As a domestic heating technology, air source heat pumps (ASHP) are increasingly being considered a cost effective option for heating homes particularly in off-gas areas. Government targets for carbon dioxide emission reduction and financial incentives and funding mechanisms are all poised to stimulate the take up of air source heat pumps in the UK.

It is widely promoted by manufacturers that heat pumps are a cost effective heating system for properties where mains gas supplies are not available. Through this project, NG-AWS engaged with the Housing Associations involved, and financed the installation of the heating systems in their properties. NG-AWS commissioned National Energy Action (NEA) to conduct this research study on the installations, to further understanding of the effectiveness and acceptability of this technology when deployed in off gas social housing situations.

The project aims as agreed with the funder in 2012 were:

To provide an independent assessment of air sourced heat pumps and their use as a solution to fuel poverty in hard to treat properties.

The focus of this project is the evaluation of the social impact of air source heat pumps in two rural off- gas grid communities.

  • Worksop - fitted with Mitsubishi ECOdan units - 10 households evaluated
  • Macclesfield - fitted with Husky PWR units - 6 households evaluated.

Within the sample of properties evaluated, 12 properties had previously been heated by electric storage heaters, 2 with solid fuel heating systems, 1 with an oil fired boiler and 1 using an electric boiler.

NEA compared running costs and controllability of the heat pump systems with these previous heating systems, and captured valuable data relating to installation and user experience. The technical efficiency of the two different models of heat pump is not examined in this study – However both have similar published efficiency ratings.

Semi structured interviews were conducted with householders at four points during the process, which started with system installations commissioned in February of 2012, and the monitoring period running until February 2013.

Tenants were generally pleased with the new systems, which provided adequate heating capacity. However several issues were identified.

The project highlighted several benefits to tenants of ASHP heating systems when they were fitted in appropriately insulated off gas properties, correctly specified and supported. The overwhelming majority of tenants (81 %) were happy with their new systems AND would recommend them to others.

Benefits found;

  1. increased thermal comfort,
  2. lower heating costs,
  3. improved controllability of heating
  4. Increased automation compared to storage or solid fuel.

The project also highlighted a number of recommendations for future ASHP installations where the social impacts can be improved

  1. Appropriate support and training should be provided for residents (appropriate to their ability).
  2. Tenants should be adequately supported on choice of (and changing of) their energy tariff.
  3. Appropriate specification of systems is required, with appropriate user controls for whole house heating. These controls should include TRVs, and appropriately sited thermostats and programmers.
  4. Householders should be involved in decisions of where to site controls and appliances, with housing association backup as the landlord.
  5. For future projects - consideration should be given to the deployment of additional monitoring equipment, logging energy use by time, which will provide useful data on ACTUAL patterns and timings of use, but also remove the need for residents to supply utility bills and remove inaccuracies and uncertainty from using estimated utility bills.
  6. Consideration should be given to the provision of energy displays / smart meters in conjunction with the rollout of ASHPs and supported by appropriate bespoke training to householders.

Conclusion

Air Source Heat Pumps are a cost effective way of providing affordable warmth in off gas communities - provided the systems are specified correctly by skilled technical staff, and the householder is involved in the decisions affecting them (such as positioning of radiators, buffer tanks and controls).

Further work

This project also helped to tease out more general issues which must be considered before a major roll out of heat pumps in the domestic sector. Specifically this relates to ingrained behaviour linked to long term use of electric storage heating. Tenants choosing to retain their Economy 7 tariff after the installation of the ASHP provided evidence that there is little difference between costs of operating the ASHP on the two main tariff options. NEA recommends more work be conducted to model this across different populations to fully understand the costs. Also, NEA recommends an independent evaluation of modern storage heating – provided as a replacement heating system in properties with older poorly controlled system storage heating. This technology may be more cost effective solution, and may be embraced more by the tenants, allowing them to retain a familiar heating system and energy tariff, and remove the household upheaval caused by installing new radiator based heating system in the properties.

View the complete case study here