Scottish House Condition Survey: 2024 Key Findings
Figures from the 2024 survey, including updated fuel poverty rates, energy efficiency ratings, the condition of housing and the Scottish Housing Quality Standard.
2 Energy Efficiency
The energy efficiency of a dwelling depends on its physical characteristics. Factors such as the age of construction, the dwelling type, the heating and hot water systems in use and the extent to which the building fabric is insulated, all affect energy efficiency.
The energy efficiency of a dwelling depends on its physical characteristics. Factors such as the age of construction, the dwelling type, the heating and hot water systems in use and the extent to which the building fabric is insulated, all affect energy efficiency.
Based on information about the characteristics of the dwelling collected in the SHCS physical survey and using standard assumptions about the make-up and the behaviour of the occupying household, the energy consumption associated with the dwelling is modelled. This allows us to make comparisons of modelled energy use, emissions, and energy efficiency ratings between dwellings that are independent of occupant behaviour. Further details on the methodology underpinning these measures of energy efficiency are provided in sections 1.3 and 1.4 of the Methodological and Technical notes.
In this chapter we report on:
- levels of insulation in Scottish dwellings (section 2.1);
- boiler efficiencies (section 2.2);
- Energy Efficiency Ratings (EER), also known as SAP ratings (section 2.3);
- modelled carbon dioxide (CO2) emissions from dwellings (section 2.4); and
- Environmental Impact Ratings (EIR) (section 2.5).
A breakdown of findings is also provided by household tenure and other relevant dwelling characteristics.
2.1 Insulation Measures
Installing or upgrading insulation is one of the most effective ways to improve the energy efficiency of a building. The Energy Saving Trust estimates that an un-insulated dwelling loses a third of all its heat through the walls and a further quarter through the roof. As a result, insulation can significantly reduce energy consumption and therefore lower heating bills, making it cheaper to achieve satisfactory levels of thermal comfort. (See Chapter 3 on Fuel Poverty).
Additional insulation is most commonly added to a property through the insulation of loft spaces, and by adding insulating material to external walls.
Key Points
- The majority of loft spaces are insulated. In 2024, loft insulation with a thickness of 100 mm or more had been installed in 95% of dwellings. This has been broadly stable since 2017 but represents an increase of around 24 percentage points on 2007 levels.
- In 2024, 35% of lofts were insulated to a high standard of insulation (300 mm or more), higher than to 2023 levels.
- The proportion of insulated cavity walls recorded by the SHCS was 71% in 2024.
- The proportion of solid wall dwellings with insulation was 20% in 2024.
- Levels of insulation (both loft and wall) are higher in the social sector than in the private sector. 56% of homes in the private sector have wall insulation compared to 72% in the social sector. In the private sector, 65% of lofts are insulated to 200 mm or more compared to 76% in the social sector.
2.1.1 Loft Insulation
The majority of loft spaces in Scotland are insulated.
Figure 2.1: Loft insulation (where applicable), 2003/2004 to 2024.
Description of Figure 2.1
Figure 2.1 shows that since 2007, there has been an overall improvement in the uptake of loft insulation. The proportion of all applicable housing[1] with 100 mm or more of loft insulation has increased by around 24 percentage points on 2007 levels with 95% of applicable dwellings insulated to this degree in 2024. Most of this improvement occurred before 2014.
The share of dwellings with no loft insulation has fallen from 6% in 2003/4 to around 1% in 2024. Most of this decline occurred before 2010. Since then, improvement has slowed down, suggesting that there may be barriers preventing the installation of insulation in the relatively few remaining uninsulated lofts.
Data Source: Table EE1 in ‘SHCS 2024 - Chapter 02 Energy Efficiency - tables and figures’.
Notes: [note 3]
In 2024, 35% of lofts were insulated to a high standard of insulation (300 mm or more).
Figure 2.2: Depth of loft insulation (where applicable), 2003/2004 to 2024.
