Climate Change Adaptation Case Study: Ledston Hall, West Yorkshire
This case study shows how to take a step-by-step set of pragmatic decisions to improve the thermal performance of a historic building by improving its windows sensitively and sensibly.
About the property
Ledston Hall is a former country house located in West Yorkshire, between Castleford and Leeds. The building is Grade I listed and is set within a Grade II* registered park and garden. The property has early 13th century origins and saw 7 major phases of building work and adaptions between the 16th and 20th century. The building was on the Heritage at Risk Register and largely vacant for over 70 years prior to the project.
About the adaptation:
In 2015 the architects secured listed building consent and planning permission to extensively repair and convert the Hall into 10 residential properties with function rooms within the core of the building. This application took a conservation-based approach with the retention and refurbishment of the original windows and new single glazed windows to match where required.
In light of the climate emergency and energy cost crisis, the client and design team carried out a full review of the proposals in 2020 to establish whether any further thermal improvements could be made to this historic property. The windows were one area which was explored.
Ledston Hall developed over many centuries and this adaption and evolution is still evident in the building today. Windows on the building were of different ages and design. These included timber sliding sashes, casements and Yorkshire sliding sashes as well as metal framed leaded lights. The condition of the windows varied across the building with a significant number of windows missing or in very poor condition to the north and west of the hall.
The architects engaged in consultation with Historic England and the Local Authority. By agreement of the parties, a sample window was installed in situ to assist with understanding the heritage impact double glazing would have on the listed building.
To assist further, the architects worked closely with their in-house Heritage Consultants and specialist historic glaziers to determine the age and significance of each window. A full condition survey of the windows had previously been conducted by the architects to determine which windows could be repaired and which to replace.
A ‘cocktail’ approach to the windows was agreed which aligned with the development and significance of the listed building. The historically significant windows were retained, repaired and draught sealed with historic glass conserved. More modern metal/lead window interventions and missing windows were replaced with slimline double-glazed leaded and metal windows. All new glazing was heat treated to give the rippling effect in the glass which aligned with the aesthetic of the historic glass.
What happened during the planning process?
The agents sought advice from an architect and heritage consultancy. The architect had pre-application discussions with the local authority and Historic England before applying to Leeds City Council for listed building consent and planning permission to replace the newer windows and retain, repair and thermally upgrade the existing older timber windows in the building.
The final design
There were three options of repair or replacement, depending on the age and condition of the window. A total of 63 windows were replaced with 16 millimetres double glazed units, 30 retained single glazed units, and five were replaced with mono-laminated units. Where possible, historic glass from the metal-framed windows that were removed was reused to repair single glazed windows that were being retained. Furthermore, the timber windows were repaired and draught sealed prior to redecoration.
Impact and lessons learned
- Under the new use and configuration of the building, the new windows will have reduced the overall carbon emissions of the building.
- The new windows will have improved the environment within the properties by reducing draughts and condensation on the glass to make them more comfortable for residents.
- A full understanding of the buildings historical development and significance was essential to help justify the new interventions.
- Early engagement of the statutory consultees was imperative to this scheme.
- Detailed assessment of the significance of all the windows meant the most important were retained, repaired and, in some cases, restored with more appropriate glazing. The overall level of harm to the significance of the listed building was therefore minor because of this careful consideration.
