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Publication - Research and analysis

Building regulations - new domestic buildings: identification and assessment of energy standard improvements

Published
24 July 2026
Directorate
Local Government and Housing Directorate
Topic
Building, planning and design, Energy
ISBN
9781836913122

Technical analysis to consider the implications of modelling method, dwelling specification and heating technology up key regulated metrics and costs to both the developer and occupier, to represent the emerging building stock in Scotland.

Part of

View supporting documents Supporting documents

Appendix B Proposed Specification Options

Table 21 2023 Notional Specification for reference to proposed scenarios
Element / System Unit Reference EPC Data (Mean)

2023 Notional

ASHP

2023 Notional

DE

2023 Notional

DHN
External Wall U-value [W/m2.K] 0.20 0.15 0.15 0.15
Floor U-value [W/m2.K] 0.15 0.12 0.12 0.12
Roof U-value [W/m2.K] 0.12 0.09 0.09 0.09
Window U-value [W/m2.K] 1.40 1.2 1.2 1.2
Air Tightness [m3/h/m2@ 50pa] 4.60 5 5 5
Heating efficiency [%] 93% 250% 93% Same as Actual
Water efficiency [%] 87% 250% 87% Same as Actual
Standing Loss [kWh/d] -

DE: 1.80 (230 litres)

MT / ET: 1.70 (210 litres)

SF: 1.39 (150 litres)

LF: 1.60 (190 litres)

DE: 1.70 (210 litres)

MT /ET: 1.55 (180 litres)

SF: 1.39 (150 litres)

LF: 1.22 (120 litres)

 N/A
SFP (SAP) [W/l/s] - N/A N/A N/A
HR [%] - N/A N/A N/A
Lighting efficacy [lm/W] - 80 80 80
PV [Wp/m2] 20.8 0

DE: 31.04

MT/ET: 30.78

SF: 15.38

LF: 15.46

DE: 31.04

MT/ET: 30.78

SF: 15.38

LF: 15.46
PV area relative to ground floor (per SAP 10.2) [%] - 0 40 40
PV panel efficiency [m2/kWp] - N/A 6.5 6.5
WWHR [%] - N/A N/A N/A
Table 22 ‘Business as Usual’ Specification
Element / System Unit Reference EPC Data (Mean)

BAU

ASHP

BAU

DE

BAU

DHN
External Wall U-value [W/m2.K] 0.20 0.17 0.17 0.17
Floor U-value [W/m2.K] 0.15 0.15 0.15 0.15
Roof U-value [W/m2.K] 0.12 0.11 0.11 0.11
Window U-value [W/m2.K] 1.40 1.4 1.4 1.4
Air Tightness [m3/h/m2@50pa] 4.60 4.6 4.6 4.6
Heating efficiency [%] 93%

DE: 323%*

MT / ET: 345%*

SF: 291%*

LF: 336%*

 100%

93% (10% gas boiler)

250% (90% electric HP)
Water efficiency [%] 87%

DE: 223%*

MT / ET: 227%*

SF: 218%*

LF: 218%*

 100% As above
Standing Loss [kWh/d] -

From integrated HIU

DE: 1.80 (230 litres)

MT / ET: 1.50 (210 litres)

SF: 1.25 (150 litres)

LF: 1.45 (190 litres)

ErP B

DE: 1.50 (210 litres)

MT /ET: 1.42 (180 litres)

SF: 1.25 (150 litres)

LF: 1.34 (120 litres)

 1.44 (Indirect HIU – SAP Default)
SFP (SAP) [W/l/s] - 0.15 0.15 0.15
HR [%] - N/A N/A N/A
Lighting efficacy [lm/W] - 80 80 80
PV [Wp/m2] 20.8 0

DE: 31.04

MT/ET: 30.78

SF: 15.38

LF: 15.46

DE: 23.28

MT/ET: 23.09

SF: 11.54

LF: 11.59
PV area relative to ground floor (per SAP 10.2) [%] - 0 40 30
PV panel efficiency [m2/kWp] - N/A 6.5 6.5
WWHR [%] - N/A N/A N/A
Table 23 ‘Good Practice’ Specification
Element / System Unit Reference EPC Data (Mean)

