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Solar thermal verification against MCS 024 and SAP

Fixed worked examples run through MEPCalc's solar thermal calculation, compared line by line with the MCS 024:2025 performance estimate method and its printed tables, with the SAP 2012 Appendix H worksheet lines it is built on, with the standard's own Appendix B fuel-saving examples, and with hand-worked SAP 10.3 Appendix H monthly worksheets for the SAP-led method.

Result
54 of 54 checks pass
Cases
13 worked examples
Version / published
v1.0 · 2026-09-28
Engine fingerprint
df84f8eefac9

Why we publish this

MCS 024:2025 is the estimate an MCS installer must give the customer before the contract for a solar thermal system. It runs the SAP 2012 Appendix H annual worksheet with the standard's own inputs: an occupancy N from the residents (or from the floor area by SAP 2012 Table 1b when unknown, capped at 6), a daily hot water demand of 25N + 36 litres, an energy content of 4.190 × Vd × 365 × 37 ÷ 3600, a solar-to-load ratio that adds the cylinder loss C and the hot water use factors h1 and h2 to the load, and the EN 12976 collector defaults where no test certificate exists. The annual solar input Qs is then divided by the back-up heater's solar efficiency factor A1 from Appendix A to give the fuel saving.

Every line of the MCS case below was derived by hand from the printed method, with the working shown, so the check is against the standard rather than against the calculation code itself. The solar radiation S on those cases is the SAP Appendix U figure already derived by hand on the PV verification page (region 0, south, 35°: 1081.4 kWh/m²). MCS 024 prints the cylinder loss C at six volumes; between them MEPCalc reads it linearly, as the MCS SPE calculator tool does, and the one case that needs an in-between volume says so. MEPCalc follows the MCS documents as published; it does not claim MCS certification or compliance.

The SAP 10.3 Appendix H monthly method runs alongside as the other estimate. Its three cases are hand-worked worksheets (H1) to (H24) with the June working shown, on the calculator's own daily-litres demand.

What these calculations do not model

  • Other irradiance sources. The calculation can also take a weather-station dataset or a manually entered annual radiation on the SAP-led method. Neither is a SAP or MCS value, and the MCS estimate is not offered on those paths, so only the Appendix U path appears above.
  • The monthly split of the MCS figure. MCS 024 is an annual estimate. The calculator splits it across the year by each month's share of the Appendix U radiation (SAP 2012 equation (H2)) for the chart only; those monthly figures are not asserted here.
  • Space heating. Both methods are hot water only (SAP 10.3 (H18) = 1, (H19) = 0). Solar contribution to space heating is not modelled.
  • Storage defaults. When no cylinder volume is entered the calculator assumes the MIS 3001 recommendation plus one day's demand and says so under Assumptions. Every case above enters its volumes.
  • Additional estimates. MCS 024 allows an estimate by another method alongside its own, provided it is not given greater prominence. The SAP 10.3 figure shown for comparison is that additional estimate; it is not part of the MCS method and is not asserted against MCS 024.

How to read the tables

  • Expected is the value printed in the standard, or a hand calculation from printed values. The working is shown under each quantity.
  • Tolerance is exact for tabulated values and selected sizes, and ±2 % for calculated quantities such as the energy content of hot water, the collector and storage factors, the solar-to-load ratio, the annual solar input to the cylinder, the fuel saving, and the SAP 10.3 annual solar heat.
  • Every check re-runs automatically whenever the calculation code changes, and this page is regenerated from those results. The engine fingerprint above identifies the calculation code the results came from.

Sources

  • MCS 024:2025 Issue 1.0 (01/01/2025), Solar Heating Performance Estimate
  • MCS Technical Note: Calculation for Solar Thermal Total Installed Capacity v1.1
  • SAP 10.3 (13-01-2026), The Government's Standard Assessment Procedure, Appendix H
  • SAP 2012 version 9.92 (October 2013), Appendix H and Table 1b

Printed page numbers refer to the editions above.