Description of Figure 2.2
Since 2009 the thickness of loft insulation has notably increased. In 2024, 67% of dwellings with lofts had insulation with a depth of 200 mm or more compared to 27% in 2009. Much of this increase occurred between 2009 and 2013, when the percentage increased from 27% to 62%. This can largely be attributed to the installation of top-up insulation. The estimated number of dwellings with loft insulation of 200 mm or more in 2024 is similar to 2023. However, the estimated number of dwellings with loft insulation of 300mm or more rose from 32% to 35% between 2023 and 2024.
Data Source: Table EE1 in ‘SHCS 2024 - Chapter 02 Energy Efficiency- tables and figures’.
Notes: [note 3]
Levels of loft insulation are higher in the social sector than in the private sector.
Figure 2.3: Depth of loft insulation (where applicable) by tenure, 2003/2004 to 2024.
Description of Figure 2.3
As shown in Figure 2.3 in 2024, 34% of private sector dwellings had a high standard (300 mm or more) of loft insulation, lower than 41% of dwellings in the social sector. 94% of private housing lofts were insulated to 100 mm or more and 65% to 200 mm or more. In the social sector, around 99% of dwellings had lofts insulated to 100 mm or more, and 76% had 200 mm or more of loft insulation.
One of the reasons for the difference in uptake of loft insulation over time between the private and social sector is that the Scottish Housing Quality Standard (SHQS), which was introduced in 2004 and applies only to social sector housing, required dwellings to have of loft insulation if there was an appropriate loft space. (see section 5.2.3 for more information).
However, the difference in the proportion of lofts with 100 mm or more of insulation between the private and social sectors has been reducing gradually, from 17 percentage points in 2003/04 (81% in the social and 64% in the private sector) to around 5 percentage points in 2024 (around 99% in the social sector and 94% in the private sector).
Data Source: Table EE2a in ‘SHCS 2024 - Chapter 02 Energy Efficiency- tables and figures’.
Notes: [note 3]
2.1.2 Wall Insulation
The presence of cavity wall insulation (CWI) added since built is becoming increasingly difficult for SHCS surveyors to identify as over time the injection holes age, fade, or are covered up by later work. Additionally, contractors are also getting better at concealing their work. This may mean that the SHCS underestimates the number of homes which have had CWI installed (see section 6.2.2.4 of the 2019 SHCS key findings report). Therefore, despite efforts to maintain the high quality of the SHCS physical survey fieldwork, some misclassifications may remain.
In Scotland around 78% of dwellings (or around 1.98 million) have external cavity walls and the remaining 22% (or 573,000) have solid or other construction types of external wall. These “other” types may include steel, brick, block or dwellings made from prefabricated concrete. As the improvement of solid and other wall types generally requires more expensive interventions than CWI, this diverse group is addressed together in this chapter.
Higher insulation levels in new buildings have been required by building standards since 1983 when the Building Standards (Scotland) Amendment Regulations 1982 came into force. These dwellings are therefore treated as insulated when built for the purposes of this report.
In 2024, 71% of cavity wall dwellings in Scotland were insulated.
Figure 2.4: Cavity wall insulation, 2012 to 2024.
Description of Figure 2.4
In 2024, 71% of cavity wall dwellings in Scotland were insulated, similar to the level in 2014. The long term trend shows a decrease in the share of uninsulated cavity walls of around 6 percentage points between 2012 and 2014, but has remained fairly stable since then.
Data Source: Table EE3a in ‘SHCS 2024 - Chapter 02 Energy Efficiency- tables and figures’.
Notes: [note 4]
In 2024, 20% of dwellings with solid and other wall types in Scotland were insulated.
Figure 2.5: Wall insulation of solid and other wall types, 2012 to 2024.
Description of Figure 2.5
Figure 2.5 shows the levels of insulation in dwellings with solid or other construction type walls recorded by the survey from 2012 to 2024. The results show that 20% of dwellings in this category had insulated walls in 2024, similar to 2023, but a 10 percentage point increase from 2012. 682 dwellings with solid walls were surveyed in 2024 as part of the SHCS.
