or sunflowers, ageing heating systems have to be retrofitted. One environmentally friendly option is modern oil heating, which can be operated with pure bio heating oil. However, bio heating oil is currently only available locally to a limited extent and is thus not an option that extends to the whole country. Due to the high carbon emissions, house builders will no longer be allowed to install oil heating as the sole fossil fuel heating system in new buildings from 2025 onwards. The attractiveness of oil heating is based on the relatively low purchase price. A retrofit in an old building with an existing tank costs around 6,000 euros, and in a new building with a tank and depending on the size, up to 10,000 euros. 

In the past, night storage heaters offered inexpensive heating for living spaces. They are hardly used anymore today, because even in old buildings they have largely been replaced by energy-efficient heating systems. Nevertheless, electric heaters are found in many homes primarily as supplementary heaters. Electric underfloor heating, for example, can easily be retrofitted in old buildings or rental apartments - all it takes is a socket. A fan heater or one of the newer infrared heaters quickly warm up the bathroom before showering. The small and above all inexpensive electric heaters are just as suitable for a partial increase in room temperature, for example in the reading corner, without having to heat the entire room. Electric heaters also include towel heaters in the bathroom, which allow damp towels to dry more quickly and warm them pleasantly before bathing or showering. While electric heating as the sole heating method no longer pays off due to exorbitant electricity prices, supplementary use can not only provide better living comfort, but also save heating costs in the event of a short-term higher heating demand.

Wood heating systems have a long tradition and are synonymous with cosiness. Long before there was oil or gas heating, people used wood for heating and cooking. Even today, wood heating is still an appealing option with its high heat output and sustainable, rapidly renewable fuel. While fireplaces and log heating systems require manual loading, automatically controlled pellet heating systems ensure a constant temperature in the living rooms even when you are absent. In addition to a fireproof room for the heating system, adequate space is needed to store the wood or pellets. While a log boiler costs around 6,000 euros, pellet boilers for a single-family house start at 10,000 euros, depending on the heat output. In addition, there are costs for the pellet store, a hot water tank and possibly for a solar thermal system. A complete and automated pellet heating system requires an investment of 12,000 to 20,000 euros. This makes homeowners independent of fossil fuels or energy suppliers.

One heating system for everything: A combined heat and power plant in your own home provides energy-efficient cogeneration of heat and power (CHP). Burning either fossil fuels or environmentally friendly biofuels produces heat when electricity is generated, which at the same time heats the water for the radiators with the help of a turbine. CHP is one of the most efficient heating systems with a degree of utilisation of 90 percent and more. In contrast to district heating, the energy is generated in-house, which means there are no line losses. Fuel cell heating works in a similar way, producing electricity and heat with the help of so-called cold combustion. In contrast to the CHP unit, however, the fuel cell heating system lacks flexibility in the choice of fuels. It only uses natural gas as an energy source and produces hydrogen from it. However, the emissions are even lower than with CHP and it is also more energy efficient. 

The fuel cell heating system also requires very little maintenance and space. Both heating systems are expensive to purchase and only pay off if the energy demand in the single-family home is high. A nano-CHP for 14,000 to 17,000 euros is often only suitable as a supplementary heating system and can only rarely be found on the market. A micro-CHP unit can provide sufficient heat on its own, but it is oversized for most families. With acquisition costs between 25,000 and 35,000 euros, the micro-CHP is not necessarily an economical heating system for a single-family house. Fuel cell heating systems cost between 18,000 and 33,000 euros, depending on the heating load, plus a gas connection if it is not already available. BAFA or KfW support the purchase of both heating systems with various subsidy programmes. 

Heat pumps require electricity for their operation. Nevertheless, this heating system is environmentally friendly and energy efficient. This is because, unlike electric heating, electricity consumption only accounts for around 20 to 35 percent of the heat generated. Heat pumps are particularly effective in combination with underfloor heating and achieve the highest energy efficiency. A heat pump draws the remaining energy it needs from the environment. To be exact, this heat can be drawn from the air, the water or geothermal brine. An air-source heat pump costs between 10,000 and 15,000 euros. It usually has a slightly higher electricity consumption than the other heat pumps because the energy efficiency of the ambient air is not as good as that of the ground or water. Water-to-water heat pumps, which draw heat from groundwater, or brine-to-water heat pumps, which use geothermal heat, are more energy-efficient. However, due to the deep subsurface drilling involved, these heating systems can cost between 20,000 and 30,000 euros. These boreholes, by the way, almost always require a permit. Heat pumps are one of the innovative types of heating that use renewable energy and are extremely energy efficient under the right conditions. This is why the federal subsidy for efficient buildings supports the purchase of heat pumps, which are already standard in new buildings. In old buildings, good insulation and, ideally, underfloor or wall heating are required in any case in order for the heat pump to perform to its full potential.

