Hygrothermal Assessment for the Jumbo Water Tower Retrofit

Ecosophy Studio was commissioned by QODA Consulting to carry out a preliminary hygrothermal analysis to understand how different insulation strategies may affect the cast-iron bolted tank plates of the Jumbo Water Tower and the existing roof structure.

The project forms part of the restoration and adaptive reuse of the Jumbo Water Tower, a Grade II–listed Victorian water tower in the UK, and one of Colchester’s most treasured historic assets. The vision is to transform the landmark into a fully accessible community, culture, and events hub while preserving its unique architectural and heritage significance.

Decommissioned in 1984, this unique Victorian building has suffered decades of neglect. As a result, its key fearure -the cast-iron bolted tank plates and their fixings- were already experiencing significant deterioration. Assessing the hygrothermal impact of any insulation upgrade before any retrofit design could progress became therefore essential not only for the structural integrity of the water tank itself, but also for the long-term preservation of the building’s historic fabric.

Ecosophy Studio carried out detailed hygrothermal modelling to evaluate how different insulation approaches would influence moisture behaviour within the tank structure. The objective was to support a retrofit strategy that delivers a thermally efficient and moisture-safe thermal envelope while protecting vulnerable heritage components.

The assessment explored the benefits and drawbacks of each thermal upgrade option, with a particular focus on strategies for improving the hygrothermal conditions contributing to the deterioration of the cast-iron bolted tank—one of the building’s defining architectural features. The study also analysed moisture-related risks for key elements of the existing roof structure that will be retained as part of the redevelopment.

This work provides an essential technical foundation for decision-making, supporting a retrofit approach that balances energy performance, moisture safety, and heritage conservation.

The Jumbo Water Tower. Image Credit: The Architect's journal

Sketch section showing future activity throughout Jumbo. Image Credit: Purcell

Image Credit: Purcell