How to reduce your HVAC system’s carbon footprint

Why should we reduce carbon emissions?

When we burn fossil fuels to heat and cool our buildings, we produce carbon emissions. Together with other greenhouse gasses, the emissions of carbon dioxide are a primary cause of global warming, which in turn has a destructive impact on our planet. To slow down climate change and minimise its effects, we must reduce carbon emissions. As individuals we can do so by, for example, consuming local and seasonal products or cycling instead of driving. Reducing the carbon footprint of our buildings, however, requires other actions as this involves things such as heating, cooling and electrical use.

Why is it so hard to decarbonise our heating?

Since European governments have committed to a Net Zero carbon emissions target by 2050, our buildings need to keep up with this movement. Given the enormous building stock in the EU, of which 75% is currently considered to be energy inefficient, this is a major challenge. In addition to the size of the building stock, certain factors add to the challenge of reducing the carbon emissions. Awareness, for example, is still relatively low. Lots of people are still not familiar with low carbon heating and the existing financial incentives. Moreover, 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.

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 source and generator. While 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.

A study by the ITG Dresden shows that replacing the heat generator in an existing heating system can save an average of 2.7 ton of CO₂ per year. If the system is further optimised and the flow temperature is reduced to 35 °C, for example, a further 0.46 ton per year can be saved. A further CO₂ savings potential of 0.29 ton per year is offered by the room temperature control. Overall, the entire heating system, i.e. heat generation, heat transfer and the optimisation of the room temperature control, has a CO₂ savings potential of up to 3.45 ton per year.

2. Ensure the heat emitters are dimensioned properly

For both thermal comfort and energy efficiency it’s important that the heat emitters are all aligned with the energy source and the system’s flow temperature. This entails choosing the right kind of radiators, but also dimensioning them correctly.

3. Don’t forget about hydronic balancing

In addition to the dimensions of the radiators, 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 radiator is supplied with the necessary amount of warm water, energy consumption can be reduced by 5 to 15%. Using the right radiator valves, this is a piece of cake.

4. 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 10% 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.

5. Schedule regular maintenance

HVAC systems are often ignored until something is wrong with them. However, regular maintenance is important to keep them running efficiently and to guarantee good air quality. Part of the maintenance is regularly changing the air filters. If they are clogged, the air flow is restricted, and the system will have to work harder to meet the temperature requirements. This means a higher energy consumption and more carbon emissions.

6. Ensure good insulation

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.

7. Reduce heat loss

Finally, unsealed walls, windows and doors can create unpleasant draughts but also generate significant heat losses. The same goes for ductwork leaks as a result of poor connections in the HVAC system. By sealing up those air leaks draughts and unnecessary energy consumption can easily be avoided.