Data Source: Table EE3a in ‘SHCS 2024 - Chapter 02 Energy Efficiency- tables and figures’.
Notes: [note 4]
The information in Table 2.1 breaks down the type of cavity wall into hard to treat cavities (HTTC) and standard cavity walls using the ECO definition as far as possible with the available data (further details are available in section 2.6 of the Methodological and Technical notes).
HTTCs have certain attributes which make CWI more expensive, complex or inadvisable. Standard cavity walls have no such barriers.
Overall levels of wall insulation were higher in the social sector than in the private sector.
Around 72% of dwellings in the social sector had insulated walls, with 75% of cavity wall dwellings, and 50% of dwellings with solid and other wall types estimated to be insulated in 2024.
In the private sector, 70% of cavity wall dwellings and 15% of solid and other wall dwellings, had insulation in 2024. Over half (56%) of all private sector dwellings had insulated walls.
Overall, 71% of cavity wall dwellings in Scotland have wall insulation. 31% have had retrofit cavity wall insulation, which is generally the lowest cost improvement available; the remainder of insulated cavity walls were insulated as built (33%) or insulated in another way such as with internal and external wall insulation (8%).
Levels of insulation are higher in the social sector at 72% (all wall types) compared with 56% in the private sector. This is driven by higher levels of insulated solid walls in the social sector (50%) compared to the private sector (15%). Within wall type, this tenure divide is also apparent for more expensive insulation measures such as internal / external insulation of cavity walls 15% of cavity wall dwellings in the social sector; compared to 5% of private dwellings.
Notes: [note 4]
2.2 Boilers
The heating system is a key factor in the thermal efficiency of a dwelling. Around 87% of households use a gas or oil-fuelled boiler. Trends in boiler efficiency are closely related to developments in energy efficiency and building standards regulations:
- From 1998, minimum boiler efficiency standards were set by European Council Directive 92/42/EEC
- In 2007, Scottish Building Standards increased the efficiency requirements for all new and replacement boilers, details are available in the Domestic Building Services Compliance Guide for Scotland.
- From February 2023 boiler efficiency standards were again increased for all new and replacement boilers, details are available in the updated Domestic building services compliance guide
Building regulations in Scotland effectively require the installation of a condensing boiler[2] for gas and oil-fuelled heating when boilers are replaced in any dwelling. Prior to 2024 regulations essentially also required their installation in any new build property with gas or oil heating. However, from April 2024, the New Build Heat Standard now only allows zero direct emission heat solutions (this definition includes heat networks, bioenergy and peat) to be installed in new builds. Therefore, over time the percentage of dwellings with gas or oil boilers is expected to decrease.
Since 2016 in order to track the improved efficiency of gas and oil boilers associated with the rising standards of the regulatory framework the SHCS records the age of the household's heating system and contains sufficient data to derive the Seasonal Efficiency (SEDBUK) ratings of surveyed boilers. Further details can be found in section 1.4 of the Methodological and Technical notes.
Previous key findings reports assessed boiler efficiency against the minimum requirements set from 2007. These were: a minimum efficiency of 88% for condensing standard gas, oil and LPG boilers; for condensing combination boilers, 86% for oil, and 88% for gas and LPG; for ranges, back boiler and combined primary storage units (CPSUs), 75% when gas, and 80% when oil[3].
However, from the 2024 wave of the survey boiler efficiency is measured against the new standards which took effect in February 2023. These are: 92% for condensing standard or combination gas boilers (including LPG). 91% for oil condensing standard boilers, and 86% for oil condensing combination boilers. For ranges, back boiler and combined primary storage units (CPSUs) the efficiency standards have remained, 75% when gas, and 80% when oil.
Due to the change in efficiency standards there has been a large decrease in the number of dwellings with boilers which meet the current efficiency standards. This is due to the fact that the SHCS will only capture a small number of dwellings with new boilers each year and as such most dwellings in the achieved sample of the survey will have had their boilers installed under the previous building standards, set in 2007, which had less stringent efficiency criteria. In order to allow comparisons to previous years we have produced two estimates, one for the current standard and one for the previous standard.
