Potential heat network zones: first national assessment
Analysis to identify and characterise potential zones for heat networks in Scotland. It provides further detail on the analysis criteria, assessment methodology, limitations, definitions and the interpretation of the outputs.
4 Summary analysis – Baseline criteria
This Section details the key trends and outputs from the First National Assessment of Potential Heat Network Zones using the Baseline screening criteria (a linear heat density of 4,000 kWh/m/yr and at least two anchor loads). This is not an exhaustive analysis and is focused at the national level primarily.
4.1 Characterisation of demands - Baseline
The Baseline screening criteria identifies 647 potential heat network zones (712 if split by local authority boundaries). These cover 44,426 Ha with approximately 25.7 TWh of heat demand within potential heat network zones (55% or 14.1 TWh/yr comes from anchor loads – some of which are likely to already be connected to heat networks). This is approximately 32% of the Scottish total of approximately 79 TWh/yr heat demand in 2020 (this value is a national figure from a different source; the total for the Scotland Heat Map is 62 TWh/yr, differences are due in part to factors like consideration of process heat being greater in the national data rather than point level data in the Scotland Heat Map). However, it should be noted that whilst a property falls within a potential zone it may not be viable for connection; this demand total is merely to establish the upper band of demand within potential zones to consider.
421,000 different demand properties fall within these Baseline potential zones, with 18% being non-domestic and the remaining 81% domestic, the remaining 1% was unattributed loads. A breakdown of these 340,000 domestic properties by tenure is provided in Figure 4—1.
Owner occupied is the largest overall share of properties falling within the Baseline potential zones at 61%, matching the national percentage of properties for this tenure. The private rented sector averages 13% of properties nationally, and 16% of domestic properties that fall within potential heat network zones are of this tenure. This is significant as the private rented sector has historically been perceived as the hardest to engage with in regard to uptake of low carbon technology.
Domestic demand by tenure broadly matches the split seen by property count. Local authority ownership makes up 9.4% of domestic heat demand (667 GWh/yr), housing association 10.2% of domestic heat demand (725 GWh/yr), owner occupied 62.4% of domestic demand (4,447 GWh/yr) and privately rented the remaining 18% (1,279 GWh/yr).
Although making up the vast majority of the property counts for Baseline potential zones, domestic properties falling within potential zones only make up approximately 28% (7.1 TWh) of the heat demand share. This is lower than the 43% share of national heat demand, with the lower proportion due to residential areas being far away from major anchor loads and thus falling outside the buffers around the anchor loads that define potential zones.
The 74,000 non-domestic heat demands that fall within Baseline potential heat network zones make up the remaining 69% approximately (17.6 TWh) of heat demand falling within potential zones (domestic and non-domestic load percentage do not add up to 100 due to the Scotland Heat Map data not aligning precisely to the detailed domestic and non-domestic datasets) and have been characterised by building size (using floor area). The breakdown of these in terms of property count by floor area category is provided in Figure 4—2.
Although relatively low in count (9,471), the largest non-domestic buildings (by floor area, > 1000 m2) do have a large share (65.7%) of the total non-domestic demand relating to 11,589 GWh/yr (see Figure 4—3).
The relatively high proportion of these large buildings is to be expected, as by being larger they will tend to have a higher heat demand. Furthermore, this larger demand means they are more likely to be anchor loads and thus have a greater likelihood of being within a potential heat network zone.
In some situations, buildings will contain multiple properties, which can be a mix of domestic and non-domestic, multiple types of non-domestic use and multiple domestic tenure types. In these instances, there will be specific considerations and opportunities in connecting a building to a heat network. At a national level there are approximately 106,000 (25%) such properties within potential heat network zones identified with the Baseline criteria, with a total heat demand of 7 TWh or approximately 28% of the total demand identified within Baseline potential heat network zones.
95,000 properties (23%) within Baseline potential heat network zones have some form of heritage designation (within the heritage property section of this methodology, the three groups of building designation are considered: listed buildings, within a conservation area, and within a world heritage site), these have a total demand of approximately 6.5 TWh or 25% of total demand identified within Baseline potential heat network zones. Properties built pre-1919, which can act as a proxy for heritage buildings without designation, make up approximately 8.5 TWh (approximately 3 TWh domestic and 5.5 TWh non-domestic) of heat demand within potential zones from 127,000 total properties (approximately 69% of which are domestic). It should be noted that there will be properties which are counted both within the designated heritage status measures and the pre-1919 heritage building proxy, so these values should not be aggregated.
In some instances, potential heat network zones fall within multiple local authority boundaries. In such cases, to realise the maximum potential of these opportunities, local authorities will need to coordinate consideration of these. Such cross-boundary potential zones would not be identified if a local authority were to carry out this analysis, as the national data would not be available. A total of 30 potential zones fall within two or more local authority areas with the Baseline criteria. This is approximately 4% of the total potential heat network zones identified.
The final characteristic considered is fuel poverty. This can add considerable sensitivity to how a potential heat network is taken forward. Within the potential heat network zones identified at the Baseline criteria, an estimate of 26.1% of total domestic properties are households in fuel poverty (approximately 91 thousand households and 1,400 GWh/yr heat demand) and 12.7% of households in extreme fuel poverty (approximately 44 thousand households and 800 GWh/yr heat demand).
4.2 Characterisation of geographic distribution - Baseline
Potential heat network zones are focused, as would be expected, in the more urban areas of Scotland – especially within the central belt. This is shown in Figure 4—4, which maps the potential heat network zones identified across Scotland, a full A3 version of this image can be found in the map pack (under the map ID Nat-1B).
In analysis of the central belt area, it contained approximately 68% of the national demand in potential heat network zones identified using the Baseline criteria, despite covering only approximately 9% of the land mass of Scotland.
Other than the central belt there is a general focus of potential zones being around the coastline, matching the general trend for urban development in such areas. It should be emphasised at this point that some demands are not captured within the Scotland Heat Map (e.g. process heat loads) or are very isolated from other demands. This can result in some areas where you would expect to see a potential zone not being flagged. In these instances when local authorities review their own opportunities local knowledge will be key to overcoming such information gaps.
These point-based heat network zones can be attributed to the different local authority areas within Scotland, as presented in Figure 4—5 (see map ID Nat-2B in the map pack).
Figure 4—5 highlights that rural areas without large towns and cities often have less heat network potential, notably local authority areas which are entirely made up of islands. These island areas tend to have far lower populations so the total demand available for potential heat network zones will be lower.
A more detailed analysis is also possible, with demands being reported in the context of their rural/urban classification. The breakdown of demands for heat network zones according to the Baseline classification is shown in Figure 4—6.
The influence of being in a more urban area is large for both domestic and non-domestic properties but greater for domestic than non-domestic properties. This is in part due to potential heat network zones being identified using a linear heat density approach. This means that larger demands (which will more often be non-domestic) determine the extent of potential heat network zones and thus fall within them, this will have a greater impact on percentage of demand share in more sparsely developed areas.
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