Futureproofing buildings at Westonbirt, The National Arboretum
Doug Johnson
How detailed building performance analysis is helping rural estates and visitor attractions plan for net zero.
Westonbirt, The National Arboretum near Tetbury in Gloucestershire, has one of the world’s most celebrated botanical collections. It is home to over 2,500 different species of trees and shrubs gathered from across the globe, as well as five national tree collections.
Created in the 1800s by Victorian landowner Robert Holford and his family, the 600-acre estate has been managed by Forestry England since 1956. The arboretum welcomes hundreds of thousands of visitors every year and is supported by over 300 volunteers. It also conducts important scientific research and plays a significant role in education and international tree conservation of some of the world’s rarest trees.
The arboretum is now one of the most visited pay-to-enter attractions in the Southwest. Visitor numbers have doubled in the last 10 years, putting greater pressure on the park’s infrastructure, along with balancing the additional challenge of climate change.
This has created the need for a long-term, sustainable plan to improve the energy efficiency and decarbonisation of the buildings on the estate – from the visitor’s centre, café and restaurant to the Great Oak Hall, offices and other amenities.
A Strategic Approach to Decarbonisation in a Sensitive Rural Setting
Following a tender process, Mesh was appointed to develop a clear and practical pathway towards reducing operational carbon emissions across the Westonbirt estate.
The brief extended beyond simply replacing technologies. It required a holistic understanding of how its buildings perform – from the café and restaurant to the offices, how they will be used in the future, and how climate change will affect user comfort and long-term resilience.
For rural estates, parks and visitor attractions, these challenges are increasingly common – constrained infrastructure, seasonal and variable occupancy or visitor numbers, heritage considerations, and the need to balance capital investment with long-term operational savings.
Integrated Analysis to Inform Decision-making
Mesh carried out a series of integrated building performance and services engineering assessments to help Forestry England understand the feasibility, economic implications and long-term benefits of different strategies.
The analysis included:
These analyses used dynamic simulation models for each building to create an integrated energy strategy that simplified decision-making and cost planning for the client.
Addressing Rural and Heritage Challenges
Each building at Westonbirt presented different challenges, with variations in age, construction type and patterns of use. The Grade I landscape status required careful consideration of installations and changes to heritage buildings.
The rural electrical supply was originally designed for smaller-scale loads and required detailed investigation to ensure future compatibility with all-electric systems, such as instant hot water and EV charging stations, and to transition away from fossil fuels.
These are issues shared by many rural estates and visitor attractions, where infrastructure constraints and heritage considerations can make decarbonisation a huge challenge without robust technical evidence to inform decision making.
Practical Recommendations
Mesh’s recommendations focused on realistic, deliverable measures that could be implemented in phases to reduce carbon emissions and energy costs – and using a refurbishment-first approach.
Several recommendations have already been implemented, providing immediate benefits whilst informing longer-term refurbishment plans
Supporting the Journey Towards Net Zero for Estates and Attractions
Reflecting on the project, Forestry England highlighted the value of detailed analysis to shape decisions and specifications that balance sustainability, user comfort and operational resilience.
According to Sophie Nash, Programme Manager at Forestry England:
“Our aim with this project was to use detailed analysis to steer our specifications for remediation and upgrading works to improve the energy efficiency and sustainability of our most heavily-used buildings at Westonbirt.
We needed to examine the options for upgrading our electricity capacity which is currently constrained with this being a rural site and yet demand continues to increase. The third element was to undertake a detailed study for overheating and how the predicted rise in temperatures would affect some of our buildings and users in the summer months.
We are happy with the assessments carried out which were very thorough and detailed.
Our intention is to move forward with Mesh’s recommendations and to feed this insight into the design and specification of refurbishment and remediation works in a phased approach. The first of these recommendations have now been actioned.”
