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Heat pumps vs. traditional HVAC systems: a comparative guide
The basics of heat pump and traditional HVAC systems
Conventional HVAC systems typically rely on combustion-based heating methods such as gas and oil boilers. The most common configuration is a hydronic heating system in which a boiler circulates heated water through a pipe network to radiators or underfloor heating.
The standard operating principle of a conventional HVAC system is combustion-based heating whereby fuel is burned in a heat exchanger and heat is then transferred to water. Condensing boilers capture heat from the exhaust gases, which boosts their efficiency and results in a typical AFUE (Annual Fuel Utilization Efficiency) rating of 90 to 95%. Older, non-condensing boilers have a lower efficiency as some heat is lost through flue gases. Efficiency ratings then drop to around 70 to 80%.
Contrary to combustion systems, heat pumps use a reversible refrigeration cycle to transfer heat rather than generate it. In heating mode the outdoor exchanger acts as an evaporator, absorbing environmental heat from the air, water, or ground. The refrigerant in the heat pump is compressed, which raises its temperature. The indoor coil then acts as a condenser, releasing heat to the heating water.
Various types of heat pumps are available, including hybrid, air-source, ground-source, and water-source heat pumps. Most models are equipped with inverter-driven compressors, which allow for variable-speed operation according to the demand. This reduces energy consumption compared to traditional on/off compressors. Technological advancements also allow for the integration of smart controls and sensors so that adaptive algorithms optimize efficiency based on real-time conditions.
Heat pump systems vs. traditional HVAC systems
“EU climate goals for 2030 include a 55% reduction in greenhouse gas emissions compared to 1990 levels. The achievement of these goals, however, heavily depends on the actions of individual member states, which need to intensify efforts to comply with European directives. Improving the energy efficiency of residential and non-residential buildings is an important part of this and heat pumps are considered one of the key technologies to achieve sustainability goals. Today heat pumps still represent a relatively small share of heating solutions in use, but there is a clearly noticeable transition,” says Silvia Morassutti, Global Product Manager Heat Pumps at Purmo Group.
Choosing between heat pumps and traditional HVAC systems requires a thorough understanding of their efficiency, cost-effectiveness, environmental impact, and suitability for different climates. So let’s compare both systems in terms of their key features:
1. Energy efficiency
As mentioned, traditional boilers have AFUE ratings ranging from 70 to 80% for non-condensing models to 95% for condensing models. This means that residual energy is lost with the exhaust gas. Heat pumps operate at a much higher efficiency as they typically produce 3 to 4 units of heat for every unit of electricity consumed, resulting in 300 to 400% efficiency (COP >3), depending on the type of heat pump and the thermal efficiency of the building in which it’s installed.
To maximize the efficiency of both a conventional HVAC system and a heat pump system, the building needs to be well-insulated. However, the degree of insulation will have a greater impact on the performance of the heat pump system since this typically operates at lower system temperatures.
Discover the pros and cons of low-temperature heating
2. Environmental impact
Heat pumps eliminate direct carbon emissions, whereas gas boilers emit about 215 grams of CO2 per kWh of heat delivered.1 As conventional heating systems rely on fossil fuels and contribute to carbon emissions, they are increasingly criticized in light of global and national climate targets. However, it’s important to consider the system as a whole, because adding, for example, smart thermostats and thermostatic radiator valves (TRVs) to a conventional heating system will already help to reduce its carbon footprint.
Read more about smart controls
Heat pumps don’t burn any fossil fuels, but they do require electricity. The pump’s environmental impact thus depends on how much of that electricity is produced via renewable sources such as wind, solar, or hydropower. But, of course, heat pumps remain a reliable method for reducing emissions. According to the EHPA (European Heat Pump Association), the 24 million heat pumps currently installed in Europe avoid the greenhouse gas emissions produced by 7.5 million combustion cars.2.
3. Operating costs
With a boiler system users can benefit from lower gas prices. However, this advantage diminishes with additional CO2 levies. Heat pumps, on the other hand, are more efficient but can have similar or even higher operating costs due to the higher cost of electricity compared to gas. This, of course, depends on the national energy prices, the potential use of solar panels and power storage, and the building’s insulation level. The better the building is insulated, the more efficient a heat pump system will be able to operate and the lower its operating costs. An energy audit is therefore recommended prior to the installation of a new heat source.
4. Performance in cold climates
A conventional HVAC system maintains a consistent performance regardless of the outdoor temperatures and thus provides reliable heating in colder climates. The efficiency of a heat pump can, however, decrease in extremely cold temperatures. This may mean you need to integrate an additional heat source into the system to guarantee indoor climate comfort on the coldest days of the year.
5. Installation considerations
In contrast to an uncomplicated boiler system, the installation of a heat pump is more complex. Moreover, boiler systems are typically installed indoors and, depending on the type of boiler, require little space, which makes them suitable for properties with limited outdoor space. Heat pumps, however, require authorisation and take longer to install due to the complexity of the system (indoor and outdoor units, wall penetration, etc.). In addition, heat pumps usually require outdoor space for the outdoor unit. Ground source systems require sufficient land for ground loops and excavation work should be considered in the timing of the installation.
6. Maintenance
Both conventional HVAC systems and heat pump systems should be serviced regularly by a professional. This will help to keep the system running efficiently and safely.
Conclusion
As both technology and the energy landscape evolve, it’s important to carefully asses each project based on the occupants’ needs, the specific conditions of the building and its climate as well as any budgetary constraints. For clients in moderate climates or those seeking sustainability, a heat pump system is an excellent choice. Traditional HVAC systems, however, may still be preferable in extremely cold regions or where fossil fuel heating is more economical.
Should you have any questions about this comparison or the solutions needed to create a perfectly aligned system, please don’t hesitate to reach out to our experts. We are happy to assist with tailored advice and the most suitable products.
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Sources:
1. https://mail.gshp.org.uk/HVR_Awards_CO2_Calculator_Heat_Pumps.html
2. https://www.ehpa.org/wp-content/uploads/2024/08/Executive-summary_EHPA-heat-pump-market-and-statistic-report-2024-2.pdf