Renewable and zero direct emissions heating systems in affordable housing projects (phase 2): evaluation

An evaluation of the selection, installation and performance of zero direct emissions heating (ZDEH) systems installed in new affordable homes in Scotland.

Executive summary

  • Seven of eight stakeholders had previous experience with ZDEH, with ASHPs a default option for many off-grid locations. Motivations to install the ZDEH system included off-grid locations, upcoming NBHS regulations and fuel poverty concerns.
  • All stakeholders had experienced at least one challenge during the implementation of a ZDEH system, however commissioning appeared to be a smoother process. The largest two challenges are related to the supply chain and geographical location of the project, which often go hand-in-hand. Cost, grid constraints, and billing and metering were also challenges experienced.
  • Seven of eight stakeholders were happy with the performance of the ZDEH system and only required general maintenance, which was expected. Overall tenant satisfaction, quantified by surveys and number of complaints, is deemed to be high by housing providers.
  • Monitoring of zero direct emissions heating (ZDEH) systems is rarely conducted by affordable housing providers. Only three of the participating projects were able to provide real-world heat demand or cost data, for a handful of homes within their developments. Many stakeholders had not considered monitoring and would be less likely to do so unless it became a requirement.
  • Real data on the actual performance of ZDEH systems is very limited both in this project and more widely in industry. When compared to estimated annual energy consumption in an average gas-heated home and against averaged gas tariffs (using data from BEIS and the Energy Saving Trust), data from operational ASHPs are found to be less expensive, or equivalent to gas to run. The exception being for larger homes (4+ beds) which are difficult to correlate against the averaged data.
  • A knowledge hub is welcomed by the housing sector and many existing organisations are interested in supporting, hosting and collaborating on such a resource. The hub needs to be well defined, funded, dynamic, and deliver real data and insights to pertinent housing sector topics (that can't be found elsewhere) to be useful and attract high engagement.



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