Renewable and zero emissions heating systems in affordable housing projects: evaluation

Appendix B. Individual project data

B0. Overview

In this appendix, the information collected for each project is presented in two tables – an overview and then a per-unit cost breakdown. The second table has not been included if insufficient data was provided, and this is explained in the project's overview. If data is not available but it has been possible to estimate a value, cells are marked with a (B) and the estimation is explained underneath. Where information is yet to be established because the project is at an early stage, cells are marked (P).

An example overview table is provided below, which lists and explains the metrics considered for each of the projects.

Table 21: Example project overview

Metric	Information
Location	The project's local authority area
Unit count	The number of affordable housing units included in the project
Unit types	The number of different affordable housing unit types included in the project
Progress	Whether the project is in the pre-construction phase, under construction or complete
On-gas grid	Whether the project is situated on or off the gas grid
Section 75	Whether or not the project forms the Section 75 affordable housing obligation for a larger development
Sustainability target	The energy demand target that the project is designed to achieve
Heating system	The technology (or technologies) that are included in the project's heating and hot water generation and storage system
Capex extent	The components and services included in the capital expenditure (capex) cost provided
Capex source	The source of the capex figure
Opex	Whether the project estimated an operational cost (opex) to the occupants to run the heating system
Counterfactual	Whether the project has costed an alternative (counterfactual) heating system

B1. Solar PV (individual)

Project 1

An overview of Project 1 is provided in Table 22. A per-unit table has also been provided.

Table 22: Project 1 overview

Metric	Information
Location	North Ayrshire
Unit count	34
Unit types	7
Progress	Under construction
On-gas grid	No
Section 75	No
Sustainability target	Aspect Silver Level 1 and 2
Heating system	Rooftop solar PV modules, electric boiler
Capex extent	Installed costs of PV, boiler
Capex source	Averaged actual costs
Opex	Estimates provided
Counterfactual	None considered

Table 23: Project 1 costs per unit

Unit	1	2	3	4	5	6	7
Description	2-bed mid (A)	2-bed mid (B)	2-bed end	2-bed bungalow	2-bed WC bungalow	3-bed det.	4-bed WC det.
Count	3	6	8	8	2	3	4
Footprint (m2)	88	84	83	63	63	119	112
Heat demand	3598	3523	3902	3485	3561	5227	5000
Heat demand per m2	41.0	41.7	47.1	55.4	56.6	44.0	44.6
Installation capex	£5,538	£5,538	£5,538	£5,538	£5,538	£5,538	£5,538
PV capex	£1,870	£1,870	£1,870	£1,870	£1,870	£1,870	£1,870
Network capex	Not considered
Total capex	£7,408	£7,408	£7,408	£7,408	£7,408	£7,408	£7,408
Capex per m2	£84.4	£87.8	£89.5	£117.8	£117.8	£62.4	£66.0
Est. opex	£475	£465	£515	£460	£470	£690	£660
Est. opex per m2	£5.4	£5.5	£6.2	£7.3	£7.5	£5.8	£5.9

Project 2

An overview of Project 2 is provided in Table 24. A per-unit table has also been provided.

Table 24: Project 2 overview

Metric	Information
Location	North Ayrshire
Unit count	18
Unit types	7
Progress	Under construction
On-gas grid	No
Section 75	No
Sustainability target	Aspect Silver Level 1 and 2
Heating system	Rooftop solar PV modules, electric boiler
Capex extent	Averaged actual costs
Capex source	Actual costs
Opex	Estimates provided
Counterfactual	None considered

Table 25: Project 2 costs per unit

Unit	1	2	3	4	5	6	7
Description	3-bed end	3-bed terrace	2-bed end	2-bed mid	2-bed WC bungalow	3-bed WC det.	4-bed WC det.
Count	1	2	7	2	3	2	1
Footprint (m2)	96	93	63	63	63	119	143
Heat demand	4205	3712	3598	3333	3598	5152	6606
Heat demand per m2	44.0	39.9	57.2	53.3	57.2	43.4	46.3
Installation capex	£4,675	£4,675	£4,675	£4,675	£4,675	£4,675	£4,675
PV capex	£1,603	£1,603	£1,603	£1,603	£1,603	£1,603	£1,603
Network capex	Not considered
Total capex	£6,278	£6,278	£6,278	£6,278	£6,278	£6,278	£6,278
Capex per m2	£65.7	£67.5	£99.8	£100.4	£99.8	£52.9	£44.0
Est. opex	£555	£490	£475	£440	£475	£680	£872
Est. opex per m2	£5.8	£5.3	£7.6	£7.0	£7.6	£5.7	£6.1

