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.

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• 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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