Futureproofing buildings at Westonbirt, The National Arboretum

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:

• 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.