Balancing Environmental and Socioeconomic Sustainability: A Case Study on Heat Pumps and the Path to Net Zero for Engineering Education

We recently published a case study on the feasibility of heat pumps to reach net zero in the Engineering Professor’s Council (EPC) ethics toolkit, which is available under a CC BY-SA 4.0 license.1 The EPC is a representative body that provides a range of toolkits with resources designed to help educators and trainers integrate aspects including sustainability, ethics, and enterprise into teaching.  

Engineering is key to technological, economic, and societal progress and plays a vital role in moving towards a sustainable future. We have a significant challenge in engineering education: the tendency to view engineering as a purely technical discipline within an apolitical and acultural bubble. However, collaborations involving multiple stakeholders – industry, governments, consumers – are vital to drive change and achieve effective sustainable development by setting policies and incentives that encourage growth and adoption of low-impact technologies. It is important our engineers of the future are aware of our wider professional responsibilities including the social, economic, and cultural context in which they operate.  

Figure 2: AI-generated image illustrating the competition between new and old heating technologies. 2 

This case study was designed to integrate the socioeconomic aspects of sustainability into the engineering challenge of sustainable heating in the UK. Heating is currently responsible for one-third of the UK’s annual carbon footprint, of which 17 % is associated with space heating of homes – comparable to the contribution of petrol and diesel cars.3 Heat pumps are a potential alternative to natural gas boilers, particularly for domestic heating. A heat pump receives heat (from the air, ground, or water) and work (in the form of electricity to a compressor) and then outputs the heat to a hot reservoir (the building you are heating). Worldwide adoption of heat pumps is growing rapidly with the UK Government pledging to increase the number of heat pumps installed to over 600,000 per year by 2028.4 

In this case study students participate in a guided discovery, applying their thermodynamics knowledge alongside discussions to explore the wider themes of sustainability. We have run a version of this study for two-years with undergraduate engineering students as part of their second-year thermodynamics unit. They navigate the need to balance performance, cost, and impact on the consumer. In a memorable part of the session students discover that the lifetime cost of ground-source heat pumps can equal or surpass that of natural gas boilers, due to their high capital cost and the current high cost of energy. This revelation around the increased cost of energy for renewables was a surprise to quite a few students who expected the renewable, greener option to be cheaper and lead to a shift in perspective.  

Prior to this, we ask students to select their preferred heat pump technology (air-source or ground source). The majority select the ground-source heat pump because it has a better thermodynamic performance. The interplay between the improved performance but high capital cost of the ground-source heat pump is used to draw out an important principle: that the ideal or most perfect solution is not always necessary for an effective outcome and that engineers often navigate a balance between performance and cost. Air-source heat pumps, whilst having a lower performance, have a much lower capital cost, installation footprint, and fewer constraints, and so are used quite effectively in practice. Alongside this, the differences in capital investment of these heat pumps allows students to consider how aspects of policy, primarily the importance of bursaries or subsidies, can make renewable technologies more attractive to consumers and increase uptake.  

Figure 1: AI-generated image illustrating the uncertainty around heat pump technology and energy prices. 5 


A final key focus of this case study is the social dimension of sustainability, particularly considering consumer needs. Ultimately, even if you offset the capital cost of a heat pump, it is the consumer who will need pay the energy bill and there is growing concern around the affordability of energy. In the UK, electricity costs remain closely tied to natural gas prices and are four-times the cost. Consequently, even though heat pumps can require only up to a quarter of the energy that boilers do for the same heating output, the financial impact on consumers can be comparable or even greater. This is especially important in the context of unstable energy prices and increasing energy poverty. The UK faces a real challenge in the quality of its housing stock, with significant heat loss from homes disproportionately affecting low-income communities.6 Indiscriminately installing heat pumps in properties that have not been properly evaluated or modified can lead to additional financial strains.  

Students really engaged with the different aspects of this case study and feedback has been very positive, which inspired the submission to the EPC ethics toolkit. The real-world applicability, workshop-style lectures, and link to wider global themes were aspects they particularly appreciated. Further case studies are available in the ethics toolkit and the EPC plans to release a sustainability-specific toolkit early next year.  


References/Further Reading 

  1. Rowlandson, J. L. Case study: Feasibility of installing heat pumps at scale to reach net zero – Engineering Professors Council.
  2. OpenAI. [AI Generated Image] Prompt: Generate an image of a heat pump and gas boiler in a boxing match. ChatGPT [Large Lang. Model. (2023).
  3. Decarbonising heat in homes – Business, Energy and Industrial Strategy Committee.
  4. Energy Security Bill factsheet: Low-carbon heat scheme – GOV.UK.
  5. OpenAI. [AI Generated Image] Prompt: An air source heat pump showing the uncertainty around the technology and energy prices. ChatGPT [Large Language Model] at (2023).
  6. Bolton, P., Kennedy, S. & Hinson, S. Fuel poverty in the UK. at