Worked examples

ST-01

MCS 024 §2 estimate — 4 m² flat plate, 3 residents, 200 L cylinder, condensing gas boiler

Inputs

  • 4 m² flat plate glazed collector, MCS 024 §2 (f) defaults η0 0.75, a1 6.0 W/m²K, a2 0.016 W/m²K²
  • South-facing at 35°, SAP region 0 (UK average): S = 1081.4 kWh/m² (the PV page's hand-derived Appendix U figure)
  • 3 full-time residents; both electric and non-electric showers; not a water-efficient dwelling
  • 200 L twin-coil cylinder, 100 L dedicated to solar; no overshading
  • Back-up heater: gas system boiler, post 1998, condensing (A1 0.768)

The whole MCS 024 worksheet on one case, each line derived by hand from the printed method. The same system by the SAP 10.3 Appendix H monthly method on the calculator's 150 L/day demand gives 1 488 kWh; the MCS figure is the one an MCS installer gives the customer.

Checks for case ST-01
QuantityExpectedSourceMEPCalcΔToleranceResult
Household occupancy N (full-time equivalent)
3
MCS 024:2025 Issue 1.0 (01/01/2025), Solar Heating Performance Estimate
§2 (a), printed p7
30.00 %exactPass
Daily hot water demand Vd = 25N + 36
Vd = 25 × 3 + 36 = 111 L/day
111L/day
MCS 024:2025 Issue 1.0 (01/01/2025), Solar Heating Performance Estimate
§2 (c) and (d), printed p7
111L/day0.00 %exactPass
Energy content of hot water Σ(45)
Σ(45) = 4.190 × 111 × 365 × 37 ÷ 3600 = 1744.7 kWh
1744.7kWh/yr
MCS 024:2025 Issue 1.0 (01/01/2025), Solar Heating Performance Estimate
§2 (c) and (d), printed p7
1744.7kWh/yr0.00 %±2 %Pass
Hot water use adjustment H = h1 × h2 × h3
1
MCS 024:2025 Issue 1.0 (01/01/2025), Solar Heating Performance Estimate
§2 (e), printed p7–8 (h1 1.00 both shower types, h2 1.00, h3 1.0)
10.00 %exactPass
Annual cylinder heat loss C
505kWh/yr
MCS 024:2025 Issue 1.0 (01/01/2025), Solar Heating Performance Estimate
§2 (e), printed p7–8 (C at 200 L)
505kWh/yr0.00 %exactPass
Linear heat loss coefficient a* = 0.892 (a1 + 45 a2)
a* = 0.892 × (6.0 + 45 × 0.016) = 5.9942
5.9942W/m²K
SAP 2012 version 9.92 (October 2013), Appendix H and Table 1b
Appendix H worksheet (H1)–(H17), printed p78–79 (H3b)
5.9942W/m²K0.00 %±2 %Pass
Collector performance factor f1 (H10)
a*/η0 = 5.9942 ÷ 0.75 = 7.9923; f1 = 0.97 − 0.0367 × 7.9923 + 0.0006 × 7.9923² = 0.7150
0.715
SAP 2012 version 9.92 (October 2013), Appendix H and Table 1b
Appendix H worksheet (H1)–(H17), printed p78–79 (H10, ratio < 20)
0.7150.00 %±2 %Pass
Solar energy available (H7)
H7 = Aap × η0 × S × overshading = 4 × 0.75 × 1081.4 × 1.0 = 3244.2 kWh
3244.2kWh/yr
SAP 2012 version 9.92 (October 2013), Appendix H and Table 1b
Appendix H worksheet (H1)–(H17), printed p78–79 (H7)
3244.3kWh/yr0.00 %±2 %Pass
Modified solar-to-load ratio (H8)
(H8) = 3244.2 ÷ {[1.0 × 1744.7] + 505} = 1.4420
1.442
MCS 024:2025 Issue 1.0 (01/01/2025), Solar Heating Performance Estimate
§2 (e), printed p7–8
1.44210.01 %±2 %Pass
Utilisation factor (H9)
1 − exp(−1 ÷ 1.4420) = 0.5002
0.5002
SAP 2012 version 9.92 (October 2013), Appendix H and Table 1b
Appendix H worksheet (H1)–(H17), printed p78–79 (H9)
0.50020.00 %±2 %Pass
Effective solar volume Veff (H13)
Veff = 100 + 0.3 × (200 − 100) = 130 L
130L
SAP 2012 version 9.92 (October 2013), Appendix H and Table 1b
Appendix H worksheet (H1)–(H17), printed p78–79 (H13, combined cylinder)
130L0.00 %±2 %Pass
Storage volume factor f2 (H16)
Veff/Vd = 130 ÷ 111 = 1.1712; 1 + 0.2 ln 1.1712 = 1.032, capped at 1.0
1
SAP 2012 version 9.92 (October 2013), Appendix H and Table 1b
Appendix H worksheet (H1)–(H17), printed p78–79 (H16)
10.00 %exactPass
Estimated annual solar input to the cylinder Qs (H17)
Qs = 3244.2 × 0.5002 × 0.7150 × 1.0 = 1160.2 kWh
1160.2kWh/yr
SAP 2012 version 9.92 (October 2013), Appendix H and Table 1b
Appendix H worksheet (H1)–(H17), printed p78–79 (H17)
1160.2kWh/yr0.00 %±2 %Pass
Solar efficiency factor A1 of the back-up heater
0.768
MCS 024:2025 Issue 1.0 (01/01/2025), Solar Heating Performance Estimate
Appendix A, Table A1, printed p11–12 (gas, post 1998, condensing, system boiler)
0.7680.00 %exactPass
Estimated annual fuel saving Qs ÷ A1
1160.2 ÷ 0.768 = 1510.7 kWh
1510.7kWh/yr
MCS 024:2025 Issue 1.0 (01/01/2025), Solar Heating Performance Estimate
Appendix A, printed p11 (Qs ÷ A1)
1510.7kWh/yr0.00 %±2 %Pass
Additional fuel energy saving Qs × {(1/A1) − 1}
1160.2 × {(1 ÷ 0.768) − 1} = 350.5 kWh
350.5kWh/yr
MCS 024:2025 Issue 1.0 (01/01/2025), Solar Heating Performance Estimate
§2 (additional fuel energy saving), printed p9
350.5kWh/yr0.00 %±2 %Pass
Installed capacity, aperture × 0.7
4 × 0.7 = 2.8 kWth
2.8kWth
MCS Technical Note: Calculation for Solar Thermal Total Installed Capacity v1.1
§2, the 0.7 kWth per m² of aperture convention
2.8kWth0.00 %exactPass

