background
When it comes to heat pumps, there are many misconceptions circulating. How efficient are the systems? Can this save heating costs? And do the devices also work in extreme cold? An overview.
If large parts of the Building Energy Act (GEG) come into effect in Germany from 2024, this should – according to Economics Minister Robert Habeck from the Greens – help the heat pump finally achieve a breakthrough. The ambitious goal: half a million newly installed devices per year. After all, the heat pump is one of the key technologies for the heat transition.
The months-long wrangling over the so-called heating law has led to great uncertainty – and the associated reluctance to buy – among consumers. Many prejudices, as well as claims that have already been refuted, persist.
Very large CO2Savings potential
In the current E.ON Future Index, a comprehensive market study by the energy company, the CO2 saving potential of heat pumps becomes particularly clear: “If all homeowners switched without heat pumps or other renewable heating systems, a total of almost 30 million tons of CO2 could be saved per year.”
However, according to the survey, only a little more than six percent of German homeowners are currently planning to make the switch within the next twelve months. Even if everyone followed their words with action, the savings potential for 2024 would only be a good 1.7 million tons of CO2.
The proportion of heat pumps is still low
Currently, around half of the 41 million households in Germany still use natural gas for heating, a quarter use heating oil, and around 14 percent use district heating. Even though a total of almost a million heaters were installed in 2022, only 236,000 of them were heat pumps that run on electricity.
That corresponded to an increase of 53 percent; However, two thirds of all heaters sold are still powered by gas or oil. The discussion about heating and the heat pump itself caused a significant drop in sales figures this year.
Expensive and inefficient?
The argument that is often put forward is that heat pumps are not only expensive, but also inefficient. Heat pumps are among the most economical heating systems currently available on the market. Their efficiency, the so-called COP (Coefficient of Performance), is typically between three and five. This means that heat pumps extract between three to five units of heating energy from the environment in order to consume one unit of electrical energy. In comparison, traditional heating systems such as oil or gas heaters typically have a COP of 0.85 to 0.95.
It is difficult to generalize how expensive a heat pump is to purchase. In fact, the pure acquisition costs for modern, good brand models are in the five-figure range. However, how much assembly and installation ultimately amounts to is very different and varies greatly. This can also lead to significant price differences regionally. There is also always the question of the extent to which funding opportunities can be exploited when installing or switching. Depending on the property, up to 70 percent of total funding is possible with the GEG.
Heating with a heat pump becomes cheaper
What is often ignored when making comparisons is that current subsidies – such as a reduced VAT rate on natural gas and district heating – initially only apply until March 2024. These, says energy efficiency expert Martin Sambale from the Allgäu Energy and Environment Center (EZA), are likely to be abolished again: “The CO2 tax will soon be increased again. This means that step by step we will also have correspondingly higher charges for the gas price. ” From 2024 onwards, the CO2 tax on oil and gas will cost 40 euros per ton. If CO2 pricing is switched to Europe-wide emissions trading in just over three years, over 80 euros per ton of CO2 burned is very likely.
However, high electricity prices are also a deterrent when it comes to switching to heat pumps. So-called “smart meters” – intelligent electricity meters, the installation of which will be free from 2024 – will in future be able to record electricity consumption every quarter of an hour and make it transparent. This technology then enables billing according to the time of day and thus “dynamic electricity tariffs”. Energy consumption can then be shifted to times when prices on the European electricity market are lower in order to reduce costs.
Even if such tariffs won’t be mandatory across the board for just over a year, the 2023 heating index from the non-profit consulting company “CO2online” shows in comparison to fossil heating: “The costs for heating with heat pumps fall the most. Minus 20 percent. The reason for this is again Greater range of heat pump electricity tariffs.”
Therefore, it is generally not correct – even if it is often done – to compare an average heating oil price per liter with an average electricity price of 40 cents per kilowatt hour. According to Stiftung Warentest, good heat pumps need a good 5,000 kilowatt hours of electricity per year to heat a moderately insulated, 140 square meter apartment to at least 20 degrees. The price differences are therefore enormous if special heat pump tariffs are used instead for the calculation or if part of the household electricity is generated via a PV system.
Useful: Smart Grid Technology
With the new technical possibilities resulting from the nationwide introduction of dynamic electricity tariffs, so-called smart grid-ready heat pumps (SGR) could also help to significantly reduce electricity costs. Smart grid technology, a type of intelligent energy distribution system, is primarily intended to increase efficiency in the area of energy supply.
“This also applies to heat pump customers. There you can take advantage of such prices with a smart grid-ready heat pump that is already prepared and integrated in terms of hardware,” says Norbert Endres, energy advisor at the Bavarian Consumer Center. For example, an SGR interface can signal to the heat pump when excess energy from the solar system is available to heat up the hot water tank for later use.
Also for Existing building suitable
Another misconception about heat pumps that persists: they are only for modern single or two-family homes. Heat pumps can be used efficiently both in new buildings – which is of course easier – and in existing buildings. Incidentally, additional insulation measures also make sense with fossil heating systems. Air-water heat pumps can also be used flexibly and can, for example, be combined with an existing gas heating system in order to still achieve the 65 percent renewable energy required by the GEG.
According to Andreas Holm, professor at Munich University of Applied Sciences and one of Germany’s leading heat pump experts, installing a heat pump in half of all buildings makes economic and technical sense. “That’s almost ten million buildings in which you can install a heat pump today without hesitation or without thinking too much about it,” calculates the building physicist. “For the other buildings, certain measures are absolutely necessary and sensible. I can always install them, it’s a question of the efficiency of the operation.”
Heat pumps run efficiently in frosty conditions
Modern heat pumps are able to work efficiently even at low outside temperatures. Air-to-water heat pumps can extract heat from the air even at temperatures well below freezing. In Germany, where winters are now relatively mild, low temperatures are usually not a problem.
A field study by the University of Oxford recently showed that heat pumps continue to work effectively even at extremely low temperatures of up to 30 degrees below zero: “Even if the efficiency of heat pumps decreases in extreme cold and additional heating may be necessary, air heat pumps can be compared “offer significant efficiencies compared to other systems on both an instantaneous and annual basis,” the report states.
Sensitive topic: noise
It is already foreseeable that complaints about noise from heat pumps and disputes between neighbors will increasingly concern not only the courts, but also building authorities and lower nature conservation authorities. The latter are usually responsible for the corresponding measurements. Even though modern heat pumps are very quiet and often make less noise than a refrigerator, the perception of noise varies and is very subjective. Many of the common air-water heat pumps have an extra quiet mode, but such functions affect performance.
The manufacturer Bosch uses a sound diffuser in its latest Compress models, which supposedly helps here. Other German air heat pumps in the current study by Stiftung Warentest (from October 2023) all scored “good” in the area of noise development. However, under laboratory conditions, as Daniel Kastner from Stiftung Warentest restricts: “How the pump really sounds outside in the garden depends on many factors. Where exactly you put it, how it is aligned, whether there is a wall in the way somewhere stands or a tree. Whether the sound is refracted or reflected back.”
New, more environmentally friendly Refrigerant
Even though the refrigerants that circulate in heat pumps normally remain in the device, the fluorinated greenhouse gases used are increasingly being criticized. However, modern heat pumps – such as the recently tested models from Viessmann, Wolf and Vaillant – now use the much more environmentally friendly propane.
Since propane is not only more cost-effective, but also increases the efficiency of heat pumps due to its thermodynamic properties, the refrigerant is likely to become more popular soon. Especially since the EU has already banned certain other refrigerants that are extremely harmful to the climate.