4% of gas and oil boilers met the minimum efficiencies specified by the current Building Standards, in 2024.
Figure 2.6: Gas and oil boiler types, 2012 to 2024[4].
Description of Figure 2.6
In 2024 the survey found that 96% of the domestic gas and oil boilers in Scotland have been installed since 1998, when the European Boiler Efficiency Directive minimum standards came into effect. The proportion of new boilers, those installed since 1998, has increased by around 15 percentage points since 2012. In 2024, 90% of gas and oil boilers were condensing boilers. This represents an increase of 52 percentage points since 2012.
Under the new building standards only 4% of dwellings meet the current boiler efficiency standards. This will increase over time, as the new boiler efficiency standards only apply to new or replacement boilers. Under the previous standards, set in 2007, around 84% of gas and oil boilers met the minimum efficiencies, an increase over the 2023 figure of 79%[5].
Data Source: Table EE5a in ‘SHCS 2024 - Chapter 02 Energy Efficiency- tables and figures’.
2.3 Energy Performance Certificates
Key Points
- In 2024, 56% of Scottish homes were rated as EPC band C or better under SAP 2012 (RdSAP v9.93), with around 10% of properties rated in the lowest EPC bands (E, F or G).
- Under SAP 2009, which allows for comparisons over a longer period, 62% of dwellings were rated C or better, up 38 percentage points since 2010. In the same period, the proportion of properties in the lowest EPC bands (E, F or G) has reduced from 27% in 2010 to 8% in 2024.
- Under SAP 2012 v9.93, the median EE rating in 2024 was 70, which is equivalent to Band C. This is an increase from 67 in 2018 which is equivalent to band D.
Energy Performance Certificates (EPC) were introduced in January 2009 under the requirements of the EU Energy Performance Building Directive (EPBD). They provide energy efficiency and environmental impact ratings for buildings based on standardised energy usage. EPCs are required when a property is either sold or rented to a new tenant.
EPCs are generated through the use of a standard calculation methodology, known as Standard Assessment Procedure (SAP). SAP is the UK Government approved way of assessing the energy performance of a dwelling, taking into account the energy needed for space and water heating, ventilation and lighting and, where relevant, energy generated by renewables.
The Energy Efficiency Rating (EER) is expressed on a scale of 1-100 where a dwelling with a rating of 1 will have very poor energy efficiency and higher fuel bills, while 100 represents very high energy efficiency and lower fuel bills. Ratings can exceed 100 where the dwelling generates more energy than it uses.
Ratings are adjusted for floor area so that they are essentially independent of dwelling size for a given built form.
For Energy Performance Certificates, EERs are presented over 7 bands, labelled A to G. Band A represents low energy cost and high energy efficiency, while band G denotes high energy cost (and low energy efficiency).
Energy Efficiency Ratings reported in this publication are calculated under two versions of SAP, the SAP 2009 methodology and the SAP 2012 methodology. Using SAP 2009 enables us to examine the trend in the energy efficiency of the housing stock since 2010.
Trends for EPC and EER ratings under SAP 2009 are presented in the excel tables available at ‘SHCS 2024 - Chapter 02 Energy Efficiency- tables and figures’ in infographic EE1, Table EE7A and B, and Figure EE8.
SAP is periodically reviewed by the UK government to ensure it remains fit for purpose and to address its continued application across an increasing range of carbon and energy reduction policy areas. SAP is used for assessment of new buildings whilst a ‘reduced data’ version of the methodology, RdSAP, is applied to the assessment of existing buildings.