Solar thermal is the only heating system that exclusively uses a source of free and constantly renewable energy. Homeowners collect the sun's energy during the day with solar panels on the roof. With the help of a heat exchanger, the solar energy heats the water in the buffer tank. From there, it flows into the radiators or is used to supply hot water. Since the demand for heat in Germany is high, especially in winter, and solar radiation is relatively low during this time of year, solar thermal energy is primarily suitable as a supplementary heating system. Its advantage is that it can be combined with almost any heating system to create hybrid heating. Although the heating system, which depends on the sun, only absorbs 20 to 30 per cent of the nominal output of solar energy in winter, solar thermal energy makes a significant contribution to reducing energy costs, especially in new buildings with excellent insulation. 

State subsidies and the free energy source make the use of solar heating attractive. Thus, the initial investment costs of 8,000 to 12,000 euros plus optional storage tanks or a second heating system pay for themselves in around 15 to 20 years. Retrofitting is possible at any time without much effort, even in old buildings. Theoretically, it is possible to use only solar thermal energy if the roof is optimally aligned and not shaded. Only when larger storage tanks are used does this take up a significant amount of space in the house. Baden-Württemberg and Berlin have introduced mandatory solar installations for new buildings. Solar heating is to become mandatory throughout Germany as the heating system of the future, possibly from 2023.

Currently, most heating systems in Germany use fossil fuels. Gas heating in particular remains very popular, as it does not require its own fuel storage. But fossil fuels are scarce, harm the environment and make homeowners dependent on the sometimes-exorbitant world market price. Thus, neither gas nor oil heating are regarded as heating systems of the future. A hybrid system of gas heating and heat pump or pellet heating with solar thermal, for example, can already bring significant advantages in terms of energy efficiency. The heating systems of the future are definitely the types of heating that have the option of using renewable energies. They make property owners more independent of fluctuating energy prices and can sometimes achieve savings of several thousand euros per year. For more details, see our continuing article on the topic of heating systems of the future.

Anyone commissioning a building project should choose the future-proof heating systems that will do the best job in their particular location right from the start when building their new home. Sunny roofs are ideal for solar thermal energy, while the southern regions of Germany with a Mediterranean climate are best suited for an air-source heat pump. We have dealt in detail with the question of which heating system is most suitable for new buildings. When it comes to modernising heating systems in old buildings, there are not always that many different heating systems to choose from. What is decisive when selecting the ideal heating system for an old building are the local conditions, the structural requirements and the environment. We reviewed which heating system is best suited for an old building under which circumstances.

The various types of heating differ in many respects. While some types of heating work well in some regions, they are not as efficient in other parts of Germany. This can vary from house to house and plot to plot. Policymakers also impose requirements that restrict the choice of heating system for new or old buildings. Then there is the required heating load, which can also vary considerably. The purchase of a combined heat and power unit probably pays off for very few homeowners, unless both the electricity and heat demand are above average. Depending on the size and alignment of the roof as well as the location in Germany, a solar thermal with photovoltaic system can cover part or all of the household's energy needs. However, it will either be insufficient in winter due to fewer hours of sunshine or oversized in summer. 

Hybrid heating systems are often the ideal solution and can be customised. A biogas heating system with a geothermal heat pump and underfloor heating, for example, meets the demand for heat all year round in all kinds of weather and at all times of day, and uses only renewable energies. Not to be overlooked are the initial costs, which require a significantly higher initial investment for some heating systems. In each case, it is necessary to check which state or regional subsidies are available for the various heating systems. Another consideration is how quickly a heating system will pay for itself. The higher the heating requirement, the more quickly the energy cost savings will offset the acquisition costs. These factors can influence the choice of heating system:

• purchase price versus energy savings and subsidies

• the location in case of solar thermal or heat pump

• structural requirements (underfloor heating, storage facilities, roof space)

• legal requirements for new or old buildings

• own energy consumption for heating and, if applicable, electricity

• choice and availability of fuel