Eurofuel experts debate on hybrid systems (spoiler: they are a great solution!)

At the June 15 "Eurofuel briefing" that took place in Edinburgh, participants bowed to the topic of HYBRID HEATING.

Eurofuel board members and experts from the Technical and PR Committees took part in the discussion. It was a fascinating seminar because inspiring insights from various countries were shared. Present were: UK, Ireland, Finland, Germany, Italy, France, Austria, US and Belgium. We summarize the main points for you below.



Started with the question: but what exactly is the definition of a hybrid heating system?

There is no sharp definition, and with the new ecodesign directives on the horizon, the definition may still change but in a broad definition it is the combination of two or more energy sources to heat a house and/or produce hot domestic water. We at Eurofuel specify that one type must be renewable (i.e. heat pump, photovoltaics, solar thermal energy, wood) and the other a heating boiler (operating on liquid or gaseous fuels). The key principle is that renewable energy is used as much as possible with the boiler used as a reliable back-up solution for periods of lower renewable energy production of and/or very low external temperatures.


Advantages in general:

Hybrid heating is very suitable for existing houses (built until the 90s) which are the majority of the building stock and typically have higher heating demands. Those who opt for a hybrid heating system do not have to do a deep renovation of their home right away. The system works with conventional radiators and does not need a switch to low-temperature or underfloor heating. Moreover, it does not exclude additional efforts (insulation, solar panels, etc.) later. In a first step, these households make a significant part of their heating needs sustainable by using renewable energy and retain the option of using a fuel in case of too cold weather conditions or electricity peaks, which also has benefits for the electricity grid. Hybrid heating gives a large group of households the opportunity to take a first and affordable step towards immediate sustainability of their energy consumption in their homes. See further explanations in video:

Indeed, the investment in a hybrid heating system can be relatively modest, as it consists of a small electric heat pump -sized to cover the most heat demand during the year- combined with a liquid fuel- boiler to cover the short but high peak demand in winter. Even on particularly cold days, comfort is guaranteed as the boiler can kick in when the heat pump cannot cope efficiently.  / In addition to the limited investment cost, the consumer’s energy bill can be reduced significantly with smart controls because of the high efficiency of the heat pump and the ability to switch to the lowest cost energy vector (liquid fuel or electricity) at any time when using a smart system which can respond to energy price signals (if dynamic prices are implemented).

The quantification of the running costs of a hybrid system and the environmental benefits presented by Finland makes the benefits more concrete.


The table and the case presented show that:

  • the construction and operating costs of hybrid heating are clearly lower
  • emissions from hybrid heating are lower
  • heating power is sufficient in all conditions
  • maintenance and crisis readiness in a hybrid solution can be easily and inexpensively ensured


What does the legislation say?

Under the Energy Performance of Buildings Directive (EPBD), it remains possible to install hybrid systems in both ‘new buildings – Article 7’ and ‘existing buildings – Article 8’ provided that the boilers are certified to run on renewable fuels and not exclusively using fossil fuels. Other EU legislation such as ecodesign and energy labelling for space heaters also allow for hybrid heating systems to be put on the market.

But the legislation varies from country to country and is also inherently linked to national legislation.    For example  Germany has recently adopted a new ‘Building Energy Act’ that regulates the installation of heating systems in buildings from Jan. 1, 2024. : in this legislation as far as possible, every newly installed heating system is to be powered by at least 65 percent renewable energy.  Stand-alone boilers on liquid or gaseous fuels can still be installed. In future, however, they must consist of at least 65 percent green gases (e.g. biomethane) or green liquid fuels.

Moreover, boilers on liquid or gaseous fuels can also be installed in combination with other renewable heating systems as a hybrid system. Example: if a heat pump alone is not sufficient to cover the peak load in winter, it can be supplemented with a boiler. The latter then supports only on particularly cold days. To meet the 65 percent renewable energy target, heat pump or biomass heating must be used as a priority and meet minimum performance requirements. When a boiler breaks down in an existing building, a new replacement boiler on liquid or gaseous fuels can be installed with a three-year transition period but must then be converted to a heating system with 65 percent renewable energy after the expiration of the three years. The law also contains transitional provisions for older homeowners that do not need to fulfill the new requirements and so-called individual gas heating systems in apartments.

As a conclusion: different EU member states are looking into various pathways to decarbonize their existing building stock and hybrid systems can be one of them.