For rural estates, landowners, parks and visitor attractions across the UK, this project for Forestry England demonstrates how a data-led, whole-building approach can accelerate decarbonisation and create a clear route towards net zero – even in the most sensitive heritage environments.
How Mesh Supported Forestry England
• Renewable energy feasibility studies
• Initial fabric optimisation
• Dynamic overheating and ventilation modelling
• Building energy and electrical capacity analysis
• Low-carbon heating and hot-water strategy
If you manage or advise a rural estate, heritage site or visitor attraction and are exploring how to improve the energy efficiency of buildings and reduce carbon emissions, Mesh can provide independent analysis to guide strategic direction for futureproof decision making and long-term resilience in the face of climate change.
Created in the 1800s by Victorian landowner Robert Holford and his family, the 600-acre estate has been managed by Forestry England since 1956. The arboretum welcomes hundreds of thousands of visitors every year and is supported by over 300 volunteers. It also conducts important scientific research and plays a significant role in education and international tree conservation of some of the world’s rarest trees.
The arboretum is now one of the most visited pay-to-enter attractions in the Southwest. Visitor numbers have doubled in the last 10 years, putting greater pressure on the park’s infrastructure, along with balancing the additional challenge of climate change.
This has created the need for a long-term, sustainable plan to improve the energy efficiency and decarbonisation of the buildings on the estate – from the visitor’s centre, café and restaurant to the Great Oak Hall, offices and other amenities.
A Strategic Approach to Decarbonisation in a Sensitive Rural Setting
Following a tender process, Mesh was appointed to develop a clear and practical pathway towards reducing operational carbon emissions across the Westonbirt estate.
The brief extended beyond simply replacing technologies. It required a holistic understanding of how its buildings perform – from the café and restaurant to the offices, how they will be used in the future, and how climate change will affect user comfort and long-term resilience.
For rural estates, parks and visitor attractions, these challenges are increasingly common – constrained infrastructure, seasonal and variable occupancy or visitor numbers, heritage considerations, and the need to balance capital investment with long-term operational savings.
Integrated Analysis to Inform Decision-making
Mesh carried out a series of integrated building performance and services engineering assessments to help Forestry England understand the feasibility, economic implications and long-term benefits of different strategies.
The analysis included:
- Renewable energy feasibility studies – evaluating air and ground source heat pumps, solar photovoltaics, EV charging, comfort cooling, and low-carbon hot-water solutions for buildings with fluctuating visitor numbers.
- Fabric optimisation – Assessing walls, insulation, roofs, floors and glazing to identify cost-effective improvements with realistic payback periods and lower embodied-carbon impacts, supporting a refurbishment-first approach.
- Overheating and ventilation modelling – Dynamic thermal modelling (TM52) to mitigate the risk of overheating in the peak summer months and the impact of climate change on occupier comfort. The study investigated cooling using heat pumps, the viability of mechanical ventilation and heat recovery (MVHR) and solutions to increase natural ventilation as alternatives to carbon and energy-intensive air conditioning.
- Electrical infrastructure and capacity review – Assessing the existing site electrical supply and predicting energy supply and demand to accommodate future electrification, EV charging and additional loads from Westonbirt’s summer event programme.
These analyses used dynamic simulation models for each building to create an integrated energy strategy that simplified decision-making and cost planning for the client.
Addressing Rural and Heritage Challenges
Each building at Westonbirt presented different challenges, with variations in age, construction type and patterns of use. The Grade I landscape status required careful consideration of installations and changes to heritage buildings.
The rural electrical supply was originally designed for smaller-scale loads and required detailed investigation to ensure future compatibility with all-electric systems, such as instant hot water and EV charging stations, and to transition away from fossil fuels.
These are issues shared by many rural estates and visitor attractions, where infrastructure constraints and heritage considerations can make decarbonisation a huge challenge without robust technical evidence to inform decision making.
Practical Recommendations
Mesh’s recommendations focused on realistic, deliverable measures that could be implemented in phases to reduce carbon emissions and energy costs – and using a refurbishment-first approach.