ST-02

MCS 024 Appendix B — Qs 1,600 kWh, condensing gas boiler post 1998

Inputs

  • Calculated solar input Qs of 1 600 kWh (the standard's own figure)
  • Back-up heater: gas condensing boiler, post 1998
Checks for case ST-02
QuantityExpectedSourceMEPCalcΔToleranceResult
Solar efficiency factor A1 of the back-up heater
Table A1: 76.8 %
0.768
MCS 024:2025 Issue 1.0 (01/01/2025), Solar Heating Performance Estimate
Appendix A, Table A1, printed p11–12
0.7680.00 %exactPass
Estimated annual fuel saving Qs ÷ A1
1 600 ÷ 0.768 = 2 083 kWh
2083kWh/yr
MCS 024:2025 Issue 1.0 (01/01/2025), Solar Heating Performance Estimate
Appendix B, printed p14
2083.3333kWh/yr0.02 %±2 %Pass

ST-03

MCS 024 Appendix B — Qs 1,600 kWh, pre-1979 floor-mounted gas boiler

Inputs

  • Calculated solar input Qs of 1 600 kWh
  • Back-up heater: gas, pre 1979, open or balanced flue, floor mounted
Checks for case ST-03
QuantityExpectedSourceMEPCalcΔToleranceResult
Solar efficiency factor A1 of the back-up heater
Table A1: 48.8 %
0.488
MCS 024:2025 Issue 1.0 (01/01/2025), Solar Heating Performance Estimate
Appendix A, Table A1, printed p11–12
0.4880.00 %exactPass
Estimated annual fuel saving Qs ÷ A1
1 600 ÷ 0.488 = 3 279 kWh
3279kWh/yr
MCS 024:2025 Issue 1.0 (01/01/2025), Solar Heating Performance Estimate
Appendix B, printed p14
3278.6885kWh/yr0.01 %±2 %Pass

ST-04

MCS 024 Appendix B — Qs 1,600 kWh, ground-to-water heat pump

Inputs

  • Calculated solar input Qs of 1 600 kWh
  • Back-up heater: ground to water heat pump

A heat pump's A1 above 1 means the fuel saved is less than the solar input: the pump would have delivered that heat from less electricity.

