The secret to high heat pump efficiencies

August 22, 2023

Consumer Advice

We have collected data from 50 heat pumps from a 1 year period, and have data for another 57 incoming for the same year. These figures will be reflected and updated on the below graphs as the data comes in.  The installations were completed by engineers who had completed online heating theory training, and 85% of which had not installed a heat pump previously, or completed any other heat pump training.

This analysis has aimed to explore several questions that are often raised around heat pumps. Specifically:

  1. Can heat pumps perform well in older properties? A common narrative for heat pump is that they will only work in new, well insulated properties.
  2. How do Heat Geek installations compare to others? In the past year, there have been reports published from several large scale trials, notably the Electrification of Heat Project. These systems achieved an average SCOP of 2.8.
  3. How well do systems perform compared to their predicted performance? Before a heat pump is installed, a predicted performance will be made.

The findings show that these Heat Geek trained installations achieved sufficiently higher efficient heat pumps than the national average. In addition, the work highlights that property age is not a proxy for if a heat pump will work, or how efficient it is among some others.

All of our data come from on board measuring directly from the heat pump (currently Vaillant). The results and metrics will be updated as we continue to gather data from these systems.

The impact of property age?

Traditional thinking for heat pumps is that older properties are less efficient for heat pump installations. Older properties generally have lower thermal performance, both having high amounts of heat loss through walls, floors and ceilings, and with lower air tightness leading to a lot more heat being lost through ventilation.

Figure 1 compares the Seasonal Coefficient of Performance (sCOP) of systems against property age. Data is displayed for both the predicted performance and actual. The plot only shows data for heating performance, which was selected as this is more impacted by the building fabric than the hot water efficiency performance.

Systems on average achieve a SCOP of 4.20 for heating only. It can be seen that this includes several examples of properties built before 1925, and these are homes with generally poor thermal performance compared to modern building standards.

Finally, the predicted performance of systems before installation was 3.85, meaning that systems were performing over 10% more efficiently than expected. 

high heat pump efficiencies

Figure 1: SCOP vs Property Age

Figure 2 shows the same graph as Figure 1, but now is just filtered to Heat Geek Elites. This is a select cohort of installers who have both gone through the Heat Geek training and have extensive practical experience installing heat pump systems. For this set of installations, the average SCOP has increased to 4.48.

Figure 2: SCOP vs Building Age, focussing on Heat Geek Elite Installations

Systems Including Hot Water Demand

Figures 1 and 2 displayed the SCOP without hot water demand. This was selected to help explain the impact of the building fabric on the SCOPs. However, it is important to consider the hot water heat, as this demand does generally lower the SCOP of a system. Figure 3 shows the SCOP for the Heat Geek Elite installations, including hot water and heating. This results in a reduction in the SCOP from 4.48 to 4.26. 

Caveats

We are continuing to build our evidence base to support our views that high efficiency heat pump installations are not an exception, but can become the norm with proper system design and training. Currently, the sample size of this analysis is too small to perform detailed statistical testing, but we will add to this work as more systems come online.

Meet our data scientist - Dr Mikey Harper

Michael will be analysing and watching our installations moving forward, picking our key metrics on how we can improve practices over time and also increase prediction accuracy.  If you have any questions, about this data or work, we’d love to hear from you! Please comment below.

Results Comparison

Results Comparison

Take a look at our heat geeks live installations here.

https://heatpumpmonitor.org/

Watch them live here

Mytchett - Heat geek house

Bristol

Sheffield

Camberley, Surrey

Heat Geek towers, Camberley

Telford

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