- Transitioning from the existing gas space heating systems to air-source heat pumps.
- Using on-demand electric hot-water systems to address significant variations in visitor footfall through the year.
- Improving user comfort during the peak summer months through natural ventilation strategies, such as automatic opening rooflights, supported by cooling using heat pumps to support the move away from air conditioning.
- Fabric improvements, such as increasing insulation to roofs and external walls
- Phased upgrading of the electrical supply to future-proof the estate for expansion and accommodate EV charging and cooling loads, and to create a more resilient estate.
Several recommendations have already been implemented, providing immediate benefits whilst informing longer-term refurbishment plans
Supporting the Journey Towards Net Zero for Estates and Attractions
Reflecting on the project, Forestry England highlighted the value of detailed analysis to shape decisions and specifications that balance sustainability, user comfort and operational resilience.
According to Sophie Nash, Programme Manager at Forestry England:
“Our aim with this project was to use detailed analysis to steer our specifications for remediation and upgrading works to improve the energy efficiency and sustainability of our most heavily-used buildings at Westonbirt.
We needed to examine the options for upgrading our electricity capacity which is currently constrained with this being a rural site and yet demand continues to increase. The third element was to undertake a detailed study for overheating and how the predicted rise in temperatures would affect some of our buildings and users in the summer months.
We are happy with the assessments carried out which were very thorough and detailed.
Our intention is to move forward with Mesh’s recommendations and to feed this insight into the design and specification of refurbishment and remediation works in a phased approach. The first of these recommendations have now been actioned.”
For rural estates, landowners, parks and visitor attractions across the UK, this project for Forestry England demonstrates how a data-led, whole-building approach can accelerate decarbonisation and create a clear route towards net zero – even in the most sensitive heritage environments.
How Mesh Supported Forestry England
• Renewable energy feasibility studies
• Initial fabric optimisation
• Dynamic overheating and ventilation modelling
• Building energy and electrical capacity analysis
• Low-carbon heating and hot-water strategy
If you manage or advise a rural estate, heritage site or visitor attraction and are exploring how to improve the energy efficiency of buildings and reduce carbon emissions, Mesh can provide independent analysis to guide strategic direction for futureproof decision making and long-term resilience in the face of climate change.
Images: Forestry England / Johnny Hathaway / Brian Martin / Rob Cousins
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Mesh has been announced as a runner up for Energy Consultancy of the Year at the National Energy Efficiency Awards. This latest accolade follows our success in winning Regional Energy Efficiency Consultancy of the Year at the South East Energy Efficiency Awards. According to Doug Johnson, Founding Director of Mesh: "As one of the smaller, specialist consultancies, this was a significant achievement for such a prestigious award and in a highly competitive category. The awards event was a fantastic celebration of innovation and achievement in improving energy efficiency across the built environment. Our teams are committed to excellence in both building performance analysis and building services design – delivering practical solutions and strategies for our clients to accelerate decarbonisation and improve the energy efficiency of new and existing homes and buildings. It is wonderful to have our team's talent and hard work recognised with this national accolade from the industry."