Checks for case ST-04
QuantityExpectedSourceMEPCalcΔToleranceResult
Solar efficiency factor A1 of the back-up heater
Table A1: 150 %
1.5
MCS 024:2025 Issue 1.0 (01/01/2025), Solar Heating Performance Estimate
Appendix A, Table A1, printed p11–12
1.50.00 %exactPass
Estimated annual fuel saving Qs ÷ A1
1 600 ÷ 1.50 = 1 067 kWh
1067kWh/yr
MCS 024:2025 Issue 1.0 (01/01/2025), Solar Heating Performance Estimate
Appendix B, printed p14
1066.6667kWh/yr0.03 %±2 %Pass

ST-05

MCS 024 §2 (b) — occupancy unknown, 100 m² floor area (SAP 2012 Table 1b)

Inputs

  • The ST-01 system with the occupancy unknown and a total floor area of 100 m²
Checks for case ST-05
QuantityExpectedSourceMEPCalcΔToleranceResult
Household occupancy N (full-time equivalent)
N = 1 + 1.76 × [1 − exp(−0.000349 × (100 − 13.9)²)] + 0.0013 × (100 − 13.9) = 2.7395
2.7395
SAP 2012 version 9.92 (October 2013), Appendix H and Table 1b
Table 1b, printed p196
2.740.02 %±2 %Pass
Daily hot water demand Vd = 25N + 36
25 × 2.7395 + 36 = 104.49 L/day
104.49L/day
MCS 024:2025 Issue 1.0 (01/01/2025), Solar Heating Performance Estimate
§2 (c) and (d), printed p7
104.49L/day0.00 %±2 %Pass
Energy content of hot water Σ(45)
4.190 × 104.49 × 365 × 37 ÷ 3600 = 1642.4 kWh
1642.4kWh/yr
MCS 024:2025 Issue 1.0 (01/01/2025), Solar Heating Performance Estimate
§2 (c) and (d), printed p7
1642.4kWh/yr0.00 %±2 %Pass
Estimated annual solar input to the cylinder Qs (H17)
(H8) = 3244.2 ÷ (1642.4 + 505) = 1.5108; (H9) = 0.4841; Qs = 3244.2 × 0.4841 × 0.7150 × 1.0 = 1123.0 kWh
1123kWh/yr
SAP 2012 version 9.92 (October 2013), Appendix H and Table 1b
Appendix H worksheet (H1)–(H17), printed p78–79 (H17)
1123kWh/yr0.00 %±2 %Pass

ST-06

MCS 024 §2 (a) cap — 8 residents count as 6; 250 L cylinder; storage factor below 1

Inputs

  • The ST-01 system with 8 full-time residents and a 250 L twin-coil cylinder (100 L dedicated)
Checks for case ST-06
QuantityExpectedSourceMEPCalcΔToleranceResult
Household occupancy N (full-time equivalent)
6
MCS 024:2025 Issue 1.0 (01/01/2025), Solar Heating Performance Estimate
§2 (a), printed p7 (whichever is the lower of the total and 6)
60.00 %exactPass
Daily hot water demand Vd = 25N + 36
25 × 6 + 36 = 186 L/day
186L/day
MCS 024:2025 Issue 1.0 (01/01/2025), Solar Heating Performance Estimate
§2 (c) and (d), printed p7
186L/day0.00 %exactPass
Annual cylinder heat loss C
586kWh/yr
MCS 024:2025 Issue 1.0 (01/01/2025), Solar Heating Performance Estimate
§2 (e), printed p7–8 (C at 250 L)
586kWh/yr0.00 %exactPass
Effective solar volume Veff (H13)
100 + 0.3 × (250 − 100) = 145 L
145L
SAP 2012 version 9.92 (October 2013), Appendix H and Table 1b
Appendix H worksheet (H1)–(H17), printed p78–79 (H13)
145L0.00 %±2 %Pass
Storage volume factor f2 (H16)
Veff/Vd = 145 ÷ 186 = 0.7796; f2 = 1 + 0.2 × ln 0.7796 = 0.9502
0.9502
SAP 2012 version 9.92 (October 2013), Appendix H and Table 1b
Appendix H worksheet (H1)–(H17), printed p78–79 (H16)
0.95020.00 %±2 %Pass
Estimated annual solar input to the cylinder Qs (H17)
Σ(45) = 2923.6; (H8) = 3244.2 ÷ (2923.6 + 586) = 0.9244; (H9) = 0.6610; Qs = 3244.2 × 0.6610 × 0.7150 × 0.9502 = 1457.0 kWh
1457kWh/yr
SAP 2012 version 9.92 (October 2013), Appendix H and Table 1b
Appendix H worksheet (H1)–(H17), printed p78–79 (H17)
1457kWh/yr0.00 %±2 %Pass