SHCS energy modelling for SAP 2012 in this report is based on RdSAP (v9.93). The RdSAP (v9.93) was released on 19 November 2017 and contains revisions to the underlying assumptions used within the SAP calculations. The most notable update to the methodology in v9.93 was a change to the default U-values of cavity, solid and stone walls, built prior to 1976. Compared to v9.92, U-values for solid, insulated stone and uninsulated cavity walls have improved, whereas they have declined for insulated cavity walls.These U-values are used to calculate the rate of heat loss through the walls, which contributes to the overall thermal performance of the building fabric of the dwelling. Data on the basis of RdSAP v9.93 is presented from 2018.
2.3.1 Energy Efficiency Rating, SAP 2012
This section examines the energy efficiency profile of the Scottish housing stock under the SAP 2012 methodology (RdSAP v9.93) with time series analysis is presented from 2018. Further breakdowns by household and dwelling characteristics for 2024 are also presented.
The Scottish housing stock is gradually becoming more energy efficient.
Infographic 2.1: Mean and median EER relative to EPC bands, SAP 2012, 2018-2024 .
Description of Infographic 2.1
In 2024, the mean energy efficiency rating of the Scottish housing stock under SAP 2012 (RdSAP v9.93) was 68.1 and the median was 70 points. The mean rating is similar to the 2023 figure, however there was an increase between 2022 and 2024, from 66.6 to 68.1.
Data Source: Table EE6 in ‘SHCS 2024 - Chapter 02 Energy Efficiency- tables and figures’.
Scottish housing is gradually moving up through the EPC bands.
Figure 2.7: Distribution of the Scottish Housing Stock by EPC Band, SAP 2012, 2018-2024
Description of Figure 2.7
Figure 2.7 shows that 56% of all properties in 2024 were rated C or better under SAP 2012 (RdSAP v9.93) similar to 2023 but an increase of around 13 percentage points from 2018. 10% of properties in 2024 were in bands E, F or G.
Data Source: Table EE7a in ‘SHCS 2024 - Chapter 02 Energy Efficiency- tables and figures’
Notes: [note 5]
Housing in the social sector tends to be more energy efficient than the owner occupied or private rented sector.
Figure 2.8: Percentage of dwellings by EPC band and tenure in 2024 .
Description of Figure 2.8
As shown in Figure 2.8, 71% of social housing is in band C or better under SAP 2012 (RdSAP v9.93). Higher than both the private rented sector at 50% and the owner-occupied sector at 52%. Around 2% of dwellings in the social sector are within EPC bands E, F or G, while 12% of owner-occupied dwellings and 14% of the private rented sector are within these EPC bands. These differences could be driven by the Scottish Housing Quality Standard (SHQS) and the Energy Efficiency Standard for Social Housing (EESSH) which introduced minimum energy efficiency levels for the social sector.
Data Source: Table EE8a in ‘SHCS 2024 - Chapter 02 Energy Efficiency- tables and figures’.
Across Scotland, 2% of properties were in bands F or G in 2024.
Figure 2.9: Proportion of homes in EPC Band F or G by dwelling and household characteristics, SAP 2012 v9.93.
Description of Figure 2.9
Figure 2.9 shows that dwellings in the lowest energy efficiency bands (F and G) are more likely to be older pre-1919 dwellings (9%), non-gas heated properties (12% for electric, 9% for oil and 11% for other fuels), detached properties (5%), off gas grid properties (14%), and in rural areas (10%). Across Scotland as a whole, 2% of properties were in bands F or G in 2024.
Data Source: Table EE9 and EE10 in ‘SHCS 2024 - Chapter 02 Energy Efficiency- tables and figures’.
For sample sizes and corresponding values for EPC Bands ABC and DE, as well mean EPC ratings , please see Tables EE9 and EE10 in ‘SHCS 2024 - Chapter 02 Energy Efficiency- tables and figures’.
There is a strong association between tenure and mean energy efficiency rating.
Mean SAP 2012 (RdSAP v9.93) ratings ranged from 65.8 in dwellings owned outright to 73.5 in housing association dwellings, a statistically significant difference. Furthermore, social housing as a whole is more energy efficient than the private sector, with a mean EER of 71.8 compared to 66.9 for private dwellings.
