Social Housing Retrofit Boreholes
This section illustrates the costs of replacing the heating and hot water systems in 28 social housing properties with Kensa ground source heat pumps. The scheme features an individual Kensa Shoebox Heat Pump in each house, connected to a Shared Ground Loop Array of boreholes.
We have provided a ground source heat pump design with schematic drawings and ground source heat pump installation costs for both self-financed and funded split ownership shared ground loop array options versus an electric night storage heater (NSH) alternative.
Example: Finances
Kensa has calculated example costs below to illustrate the upfront finance required for self-financed and funded split ownership Shared Ground Loop Arrays in a typical retrofit housing development featuring the Kensa Shoebox heat pump.
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Heat Pump System
| System architecture | Shared Ground Loop Arrays |
| Total heat pump capacity | 135.9kW |
| Equipment type | 28 x 6kW Shoebox |
| Design conditions | 0/50°C |
| Potable DHW temp | 60°C |
| Integral immersion heaters | No (DNO friendly) |
| Ground array type | Boreholes |
| Total depth of boreholes | 2,500 metres |
*Boreholes based on average ground conductivity. Average 18 sq/m per property – each borehole serves a minimum of 2 properties.
Total Project Costs, Savings & Returns vs Electric NSH
| Kensa Ground Source Heat Pumps & Shared Borehole Ground Array | Electric NSH |
| Finance Option | Self-Financed | Funded Split Ownership | Self-Financed |
| Lifetime Expectancy: Appliance | Up to 20 years | Up to 20 years | Up to 10 years |
| Lifetime Expectancy: Infrastructure | Up to 100 years | Up to 100 years | - |
| | | |
| Carbon Saved vs. NSH (over 20 years)* | 3,614 TCO² | 3,614 TCO² | - |
| Local NOx Emissions Saved** | 13.1 kgNOx/y | 13.1 kgNOx/y | 13.1 kgNOx/y |
| | | |
| Appliance, Infrastructure & Project Management Cost ^ | £419,750 | £168,425 | £136,613 |
| | | |
| Running Cost Savings vs. NSH (over 20 years)*** | £319,531 | £319,531 | - |
| Servicing Costs Per Property (over 20 years)**** | £2,000 | £2,000 | £2,000 |
| | | |
| ECO Funding Contribution | £36,137 | £36,137 | Not eligible |
| RHI Income (over 20 years)***** | £592,260 | - | Not eligible |
| | | |
| Net cost (after 20 years)****** | £208,647 profit | £132,288 cost | £136,613 cost |
*Carbon saving based on carbon emissions of 0.519kgCO2/kWh for electric. Assumes 100% efficiency for electric and 300% efficiency for ground source heat pumps.**NOx emission based on 44mg per kWh based on a worcester greenstar combi. ***Based on electric at 15p/kW/hr and COP of 3. ****Ground source heat pumps have no requirement for annual maintenance. However, it is good practice for the heating distribution system to be proactively checked and maintained to ensure optimum performance G3 Cylinder check will be requried. *****The Non-Domestic RHI is a 20 year index linked funding stream which assumes inflation at 3%. ******Net cost does not include servicing and running costs. ^ Retrofit costs include internal fit out i.e. new radiator systems. Tenant network connection fee applies.
Please note: The Non-Domestic RHI has now ended. Visit Kensa Heat Pumps to explore current funding options.
Example: Capex
Cumulative Deficit / Surplus Over 20 Year RHI Period
Counterfactual based on electric NSH costs
Please note: The Non-Domestic RHI has now ended. Visit Kensa Heat Pumps to explore current funding options.
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Ground Source Review: South Shropshire Housing Association Kensa Heat Pumps’ contracting division, Kensa Contracting Ltd, were appointed by South Shropshire Housing Association as the principal contractor for a £500k heating upgrade scheme comprising ground source heating systems at two of Shropshire’s sites; St Mary’s Place and College Close in Cleobury Mortimer,Shropshire. The scheme comprises twenty…
Download Kensa’s two-page guide to funded Shared Ground Loop Arrays in new build developments, including funded project examples and details of the funding mechanism.
