Anyone installing a new heating system today is making a decision for the next 20 years, including a decision about future energy costs. The new “co2online heating cost forecast” shows that heating with gas or oil will be significantly more expensive over the next 20 years than using climate-friendly alternatives such as heat pumps.
According to the calculation, the additional costs over a period of 20 years amount to as much as 42,000 euros. The reasons are rising CO₂ prices, higher network costs and legally required blends of biomethane, hydrogen or bio-heating oil. The so-called “bio escalator” adds further to the cost of fossil-fuel heating systems.
For the forecast, the non-profit consultancy co2online calculated the heating costs of various systems for an average detached house up to 2045. It used current data from the Heating Cost Index and the German Environment Agency.
“When choosing a heating system, the focus is too often on the purchase cost. Total costs over its service life are more decisive,” says Tanja Loitz, Managing Director of co2online. “Our calculation shows that fossil-fuel heating systems are becoming a cost trap for households. The bio escalator offers no protection from that.”
Heat pumps offer a clear cost advantage
The differences become particularly clear when long-term heating costs are considered. According to the co2online heating cost forecast, an air-to-water heat pump will cost around 24,500 euros between 2026 and 2045. Over the same period, a gas heating system will incur heating costs of around 55,600 euros and an oil heating system as much as 67,200 euros.
The required blending makes fossil-fuel heating even more expensive because fuels such as biomethane, hydrogen and bio-heating oil are expensive and available only in limited quantities. Biomethane increases the cost of a gas heating system to 65,100 euros, while hydrogen raises it to 66,500 euros. No reliable long-term data is currently available for bio-heating oil, but it can be expected to incur additional costs compared with conventional heating oil.
In the long term, heating with gas or oil therefore costs around 31,000 to 42,000 euros more than heating with a heat pump.
Moreover, existing heating systems are not always readily suitable for higher blend levels. Owners may therefore have to budget for additional investment in conversions or retrofits.
Why heat pumps cost less
Heat pumps operate much more efficiently than fossil-fuel heating systems. On average, they produce around four kilowatt-hours of heat from one kilowatt-hour of electricity. At the same time, electricity is increasingly generated from renewable sources and is not subject to a CO2 price.
Their costs therefore develop much more steadily than those of fossil fuels. The forecast also shows comparatively stable costs for district heating. Pellet heating remains cheaper than oil and gas, but over the long term it too will be more expensive than heat pumps.
Owners hesitate over replacing their heating systems
“The current legislative proposals are increasing uncertainty among homeowners. The result is decision-making stress,” says Loitz. “Yet mature technical and economical solutions are available that make us independent of energy imports and are also genuinely climate-friendly.”
To support owners in their decision, co2online offers personalised online advice through its free “Modernisation Check”. It allows owners to calculate future heating costs, potential savings and the cost-effectiveness of modernisation measures for their own building.
Methodology
The co2online heating cost forecast examines how heating costs for an average detached house with 130 square metres of living space will develop between 2026 and 2045.
The calculation is based on data from the current Heating Cost Index, energy-price assumptions from the German Environment Agency (as at May 2026) and the currently known requirements of the planned Building Modernisation Act. The calculation is a forecast and does not guarantee future prices. Political conditions and global developments may alter the actual trajectory of costs.
co2online will be happy to provide its detailed heating cost forecast methodology on request. Contact: Alexander Steinfeldt (presse@co2online.de)
About co2online
The non-profit consultancy co2online stands for climate action that works. Since 2003, more than 50 energy and communications experts have used campaigns, energy calculators and practical checks to help reduce electricity and heating-energy consumption in private households to a minimum. The actions prompted by these initiatives make a measurable contribution to reducing CO2 emissions. The focus is on electricity and heating energy in buildings, modernisation, construction and help with funding. co2online is supported by organisations including the Federal Ministry for the Environment, Climate Action, Nature Conservation and Nuclear Safety (BMUKN), the German Environment Agency, and representatives of the media, academia and business.