Heating in new buildings: What is the right choice?

House builders still have the choice of installing a fossil fuel heating system. By 2026 at the latest, the installation of oil heating systems will be largely banned. But already today there are no longer any subsidies for oil or gas condensing boilers. The GEG also requires high energy efficiency for new buildings. This means that the new building must be constructed in such a way that it uses around 30 percent less energy for heating than a comparable existing building. Moreover, the law stipulates that a share of heat generation should come from renewable energies. When making a purchase decision, it is important to bear in mind the dependence of the energy sources being phased out on the world market price as well as the carbon tax on heating oil and gas. The price risks make the installation of fossil fuel heating in new buildings and the level of future energy costs quite unpredictable. Nevertheless, gas heating in particular remains popular.

There are two reasons for this. On the one hand, the gas heating system only needs a building connection, but no fuel storage. This can certainly be a consideration in the case of smaller living spaces. Far more often, house builders install these heating systems in their new buildings for cost reasons. This is because both gas and oil heating systems are significantly cheaper to purchase than renewable energy heating systems. At least at first glance. Because the costs of installing a gas heating system and the monthly fees for the gas connection should not be forgotten. Depending on the region and the energy supplier, this can cost between 1,000 and 4,000 euros, and that is in addition to the purchase price of 5,000 to 10,000 euros for the gas condensing boiler, depending on the heating load. 

Heating with gas alone is not eligible for funding and is only permitted if the primary energy requirement is low. One possible solution is renewable-ready gas heating systems, in which a hybrid solution with a type of heating that uses renewable energies is installed in the new building. This option is subsidised by the Federal Office of Economic Affairs and Export Control to the amount of 20 percent, provided that the second type of heating system is installed within two years. This allows developers to defer the costs for a little while. The prerequisite for this is that the strict requirements of the GEG are nevertheless observed. By the way, subsidies of up to 45 percent are available from various programmes for a gas hybrid heating system with solar thermal, if they are installed together right from the start.

Apart from the relatively low purchase price of about 6,000 to 10,000 euros, oil heating has its advantages especially if there is no gas connection. The installation of oil heating systems is expected to be banned from 2026. Accordingly, if the heating needs to be replaced because it is old or needs to be repaired, the entire heating system must be replaced. Such a retrofit sometimes ends up costing more than a slightly higher investment in a future-proof heating system for a new building. The same risks apply to oil as to gas. Here, too, the carbon tax takes effect and makes fossil fuels more expensive. Furthermore, oil condensing heating can only be used alone in new buildings in exceptional cases, unless it exclusively uses bio heating oil.

The numerous requirements of the GEG for heating systems in new buildings do not favour the use of fossil fuel heating systems. If there is a biogas plant in the vicinity of your property, you can consider yourself lucky. This is because a gas condensing boiler operated with biogas meets all the requirements of the GEG. So far, however, there is no nationwide supply of pure biogas in Germany, so it can only serve as an alternative in rare cases. Another option is offered by so-called hybrid heating systems. These combine a gas heating system with solar thermal energy, for example. This combination is particularly popular due to its space-saving installation. This is because both types of heating do not require fuel storage and thus no separate boiler room. However, this hybrid heating system is not a truly energy-efficient and future-proof heating system, because the risk of high energy costs still remains if conventional energy sources are used. Solar thermal energy is particularly inefficient in winter and requires large dimensioning in order to significantly reduce the load on the gas heating system. In this case, the purchase costs are so high that other modern and energy-efficient heating systems are preferable.

In the spirit of the energy transition and with a view to future-oriented technology, many people are now opting for a modern type of heating system in their new building. In addition to solar thermal energy, the heat pump is the epitome of innovative heating. It draws its energy from the environment, such as the air, the groundwater or the ground. The heat pump is particularly efficient in combination with a panel heating system such as underfloor heating throughout the house. Since the heat pump uses around 20 to 30 percent electricity for its heating activity, a photovoltaic system can reduce the energy costs to almost zero. The higher replacement investments for the new heating system are offset relatively quickly if there is a corresponding demand for heating. The various heat pumps differ not only in the type of energy source, but also in terms of energy efficiency and purchase costs. Funding is available for the installation of the heating system in new buildings as part of the KfW Efficiency House subsidy.

Due to the permit-free and simple installation as well as the associated low purchase price, the air-to-water heat pump is very often the heating system of choice in new buildings. Compact heat pumps can be installed indoors or outdoors, depending on the model. For split heat pumps, similar to split air conditioners, the evaporator is outside the building and the other units are inside. The air-to-water heat pump is suitable as a heating system not only for underfloor heating, but also for water-bearing central heating systems. The lower initial costs compared to a brine-to-water heat pump make it attractive as a new heating system for new buildings. But the air-to-water heat pump uses the cold outside air in winter, which can lead to ice build-up. To heat the air, the heat pump then needs more electricity, which is why it is somewhat less efficient than the geothermal heat pump. The strengths of the heat pump also become apparent if used as an RE hybrid heating system together with a gas heating system or a solar thermal system. If you then add a photovoltaic system, you don't need to worry about the slightly higher electricity consumption.

