Balancing investment in clean heat and energy efficiency in Scottish housing retrofit

There is conflicting information on the desirable level of fabric performance for a home to be considered suitable for clean heat. Some studies look at a system’s capability to maintain a desired indoor temperature during the coldest expected weather conditions. Others consider running cost implications, with the aim of avoiding increased heating costs compared to the existing home heating system. Climate and property characteristics in Scotland must be considered to fully understand efficiencies and costs.

Improving a home’s fabric can reduce peak heating loads and therefore help improve heating system efficiencies and reduce running costs. The literature also suggests other options to achieve clean heat given potential property constraints, including:

• Radiator upgrades
• High temperature heat pumps
• Demand shifting using Time-of-Use tariffs
• Self-generation of power via solar
• Different heat pump systems (e.g. hybrid heat pumps or air to air heat pumps)

The cost-effectiveness of measures will vary by tenure, and the viability of various options will depend on the circumstances:

• Owner-occupiers may prefer solutions with a better whole-life cost
• Renters may favour options that do not increase ongoing energy bills
• For others, minimising disruption or space loss may be a priority
• For social landlords, economies of scale may have the biggest influence.

There has been limited exploration of the specific impact of the fabric versus clean heat balance on fuel poverty. No research appears to have assessed impacts following the Scottish Government’s approach to assessing fuel poverty statistics. However, retrofit offers opportunities to improve household health and wellbeing, as well as tackling high energy bills and reducing fuel poverty risk. Many homes and households at risk of fuel poverty or with particular health needs may require more extensive retrofit measures.

Retrofit opportunities noted by stakeholders, included:

• Using ‘trigger points’ for retrofit measures when other home upgrade or renovation works are undertaken can be more practical and cost-effective.
• Raising awareness of the health and comfort benefits of retrofit could be more motivational than carbon or cost arguments.
• A stronger focus on commissioning and aftercare with new clean heat systems could improve system efficiencies and end user satisfaction and may negate the need for more extensive measures to deliver acceptable heating running costs.

Recommendations

• Policies should remain flexible and avoid prescribing a single retrofit pathway across all homes.
• Those in fuel poverty, or significantly at-risk, should be supported with more extensive retrofit measures to reduce running costs and improve comfort.
• Therefore, a modelling exercise should be undertaken to investigate the extent of measures likely to be required to remove Scottish homes from fuel poverty (or at least close the gap) while decarbonising.