Project 3

An overview of Project 3 is provided in Table 26. A per-unit table has also been provided.

Table 26: Project 3 overview

Metric	Information
Location	North Ayrshire
Unit count	2
Unit types	1
Progress	Complete
On-gas grid	No
Section 75	No
Sustainability target	Gold
Heating system	Rooftop solar PV modules, Sunamp heat battery
Capex extent	Sunamp and PV installation
Capex source	Actual costs
Opex	Estimates provided
Counterfactual	Gas boilers and PV to meet Silver Aspects 1 and 2

Table 27: Project 3 costs per unit

Unit	1
Description	2-bed terrace
Count	2
Footprint (m2)	85
Heat demand	3462
Heat demand per m2	40.5
Installation capex	£4,950
PV capex	£1,603
Network capex	Not considered
Total capex	£3,520
Capex per m2	£8,470
Est. opex	£99.2
Est. opex per m2	£269
Alt capex	3.1
Alt capex per m2	£4,180
Est. alt opex	48.9
Est. alt per m2	309

Project 4

An overview of Project 4 is provided in Table 28, and per-unit data in Table 29. A partial data set has been provided for this project, so the units' heat demand has been estimated.

Table 28: Project 4 overview

Metric	Information
Location	North Lanarkshire
Unit count	2
Unit types	1
Progress	Complete
On-gas grid	Yes
Section 75	Yes
Sustainability target	Gold
Heating system	Rooftop solar PV modules, Sunamp heat battery
Capex extent	Heating system installation, including electrician costs
Capex source	Developer
Opex	Not provided – estimated from maximum Gold heat demand
Counterfactual	Not costed

Table 29: Project 4 costs per unit

Unit	1
Description	2-bed semi
Count	2
Footprint (m2)	83
Heat demand	2502 (B)
Heat demand per m2	30 (B)
Installation capex	£4,132
PV capex	£4,794
Network capex	Not considered
Total capex	£8,926
Capex per m2	£107.0
Est. opex	£246 (B)
Est. opex per m2	£2.9 (B)

B2. Air Source Heat Pumps (Individual)

Project 5

An overview Project 5 is provided in Table 30, and per-unit data in Table 31. All available information is included, although a counterfactual has not been costed.

Table 30: Project 5 overview

Metric	Information
Location	Perth & Kinross
Unit count	4
Unit types	3
Progress	Pre-construction
On-gas grid	No
Section 75	Yes
Sustainability target	Silver
Heating system	ASHPs only
Capex extent	Heating system installation
Capex source	Developer's estimates
Opex	Developer's estimates
Counterfactual	Direct electric heaters (costs not provided)

Table 31: Project 5 costs per unit

Unit	1	2	3
Description	3-bed semi	2-bed GF flat	2-bed 1F flat
Count	2	1	1
Footprint (m2)	99	60	70
Heat demand	5639	3656	4321
Heat demand per m2	57.0	60.9	61.7
Installation capex	£5,500	£5,500	£5,500
Network capex	Not considered
Other heating capex	N/A
Total capex	£5,500	£5,500	£5,500
Capex per m2	£55.6	£91.7	£78.6
Est. opex	£437	£366	£400
Est. opex per m2	£4.4	£6.1	£5.7

Project 6

An overview of Project 6 is provided in Table 32, and per-unit data in Table 33. All available data has been shared.