ST-07

MCS 024 evacuated tubes — §2 (f) defaults and the IAM factor Kθ(50T) × Kθ(50L)

Inputs

  • 3 m² evacuated tube collector, MCS 024 §2 (f) defaults η0 0.60, a1 3.0 W/m²K, a2 0.008 W/m²K²
  • Incidence angle modifiers at 50° from the test report: transverse 1.10, longitudinal 0.95
  • Otherwise as ST-01
Checks for case ST-07
QuantityExpectedSourceMEPCalcΔToleranceResult
Incidence angle modifier factor (evacuated tubes)
1.10 × 0.95 = 1.045 (higher than 1.0, so applied)
1.045
MCS 024:2025 Issue 1.0 (01/01/2025), Solar Heating Performance Estimate
§2 (evacuated tube collectors), printed p9
1.0450.00 %±2 %Pass
Linear heat loss coefficient a* = 0.892 (a1 + 45 a2)
0.892 × (3.0 + 45 × 0.008) = 2.9971
2.9971W/m²K
SAP 2012 version 9.92 (October 2013), Appendix H and Table 1b
Appendix H worksheet (H1)–(H17), printed p78–79 (H3b)
2.9971W/m²K0.00 %±2 %Pass
Collector performance factor f1 (H10)
a*/η0 = 4.9952; f1 = 0.97 − 0.0367 × 4.9952 + 0.0006 × 4.9952² = 0.8016
0.8016
SAP 2012 version 9.92 (October 2013), Appendix H and Table 1b
Appendix H worksheet (H1)–(H17), printed p78–79 (H10)
0.80160.00 %±2 %Pass
Solar energy available (H7)
3 × 0.60 × 1081.4 × 1.0 × 1.045 = 2034.1 kWh
2034.1kWh/yr
MCS 024:2025 Issue 1.0 (01/01/2025), Solar Heating Performance Estimate
§2 (evacuated tube collectors), printed p9 (H7 with the IAM factor)
2034.2kWh/yr0.01 %±2 %Pass
Estimated annual solar input to the cylinder Qs (H17)
(H8) = 2034.1 ÷ 2249.7 = 0.9042; (H9) = 0.6691; Qs = 2034.1 × 0.6691 × 0.8016 × 1.0 = 1091.1 kWh
1091.1kWh/yr
SAP 2012 version 9.92 (October 2013), Appendix H and Table 1b
Appendix H worksheet (H1)–(H17), printed p78–79 (H17)
1091.1kWh/yr0.00 %±2 %Pass
Installed capacity, aperture × 0.7
3 × 0.7 = 2.1 kWth
2.1kWth
MCS Technical Note: Calculation for Solar Thermal Total Installed Capacity v1.1
§2, the 0.7 kWth per m² of aperture convention
2.1kWth0.00 %exactPass

ST-08

Overshading — modest (20 % to 60 % of sky blocked), Table H2 factor 0.8

Inputs

  • The ST-01 system with modest overshading of the collector

With shading present the estimate carries the MCS 024 §3.1 a ii note; the notes are checked in the hermetic gate rather than here.

