HMP Exeter – New Visitors Building, Devon

Build Energy provided technical consultancy for the New Visitors Building at HMP Exeter, a new-build facility on the existing prison site at New North Road, Exeter. The building delivers modern, purpose-built accommodation for prisoner family visits, replacing outdated visiting facilities with a structure that meets current standards for welfare, family contact, and operational security. Vinci Construction UK Ltd was the principal contractor, with Mace Group acting as project manager on behalf of His Majesty’s Prison and Probation Service. The project targeted BREEAM Excellent under the BREEAM New Construction 2018 scheme, a rating that required technical evidence across multiple credits – all of which formed part of our scope.

HMP Exeter is a Category B local prison holding adult male prisoners on remand and serving short to medium sentences. The new visitors building sits physically separate from the main prison buildings and forms part of HMPPS’s capital investment programme to modernise visiting facilities across the estate. Construction ran from late 2022 into 2023, with commissioning and post-construction verification extending into 2024.

The BREEAM Excellent target reflects both HMPPS sustainability requirements and the Ministry of Justice’s broader commitment to reducing the environmental impact of the prison estate. Achieving that rating on a secure custodial site brings specific logistical constraints. All personnel require escorts, working hours are governed by the prison regime, and access to plant rooms and service voids must be planned carefully around operational demands.

Build Energy’s involvement spanned RIBA Stage 5 (construction) through to RIBA Stage 6 (commissioning) and post-construction verification. Our scope covered seven distinct BREEAM credit areas, each requiring independent evidence prepared separately and submitted to the BREEAM assessor for scoring.

Build Energy was not the BREEAM assessor on this project. Our role was to provide the specialist technical reports, calculations, and test data that the assessor required to evaluate each credit. A licensed BREEAM assessor independently reviews that evidence and submits to BRE for certification – a separation of roles that is standard practice on BREEAM Excellent projects. Several services involved both design-stage and post-construction work. Two of them – the Indoor Air Quality Plan and the Commissioning Stage Services – ran across the full construction and handover period.

Energy Modelling – BREEAM Ene 01

We produced the energy calculations for the visitors building to support BREEAM Ene 01 – Prediction of Operational Energy Consumption. This credit requires a whole-building energy model that calculates predicted annual energy use and carbon emissions measured against a notional baseline. BREEAM awards credits on a sliding scale based on the percentage improvement over that baseline, so the accuracy of the model directly affects how many credits the building can claim. Our calculation covered the building fabric, heating and ventilation systems, and lighting, producing the documentation the BREEAM assessor needed to evaluate and score the credit.

Thermal Comfort – BREEAM Hea 04

We produced a thermal comfort assessment to support BREEAM Hea 04, which requires the building to demonstrate acceptable internal conditions across a range of weather scenarios. Performance is assessed against CIBSE TM52 and EN 15251. Prison visitors centres present a particular challenge for this assessment: visiting sessions involve high occupant density within a short window, so the model must account carefully for heat gains during those peak periods. Our assessment confirmed the design met the required thresholds and provided the evidence for the BREEAM assessor’s submission.

Indoor Air Quality – BREEAM Hea 02

Our Hea 02 scope covered two distinct deliverables: an Indoor Air Quality Plan produced before construction began, and Indoor Air Quality Testing carried out after construction was complete.

The IAQ Plan specifies the measures the contractor must follow during the construction and fit-out phase – covering material selection, ventilation management, protection of ductwork, and the pre-occupancy flush-out programme. The plan is agreed before works start and followed throughout the build, with the goal of preventing construction-phase pollutants from affecting the indoor environment once the building is occupied.

IAQ Testing takes place after construction and before first occupancy. We measure concentrations of key pollutants – including volatile organic compounds, formaldehyde, and carbon dioxide – against the limits set out in BREEAM Hea 02 and the relevant British and European standards. Where elevated concentrations are found, we advise on remedial action before the building is handed over.

Acoustic Report – BREEAM Hea 05

We produced an acoustic performance report to support BREEAM Hea 05. This credit assesses the building against applicable acoustic standards, covering sound insulation between spaces, background noise from building services, and reverberation in occupied areas. For a prison visitors building, acoustic performance is especially important: the visiting hall must support clear verbal communication between visitors and prisoners, while maintaining separation from adjacent spaces. Our report assessed the design against BB93 and the Hea 05 criteria in BREEAM New Construction 2018.

