New research from Germany shows that identifying the cheapest heating source for homes remains a challenge, as the final results depend on the assumptions made and energy prices. However, the scientists have shown that air-to-water heat pumps and gas heating systems are currently the most cost-effective solutions.
Researchers from the Technical University of Munich in Germany evaluated the environmental, economic and eco-efficiency performance of 13 different heating systems for a typical two-storey German home and found that air source heat pumps and gas systems cost the most. -effective solutions.
The scientists specified that identifying the cheapest heating source for homes remains a challenge as the final results depend on the assumptions made and energy prices. But they also pointed out that the differences in costs between all the systems analyzed are small, which they say makes it difficult to establish a clear ranking based solely on economic evaluation.
For this reason, their methodology includes both environmental and economic aspects in a single indicator. The life cycle assessment (LCA) method was applied to evaluate the environmental impacts of the systems and the net present value (NPV) approach was used to assess their economic viability. The analysis also included a best-case and a worst-case scenario with different initial investment costs.
For the two-storey house, the researchers assumed that it would operate under Munich climate conditions with a standard heating load of 5 kW and an annual heating requirement of 8,066 kWh. They also considered that all systems have a thermal storage tank that continuously heats the hot water and have a lifespan of 20 years.
The 13 systems considered in the analysis were: natural gas condensing boiler; natural gas condensing boiler with solar energy system; pellet boiler; pellet boiler with solar energy system; wood gasification boiler; wood gasification boiler with solar energy system; air heat pump; air heat pump with PV system; ground heat pump with geothermal probe; ground heat pump with geothermal probe and PV system; water heat pump; water heat pump with PV system; and a ground source heat pump with ice storage and solar collectors.
“A target supply temperature of 35 C has been specified for the considered standard outdoor temperature of -12.9 C,” the research team explains. “The calculation of the hot water requirement is based on a daily hot water requirement of 40 liters per person at 50 C, using a typical consumption profile with peak loads in the morning, afternoon and evening.”
The academics also believed that only 6% of the electricity generated by the PV system is consumed directly by the heat pump, while the remaining percentage is injected into the electricity grid or used by household appliances. “It should be noted that the systems were not optimized for self-PV consumption,” the scientists emphasized.
The analysis showed that air-to-water heat pumps with and without a PV system, as well as gas heating systems, are the most cost-effective solutions of the 13 systems examined. In terms of ‘eco-efficiency’, the scientists found that the air-to-water heat pump with a PV system and the wood gasification boiler outperform all other systems.
“Three other heating systems – water and ground source heat pumps with PV and air heat pumps – also show higher eco-efficiency than the gas heating system,” she added. “In contrast, the ice storage heat pump and pellet heating with solar thermal energy show the lowest eco-efficiency.”
Their findings can be found in the study “Assessment of the environmental, economic and eco-efficiency of residential heating systems for low-rise buildings”, which was recently published in the Journal of Construction Technology.
This content is copyrighted and may not be reused. If you would like to collaborate with us and reuse some of our content, please contact: editors@pv-magazine.com.
