With rising energy costs and growing environmental concerns, more London homeowners and developers are turning to the Passive House standard—an internationally recognised benchmark for ultra-low energy buildings. These structures are designed to maintain comfortable indoor temperatures year-round with minimal heating or cooling. One of the most crucial components in achieving this standard is air tightness.
Air leakage, even in small amounts, can significantly impact a building’s energy efficiency, comfort levels, and long-term sustainability. That’s why Passive house air leakage testing in London has become a critical step in ensuring that homes meet both the performance criteria and regulatory compliance.
Whether you’re working on a new build or retrofitting an existing property to Passive House standards, understanding and preparing for this testing process is essential to success. In this guide, we’ll walk you through everything you need to know—from why the test matters to how to prepare your property for it.
What Is Passive House Air Leakage Testing?
Passive house air leakage testing, commonly referred to as the Blower Door Test, is a diagnostic method used to measure how much air leaks through unintentional gaps and cracks in a building’s envelope. It’s an essential requirement for properties aiming to meet the Passive House standard, where airtightness plays a critical role in reducing energy consumption and ensuring optimal comfort.
The process involves sealing a powerful fan into an external door (usually the front door), which either pressurizes or depressurizes the house. By measuring the difference in air pressure and the rate at which air escapes or enters, the test calculates the building’s Air Changes per Hour (ACH) at 50 Pascals of pressure.
To meet Passive House certification, a building must achieve ≤ 0.6 ACH @ 50 Pa, meaning the entire volume of air inside the house should not leak more than 60% of its volume per hour under test conditions. This extremely low air leakage rate ensures that the building retains heat efficiently, reduces drafts, and limits moisture intrusion—all of which contribute to a healthier, more sustainable living space.
Whether you’re designing a new home or retrofitting an older one, Passive house air leakage testing in London is a crucial milestone to pass if you’re aiming for the gold standard of energy efficiency.
Why Air Tightness Matters in London Homes
When building to Passive House standards, air tightness plays a vital role in ensuring your property performs efficiently and sustainably. For eco-conscious homeowners and developers, Air Tightness Testing for Passive Houses in London is more than a box-ticking exercise — it’s a fundamental requirement for certification and long-term comfort.
London’s climate, marked by fluctuating temperatures and increasingly high energy costs, makes airtight construction especially relevant. Uncontrolled air leakage leads to significant heat loss, higher utility bills, and a greater environmental footprint. By limiting these leaks, airtight homes ensure better thermal performance and energy efficiency year-round.
To comply with standards set by the Passive House Institute (PHI) or the Passivhaus Trust UK, homes must demonstrate a maximum of 0.6 air changes per hour (ACH) at 50 Pascals during a Blower Door Test. Air tightness testing is the definitive method for verifying this, offering measurable proof that your property meets Passive House benchmarks.
Top Benefits of Air Tightness are:
- Lower Utility Bills: Airtight homes use dramatically less energy for heating and cooling.
- Enhanced Living Comfort: Eliminates cold draughts and external noise, creating a peaceful indoor climate.
- Healthier Indoor Air: Prevents moisture ingress and mould growth.
- Increased Property Value: Certified energy-efficient homes are more attractive to modern buyers.
Want to ensure your build meets Passive House standards?
Armeec Design & Build offers certified Air Tightness Testing for Passive Houses in London. Our team will guide you through the compliance process and ensure your property performs at its best.
Contact us today to schedule your test or get expert advice.
When Should the Air Leakage Test Be Done?
Timing is critical when it comes to Air Tightness Testing for Passive Houses in London. The success of your test — and ultimately, your Passive House certification — depends on when and how the test is performed during the construction timeline.
The most effective time to carry out an air leakage test is once the building envelope is complete but before finishes are applied. This includes:
- All external doors and windows installed and sealed
- Service penetrations completed and airtight
- Air barriers (membranes, tapes, etc.) fully in place
- No decorative finishes that might cover problem areas
Testing at this stage allows for accurate results and makes it easier to locate and fix any air leaks before costly interior works are done.
Scheduling air tightness testing early — and even arranging a preliminary test — helps ensure your build stays on track for certification. It gives you the chance to:
- Identify weak spots in air sealing
- Make targeted improvements with minimal disruption
- Avoid delays or costly rework during final stages
- Boost your confidence in passing the final test at first attempt
Building a Passive House in London? Don’t leave airtightness to chance.
Armeec Design & Build provides reliable, certified Air Tightness Testing for Passive Houses in London, with expert advice to help you pass with confidence.
Book your test today or speak to our Passive House consultants.