Adapting heritage buildings for modern use creates a particular engineering challenge – how do you deliver comfort and energy performance, within the constraints of a historic building? Doug Johnson, Mesh Founding Director of building performance specialists Mesh, shares his insight from a recent project. When we talk about successful heritage transformations, the conversation usually focuses on the architectural design and the restoration process. Less visible but equally important, is the role of building services engineering. Change of use breathes new life into historic buildings. However, achieving year-round comfort for visitors and occupiers of galleries, offices, hospitality or retail can be challenging, not least when occupancy levels fluctuate. Historic buildings are expected to deliver the same standards of comfort, environmental control and operational performance as modern buildings, yet they were never designed to accommodate contemporary MEP systems. Getting that balance right requires different thinking. A Grade II listed Georgian townhouse in London's Mayfair was recently transformed into a space for contemporary art. This provides a useful illustration of the principles involved and how the challenges were addressed. Dating back to the 1730s, the six-storey building in Mayfair was once home to the Burlington Fine Arts Club. It has now been sensitively converted into a suite of contemporary art galleries for Sadie Coles HQ. The objective was not simply to install heating and cooling. It was to create a comfortable, flexible, efficient and futureproof internal environment whilst ensuring that the engineering services remained almost entirely invisible. The Importance of Designing Around Occupancy A key consideration for intelligent building services design is looking at the predicted occupancy levels and whether these will vary. Museums, galleries, visitor attractions, civic buildings and cultural venues can all move rapidly from quiet periods of low occupancy to large events with significant increases in heat gain and ventilation requirements. Rather than designing for a single occupancy assumption, modelling multiple use scenarios provides a much clearer understanding of how a building needs to perform throughout the year. By analysing different occupancy patterns, environmental conditions and operational requirements, MEP systems can be sized more accurately to avoid both underperforming and over-engineered solutions which increase energy consumption. In heritage projects, this approach is particularly valuable because space for plant and services is often limited. Every piece of equipment needs to justify its inclusion. Early Co-ordination and Integration with the Architectural Design Heritage and listed buildings rarely offer generous service routes. Unlike new-build projects, where risers, ceiling voids and plant spaces can be designed in from the outset, historic buildings often require services to be threaded through a series of constrained voids. This challenge becomes even greater in tall, narrow buildings such as townhouses, where plant may need to serve multiple floors through restricted vertical routes. The lesson is clear – building services engineering has to be designed in from the outset. Early collaboration between architects, engineers and conservation specialists is essential to establish whether the proposed systems are feasible, where equipment can be located and how services can be integrated within the building fabric. The earlier this co-ordination takes place, the greater the opportunity to avoid compromise, reduce project risk and optimise energy efficiency. Increasing Capacity for Heating and Cooling in a Heritage Setting A common response to increasing heating or cooling demands is simply to add more equipment. In many heritage settings, that option is not possible. Planning restrictions, minimising visual impact and noise levels, and conservation requirements often limit the number and location of external plant units. Roofs, courtyards and rear elevations frequently offer little flexibility which demands a more intelligent approach to system design. On the Sadie Coles gallery project, instead of increasing the number of external units, a zoned strategy was developed which matched available plant capacity to individual rooms based on anticipated occupancy patterns and the predicted demand for heating and cooling. This allowed the available capacity to be used with greater energy efficiency whilst maintaining compliance with planning constraints. The broader lesson is that building performance is not solely determined by the quantity of equipment installed. Understanding how spaces are used often unlocks opportunities to achieve enhanced performance within the available infrastructure. Maintaining a Clean Aesthetic The most effective building services design is often the least visible whilst meeting performance requirements. This is particularly true in heritage settings where restored architectural features, historic detailing and carefully considered interiors should remain the focus. Achieving this requires close collaboration with the wider design team. Diffusers, grilles, fan coil units, controls and service routes must be carefully integrated into the architecture rather than be imposed upon it. In gallery environments, there is an additional consideration – the services engineering must not distract from the exhibits themselves, either visually or acoustically. This demands a level of co-ordination and design discipline that goes beyond compliance. Passive Design Matters Any building should be as energy efficient as possible and passive measures often provide some of the most effective opportunities to improve comfort whilst minimising energy