Checks for case ST-08
QuantityExpectedSourceMEPCalcΔToleranceResult
Overshading factor (H6, Table H2)
0.8
SAP 2012 version 9.92 (October 2013), Appendix H and Table 1b
Appendix H, Table H2, printed p79 (modest)
0.80.00 %exactPass
Solar energy available (H7)
4 × 0.75 × 1081.4 × 0.8 = 2595.4 kWh
2595.4kWh/yr
SAP 2012 version 9.92 (October 2013), Appendix H and Table 1b
Appendix H worksheet (H1)–(H17), printed p78–79 (H7)
2595.4kWh/yr0.00 %±2 %Pass
Estimated annual solar input to the cylinder Qs (H17)
(H8) = 2595.4 ÷ 2249.7 = 1.1536; (H9) = 0.5797; Qs = 2595.4 × 0.5797 × 0.7150 × 1.0 = 1075.8 kWh
1075.8kWh/yr
SAP 2012 version 9.92 (October 2013), Appendix H and Table 1b
Appendix H worksheet (H1)–(H17), printed p78–79 (H17)
1075.8kWh/yr0.00 %±2 %Pass

ST-09

Hot water use adjustment — electric showers only in a water-efficient dwelling

Inputs

  • The ST-01 system in a dwelling with electric showers only, compliant with Approved Document G
Checks for case ST-09
QuantityExpectedSourceMEPCalcΔToleranceResult
Hot water use adjustment H = h1 × h2 × h3
0.64 × 0.95 × 1.0 = 0.608
0.608
MCS 024:2025 Issue 1.0 (01/01/2025), Solar Heating Performance Estimate
§2 (e), printed p7–8 (h1 0.64 × h2 0.95 × h3 1.0)
0.6080.00 %±2 %Pass
Modified solar-to-load ratio (H8)
3244.2 ÷ {[0.608 × 1744.7] + 505} = 2.0719
2.0719
MCS 024:2025 Issue 1.0 (01/01/2025), Solar Heating Performance Estimate
§2 (e), printed p7–8
2.0720.01 %±2 %Pass
Estimated annual solar input to the cylinder Qs (H17)
(H9) = 1 − exp(−1 ÷ 2.0719) = 0.3829; Qs = 3244.2 × 0.3829 × 0.7150 × 1.0 = 888.1 kWh
888.1kWh/yr
SAP 2012 version 9.92 (October 2013), Appendix H and Table 1b
Appendix H worksheet (H1)–(H17), printed p78–79 (H17)
888.1kWh/yr0.00 %±2 %Pass

ST-10

Separate pre-heat cylinder — Veff is the whole solar store, C on the total volume between printed points

Inputs

  • The ST-01 system with a 150 L dedicated solar pre-heat cylinder feeding a 120 L main cylinder (270 L total storage)

MCS 024 prints C at six volumes only; the value between them follows the MCS SPE calculator tool's linear reading and is checked to the calculated tolerance.

Checks for case ST-10
QuantityExpectedSourceMEPCalcΔToleranceResult
Effective solar volume Veff (H13)
150L
SAP 2012 version 9.92 (October 2013), Appendix H and Table 1b
Appendix H worksheet (H1)–(H17), printed p78–79 (H13, separate pre-heat: Veff = Vs)
150L0.00 %exactPass
Annual cylinder heat loss C
586 + (662 − 586) × (270 − 250) ÷ 50 = 616.4 kWh
616.4kWh/yr
MCS 024:2025 Issue 1.0 (01/01/2025), Solar Heating Performance Estimate
§2 (e), printed p7–8 (C between 250 L and 300 L, read linearly as the MCS SPE calculator tool does)
616.4kWh/yr0.00 %±2 %Pass
Estimated annual solar input to the cylinder Qs (H17)
(H8) = 3244.2 ÷ (1744.7 + 616.4) = 1.3740; (H9) = 0.5170; Veff/Vd = 1.3514 → f2 1.0; Qs = 3244.2 × 0.5170 × 0.7150 = 1199.3 kWh
1199.3kWh/yr
SAP 2012 version 9.92 (October 2013), Appendix H and Table 1b
Appendix H worksheet (H1)–(H17), printed p78–79 (H17)
1199.3kWh/yr0.00 %±2 %Pass