Table 32: Project 6 overview

Metric	Information
Location	Argyll & Bute
Unit count	300
Unit types	8
Progress	Under construction
On-gas grid	No
Section 75	No
Sustainability target	Silver
Heating system	ASHPs only
Capex extent	Heating system installation
Capex source	Developer's estimates
Opex	Developer's estimates
Counterfactual	Shared biomass (costed in feasibility study)

Table 33: Project 6 costs per unit

Unit	1	2	3	4	5	6	7	8
Description	2-bed terrace	2-bed WC semi	3-bed semi	4-bed semi	1-bed flat	1-bed WC flat	2-bed flat	2-bed flat
Count	111	16	81	18	27	13	31	3
Footprint (m2)	89	95	106	122	52	69	77	97.5
Heat demand	2790	3047	3045	3125	2309	2431	2601	2707
Heat demand per m2	31.3	28.7	25.0	40.6	44.4	35.2	26.7	28.5
Installation capex	£4,944	£4,944	£5,933	£5,933	£5,933	£5,933	£5,933	£5,933
Network capex	Considered negligible
Total capex	£4,944	£4,944	£5,933	£5,933	£5,933	£5,933	£5,933	£5,933
Capex per m2	£55.6	£46.6	£48.6	£77.0	£114.1	£86.0	£60.8	£62.4
Est. opex	£368	£402	£404	£412	£305	£321	£345	£357
Est. opex per m2	£4.1	£3.8	£3.3	£5.4	£5.9	£4.7	£3.5	£3.8
Alt capex	£3,093,400 for whole site (approx. £10,300 per unit)
Alt capex per m2	£115.7	£97.2	£84.4	£133.8	£198.1	£149.3	£105.6	£108.4
Est. alt opex	£310 (B)	£338 (B)	£340 (B)	£347 (B)	£257 (B)	£270 (B)	£290 (B)	£300 (B)
Est. alt per m2	£3.5 (B)	£3.6 (B)	£3.2 (B)	£2.8 (B)	£4.9 (B)	£3.9 (B)	£3.8 (B)	£3.1 (B)

Project 7

An overview of Project 7 is provided in Table 34, and per-unit data in Table 35.

Table 34: Project 7 overview

Metric	Information
Location	Angus
Unit count	10
Unit types	1
Progress	Completed
On-gas grid	No
Section 75	Yes
Sustainability target	SAP: 81 (Project set up before the introduction of current standards)
Heating system	ASHPs only
Capex extent	Heating system installation
Capex source	Contractor's actual costs
Opex	Estimates provided
Alternative	Gas boilers

Table 35: Project 7 costs per unit

Unit	1
Description	3-bed semi
Count	10
Footprint (m2)	100m2
Heat demand	3571 (B)
Heat demand per m2	35.7 (B)
Equipment capex	£10,738
Labour capex
Network capex	Not considered
Other heating capex	N/A
Total capex	£10,738
Capex per m2	£107
Est. opex	£500
Est. opex per m2	£5.0
Alt capex	£2,944
Alt capex per m2	£29
Est. alt opex	£421 (B)
Est. alt per m2	£4.2 (B)

Project 8

An overview of Project 8 is provided in Table 36. A per-unit table has not been provided because the project is at an early stage and has not been costed in detail yet.

Table 36: Project 8 overview

Metric	Information
Location	Scottish Borders
Unit count	4
Unit types	Not yet established (P)
Progress	Preconstruction
On-gas grid	Yes
Section 75	No
Sustainability target	Silver with Gold aspects
Heating system	ASHPs and MVHR
Capex extent	Heating system installation
Capex source	Housing associations' previous projects
Opex	Not yet established (P)
Alternative	No alternative considered

Project 9

An overview of Project 9 is provided in Table 37. A per-unit table has not been provided because the project contact was not able to share any cost data.

Table 37: Project 9 overview

Metric	Information
Location	Highland
Unit count	14
Unit types	5
Progress	Pre-construction
On-gas grid	No
Section 75	No
Sustainability target	Bronze
Heating system	Air to Water heat pumps; Air to Air heat pumps
Capex extent	Not provided
Capex source	Not provided
Opex	Not provided

Project 13

An overview of Project 13 is provided in Table 38, and per-unit data in Table 39. Notably, this project is the only one to date to have considered the impact of heating systems on network costs. The alternative capex in Table 39 includes an equal share of the £107k cost for the LPG system infrastructure.