Commissioning Stage Services – Hea 05, Pol 05 & HMPPS Requirements

We provided commissioning stage services at RIBA Stage 6, covering two BREEAM credits – Hea 05 and Pol 05 – alongside commissioning testing required specifically by HMPPS. BREEAM Pol 05 relates to noise from building services plant. At commissioning we measured noise levels from the installed air handling units, fans, and other mechanical equipment, verifying that levels met the design criteria and did not cause nuisance to occupants or neighbours.

The HMPPS commissioning requirements extend beyond standard BREEAM, specifying their own testing and verification regime for new-build prison facilities. This covers building services performance against the operational demands of the establishment. We carried out interim commissioning testing during the construction phase and subsequently provided documented evidence for both the BREEAM assessor and the HMPPS client team.

Air Permeability Testing

We carried out a post-construction commercial air permeability test on the completed visitors building using fan pressurisation at 50 Pascals, measuring the rate of air leakage through the building envelope. The result demonstrates compliance with Part L of the Building Regulations and contributes to BREEAM Ene 02 credits, which are awarded on a sliding scale – a tighter envelope yields more credits. We confirmed the building’s achieved air permeability and provided the test report to the BREEAM assessor.

Thermographic Survey – BREEAM Man 04

We carried out a post-construction thermographic survey to support BREEAM Man 04 – Commissioning and Handover. A thermographic survey uses infrared imaging to scan the completed building envelope, identifying heat loss, air infiltration, thermal bridging, and defective insulation. The survey must be conducted in cool weather with a sufficient temperature differential between inside and outside to make defects visible in the thermal image. Our report identified areas requiring remedial attention before handover, and provided the photographic evidence of as-built fabric performance required for the BREEAM Man 04 submission.

HMP Exeter is one of several Ministry of Justice projects where Build Energy has provided technical consultancy. We also work with Wates Construction on three further MOJ schemes: the HMP Norwich Video Conferencing Centre, the HMP New Hall, Wakefield new houseblock, and the HMP Wayland, Norfolk houseblock expansion. Across all four projects we deliver services within the principal contractor’s supply chain, covering BREEAM evidence, energy compliance, and acoustic assessment.

Working across multiple contractors within the justice estate has given Build Energy a detailed understanding of the HMPPS capital programme. We know the specific commissioning requirements that apply to new-build prison facilities, the security protocols that govern site access and working hours, and the documentation standards expected by both HMPPS client teams and BREEAM assessors. Find out more about our work across the justice estate on our justice and MOJ framework practice page.

How does Build Energy approach BREEAM evidence delivery on a live operational prison site?

Working on a live prison site requires careful planning around the establishment’s operational regime. All personnel require escort, and access to plant rooms and service voids must be pre-approved and scheduled. Testing activities that generate noise or require extended equipment set-up need to be agreed with the site team in advance. We are experienced in coordinating this kind of access across multiple site visits and credit types. We build the necessary lead times into our programme from the outset, so delays to the BREEAM submission are avoided.

Can Build Energy cover multiple BREEAM credits on a single project, and is that more efficient than using separate specialists?

Yes – on HMP Exeter we covered seven distinct credit areas under a single appointment. These ranged from design-stage energy modelling and thermal comfort through to post-construction air permeability testing, IAQ testing, thermographic survey, and commissioning stage services. Consolidating technical services in this way reduces the number of appointments the principal contractor has to manage, gives the BREEAM assessor a consistent point of contact for the evidence package. Interdependencies between credits – for example between the IAQ Plan and IAQ Testing, or between Pol 05 and the wider commissioning programme – are managed by a single team.

What makes Build Energy’s approach to MOJ and HMPPS projects different from standard BREEAM consultancy?

Prison projects combine the technical rigour of a BREEAM Excellent target with the operational constraints of a secure custodial environment and the specific requirements of an HMPPS client. Our commissioning scope on HMP Exeter included HMPPS-specific testing requirements that go beyond the standard BREEAM credit specification – covering building services performance against the establishment’s operational needs, not just the credit criteria. Having delivered multiple projects across the MOJ estate, we understand how to align the BREEAM evidence programme with the contractor’s construction and commissioning schedule. The goal is always to minimise disruption to the prison’s day-to-day operation.