Step-by-Step Guide to Prepare Your Property
Preparing your home thoroughly is essential for a successful test. Whether you’re building new or retrofitting, this step-by-step guide ensures your project is ready for London Passive House Air Pressure Testing Services and meets stringent airtightness targets.
Seal All Penetrations
Air leaks often originate around service penetrations. Make sure to:
- Seal around windows, doors, plumbing, and electrical wiring
- Use specialist airtight membranes, grommets, and high-performance tapes
- Double-check transitions between different materials or structural elements
Check Ventilation Systems
Ventilation systems, especially MVHR (Mechanical Ventilation with Heat Recovery), can affect pressure test results:
- Temporarily seal or isolate all vents and ducts during testing
- Ensure the entire system is installed and properly sealed
- Cap or block any unused or open ductwork
Inspect External Openings
Doors and windows are common leakage points, so inspect the following:
- Ensure all windows and doors shut snugly with no gaps
- Check weather stripping is intact and seals tightly
- Inspect insulation around frames and junctions
Test Before the Test
A mock test or pre-check can save time and reduce the risk of failure:
- Use smoke pencils, infrared cameras, or handheld blower tools
- Identify and fix visible or measurable leaks early
- Address junctions, floor-wall connections, and loft hatches
Clear Communication with Testers
A successful test relies on good coordination:
- Confirm timing and access with your London Passive House Air Pressure Testing Services provider
- Provide floor plans, sections, or specifications if available
- Follow any prep checklist shared by the testing company
Armeec Design & Build offers expert London Passive House Air Pressure Testing Services, along with airtightness consulting and guidance throughout the build.
Book a site visit or call us today to ensure your Passive House project meets the gold standard for energy efficiency.
Common Issues Found During Testing
When it comes to London Passive House Air Pressure Testing Services, even well-built homes can reveal unexpected air leakage problems. Understanding common trouble spots can help you proactively fix them and avoid delays or costly re-tests.
Gaps at Junctions and Penetrations
- Junctions between walls, floors, and ceilings often contain hidden gaps.
- Service penetrations—like those for cables, pipes, or ventilation—are common leakage zones.
Fix: Use airtight grommets, sealants, or membranes around all penetrations, and pay close attention to areas behind kitchen units, stairs, and boiler cupboards.
Poorly Sealed Loft Hatches
Loft hatches are often overlooked and can leak large volumes of air.
Fix: Fit a draught-proof loft hatch with proper sealing foam or gasket, and ensure it closes tightly.
Unsealed Recessed Lights and Pipe Runs
Recessed lighting and vertical pipe chases often breach the air barrier.
Fix: Use air-tightness-rated downlight covers and seal pipe runs at both ends with suitable gaskets or expanding foam.
Incomplete Air Barrier Continuity
Breaks in the air barrier—especially at floor-wall or wall-roof transitions—can compromise test results.
Fix: Review continuity across surfaces before final finishes go in, and carry out a pre-test if possible.
Don’t let minor issues cause major failures.
Armeec Design & Build provides expert London Passive House Air Pressure Testing Services and airtightness support throughout your build.
Contact us now to ensure your project meets Passive House standards the first time around!
How to Choose a Certified Testing Company
Selecting the right company for Passive house air leakage testing in London is crucial to achieving your energy efficiency goals and ensuring your project meets certification standards. Here’s what to look for when making your choice:
Accreditation Matters
Ensure the company is accredited by recognised bodies like ATTMA (Air Tightness Testing and Measurement Association) or iATS (Independent Air Tightness Testing Scheme). These accreditations guarantee that the company follows strict testing protocols and industry standards.
Passive House Experience
Not all air testing companies are familiar with the specific requirements of Passive House standards. Choose one that has experience with Passive House or Passivhaus projects, particularly those that have successfully achieved ≤ 0.6 ACH @ 50 Pa.
Local Knowledge and Testimonials
Look for companies with positive client reviews and case studies from London-based projects. Local experience is essential to understand the quirks of older properties and borough-level compliance nuances.
Ready to ensure airtight performance?
Armeec Design & Build partners with certified experts for Passive house air leakage testing in London, ensuring you meet standards and pass the first time.
Contact us today for a trusted and efficient testing solution tailored to your property.
Conclusion
Achieving Passive House certification isn’t just about design—it’s about airtight execution. Proper preparation for Passive house air leakage testing in London is critical to ensure your home meets the rigorous standards for energy efficiency, comfort, and long-term performance.
From sealing details to test coordination, every step plays a vital role in passing the airtightness test. When done right, the rewards are long-lasting: lower energy bills, reduced carbon footprint, improved indoor air quality, and increased property value.
Looking for expert Passive House air leakage testing in London?
Contact our certified team at Armeec Design & Build today to book your airtightness test and ensure compliance with the highest standards.