Solar PV has been included as part of the heating system in the tables because the project's opex and capex figures include the impact of this technology. (This is included in the 'Other Capex' row in Table 39.)

Table 38: Project 13 overview

Metric	Information
Location	Highland
Unit count	117 (87 with individual ASHP systems)
Unit types	9
Progress	Pre-construction
On-gas grid	No
Section 75	No
Sustainability target	Silver
Heating system	ASHPs, rooftop PV and Sunamp heat batteries
Capex extent	Installation of heating system
Capex source	Contractor's quotation
Opex	Estimates provided
Alternative	LPG

Table 39: Project 13 costs per unit

Unit	1	2	3	4	5	6	7	8
Description	2-bed semi (A)	2-bed semi (B)	3-bed semi (A)	3-bed semi (B)	4-bed det.	2-bed bungalow	3-bed bungalow	2-bed cottage flat
Count	20	10	24	8	7	4	2	12
Footprint (m2)	92.1	92.1	103	103	117	89	108.0	80.3
Heat demand	2570	2570	2730	2750	3580	3064	3914	2230
Heat demand per m2	27.9	27.9	26.5	26.7	30.6	34.4	36.2	27.8
Installation capex	£6,672	£6,672	£6,672	£6,672	£6,672	£6,672	£6,672	£6,672
Network capex	Additional £79,806 (£682 per home)
Sunamp + PV capex	£4,346	£4,346	£4,728	£4,346	£5,603	£4,728	£4,728	£3,955
Total capex	£11,700	£11,700	£12,082	£11,700	£13,119	£12,082	£12,082	£11,309
Capex per m2	£127.0	£127.0	£117.3	£113.6	£112.1	£135.7	£111.9	£140.8
Est. opex	£244	£244	£239	£241	£352	£287	£298	£170
Est. opex per m2	£2.7	£2.7	£2.3	£2.3	£3.0	£3.2	£2.8	£2.1
Alt capex	£9,875	£9,875	£10,235	£10,375	£11,835	£11,235	£11,735	£11,015
Alt capex per m2	£107.2	£107.2	£99.4	£100.7	£101.1	£126.2	£108.7	£137.2
Est. alt opex	£371	£371	£389	£389	£588	£501	£466	£323
Est. alt per m2	£4.0	£4.0	£3.8	£3.8	£5.0	£5.6	£4.3	£4.0

Project 14

An overview of Project 14 is provided in Table 40. A per-unit table has not been provided as this project contact was not able to share any cost data.

Table 40: Project 14 overview

Metric	Information
Location	Glasgow City
Unit count	2
Unit types	1
Progress	Complete
On-gas grid	Yes
Section 75	No
Sustainability target	Platinum
Heating system	ASHPs, MVHR and Sunamp heat batteries
Capex extent	Not provided
Capex source	Not provided
Opex	Not provided
Alternative	Gas

Project 15

An overview of Project 15 is provided in Table 41, and per-unit data in Table 42. Notably, this is the only project to include solar thermal hot water generation, which has been denoted as the 'Other Capex' costs in Table 42.

Table 41: Project 15 overview

Metric	Information
Location	Dumfries & Galloway
Unit count	5
Unit types	3
Progress	Under construction
On-gas grid	No
Section 75	No
Sustainability target	Silver
Heating system	ASHPs, MVHR and solar thermal hot water generation
Capex extent	Heating and hot water system installation
Capex source	Quantity surveyor's estimates
Opex	From SAP reports
Alternative	None considered

Table 42: Project 15 cost per unit

Unit	1	2	3
Description	2-bed semi	3-bed semi	2-bed amenity bungalow
Count	2	2	1
Footprint (m2)	87.0	101	69
Heat demand	1215	1044	1120
Heat demand per m2	14.0	10.3	16.2
Equipment capex	£10,457	£10,457	£10,457
Labour capex
Network capex	Not considered
Other heating capex	£3,680	£3,680	£3,680
Total capex	£14,137	£14,137	£14,137
Capex per m2	£162	£140	£205
Est. opex	£199	£171	£183
Est. opex per m2	£2.3	£1.7	£2.7

B3. Air Source Heat Pumps (shared)

Project 16

An overview of Project 16 is provided in Table 43. A per-unit table has not been provided because the project is at an early stage and has not been costed in detail yet.

