liquid applied membrane for retrofit

What is Airtightness (and Why It Matters for Net Zero Buildings)

The UK’s Net Zero Target and Why Airtightness Matters

The UK is legally committed to achieving net-zero carbon emissions by 2050, and every sector is being reshaped to meet that goal.

In construction, this means delivering buildings that drastically reduce energy demand while maximising efficiency. The future of building is simple in principle: structures that retain heat in winter, stay cool in summer, and reduce reliance on energy-hungry mechanical systems.

At the heart of this shift is one critical factor - airtightness.

What Is Airtightness in Buildings?

If you’ve researched high-performance building standards such as Passivhaus, you’ll already know that airtightness plays a central role.

Passivhaus is an internationally recognised energy performance standard designed to create ultra-low-energy homes and commercial buildings. One of its most important requirements is achieving exceptional airtightness levels.

Why is this so important?

Because without airtightness, buildings lose heated air in winter and allow hot air in during summer. This forces heating and cooling systems to work harder, increasing energy use and carbon emissions.

An airtight building maintains internal comfort while dramatically improving energy efficiency.

Airtightness Explained Simply

When a building leaks air, its insulation cannot perform effectively. Warm air escapes, cold air enters, and thermal performance suffers.

Airtightness works by sealing potential leakage points throughout the building envelope, including:

  • Window and door frames

  • Floor-to-wall junctions

  • Wall-to-wall connections

  • Vertical and horizontal joints

  • Roof and ceiling junctions

  • Basement floors

By applying a continuous airtight membrane internally, air movement is controlled, and vapour is prevented from reaching insulation layers. The result is:

  • Improved thermal performance

  • Lower energy bills

  • Reduced carbon emissions

  • Greater indoor comfort

How Is an Airtight Membrane Applied?

At Intelligent Membranes, we developed a liquid-applied airtight membrane system that simplifies airtight construction.

Our membranes can be:

  • Spray applied

  • Roller applied

  • Brush applied

They adhere to a wide range of substrates, including:

  • Brick

  • Concrete

  • Timber

  • Steel

Once applied, the membrane forms a continuous, flexible, permanent airtight seal. Unlike traditional tape or sheet systems, liquid application ensures seamless coverage around complex junctions and detailing, reducing labour time while improving reliability.

Passive Purple & Airtight White: Advanced Airtight Paint Systems

To help projects achieve Passivhaus performance levels, we created Passive Purple, the world’s first liquid-applied airtight vapour control barrier.

Passive Purple is:

  • Passivhaus Certified

  • BBA Approved

  • Designed for simple spray or roller application

For projects requiring a neutral aesthetic finish, Airtight White provides the same high-performance airtightness in a colour-free option.

The result is a faster installation process for builders and long-term energy savings for occupants, all while supporting sustainable construction goals.

Why Airtightness Is Essential for Net Zero

Airtightness is more than a compliance requirement; it is a direct climate action strategy.

By reducing uncontrolled heat loss and minimising the need for mechanical heating and cooling, airtight buildings significantly cut operational carbon emissions. This makes them a key contributor to the UK’s 2050 Net Zero target.

High-performance airtight construction means:

  • Reduced heating demand

  • Lower carbon footprint

  • Improved building longevity

  • Healthier indoor environments

Contact us and learn more about airtightness

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