SAP-01

SAP 10.3 Appendix H — 4 m² flat plate, 120 L/day, region 0 south at 40°

Inputs

  • 4 m² flat plate glazed collector, SAP 10.3 Table H1 defaults η0 0.80, a1 3.5 W/m²K, a2 0, Khem(50°) 0.94; ηloop 0.9 (H5)
  • South-facing at 40°, SAP region 0 (UK average); Table U1 external temperatures
  • 120 L/day at a 50 K rise (10 °C to 60 °C); twin-coil defaults Vs 100 L, cylinder 220 L → Veff 136 L
Checks for case SAP-01
QuantityExpectedSourceMEPCalcΔToleranceResult
Annual hot water demand ΣH17
120 × 365 × 4.18 × 50 ÷ 3600 = 2542.9 kWh
2542.9kWh/yr
SAP 10.3 (13-01-2026), The Government's Standard Assessment Procedure, Appendix H
Appendix H worksheet (H1)–(H24), Tables H1–H3 (H17)
2542.9kWh/yr0.00 %±2 %Pass
Annual solar heat to hot water ΣH24
Uloop = 3.5 + (5 + 0.5 × 4)/4 = 5.25 (H11); fst = (75 × 4 ÷ 136)^0.25 = 1.2187 (H16); June: Dm = 209.0 kWh, ΔT = 55 + 3.86 × 10 − 1.32 × 14.6 − 14.6 = 59.73 K, X = 4.740, Y = 1.803, Qs,w = (1.029Y − 0.065X − 0.245Y² + 0.0018X² + 0.0215Y³) × Dm; summed over twelve months 1370.8 kWh
1370.8kWh/yr
SAP 10.3 (13-01-2026), The Government's Standard Assessment Procedure, Appendix H
Appendix H worksheet (H1)–(H24), Tables H1–H3
1370.8kWh/yr0.00 %±2 %Pass

SAP-02

SAP 10.3 Appendix H — 6 m² evacuated tube, 200 L/day, region 0 south at 40°

Inputs

  • 6 m² evacuated tube collector, Table H1 defaults η0 0.80, a1 1.8 W/m²K, a2 0, Khem(50°) 1.00
  • South-facing at 40°, SAP region 0; 200 L/day at a 50 K rise
  • Twin-coil defaults Vs 160 L, cylinder 360 L → Veff 220 L
Checks for case SAP-02
QuantityExpectedSourceMEPCalcΔToleranceResult
Annual hot water demand ΣH17
200 × 365 × 4.18 × 50 ÷ 3600 = 4238.1 kWh
4238.1kWh/yr
SAP 10.3 (13-01-2026), The Government's Standard Assessment Procedure, Appendix H
Appendix H worksheet (H1)–(H24), Tables H1–H3 (H17)
4238kWh/yr0.00 %±2 %Pass
Annual solar heat to hot water ΣH24
Uloop = 1.8 + (5 + 0.5 × 6)/6 = 3.133; fst = (75 × 6 ÷ 220)^0.25 = 1.1959; June: Dm = 348.3 kWh, X = 2.498, Y = 1.726; summed 2726.8 kWh
2726.8kWh/yr
SAP 10.3 (13-01-2026), The Government's Standard Assessment Procedure, Appendix H
Appendix H worksheet (H1)–(H24), Tables H1–H3
2726.8kWh/yr0.00 %±2 %Pass

SAP-03

SAP 10.3 Appendix H — 15 m² flat plate on 225 L/day, the demand cap in summer

Inputs

  • 15 m² flat plate glazed collector (Table H1 defaults), south-facing at 40°, SAP region 0
  • 225 L/day at a 50 K rise; twin-coil defaults Vs 375 L, cylinder 600 L → Veff 442.5 L

An oversized array: the worksheet caps each month's solar heat at that month's demand, and the calculator also warns of summer stagnation (MIS 3001:2025 §3.4.4).

Checks for case SAP-03
QuantityExpectedSourceMEPCalcΔToleranceResult
Annual hot water demand ΣH17
225 × 365 × 4.18 × 50 ÷ 3600 = 4767.8 kWh
4767.8kWh/yr
SAP 10.3 (13-01-2026), The Government's Standard Assessment Procedure, Appendix H
Appendix H worksheet (H1)–(H24), Tables H1–H3 (H17)
4767.8kWh/yr0.00 %±2 %Pass
Annual solar heat to hot water ΣH24
Uloop = 3.5 + (5 + 7.5)/15 = 4.333; fst = (75 × 15 ÷ 442.5)^0.25 = 1.2627; Qs,w is capped at the month's demand through the summer; summed 3485.7 kWh
3485.7kWh/yr
SAP 10.3 (13-01-2026), The Government's Standard Assessment Procedure, Appendix H
Appendix H worksheet (H1)–(H24), Tables H1–H3 (H24 capped at Dm)
3485.7kWh/yr0.00 %±2 %Pass