Table 43: Project 16 overview

Metric	Information
Location	Scottish Borders
Unit count	21
Unit types	Not yet established (P)
Progress	Pre-construction
On-gas grid	Yes
Section 75	No
Sustainability target	Silver with Gold aspects
Heating system	Shared ASHPs with heat interface units in each flat
Capex extent	Not yet established (P)
Capex source	Not yet established (P)
Opex	Not yet established (P)
Alternative	No alternative considered

Project 17

An overview of Project 17 is provided in Table 44. A per-unit table has not been provided because the project is at an early stage and has not been costed in detail yet.

Table 44: Project 17 overview

Metric	Information
Location	City of Edinburgh
Unit count	41
Unit types	Not yet established (P)
Progress	Pre-construction
On-gas grid	Yes
Section 75	No (although development will have non-social let flats)
Sustainability target	100% improvement versus Silver (considered to define 'Net Zero')
Heating system	Shared ASHPs with heat interface units in each flat
Capex extent	Not yet established (P)
Capex source	Not yet established (P)
Opex	Not yet established (P)
Alternative	Alternatives considered but these will not be costed

Project 13 (1-bed flats)

An overview of Project 13 is provided in Table 38, within the individual ASHP section, as the majority (87 of 117 units) incorporate individual systems. However, the development has 30 one-bed flats which are served by five separate communal ASHP systems, one per block.

Costs for these systems are presented in Table 45 below.

Table 45: Project 13 (1-bed flats) project costs per unit

Unit	1
Description	1-bed flats, 5 blocks of 6
Count	30
Footprint (m2)	48.6
Heat demand	1532
Heat demand per m2	31.5
Installation capex	£8,857
Network capex	£682
Sunamp + PV capex	£4,017
Total capex	£13,556
Capex per m2	£278.9
Est. opex	£150
Est. opex per m2	£3.1
Alt capex	£11,015
Alt capex per m2	£226.6
Est. alt opex	£251
Est. alt per m2	£5.2

B4. Ground Source Heat Pumps (Shared)

Project 18

An overview of Project 18 is provided in Table 46, and per-unit data in Table 47. The capex for the GSHP system was provided as a single cost for the whole development.

Table 46: Project 18 overview

Metric	Information
Location	West Lothian
Unit count	16 (plus one staff building)
Unit types	1
Progress	Pre-construction
On-gas grid	Yes
Section 75	No
Sustainability target	Silver
Heating system	Shared GSHPs loop with individual heat pumps, underfloor heating
Capex extent	Shared GSHPs loop and individual heat pump installation
Capex source	Quantity Surveyor's estimates
Opex	Estimated by Mechanical Consultants
Alternative	Direct electric heaters (with solar PV to pass SAP)

Table 47: Project 18 costs per unit

Unit	1
Description	1-bed terrace
Count	16
Footprint (m2)	47.7
Heat demand	2,857
Heat demand per m2	60
Installation capex	£10,871
Network capex	Not considered
Other heating capex	N/A
Total capex	£10,871
Capex per m2	£228
Est. opex	£400
Est. opex per m2	£8.4
Alt capex	£4,659 (inclusive of solar PV)
Alt capex per m2	£97.7
Est. alt opex	£1,400
Est. alt per m2	£29.4

Project 19

An overview of Project 19 is provided in Table 48, and per-unit data in Table 49.