Good

ASHP

Good

DE

Good

DHN
External Wall U-value [W/m2.K] 0.20 0.15 0.15 0.15
Floor U-value [W/m2.K] 0.15 0.11 0.11 0.11
Roof U-value [W/m2.K] 0.12 0.11 0.11 0.11
Window U-value [W/m2.K] 1.40 1.2 1.2 1.2
Air Tightness [m3/h/m2@50pa] 4.60 3 3 3
Heating efficiency [%] 93%

DE: 323%*

MT / ET: 345%*

SF: 291%*

LF: 336%*

 100%

93% (10% gas boiler)

250% (90% electric HP)
Water efficiency [%] 87%

DE: 223%*

MT / ET: 227%*

SF: 218%*

LF: 218%*

 100% As above
Standing Loss [kWh/d] -

From integrated HWC

DE: 1.80 (230 litres)

MT / ET: 1.50 (210 litres)

SF: 1.25 (150 litres)

LF: 1.45 (190 litres)

ErP A

DE: 1.07 (210 litres)

MT /ET: 1.02 (180 litres)

SF: 0.90 (150 litres)

LF: 0.96 (120 litres)

 1.00 (Indirect HIU – CIBSE CP1)
SFP (SAP) [W/l/s] - 0.15 0.15 0.15
HR [%] - N/A N/A N/A
Lighting efficacy [lm/W] - 100 100 100
PV [Wp/m2] 20.8 0

DE: 44.83

MT/ET: 44.46

SF: 22.22

LF: 22.33

DE: 33.62

MT/ET: 33.35

SF: 16.67

LF: 16.67
PV area relative to ground floor (per SAP 10.2) [%] - 0 40 30
PV panel efficiency [m2/kWp] - N/A 4.5 4.5
WWHR [%] - N/A 58 58
Table 24 ‘Best Practice’ Specification
Element / System Unit Reference EPC Data (Mean)

Best

ASHP

Best

DE

Best

DHN
External Wall U-value [W/m2.K] 0.20 0.12 0.12 0.12
Floor U-value [W/m2.K] 0.15 0.1 0.1 0.1
Roof U-value [W/m2.K] 0.12 0.1 0.1 0.1
Window U-value [W/m2.K] 1.40 0.8 0.8 0.8
Air Tightness [m3/h/m2@50pa] 4.60 1.5 1.5 1.5
Heating efficiency [%] 93%

DE: 323%*

MT / ET: 345%*

SF: 291%*

LF: 336%*

 100%

93% (10% gas boiler)

250% (90% electric HP)
Water efficiency [%] 87%

DE: 223%*

MT / ET: 227%*

SF: 218%*

LF: 218%*

 100% As above
Standing Loss [kWh/d] -

From integrated HWC

DE: 1.80 (230 litres)

MT / ET: 1.50 (210 litres)

SF: 1.25 (150 litres)

LF: 1.45 (190 litres)

ErP A

DE: 1.07 (210 litres)

MT /ET: 1.02 (180 litres)

SF: 0.90 (150 litres)

LF: 0.96 (120 litres)

 1.00 (Indirect HIU – CIBSE CP1)
SFP (SAP) [W/l/s] -

DE: 1.19

MT/ET: 0.95

SF: 0.61

LF: 0.74

DE: 1.19

MT/ET: 0.95

SF: 0.61

LF: 0.74

DE: 1.19

MT/ET: 0.95

SF: 0.61

LF: 0.74
HR [%] - 90 90 90
Lighting efficacy [lm/W] - 120 120 120
PV [Wp/m2] 20.8

DE: 22.41

MT/ET: 22.23

SF: 11.11

LF: 11.16

DE: 44.83

MT/ET: 44.46

SF: 22.22

LF: 22.33

DE: 33.62

MT/ET: 33.35

SF: 16.67

LF: 16.67
PV area relative to ground floor (per SAP 10.2) [%] - 20 40 30
PV panel efficiency [m2/kWp] - 4.5 4.5 4.5
WWHR [%] - N/A 58 58

Contact

Email: buildingstandards@gov.scot

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