Ashe Construction - Delivers Cutting-Edge Airtightness with Passive Purple at Oxford Brookes University

Intelligent Membranes partnered with Ashe Construction on the Bedford Academy extension to deliver one of the most airtight and energy-efficient school buildings in Bedford Borough. Using our Passive Purple liquid applied airtight membrane system, we achieved a world-class airtightness score of 0.43 ACH, exceeding standard building regulations and contributing to a Net Zero Carbon in Operation target.

Why Passive Purple Was Chosen

Ashe Construction needed a seamless airtightness solution that would:

  • Meet strict U-value and energy efficiency targets.

  • Work across multiple substrates, including masonry, timber, OSB, and plasterboard.

  • Eliminate weak points left by tapes and traditional sheet membranes.

Passive Purple, our flagship liquid vapour control layer, was the ideal choice. Applied via spray and brush, it forms a continuous, flexible membrane that seals complex details and irregular surfaces.

Complete Airtightness System

This project went beyond just one product. Our full airtight and moisture control system included:

  • IMAF Airtight Tape – bridging large gaps and bonding to uneven surfaces.

  • Passive Purple Brush – fibre-reinforced for high-risk junctions like pipe penetrations and beam ends.

  • Waterproof Blue Liquid DPM – acting as both an air/vapour barrier and damp-proof membrane.

  • Airtight Grommets – creating permanent seals for cables and pipework.

This integrated approach ensured airtightness continuity across every junction, penetration, and change of material.

Results

  • Airtightness: 0.43 ACH – passive-grade performance.

  • Energy Savings: Reduced heating and cooling loads.

  • Comfort: Stable indoor temperatures year-round.

  • Durability: Long-term protection from moisture and air leakage.

Why This Matters

By using liquid applied airtight membranes like Passive Purple, Bedford Academy now benefits from:

  • Lower energy bills.

  • Improved indoor air quality.

  • Compliance with modern building performance standards.

  • A sustainable building envelope that will last for decades.

High-performance airtight seal at Bedford Academy with Passive Purple liquid applied coating.Passive Purple airtight membrane ensuring low air permeability for Bedford Academy construction.Airtightness solution using Passive Purple liquid membrane applied to Bedford Academy LGS frame.

Products Used on This Project

1. Passive Purple – BIG BOY – Vapour Control Paint (11.4kg) – Spray / Roller Applied – Intelligent Membranes
A Passivhaus-certified, liquid-applied membrane used to regulate vapour movement and maintain airtightness inside the building envelope. Its seamless application prevents moisture ingress, condensation, and thermal bridging.

2. Passive Purple Brush – Home Pack (6.9kg) – Vapour Control Paint – Brush Applied – Intelligent Membranes
A fibre-reinforced version of Passive Purple, perfect for sealing joints, junctions, and difficult-to-reach areas. Used around window reveals, door frames, and service penetrations to ensure no gaps or weak points were left unsealed.

3. Airtight Tape – Intelligent Membranes
A specialised airtightness tape applied to edges, junctions, and connections before coating with Passive Purple. This reinforced the seal around complex details, boosting durability and long-term airtight performance.

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