Table 48: Project 19 overview

Metric	Information
Location	City of Edinburgh
Unit count	84
Unit types	5
Progress	Under construction
On-gas grid	Yes
Section 75	Yes
Sustainability target	Aspect Silver Levels 1 and 2
Heating system	Shared GSHPs loop with individual heat pumps, underfloor heating
Capex extent	Shared GSHPs loop and individual heat pump installation
Capex source	Actual costs
Opex	Estimated by developer
Alternative	Gas boilers

Table 49: Project 19 costs per unit

Unit	1	2	3	4	5
Description	2-bed terrace	2-bed end	3-bed terrace	3-bed end	4-bed semi
Count	16	16	34	10	8
Footprint (m2)	82	82	97	97	125
Heat demand	1674 (B)	1674 (B)	1980	1980 (B)	2552 (B)
Heat demand per m2	20.4 (B)	20.4 (B)	20.4	20.4 (B)	20.4 (B)
Equipment capex	£11,500	£11,500	£11,500	£11,500	£11,500
Labour capex
Network capex	Not considered
Other heating capex	N/A
Total capex	£11,500	£11,500	£11,500	£11,500	£11,500
Capex per m2	£140	£119	£119	£92	£92
Est. opex	£88 (B)	£88 (B)	£104	£104 (B)	£135 (B)
Est. opex per m2	1.1 (B)	1.1 (B)	1.1	1.1 (B)	1.1 (B)
Alt capex	£4,000	£4,000	£4,000	£4,000	£4,000
Alt capex per m2	49	41	41	32	32
Est. alt opex	£118 (B)	£118 (B)	£139	£139 (B)	£180 (B)
Est. alt per m2	1.4 (B)	1.4 (B)	1.4	1.4 (B)	1.4 (B)

B5. Biomass (shared)

Project 20

An overview of Project 20 is provided in Table 50, and per-unit data in Table 51. Rather than a purpose-built biomass plant for the housing development, the heat source for this project is an industrial scale biomass combined heat and power plant. The capex for the system in this project was provided as a single cost for the whole development, so the figures presented below assign an equal portion of the total cost to each of the units.

Table 50: Project 20 overview

Metric	Information
Location	Fife
Unit count	85
Unit types	11
Progress	Under construction
On-gas grid	Yes
Section 75	Yes
Sustainability target	Silver
Heating system	Shared biomass heating from Markinch biomass plant
Capex extent	District heating network and heat interface units in each property
Capex source	Actual costs
Opex	Central estimates provided
Alternative	Gas boilers – not costed

Table 51: Project 20 costs per unit (A)

Unit	1	2	3	4	5
Description	2-bed terrace	3-bed terrace (A)	3-bed terrace (B)	2-bed WC semi	2-bed semi
Count	28	15	11	4	2
Footprint (m2)	83.2	93	116.8	79.8	95.3
Heat demand	5,410 (B)	6,047 (B)	7,594 (B)	5,189 (B)	6,196 (B)
Heat demand per m2	65 (B)	65 (B)	65 (B)	65 (B)	65 (B)
Installation capex	£8,837	£8,837	£8,837	£8,837	£8,837
Network capex	Inherent to above costs
Other heating capex	N/A
Total capex	£8,837	£8,837	£8,837	£8,837	£8,837
Capex per m2	£106	£95	£76	£111	£93
Est. opex	£139 (B)	£155 (B)	£195 (B)	£133 (B)	£159 (B)
Est. opex per m2	£1.67 (B)	£1.67 (B)	£1.67 (B)	£1.67 (B)	£1.67 (B)

Table 52: Project 20 costs per unit (B)

Unit	6	7	8	9	10	11
Description	4-bed det.	4-bed WC semi	4-bed semi	5-bed detached	2-bed cottage flat	2-bed WC cottage flat
Count	2	4	2	5	6	6
Footprint (m2)	112.8	98.1	122.2	120	83.8	79
Heat demand	7,334 (B)	6,378	7,945 (B)	7,802 (B)	5,449 (B)	5,137 (B)
Heat demand per m2	65 (B)	65	65 (B)	65 (B)	65 (B)	65 (B)
Equipment capex	£8,837	£8,837	£8,837	£8,837	£8,837	£8,837
Labour capex
Network capex	Inherent to above costs
Other heating capex	N/A
Total capex	£8,837	£8,837	£8,837	£8,837	£8,837	£8,837
Capex per m2	£78	£90	£72	£74	£105	£112
Est. opex	£188 (B)	£164	£204 (B)	£200 (B)	£140 (B)	£132 (B)
Est. opex per m2	£1.67 (B)	£1.67	£1.67 (B)	£1.67 (B)	£1.67 (B)	£1.67 (B)

Project 21

An overview of Project 21 is provided in Table 53. A per-unit table has also been provided.

