ReEnergise Group

Worth School & Abbey biomass district heat network | ReEnergise

ReEnergise Group — Thu, 10 Sep 2026 13:53:54 GMT

ReEnergise replaced 35 oil boilers with a 1.6MW biomass energy centre and 1.7km heat network serving 24 buildings, saving around 940 tonnes of CO₂e a year.

ReEnergise delivered all phases of this project from concept and feasibility right through to maintenance management, resulting in the transition of the Worth School and Abbey estate away from ageing oil-fired heating to a campus-wide biomass district heat network.

The completed project replaced 35 oil boilers across 24 buildings with a new centralised low-carbon energy centre, reducing operating costs at the same time as saving approximately 940 tonnes of CO₂e carbon emissions every year, and future-proofing the estate.

Background

The extensive Worth School and Abbey estate was supplied with heat and hot water by ageing, distributed oil-fired boilers that were becoming increasingly inefficient, expensive to maintain and incompatible with their long-term sustainability ambitions.

The solution

ReEnergise conducted a detailed estate decarbonisation study and business case assessment and proposed two 800kW biomass boilers in a new build energy centre, backed-up by a new LPG boiler. This was to supply a 1.7km district heat network serving the whole estate, including capacity and connection points for future buildings. With a potential life of 50 to 100 years the heat network would facilitate future generations of centralised biomass boilers.

Biomass produces hot water at the same temperature as the old oil boilers, so there was no need for changes to the internal heat distribution systems (radiators, pipework and hot water tanks). Indeed, the improved performance of the biomass over the oil boilers meant that problems where areas were previously inadequately heated were resolved.

ReEnergise progressed the project following its step-by-step risk reduction process through design, tender, project management and finally optimization and maintenance management.

ReEnergise also secured ongoing funding for the operation of the system through the Government’s Renewable Heat Incentive (RHI) scheme, tendered for biomass fuel supply and provided a bespoke LoRaWAN monitoring system for every building, to ensure optimum performance.

The challenge

Delivering a buried district heating network across a live school and abbey estate presented significant logistical challenges. The 1.7km heat network crossed public roads, play areas, church and residential property grounds and was installed while the day-to-day operations of the estate continued.

The programme also had to be completed within demanding timescales despite COVID disruptions to meet the RHI deadlines.

Implementation

Estate decarbonisation planning.
Business case development.
Tender management including future term maintenance and biomass supply.
Full project management.
Weekly stakeholder communications.
Rolling three-week construction programme.
Coordination across school operations.
Programme completed within one year.
Close coordination between contractors, school leadership and the Abbey ensured disruption was minimised throughout construction.
Maintenance management.

Technology

New build energy centre with walking floor biomass feed system.
2 × 800kW biomass boilers.
1.6MW biomass energy centre.
LPG back-up boiler.
1.7km district heat network.
Heat metering and remote monitoring.
Future-proof network connections.

Results

24 buildings connected.
35 oil boilers replaced.
Approximately 940 tonnes CO₂e saved annually.
Lower fuel and maintenance costs.
Renewable Heat Incentive successfully accredited.
Contract variations below 3%.
Infrastructure prepared for future expansion.
Heat network designed for a service life exceeding 50 years.

Diocese of Guildford heat pump programme case study | ReEnergise

ReEnergise Group — Tue, 01 Sep 2026 10:14:30 GMT

ReEnergise planned and managed 15 heat pump installations across 11 schools, forecast to save 467 tonnes of CO₂ and 1,800 MWh each year.

Background

In 2021, the Diocese of Guildford appointed ReEnergise as its Net-Zero and Decarbonisation Consultant to help decarbonise 41 of its Church of England schools. This aligned with both diocesan values and national targets to cut carbon emissions across the public sector estate.

The challenge

Many diocesan schools were operating with ageing, fossil-fuel-based heating systems. The diocese faced the dual challenge of decarbonising these buildings while navigating the complex funding mechanisms needed to support such a large-scale transition.

The solution

We supported the diocese in securing a £253k Low Carbon Skills Fund (LCSF) grant in 2021, enabling us to produce Heat Decarbonisation Plans (HDPs) for 41 diocesan schools. Based on these, we created a prioritised implementation strategy and led a successful Public Sector Decarbonisation Scheme (PSDS) Phase 3b grant application. We were then appointed to project manage the installations.

Implementation

2021: Secured LCSF grant; 41 HDPs developed by ReEnergise.
2022: Implementation strategy developed; PSDS grant application submitted.
Early 2023: PSDS grant approved.
July 2023 – March 2025: Installation of 15 systems across 11 schools.
Installation by Aston Cord Energy Services Ltd.
Project management by ReEnergise.

Technology

The project used Viessmann air source heat pump systems tailored to each school’s needs. These covered a range of capacities from 10kW to 384kW. For example:

10kW Vitocal 150-A units, including at Newdigate Pre-School.
384kW systems using three Vitocal 200-A Pro units, including at The Priory School, Dorking.

All systems were designed to operate efficiently, even at -5°C, and are now supported by remote energy and performance monitoring for continued optimisation.

