Energy Efficient Scotland: the future of low carbon heat for off gas buildings - call for evidence

We are seeking evidence on technologies and actions necessary to support the decarbonisation of the heat supply of buildings that currently do not use mains gas as their primary heating fuel.

Current Market for Low Carbon Heat

This section covers:

  • The distinctions of Scotland's renewable and low carbon heat market
  • The existing barriers to their uptake, and the actions we can undertake to remove such obstacles in order to accelerate the uptake of low carbon and renewable sources of heat
  • We specifically ask you to reflect on building-specific restrictions, namely:
    • poor building energy efficiency;
    • building density;
    • conservation areas and listed buildings; and
    • high heat demand or need for high temperature heat.
  • We believe these factors underline the need for future policy frameworks to be flexible enough to develop bespoke solutions to decarbonising heat supply

The market for renewable and low carbon heat has grown in recent years. At present, the majority of low carbon heat installations in Scotland are likely driven by the Renewable Heat Incentive (RHI).

Over the period 2014-18 there have been in excess of 16,000 installations under the RHI in Scotland (combining domestic and non-domestic installations). Scotland has received greater than its pro-rata share of installations under the RHI, with 20% of domestic and 19% of non-domestic activity taking place in Scotland. The vast majority of domestic RHI installations in Scotland were in off gas grid properties (87%, compared to 72% in GB overall)[25].

The largest technology uptake on the non-domestic RHI has been biomass boilers with over 80% of accredited installations being some form of biomass boiler up to November 2018[26]. The domestic data shows a wider spread of technologies being supported under the RHI in Scotland, as shown in Figure 3.

Figure 3. Accredited Insrallations (Domestic RHI) Scotland


1. What evidence can you provide of low carbon heat technologies being taken up without government support?

Barriers to Uptake

Whilst a growing share of Scotland's heat is met from low carbon and renewable sources there remain a number of barriers to uptake, which will need to be overcome if deployment is to be scaled up to achieve Scotland's climate change targets. These barriers include:

  • lack of consumer and supply-chain knowledge of low carbon heat technologies;
  • the relatively high upfront costs of installing low carbon heating systems, relative to like-for-like replacement of incumbent systems;
  • the disruption of upgrading and/or replacing the internal heat distribution systems so that they are compatible with low carbon technologies e.g. re-sizing radiators, installation of a wet central heating system;
  • the need to dispose of heating systems components, in some cases prematurely, when switching to low carbon heat e.g. disposal of heating oil storage tanks.
  • potentially higher operational and / or maintenance costs;
  • limited capacity in some locations on the electricity grid to supply substantial increases in electrical heating;
  • lack of any regulatory requirement to install low carbon heating systems;
  • public finance limits to the level of support that can be provided by government to incentivise uptake; and
  • low carbon heat technologies are not suitable for some energy intensive industrial processes.

We would like you to help us better understand the extent to which these factors, and others, act as barriers to the wider adoption of low carbon technologies, specifically with respect to properties that do not use mains gas, and what the Scottish Government can do to remove such obstacles.


2. What other barriers may impede the uptake of low carbon heat in buildings not currently using mains gas?

3. What could we do to remove these barriers and support the uptake of low carbon heat? Can you give examples of successful low carbon heat implementation?

4. How can complementary systems, such as solar PV and heat pump systems be deployed to overcome such barriers?

Building-Specific Restrictions on Low Carbon Heat

Whilst there are a variety of low carbon technologies that could be deployed their suitability may be constrained by a number of building-specific factors, including:

  • poor building energy efficiency, which may prevent some low carbon technologies from operating effectively particularly where they use low temperature heat;
  • hard-to-treat properties, which typically have, solid walls, narrower cavities, are of non-traditional construction or are more than three storeys high. This can add to the complexity and cost of improving their energy performance and decarbonising their heat supply[27]
  • building density which may make it technically challenging to install certain types of low carbon heat either due to physical constraints or low demand levels. Over 30% of Scottish homes are flats which in many cases may prevent the installation of some low carbon technologies in individual units and a communal supply solution may be more appropriate. Conversely, in remote and rural communities it may not be commercially-viable to develop communal solutions due to the dispersed nature of buildings and so individual heating systems may be more suitable.
  • conservation areas and listed buildings which protect buildings and communities of historical significance. In these areas additional controls are in place, which may prevent the installation of some low carbon heat solutions, with permission required to be sought on a case by case basis.
  • high heat demand or need for high temperature heat, such as in larger building complexes such as hospitals, hotels, prisons, etc. where it may be more appropriate to consider district, communal or CHP-based solutions.

These different characteristics underline the need for future policy frameworks to be flexible enough to develop bespoke solutions to decarbonising the heat supply.


5. What do you consider to be the principal building-specific constraints on low carbon heat?

6. What can be done to overcome these constraints?

7. What evidence can you provide on the limitations of low carbon heat technologies (e.g. heat pumps) in buildings with poor energy efficiency?

8. What low carbon heat solutions are appropriate for hard-to-treat properties where there are limited opportunities to improve energy efficiency of the building fabric?

This section covers:

  • The wide range of technologies which could be deployed as replacements for existing high carbon heating systems and how the feasibility of these technologies is dictated by the property's characteristics, its location and the features of available technologies
  • The key low carbon heat technologies available, the scope for innovation and the potential constraints on the deployment of low carbon heat
  • We invite you to provide evidence on practical aspects of their large scale uptake, such as the current and prospective installation and operation costs. We are also interested in innovative new technologies that may have a role to play in the sector



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