Table 53: Project 21 overview

Metric	Information
Location	North Ayrshire
Unit count	123
Unit types	15
Progress	Under construction
On-gas grid	Yes
Section 75	No
Sustainability target	Aspect Silver Levels 1 and 2
Heating system	Shared biomass heating
Capex extent	DHN installation costs (inc. back-up system)
Capex source	Actual costs (averaged from development total)
Opex	Estimates Provided
Alternative	Gas DHN

Table 54: Project 21 costs per unit (A)

Unit	6	7	8	9	10
Description	2-bed bungalow (A)	2-bed bungalow (B)	2-bed WC bungalow	2-bed house (A)	2-bed house (B)
Count	5	7	4	13	13
Footprint (m2)	63	63	63	88	84
Heat demand	4,111	3,889	4,111	4,778	4,222
Heat demand per m2	65	62	65	54	50
Installation capex	£11,355	£11,355	£11,355	£11,355	£11,355
Network capex	Inherent to above costs
Other heating capex	N/A
Total capex	£11,355	£11,355	£11,355	£11,355	£11,355
Capex per m2	£245	£177	£206	£237	£183
Est. opex	£110	£150	£160	£145	£175
Est. opex per m2	£2.38	£2.34	£2.91	£3.02	£2.81
Alt capex	£3,015	£3,015	£3,015	£3,015	£3,015
Alt capex per m2	65.1	47.0	54.8	62.8	48.5
Est. alt opex	£110	£150	£160	£145	£175
Est. alt per m2	£2.38	£2.34	£2.91	£3.02	£2.81

Table 55: Project 21 costs per unit (B)

Unit	6	7	8	9	10
Description	2-bed bungalow (A)	2-bed bungalow (B)	2-bed WC bungalow	2-bed house (A)	2-bed house (B)
Count	5	7	4	13	13
Footprint (m2)	63	63	63	88	84
Heat demand	4,111	3,889	4,111	4,778	4,222
Heat demand per m2	65	62	65	54	50
Installation capex	£11,355	£11,355	£11,355	£11,355	£11,355
Network capex	Inherent to above costs
Other heating capex	N/A
Total capex	£11,355	£11,355	£11,355	£11,355	£11,355
Capex per m2	£245	£177	£206	£237	£183
Est. opex	£110	£150	£160	£145	£175
Est. opex per m2	£2.38	£2.34	£2.91	£3.02	£2.81
Alt capex	£3,015	£3,015	£3,015	£3,015	£3,015
Alt capex per m2	47.9	47.9	47.9	34.1	35.7
Est. alt opex	£185	£175	£185	£215	£190
Est. alt per m2	£2.94	£2.78	£2.94	£2.43	£2.25

Table 56: Project 21 costs per unit (C)

Unit	11	12	13	14	15
Description	3-bed house	3-bed WC house	4-bed house (A)	4-bed house (B)	4-bed bungalow
Count	20	1	3	1	2
Footprint (m2)	96	119	108	112	130
Heat demand	4,667	5,778	5,556	5,778	6,444
Heat demand per m2	49	49	51	52	50
Installation capex	£11,355	£11,355	£11,355	£11,355	£11,355
Network capex	Inherent to above costs
Other heating capex	N/A
Total capex	£11,355	£11,355	£11,355	£11,355	£11,355
Capex per m2	£135	£119	£96	£105	£101
Est. opex	£190	£210	£260	£250	£260
Est. opex per m2	£2.25	£2.20	£2.19	£2.31	£2.32
Alt capex	£3,015	£3,015	£3,015	£3,015	£3,015
Alt capex per m2	31.5	25.4	27.9	26.9	23.2
Est. alt opex	£210	£260	£250	£260	£290
Est. alt per m2	£2.20	£2.19	£2.31	£2.32	£2.23