Many German citizens will have to prepare for higher heating costs again this year. Households with gas heating are particularly affected, the non-profit consulting firm co2online announced on Tuesday when presenting its 2025 Heating Index. At the same time, nine out of ten households still have "savings potential" - an average of around 400 euros per year.
For the study, the consulting firm evaluated around 90,000 building data sets. While a downward trend in heating costs was still evident in many households in 2024, the development is now moving in the other direction: in 2025, heating with gas (up 15 percent) and wood pellets (up 20 percent) will be "significantly more expensive," explained co2online, citing higher energy prices and the harsh cold winter at the beginning of the year as the main causes. In contrast, costs for heat pumps (up five percent), heating oil (up three percent), and central heating (up two percent) increased "only moderately."
There is an opportunity for many people to make savings, co2online continued. 90 percent of households could reduce their costs by an average of around 400 euros per year, which would result in an estimated 22 billion euros in savings nationwide per year. Even simple savings potential remains unused in many households, short-term savings of up to ten percent in energy can be achieved simply by correctly adjusting the room temperature and the heating setting, properly ventilating with the heating turned down, and reducing hot water consumption.
In the medium term, technical measures are more effective: "Hydraulic balancing, replacing the pump, or insulating heating pipes are cost-effective measures with noticeable benefits," explained co2online. The highest savings, however, can only be achieved "through more extensive investments," such as replacing windows, insulating the building envelope, or switching to renewable heating systems.
The consulting firm sees a clear advantage here in heat pumps: while heating costs for gas and oil could, according to forecasts based on the heating index and calculations by the Ariadne research project, be "about three times as high" as they are today in the next 20 years, partly due to the rising CO2 price, heating with heat pumps has been cheaper than with natural gas and heating oil since 2022.
Fossil heating systems threaten to become a "cost trap," co2online explained. According to an example calculation for an unrenovated single-family home with gas heating, heating costs of around 120,000 euros would be incurred over a period of 20 years with the assumed price increase. By contrast, through energy-efficient modernization and a switch to a heat pump, costs could be reduced to around 16,000 euros over the same period.
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