Older households (66.8) have lower average EER ratings than families (70) and other (adults without children) households (68.3). For sample sizes and corresponding values for EPC bands DE and FG, please see Table EE9 in ‘SHCS 2024 - Chapter 02 Energy Efficiency- tables and figures’.
There is a strong association between dwelling characteristics and energy efficiency rating.
Table 2.3 shows that across dwelling types, detached properties and semi-detached properties have the lowest energy efficiency ratings on average (mean EER 65.6 and 66.1) while flats have the highest ratings (71.6 for tenements and 69.6 for other flats).
The oldest, pre-1919, properties are the least energy efficient (mean EER of 59.3 and 23% rated C or better) while those built after 1982 have the highest energy efficiency ratings (mean EER of 74.9, with 85% in band C or better).
Primary heating fuel is a key determinant of the energy efficiency rating of the dwelling. Properties heated by mains gas have an average EER rating of 70 and 61% are in band C or better. Dwellings heated by other fuels (including electricity and oil) have considerably lower ratings by comparison. The average energy efficiency rating for oil heated properties is 55.8 (corresponding to EPC band D) and only 15% are in band C or better. For electrically heated dwellings the average energy efficiency rating was 60.5 with 37% in band C or better.
Proximity to the gas grid has a similar effect on the energy efficiency rating. Dwellings on the gas grid have an average SAP rating of 69.7, higher than the average SAP rating of 56.3 for off grid dwellings.
As dwelling characteristics associated with lower energy efficiency are disproportionately represented in rural areas, the average energy efficiency profile of rural properties is lower than that for urban areas. Table 2.3 shows that the mean SAP 2012 (RdSAP v9.93) rating is 69.5 for dwellings in urban areas with 60% in band C or above. This is higher than the mean rating of 61.4 for dwellings in rural areas, where 38% of dwellings are in band C or better.
For sample sizes and corresponding values for EPC bands DE and FG, please see Table EE10 in ‘SHCS 2024 - Chapter 02 Energy Efficiency- tables and figures’.
2.4 Carbon Emissions
Key Points
- Based on the modelled energy use required to meet the SAP standard heating regime[6], the average Scottish home was estimated to produce 6.3 tonnes of carbon dioxide (CO2) per year in 2024, which is more than double the average carbon emissions per household as reported by Department for Energy Security and Net Zero (2.8 tonnes per year) in 2023, based on actual energy use. This suggests that households are not heating their homes to the SAP standard heating regime.
- Average modelled carbon emissions for all properties were 66 kg per square meter of floor area in 2024.
Carbon Emissions are the amount of greenhouse gas emissions, expressed as their carbon dioxide gas equivalent, vented to the atmosphere. Estimates of emissions from the residential sector which take into account actual energy consumption by households are reported annually by Department for Energy Security and Net Zero in the Local and Regional Carbon Dioxide (CO2) Emissions Estimates. This methodology is consistent with the Greenhouse Gas Inventory (GHGI) which is the source for monitoring progress against the Scottish Government’s climate change commitments.
In contrast, emissions reported from the SHCS are modelled on the assumption of a standard pattern of domestic energy consumption and do not reflect differences in consumption behaviour due to cost, preferences or changes in weather conditions. As such, they are distinct from the carbon emissions figures published by Department for Energy Security and Net Zero and compiled in GHG inventories.
Estimates in Scotland's Climate Change Plan are also not comparable to SHCS estimates. These figures for the residential sector relate to non-traded emissions only (i.e. exclude electricity which is covered by the UK Emissions Trading System) while SHCS estimates cover all fuel types.
This report is only concerned with the level and variations in modelled emissions from the Scottish housing stock. These estimates are produced through the use of BREDEM 2012-based models, in line with other statistics on energy efficiency and fuel poverty reported here. Information on the energy modelling is available in section 1.3 of the Methodological and Technical notes.
