June 17, 2025, 4:00 am | Read time: 4 minutes
The heat pump is a hot topic—and along with it, underfloor heating or other surface heating systems. They are considered a dream team for saving energy. But is that really the case?
Generating a lot of comfort with little energy–that’s what floor, wall, and ceiling heating systems can do. Many people find their radiant heat pleasant. Another plus: These so-called surface heating systems are invisibly installed, allowing for more design flexibility in rooms compared to systems with radiators.
What is special about a surface heating system?
Unlike radiators, surface heating systems distribute heat over a large area. This results in even heating of rooms, and the systems can often operate at lower temperatures.
“The usual room air temperature of 22 degrees Celsius in a conventionally heated building can be reduced by two degrees Celsius with a surface heating system while maintaining the same comfort,” says Axel Grimm, managing director of the Federal Association of Surface Heating and Cooling. “This saves about twelve percent energy.”
Combining heat pumps and surface heating
How much energy can actually be saved with a surface heating system largely depends on the effort required to generate the energy. “The heating system doesn’t care where the heat comes from; it works with any energy source,” says Matthias Wagnitz from the Central Association for Heating, Sanitation, and Climate. “The crucial question is, how efficiently can I generate the heat?”
Here, the heat pump as a combined low-temperature system usually leads the way. It environmentally extracts free heat from the ground or surroundings. “Heat pumps and surface heating are a perfect match for economical heating,” says Axel Grimm. Surface heating systems require much lower supply temperatures than radiators because the entire floor is used as a heating surface. They can operate at a maximum of 35 degrees, while conventional systems with radiators need 55 to 70 degrees.
More on this: Do you really need underfloor heating for a heat pump?
Can surface heating systems be retrofitted in older buildings?
Surface heating systems operate most efficiently in well-insulated houses, where energy demand is very low. “In new buildings, surface heating systems are already standard,” says Stefan Materne, energy expert at the Federation of German Consumer Organizations. “A hot water underfloor heating system is most commonly installed.”
However, surface heating systems can also be retrofitted in existing buildings if there is space for a floor, wall, or ceiling setup. In less well-insulated buildings, however, they cannot fully realize their potential. Higher supply temperatures are often needed, resulting in higher energy consumption. “But even there, they are still more efficient than radiators,” says Axel Grimm.
What are the disadvantages?
There is one disadvantage: Surface heating systems are often said to be somewhat sluggish. It takes longer for them to reach the desired temperature after being turned on. They adjust slowly to warmer outdoor temperatures and strong sunlight. They also cannot be easily adjusted up or down like radiators. “If it gets too warm, valuable room heat is lost when residents open windows to cool down,” explains Stefan Materne.
However, the energy consultant believes you can adapt to this characteristic of surface heating. “It helps to experiment a bit to find out when to start lowering temperatures in the evening and when to turn the heating back up in the morning to maintain comfortable temperatures.”
Matthias Wagnitz explains: “How quickly the temperature adjusts depends on the thermal mass that the pipe systems heat.” The heating pipes are embedded in the screed, which warms or cools relatively slowly. Depending on the thickness of the screed layer and how close the pipes are to the floor surface, the cooling or heating is felt more slowly or quickly. “In most cases, frequent switching is not worthwhile,” says Wagnitz. “It’s best to let the surface heating run in a more economical mode.” A nighttime temperature reduction is possible, though.
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Additional function: Cooling in summer
Given the increasingly hot summers, this should not be underestimated: With a heat pump, surface heating systems can also cool living spaces. While they don’t lower temperatures as much as an air conditioning unit, “you can cool the floor by two to three degrees,” says Matthias Wagnitz.
It’s important not to activate this mode only after the building has already heated up. “If the cooling is set proactively, it is pleasant and comfortable–without drafts or air movement,” says Axel Grimm.
with material from dpa