Business case

Annual CO₂ savings: estimated 467 tonnes.
Annual energy savings: 1,800 MWh.
70% reduction in energy usage across upgraded schools.
Long-term reduction in energy bills and exposure to fossil fuel price volatility.

The secured funding made the capital works affordable for the diocese, enabling progress towards Net-Zero targets.

Results

As a result of this programme, and the manner of its delivery, the Diocese of Guildford has become an example for the Church of England Net-Zero Programme.

Effective management of a complex programme with several tiers of stakeholders.
Every school was pleased with its solution.
Systems were specifically designed to match each school’s needs.
Each system was fitted with weather compensation to ensure reduction in energy usage.
As consultants, and in collaboration with the manufacturer, we continue to monitor and optimise performance and support the maintenance teams throughout the transition.

Client testimonial

“The Diocese began working with ReEnergise in 2021. Their support has been invaluable for the complexities of decarbonising estates - from advice and design to project management and securing grants. They are professional, transparent with costs, and manage projects efficiently, even under tight deadlines. Their knowledgeable and approachable staff work effectively with all our stakeholders. And their long-term commitment to Net Zero gives me confidence in continuing our partnership.”

Mike Giles
School Buildings & Estates Manager, Diocese of Guildford

The Corsham School biomass district heating case study | ReEnergise

ReEnergise Group — Tue, 01 Sep 2026 10:14:29 GMT

ReEnergise planned, designed and project-managed a biomass district heating and efficiency programme, forecast to save 277 tonnes of CO₂ and £1.56m over 20 years.

Background

The Corsham School previously relied entirely on gas for heating and hot water. In line with its net-zero strategy, the school partnered with ReEnergise to plan, design and deliver a comprehensive decarbonisation project, centred around a biomass energy solution.

The challenge

The project faced tight delivery deadlines due to the need to complete the majority of the works during school holidays to minimise disruption to student activities. Planning amendments, site constraints, asbestos removal, and the need to maintain uninterrupted heating supply during peak winter added layers of complexity.

The solution

ReEnergise managed the full lifecycle of the project: from heat decarbonisation planning, detailed design, to tendering, contract administration, contractor oversight, grant drawdown, staff handover and training.

A new biomass plant room was installed below ground, and the heat main was routed across school fields to minimise disruption. Building fabric improvements were integrated into the decarbonisation works in order to optimise energy efficiency. This included insulation, LED lighting upgrades, and domestic hot water system improvements.

Implementation

Two 300kW biomass boilers installed.
Heat main trenching scheduled for summer holidays.
Planning application managed seamlessly.
Site access challenges mitigated via compound zones, staff/student briefings and tight programme management.
Project duration: 9 months to full operation.

Technology

Energy efficiency measures: insulation, LED lighting, hot water system upgrades.
New biomass plant room with 2 x 300kW boilers.
Woodchip fuel supply.
District heat network.

Business case

Estimated CO₂ reduction: 277 tCO₂/year.
Lifetime fuel cost savings: £1.56m (over 20 years).
Public Sector Decarbonisation Scheme (PSDS) grant funding with 12% client contribution.

Results

Heating system is now net-zero in all buildings served by the biomass.
Asbestos safely removed from two plant rooms.
Domestic hot water systems upgraded to meet current standards.
Improved environmental comfort and energy performance.
No unplanned heating downtime during project.

Client testimonial

“ReEnergise were carefully chosen to write our self-funded Estate Decarbonisation Plan with a view to the School making an application for a PSDS grant. The EDP process was managed efficiently from the initial phase of data gathering to production of the final report. The school was kept engaged in the process throughout, and from the presentation of options by ReEnergise we were able to confidently select our future low-carbon heating solution. ReEnergise supported us every step of the way with the PSDS application process right through to award of the grant. We are very excited to continue to work with ReEnergise to deliver our low-carbon solutions and to start our decarbonisation journey.”

Amanda Chapman-Richardson
School Business Manager, The Corsham School

St George’s College ground source heat pump case study | ReEnergise

ReEnergise Group — Tue, 01 Sep 2026 10:14:28 GMT

ReEnergise developed and delivered an 888kW ground source system serving seven buildings, integrating passive cooling and capacity for future development.

St George’s College Weybridge operates a complex campus of buildings ranging from state-of-the-art teaching facilities to structures hundreds of years old. The College wanted to replace the existing gas-fired heating installation serving its core buildings, reduce long-term energy costs and carbon emissions, and create infrastructure capable of supporting future development.

ReEnergise developed the ground source heat pump project from initial concept through business-case modelling, design, tendering, project and site management, Renewable Heat Incentive (RHI) accreditation and subsequent optimisation.

The challenge

The project had to be delivered across a live College campus and within a demanding RHI timetable. COVID-19 initially caused the project to be paused, while later changes to the RHI reduced the proportion of capital cost expected to be recovered. Once the College decided to proceed, the team also had to manage difficult ground conditions, severe winter weather, global equipment shortages and the challenge of fitting major new plant into an existing plant room. Initial investigations indicated that 90 boreholes at 195 metres would be required. During drilling, the achievable depth proved to be approximately 140 metres and thermal response testing showed that additional boreholes would be needed. The ground array therefore had to be redesigned and extended without losing control of the programme.

