Willmott Dixon- Liquid applied Airtightness by Intelligent Membranes

Case Study: Passive Purple Airtightness Solution for Willmott Dixon at Oxford Brookes University

Client: Willmott Dixon

Location: Oxford Brookes University

Products Used: Passive Purple (liquid-applied intelligent membrane)

Package: Guaranteed Airtight Supply & Install

Sector: Education / Low-Carbon Construction

Project Overview

Oxford Brookes University embarked on a major low-carbon construction project to deliver new high-performance learning facilities. As part of the scheme, the building envelope needed to achieve airtightness levels on par with Passive House standards to reduce operational carbon and provide long-term comfort for occupants.

Willmott Dixon partnered with Intelligent Membranes to deliver a complete airtightness package — from supply to installation — ensuring consistency, quality, and guaranteed performance.

The Challenge

• Exceptional airtightness targets: Achieve near-Passive House performance levels.
• Complex building geometry: Multiple junctions, service penetrations, and mixed substrate types.
• Tight programme: Minimal disruption to the wider construction schedule.
• Sustainability requirements: Reduce air leakage to support the university’s low-carbon goals.

The Solution

We applied Passive Purple, our liquid-applied intelligent vapour control membrane, directly to the building fabric.

Why Passive Purple was chosen:

• Seamless coverage – Eliminates weak points found in traditional membrane sheets.
• Intelligent performance – Responds to humidity and temperature changes, preventing condensation and mould risk.
• Speed of application – Spray, roller, and brush options for rapid coverage across varied surfaces.
• Vapour control – Airtight while allowing controlled breathability to protect the building fabric.

Installation process:

• All substrates were prepared to ensure maximum adhesion.
• Passive Purple was spray-applied to large wall and ceiling areas, with brush application for detailed junctions.
• Critical connection points (windows, doors, service entries) were detailed to ensure a continuous airtight layer.

The Results

• Airtightness: Achieved Passive House-level performance, exceeding initial project targets.
• Energy Efficiency: Significant reduction in air leakage, lowering heating and cooling demand.
• Durability: Long-lasting airtight seal that will perform for the lifetime of the building.
• Sustainability: Directly contributed to the university’s low-carbon, high-performance building objectives.

Key Takeaways

The Oxford Brookes University project showcases how Passive Purple, combined with our Guaranteed Airtight Supply & Install Package, delivers reliable, high-performance airtightness at scale. The seamless membrane application allowed Willmott Dixon to meet challenging performance goals while staying on programme, proving Passive Purple’s value in modern, sustainable construction.