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How to reduce your HVAC system’s carbon footprint
Why is it so hard to decarbonise our heating?
Given the enormous existing building stock in the EU, 75% of which is currently considered to be energy inefficient (in Europe alone), aligning our buildings to meet the carbon emissions target is a major challenge. Especially because heating systems based on fossil fuels are well-established, relatively inexpensive, and widespread. Many people delay the transition to low-carbon alternatives because they don’t want to invest money and/or time to adapt their system.
Moreover, there is no one-size-fits-all solution. For a building to be heated efficiently, the entire HVAC system must be tailored to it as well as its occupants’ needs and habits. In addition, thermal efficiency is more than just the heating and cooling system. It’s affected by the building envelope, the degree of insulation, the division of the spaces, etc. All factors that can prove difficult to adjust in existing buildings.
Other factors adding to the challenge of reducing carbon emissions are awareness and acceptance. Lots of people are still not familiar with low-carbon heating technologies and the existing financial incentives. Concerns about performance and reliability tend to prevail. It will take time and effort to change these perceptions.
How to reduce your HVAC system’s carbon footprint?
Given the significant share that the HVAC system represent in our energy consumption, it’s a vital part of the answer to the question ‘How to reduce our carbon footprint?’. Both smaller and larger interventions allow for a significant reduction of the carbon emissions and need to be considered.
1. Choose the best energy generator
A good starting point for reducing a building’s carbon footprint is to evaluate its energy generation source. Oil and gas burners are the most carbon intensive heat generators, thermal solar panels are the least. Ground source or air source heat pumps are also a very interesting alternative as their use of renewable energy significantly reduces CO2 emissions compared to fossil fuels. We are aware, however, that not everyone is in a position to install a heat pump, but a modern condensing boiler already provides a good basis for low-temperature heating when combined with the right heat emitters..
2. Combine the heat source with the right emitters
Low-carbon heating systems run on (ultra-)low temperatures. To enjoy optimal energy efficiency and create sufficient heat output, it’s therefore important to choose the right emitter(s). Underfloor heating is often the first option on people’s minds. However, modern radiators offer an excellent alternative. For temperatures below 45°C, we recommend fan-assisted radiators such our Ulow-E2 or fan convectors such as the iVector S2.
Learn more in our guide to low temperature radiators
Electric radiators are certainly also an interesting option. They can either be used to complement a hydronic heating system or, if the building’s heat demand is low enough, also as a stand-alone heating solution. They are very efficient as they convert every watt of power into usable heat, and in case they can be powered by solar panels (PV), they are carbon neutral.
Read our guide to choosing the right oil-filled radiator
3. Ensure the heat emitters are dimensioned properly
For both thermal comfort and energy efficiency it’s also important that the heat emitters are dimensioned correctly. If the radiators are too small, for example, they won’t generate enough heat output, meaning the room often won’t get warm enough. If, on the other hand, they are too large, they’ll emit more heat than necessary and require excessive energy. Both scenarios mean an increase in energy consumption, which is exactly what we’re trying to avoid. Therefore, it’s important to find the right balance and make sure all heat emitters are sized correctly.
Find the best radiators for heat output with our product calculator
4. Don't forget about hydronic balancing
In addition to the dimensions of the emitters, their hydronic balance is also important for the energy efficiency of the heating and cooling system. By optimising the hydronic distribution and making sure every unit is supplied with the right amount of warm water, energy consumption can be reduced by 7 to 11 %. Using adjustable thermostatic valves, you can easily limit the mass flow to avoid an unbalanced water distribution.
Hydronic balancing is important for all heating systems, but especially so for low-temperature systems because it ensures the system is set to the temperatures that suit the energy source the best and allows it to work as efficiently as possible.
Read more about energy saving with hydronic balancing
5. Choose the right controls
In addition to the heat source and the emitters, the controls also play an important role in reducing the HVAC system’s carbon footprint. Better control allows for better tailoring of the system so that you only use the exact amount of energy you actually need to enjoy indoor climate comfort all year round.
The use of basic heating controls such as thermostatic radiator valves already allows for significant energy savings. If the system is upgraded with smart controls, such as the ones in our Unisenza Plus range, the potential savings increase even further as the system’s energy use is optimally tailored to the users’ habits and often learns their preferences to then automatically adjust.
Read more about CO2 savings with heating controls
6. Consider zone temperature control
A heating (and cooling) system based on the on/off control of a single zone. It often fails to create thermal comfort in every room and wastes energy by heating or cooling unoccupied rooms. Zone temperature control, on the other hand, combines multiple thermostats, each controlling the temperature of a specified zone, so that different temperatures can be set per zone. As not all areas require heating or cooling at the same time or at the same temperature, this allows for more tailored temperature control and avoids wasting energy on unoccupied rooms.
Read more about zone temperature control
7. Change the thermostat settings
Lowering the thermostat 1 or 2 degrees won’t affect indoor comfort much, but it will have a significant impact on carbon emissions. Just one degree less can reduce CO2 emissions by about 300 kg. A nice bonus is that it will also save about 6% on the energy bill. Some thermostats can be programmed to adjust automatically or to monitor occupant behaviour so that the efficiency of the HVAC system is maximised with little effort on the user’s part.
8. Schedule regular maintenance
HVAC systems are often ignored until something is wrong with them. However, regular maintenance is important to keep them running smoothly and efficiently. If all components are well-maintained, the heating system won’t have to work harder than necessary to meet the temperature requirements. This avoids a higher energy consumption and more carbon emissions.
9. Ensure good insulation and reduce heat loss
As mentioned earlier, a building’s thermal efficiency is also affected by the degree of insulation. If important areas such as the roof, floors, walls, basement and attic are properly insulated, less effort is required on the part of the HVAC system to heat or cool the building. In winter, warmth is more easily kept inside so that the heating switches on less frequently, while in summer the heat is kept out so there is less need for cooling.
Moreover, the higher the degree of insulation, the further the flow temperatures of the heating system can be lowered and the less energy it will require to heat the building. Finally, unsealed walls, windows and doors can create unpleasant draughts but also generate significant heat losses. By sealing up those air leaks, draughts and unnecessary energy consumption can easily be avoided.
Conclusion
Regardless how big or small the interventions you want or are able to do, all of the tips listed above contribute in their own way to reducing the HVAC system’s carbon footprint. So don’t hesitate to start small if that lowers the threshold. Saving energy and reducing our impact on the planet’s climate is a step-by-step process but if we all do our bit, we, at Purmo, are convinced that together we can make a difference.
Are you unsure how exactly to reduce the impact of the HVAC system in a particular application or project? Don’t hesitate to reach out to our experts. We will gladly answer any questions you might have.