The business case

The original business case showed the project could be broadly self-funding through the RHI. When the tariff fell, ReEnergise remodelled the case and confirmed that around half the project cost would be recovered. The College proceeded for the long-term operational and carbon benefits, with ReEnergise securing accreditation.

The solution

ReEnergise modelled and designed a system using four 222kW ground source heat pumps installed in the existing plant room. The revised ground array comprised 132 vertical boreholes at approximately 140 metres, serving four existing buildings and connecting a further three buildings across the College’s core.

Distribution valves and controls were upgraded to create a demand-led, climate-controlled system. When the College later planned a new teaching block, ReEnergise remodelled the system to confirm the available heating capacity and conceived and designed the addition of passive cooling using the ground array.

Implementation

Phased business-case modelling and design allowed the College to pause the project during COVID-19 before committing major expenditure.
ReEnergise managed the RHI and Tariff Guarantee process, planning requirements, surveys and technical investigations.
Drilling and thermal response testing informed the redesign from 90 × 195m to 132 × 140m boreholes.
The installation contractor was competitively appointed, with ReEnergise managing drilling, installation, commissioning and reinstatement around live College operations.
ReEnergise continues to advise on system performance, optimisation and future development.

Technology

4 × Viessmann 222kW ground source heat pumps, providing 888kW total capacity.
132 vertical boreholes at approximately 140m beneath the Orchard pitch and adjoining sports areas.
Low-carbon heat supplied to seven core College buildings using capacity from two on-site substations.
Upgraded distribution valves and demand-led climate controls.
Passive cooling using the existing ground array.

Results

Lower-cost, low-carbon heating and improved comfort across seven core College buildings.
Passive cooling, combined with on-site solar and building design, helped the College maintain its full academic programme during recent heatwaves.
RHI accreditation successfully secured.
Infrastructure designed to support future buildings and further extension.
Continued engineering advice and optimisation across heating, cooling and controls.

Client testimonial

“Without the patience, clarity and expertise of ReEnergise we would not be saving the money we are or have as comfortable an environment as we do. Money well spent.”

Greg Cole
Bursar, St George’s College, Weybridge

Hockerill College heat decarbonisation case study | ReEnergise

ReEnergise Group — Tue, 01 Sep 2026 10:14:27 GMT

ReEnergise redesigned and project-managed a combined biomass and heat pump solution, forecast to save 84 tonnes of CO₂e and £11,000 a year.

Hockerill College has replaced gas-fired heating systems with a combination of biomass and air source heat pump (ASHP) technologies. The work, supported by a £555k grant through the Public Sector Decarbonisation Scheme (PSDS) and project-managed by ReEnergise, included a new district heating system for student accommodation and the Science Building, and ASHPs for a separate music building.

The project is expected to save approximately 84 tonnes of CO₂e per year and approximately £11,000 annually in energy costs.

Background

Prior to this project, Hockerill College relied on gas for all its heating and hot water. The college partnered with ReEnergise to transition to low-carbon heating systems and reduce long-term energy costs.

The challenge

The college site posed several logistical challenges. For example, the need to minimise visual impact due to its location in the Bishop’s Stortford conservation area, and tight site conditions for construction. The project team also needed to avoid any disruption to heating supply during term time and maintain clear communication with the college throughout.

The solution

The original system had been scoped to be a Ground Source Heat Pump (GSHP) system, but during the outline design stage it was determined that the resulting changes required to the internal distribution system would exceed the anticipated grant budget. It was therefore agreed with the college to opt for a biomass system. The biomass installation was built below ground to minimise impact on local views.

The Music Building, also in scope for the project, was better served by opting for a separate stand-alone ASHP system due to its distance from the biomass energy centre.

Energy efficiency improvements included new VSD pumps, and a water treatment system to mitigate hard water issues.

Implementation

Subsurface biomass energy centre installed due to restricted access.
ASHPs deployed to serve the separate Music Building.
Weather compensation has been utilised on both systems to allow them to reduce consumption by altering the output in line with the weather conditions at the time.
Water treatment device added to help prevent corrosion of the system.
Project duration: 12 months (2 months for system installation).
Ensuring no downtime to heating during the switch-over period.

Technology

Biomass boilers using sustainably sourced woodchips.
Underground fuel store and plant room.
Air Source Heat Pumps for heating a separate building.
Variable Speed Drive (VSD) pumps.
Water treatment device (Elysator).

Business case

Annual CO₂ savings: approximately 84 tonnes.
Annual financial savings: approximately £11k.
PSDS-funded with client contribution.

Results

£555k in grant funding successfully drawn down.
Delivered under budget and on time with contingency remaining.
Improved heating system reliability and efficiency.
Enhanced occupancy comfort and reduced environmental impact.