To derive emissions estimates, modelled energy demand is combined with carbon intensity factors as adopted for the 2012 edition of the SAP (see section 1.3 of the Methodological and Technical notes). These are carbon dioxide (CO2) equivalent figures which include the global warming impact of methane (CH4) and nitrous oxide (N2O) as well as carbon dioxide (CO2).
2.4.1 Modelled Emissions by Dwelling Type and Age of Construction
The annual modelled emissions from a property reflect the energy use for the whole dwelling heated according to the SAP standard heating regime[7].
Newer dwellings have lower modelled emissions than older ones.
Table 2.4 shows that on average newer dwellings have lower modelled emissions than older ones, likely as a result of their better thermal performance and higher energy efficiency (as shown in section 2.3). Post-1982 tenement and other flats have the lowest modelled emissions on average (3.1 and 3.0 tonnes per year, respectively).
Across all age bands, detached houses have the highest modelled emissions (between 17.3 tonnes per year for pre-1919 dwellings to 7.5 tonnes per year for post-1982 dwellings). As shown in section 1.3 of this report, they are also the most likely to use high carbon-intensity fuels, such as oil, in place of mains gas.
For more information, please see Table EE12 in ‘SHCS 2024 - Chapter 02 Energy Efficiency- tables and figures’.
Older dwellings have higher modelled carbon emissions per square meter of floor area.
Older dwellings tend to be larger, thus generally having greater heat requirements and energy use (see section 1.2). When analysing emissions we control for this by dividing modelled emissions by total internal floor area, to derive carbon dioxide (CO2) emissions per square meter (kg/m2). Controlling for floor area in this way (Table 2.5) shows that in general older dwellings have higher emissions per square meter than newer dwellings of equivalent type, as well as higher emissions overall. For example, pre-1919 detached houses have the higher modelled emissions per square meter (100 kg/m²) than detached 1919-1982 dwellings (70 kg/m²) and post 1982 detached dwellings (52 kg/m²). Post-1982 dwellings have the lowest emissions of any age band.
For more information, please see Table EE12 in ‘SHCS 2024 - Chapter 02 Energy Efficiency- tables and figures’..
2.4.2 Modelled Emissions by Tenure
Average modelled carbon emissions per m2 have reduced from 73 kg/m2 in 2018 to 66 kg/m2 in 2024, showing a long term trend of reducing emission from the Scottish housing stock.
Private rented sector dwellings have higher overall modelled carbon emissions than other tenure types.
Figure 2.10: Average modelled emissions by tenure, 2018 to 2024.
Description of figure 2.10
Figure 2.10 shows how emissions differ across tenure for the period 2018 to 2024. In 2024, the highest emissions were observed for private rented sector dwellings (77 kg/m2) with housing association dwellings (58 kg/m2) having the lowest. Modelled emissions were similar to the previous year across all tenures with the exception of local authority managed dwellings which reduced from 68.8 kg/m2 to 64 kg/m2. However, the longer time series shows a decreasing trend over the 2018-2024 period for all tenures.
Changes to the energy modelling methodology mean that figures for 2018 to 2024 by tenure are not fully comparable to earlier years[8].
Differences that were statistically significant were seen in all sectors when looking at the longer time series between 2018 and 2024 with the exception of the PRS. The largest reductions were found in owner occupied dwellings, reducing from 75 kg/m2 to 67 kg/m2, housing association dwellings reducing from 66 kg/m2 to 58 kg/m2 and in local authority dwellings which reduced from 73 kg/m2 to 64 kg/m2.
Data Source: Table EE13 in ‘SHCS 2024 - Chapter 02 Energy Efficiency- tables and figures’.
2.5 Environmental Impact Rating
The Environmental Impact Rating (EIR) represents the environmental impact of a dwelling in terms of carbon emissions associated with fuels used for heating, hot water, lighting and ventilation. Ratings are adjusted for floor area, so they are independent of dwelling size for a given built form. Emissions for this measure are calculated using the SAP methodology.
EIRs for this report are based on SAP 2012 under RdSAP v9.93.
