Thedden Grange Clean Heat Project – feasibility study completed

In February 2022 Energy Alton applied for an RCEF Phase 1 grant to complete a clean heat and renewable energy generation feasibility study for Thedden Grange. We contracted Basingstoke Energy Services (BES) to carry out the study and they produced a comprehensive report. We expected the Thedden Grange project to be a challenge as the buildings date from the early 19th century and were divided into 7 separate dwellings in 1975, and we were right; but the report was finally completed in January 2024.

The study considered not just the current energy needs of the Grange, but also likely needs over the coming decades. Whilst there are complex interactions between how much powering down (reducing energy use) and powering up (generating renewable energy for consumption) is carried out, or is acceptable to the residents of Thedden Grange, some clear conclusions can be drawn from this report.

This report has shown that powering down is both technically and economically feasible. Both basic improvements and aspirational changes offer reasonable paybacks. Basic improvements can be implemented rapidly and with relatively small capital outlays. Aspirational improvements are more expensive and have longer payback periods.

Electrification is the key to powering down and decarbonising the Grange, with heating being the primary focus area.  Replacement of existing direct electric and fossil fuelled heating systems with air source heat pumps offers good financial returns and leads to deep de-carbonisation (even without a an accompanying powering up project); and, as grid electricity itself becomes zero-carbon, so does the Grange.

However, there are substantial differences in the financial returns open to individual homeowners. Those with high heat demand and direct electric heating have by far the best financial motivation for electrification. It would therefore be impossible to even out the financial benefits across all seven homes in any community-based approach.

For this reason, the better approach for powering down could be to allow each homeowner to make their own decisions on powering down their own homes.

Powering up offers both good financial and environmental returns, particularly using solar PV and therefore offers the most suitable prospect for a community investment project. An 80-110kW peak solar PV array would supply up to 30% of the electrified Grange’s electricity needs; and would further reduce the Grange’s carbon footprint. 

Power generated onsite will further increase the savings each homeowner could achieve through electrification by providing much lower cost electricity than that available from the grid and by exporting excess electricity to the grid.

Should the residents choose to prioritise environmental over financial returns then a small-scale wind turbine (20-30kW) would also be feasible; however capital costs are far higher thus leading to lower overall returns. Planning constraints may also be a barrier.

Energy Alton believes that this study will advance the knowledge of the issues associated with, and approaches to, de-carbonising older properties. Energy Alton also believes that this study provides the Thedden residents with a number of options to reduce their carbon footprint and reduce their energy costs in the medium to long term.