This heat pump is the most efficient when available. It draws energy from the ground. There are two variants. Geothermal probes require little space, but a very deep borehole of between 15 and 100 metres. This energy extraction requires a permit from the mining office, which is only granted if it does not compromise the groundwater. Therefore, this type of heat pump is not always suitable as a new heating system. Another alternative is to use geothermal collectors or ring trench collectors to collect the geothermal heat just below the frost line. However, this requires a larger plot of land, as the geothermal collectors should be twice as large as the living area. Trench collectors use less space. For a single family house, however, they still need around 40 to 80 metres in length. However, both collectors do not require a permit. The brine-to-water heat pump absorbs the energy through the brine into a refrigerant. In the heat pump, it is turned into a gas that transfers the heat to the storage water heater and the heating water buffer tank of the heating system.

The water-to-water heat pump extracts the heat from the groundwater. The installation is complex and requires a permit, which is why this heat pump is rarely used as a new heating system in new buildings, despite the fact that groundwater provides optimum heat all year round and is particularly energy-efficient. The groundwater heat pump needs two wells to function. The extraction well brings the groundwater to the top and this then runs back into the groundwater layer via the injection well after the heating process. The electricity consumption is somewhat higher with this heat pump due to the pumps required in the wells. The regional water authority only grants permission for the new heating system if the conditions are optimal.

When it comes to using free energy sources, solar thermal energy is at the top of the list. This is because this heating system only uses electricity for the control but not for heating like the heat pump, nor does it have any emissions. Solar power is free and clean. For this reason, solar thermal energy is standard for heating in new buildings. But unfortunately, the solar systems also have their drawbacks. In winter, the heat demand is at its highest and the solar radiation at its lowest. The sunny roof area should not only be sufficiently large, but should also face south if possible. This is not always the case, which is why solar systems are the ideal heating systems to supplement another heating system and thus save money. For cost reasons, many house builders combine solar thermal with a gas condensing boiler. Combinations of solar thermal with heat pumps are suitable for renewable energy hybrid heating, or in addition to heating with biomasses such as wood or pellets. BAFA promotes solar thermal energy with grants or loans as a supplementary heating system of the future.

Pellet heating systems are comparable to an oil-based heating system and also require a large fuel storage. If more than 6.5 tonnes of wood pellets are stored at the same time, the storage room must comply with special fire protection regulations. Nevertheless, pellet heating systems are more energy-efficient and environmentally friendly. They emit around 97 percent less CO2 than oil heating. On the other hand, particulate matter is produced when the wood pellets are burnt. To qualify for public funding, fully automatic pellet heating systems must not emit more than 2.5 mg/m3 of particulate matter. Nevertheless, biomass heating systems in new buildings can be an interesting option for the developer. As a rule, these heating systems are around 40 percent cheaper to maintain than oil heating systems. Wood is a renewable resource that is relatively cheap compared to fossil fuels at present. It remains to be seen how this will develop in the future when many gas or oil heating systems are replaced by this type of heating. Heating with wood chips or logs is more of a supplementary heating system. Although they are comparatively cheap to buy, they require manual loading with wood. If you work away from home, you can expect a cold house when you return home in the evenings in winter. Moreover, wood processing and storage is costly.

If you are building on a tight budget, you are usually looking for a heating system for new buildings that is inexpensive to buy. In this respect, condensing boilers for natural gas or heating oil are still unrivalled. But in order to meet the GEG requirements for new buildings, house builders can rarely do without supplementary heating such as solar thermal. At the same time, the risk for the energy sources being phased out and subject to strong price fluctuations remains unpredictable during the operating life of the heating system in the coming decades. A higher investment in the new heating system pays off in almost every case. Environmentally friendly and energy-efficient heating systems that are fit for the future, such as heat pumps, should be the first choice when it comes to buying a new heating system for a new house. 

Independence from energy suppliers and world market prices brings greater savings in the long run. The reduction of carbon emissions from a heating system is not only due to environmental reasons. Rather, it is to be expected that there will be further taxes and regulations for fossil heating systems in the coming years and decades. Environmental protection, energy efficiency and renewable energies inevitably go together. Especially in new buildings, modern heating systems are easier to plan and install than to retrofit. Whether the new heating system is ultimately a future-proof heating system using biomass or an RE hybrid heating system for new buildings is an individual decision.