Diocese of Guildford heat pump programme case study | ReEnergise

We managed a complex, multi-site heat pump installation programme across 11 schools. It is estimated to save over 467 tonnes of CO₂ annually.

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