consumption. In the Mayfair gallery, a glazed roof lantern was both a beautiful architectural feature and a potential source of overheating. Rather than relying solely on active cooling, actuated roof lights were incorporated into the glazing above to allow warm air to be purged naturally from the space below. Combined with natural ventilation through restored sash windows, this approach reduced cooling demand whilst improving thermal comfort. These principles are not new, but remain highly relevant. Understanding airflow, solar gain and natural ventilation can often deliver significant benefits alongside the design of mechanical systems. Futureproofing Heritage Assets Buildings that have survived for centuries have often done so because they have adapted over time. The services strategy should support that continued evolution. Futureproofing does not necessarily require major additional investment. Sometimes it simply means incorporating connection points, spare capacity or flexible infrastructure that allows future adaptations to be made more easily. In the case of the gallery project, provision was included for supplementary low-level electric heating should the building use change. Such measures may never be required, but they provide resilience and flexibility that can extend the useful life of the building with the least disruption possible. Services Engineering to Support Heritage Buildings Successful heritage refurbishment is not about choosing between conservation and performance. It is about achieving both. The most effective building services solutions are those that support the architectural and client vision, improve comfort, reduce energy consumption and remain largely unseen by the people using the building. When done well, engineering becomes part of the fabric of the building rather than an addition to it. That is ultimately what intelligent building services design should achieve – modern performance delivered in a way that respects the past whilst preparing buildings for the future. The Project Team: Client: Sadie Coles HQ Lead contractor (design and delivery): Work Ltd Architectural partner: Giles Reid Architects MEP design / building performance: Mesh About Mesh Mesh offers a range of design and engineering services to help organisations in the public and private sectors to improve the energy efficiency of new and existing buildings, housing and estates. This includes support for architects; planning; thermal modelling and overheating analyses; carbon reduction strategies; feasibility studies for renewable technologies; MEP design, and regulatory compliance.

Mesh has been appointed to work on three new care home projects – in Cambridge, Barnstaple and in the Exmoor National Park – providing assistance with regulatory compliance, analysis to mitigate overheating, energy strategy development, and low-carbon services design, engineering, and specification. There has been a significant increase in demand for Mesh's building performance services for care home projects this year. There are a number of drivers: Running costs - there is a clear need to reduce operational costs in care homes given global uncertainty around energy prices. Comfort - It is vitally important to maintain the comfort of residents and vulnerable people, and particularly to reduce the risk of overheating in light of climate change and rising temperatures in the summer months. Performance - New build care homes and extensions have to perform over time rather than simply meet minimum requirements for statutory compliance. Sustainable living - In a competitive care home market, more sustainable living accommodation means lower bills for residents and enhanced wellbeing. Dylan Ross of Mesh: “Care homes are occupied 24/7 so building performance and energy efficiency really matters. We are seeing more care home developers and operators look beyond regulatory compliance and at how their buildings will actually perform over time – in terms of energy use, thermal comfort and maintenance implications. Our role is to bring building performance and services design together using evidence-led solutions to help inform decision making and deliver buildings for social care that maximise comfort for residents and minimise energy consumption, carbon emissions and running costs for care home operators.” Mesh specialises in improving the energy efficiency of both new and existing buildings, and works with care home operators, developers and architects.

Mesh Works with Hampshire & IOW Fire & Rescue Service to Improve the Energy Efficiency of its Estate
Building performance specialist Mesh has worked with Hampshire Fire & Rescue Service to improve the energy efficiency of its building estate and support decarbonisation.

Reducing the Environmental Impact of our Business and Supporting Global Carbon Reduction Initiatives
As part of our sustainability and netzero commitments, we contribute to the Climate Action Workforce – a service provided by Ecologi that allows businesses to fund certified carbon reduction and tree-planting projects on behalf of their employees. This helps us to engage our teams in collective environmental impact, supporting global reforestation, habitat restoration, and certified carbon avoidance initiatives. In the past month, we have contributed to: - Agroforestry in Kenya - The provision of fuel-efficient cooking stoves in Uganda - Protection of the Matavén forest in eastern Colombia. Since Mesh joined the Ecologi scheme, we are proud to have supported 85 global projects , each carefully vetted for quality and impact. If you would be interested in measuring and reducing your business carbon footprint and contributing to global carbon reduction schemes, do check logout Ecologi .
























