Aengevelt: “Bio-Treppe” massively increases heating costs
Although DIP partner Aengevelt Immobilien welcomes the lifting of the investment obligation of the recently repealed Heating Act, it points out that the so-called “bio-staircase” of the new Building Modernisation Act will more than double heating costs if gas heating systems continue to be operated. In the future, landlords will have to bear a significant part of the heating costs.
The Building Modernisation Act, which replaces the Building Energy Act (“Heating Act”) passed by the traffic light coalition voted out of office, has been in force since 29 July 2026. A key point of the controversial previous law, that newly installed heating systems must use at least 65% renewable energies, has been dropped. To this end, the climate targets are to be achieved through the so-called “bio-staircase”. New gas and oil heating systems must use an increasing proportion of biogenic fuels (e.g. biomethane) or climate-neutral hydrogen or synthetic methane. From 2029, the quota is to be at least 10%, from 2030 at least 15%, from 2032 at least 30% and from 2040 at least 60%. The climate-neutral gases must be added by the local gas suppliers. In the case of oil heating systems, biodiesel must be added analogously.
According to a meta-study by the Scientific Services of the German Bundestag, which was presented on 7.7.2026, hydrogen is largely ruled out as energy for heating buildings, as the quantities generated or imported with the help of electricity from wind and photovoltaics are needed by industry. This also applies to synthetic methane, which is produced with hydrogen. This means that the requirements of the “Bio-Stairs” will largely be met by biomethane, which is produced from renewable raw materials such as corn, grass, beets or grain, from liquid manure or from waste and residues. However, capacity bottlenecks are also to be expected for biomethane, considering that of the approximately 10,000 biogas plants in Germany, only 270 have the technology to process biogas into biomethane, and because the transport sector is also increasingly consuming biomethane. In addition, biomethane is significantly more expensive than natural gas, although the price spread has increased due to increased production costs. According to research by Aengevelt, the price of natural gas for long-term supply contracts is currently around €37/MWh, while biogas costs €85 to €100/MWh, depending on the type of production.
For owners and tenants of buildings, this means that the costs for building heating will increase due to the “bio-staircase”. The Institute of the German Economy (IW) recently calculated that heating costs in a partially renovated old apartment will increase by 80% by 2040 compared to the current level, and by as much as 119% by 2045. 74% of these price increases are caused by the “bio-staircase”; 21% through rising network fees, because the fixed costs for the gas networks are distributed among fewer and fewer customers, and 5% through the CO2 levy. According to the new legal regulation, a considerable part of these additional costs must be borne by the landlord.
According to Aengevelt, whether a heat pump is the more economical solution depends on the specifications of the building, such as insulation, orientation, geometry and existing radiators. The heat pump can only prove to be cheaper in the long term, but this prevents many, especially older owners, from making a costly investment. The costs for district heating, if it is available locally at all, are often uncompetitive due to exorbitant connection costs and dependence on the supplier.
Dr. Wulff Aengevelt, Managing Partner of DIP partner Aengevelt Immobilien: “Although the new Building Modernisation Act has abolished the investment obligation standardised by the traffic light, it confronts tenants and landlords with massively rising heating costs. In this way, landlords should also pay n parts of possible unreasonable tenant energy waste. which is triggered by unreasonable tenant behaviour. The new law shows that we still have to pay too dearly for overambitious climate protection when heating costs alone could more than double by 2045.”