The Environmental Impact Rating (EIR) of Scottish dwellings has gradually increased over time.
Infographic 2.2: Median EIR relative to Band, 2018 to 2024.
Description of infographic 2.2
In 2024, the mean EIR rating was 65 and the median was 67, both of which fall into band D. Infographic 2.2 illustrates the increasing trend in the mean and median EIR between 2018 and 2024. This indicates that the environmental impact of Scottish housing is gradually falling over time but has remained within band D.
Data Source: Table EE14a in ‘SHCS 2024 - Chapter 02 Energy Efficiency- tables and figures’.
In 2024, 44% of dwellings had an EIR of band C or above.
Figure 2.11: EIR Bands in the Scottish Housing Stock, 2018 – 2024, SAP 2012.
Description of figure 2.11
As shown in figure 2.11, 44% of dwellings had EI ratings in band C or better under SAP 2012 (RdSAP v9.93) in 2024 an improvement on the 2022 figure of 40%. In 2024 19% of dwellings were rated E, F or G in terms of their environmental impact, similar to the 2023 rate of 20% but lower than 2022 rate of 23%.
Data Source: Table EE15 in ‘SHCS 2024 - Chapter 02 Energy Efficiency- tables and figures’.
Environmental Impact Ratings (EIRs) vary across different type of dwellings.
Dwellings built post-1982 have (higher) better EIRs than other dwellings, with 74% rated band C or better. Flats have a lower environmental impact (higher EIR) than houses, as do gas heated properties compared to those heating using oil or electricity.
Oil heating systems and houses are more common in rural areas, leading to higher environmental impacts (lower EIRs) for rural dwellings. Dwellings on the gas grid have better EIRs than dwellings off the gas grid, with 47% of dwellings on the gas grid rated band C or better compared to 20% for dwellings off the gas grid.
This is likely due to gas having a lower emissions factor (0.216 kg of carbon dioxide per kilowatt hour) than electricity (0.519) in the underlying SAP methodology used in this report. See table 1.5 in the Technical and Methodological notes for a full list of emissions factors used.
For sample sizes and corresponding EIR bands DE and FG, please see Table EE15 in ‘SHCS 2024 - Chapter 02 Energy Efficiency- tables and figures’.
[1] Dwellings without loft spaces are excluded from this analysis. A dwelling is classified as ‘not applicable’ for loft insulation if it has a flat roof or another dwelling above it (i.e. it is a mid- or ground-floor flat). Furthermore, in some instances dwellings with lofts cannot provide access to the surveyor (such as incidences with a locked hatch). These dwellings are also excluded from this analysis on depth of loft insulation, and therefore the count of applicable dwellings may vary each year. However, these dwellings are given the default appropriate Scottish Building Regulation standard of loft insulation for dwellings of the relevant age when modelling energy consumption.
[2] This design has higher running efficiencies; a portion of the heat that would be lost through vented water vapour is recovered through condensation in a heat exchanger.
[3] For existing dwellings, there are occasions where it may not be practical to install a condensing boiler. The Condensing Boiler Installation Assessment Procedure Guide offers further guidance in this area. Where a non-condensing boiler is installed this may result in a boiler with poorer efficiency than that of a newly installed condensing boiler of the same fuel type.
[4] The new boiler efficiency standards only apply to new or replacement boilers.
[5] See section 1.4 of the Technical and Methodological notes for previous boiler efficiency standards.
[6] The standard heating regime is: 21°C in the living room and 18°C in other rooms for 9 hours a day during the week and 16 hours a day during the weekend. See section 3.1 for a breakdown of the 4 heating regimes used to measure fuel poverty in the SHCS.
[7] The standard heating regime is: 21°C in the living room and 18°C in other rooms for 9 hours a day during the week and 16 hours a day during the weekend.
[8] Although broadly comparable emissions pre 2018 were calculated based on SAP 2012v9.92 while those post 2018 are calculated using SAP 2012 v9.93. See section 1.3 of the methodology notes for full details.