Residential

Residential, Commercial and PassivHaus accredited Air Tightness Testing

With an industry-leading reputation, unrivalled experience and nationwide coverage, and a dedicated in-house site services team, your air tightness requirements are in safe hands.  One of our founder services back in 2006, we take immense pride in our Air Testing service, from guidance and support at initial enquiry, to mid-build site audits and pre-tests to ensure you’re ready for the final test.   Our team of engineers aren’t simply just air testers that turn up, test and go, our team will guide, support, consult and above all, care about your building project and how it performs.

We pride ourselves on making sure your building project not only achieves compliance, but goes above and beyond compliance and minimises its heat loss as much as possible, ensuring more occupancy comfort and lower heating bills. Please refer to some of our case studies here.

What is Air Tightness Testing?

Air tightness testing is a recognised method of measuring the extent to which air is lost through leaks in the building fabric. Air leakage is the uncontrolled flow of air through gaps and cracks in a buildings fabric (often referred to as infiltration and draughts) and not ventilation, which is the controlled flow of air in and out of the building.  

Essentially, a more air-tight building translates to better energy efficiency, lower heating and cooling costs and a much more comfortable living, working or storage environment.  To view the full benefits of air tightness testing please click here.

How is Air Tightness Measured?

Air tightness is measured by calculating the rate of air leakage per square meter of the building’s external envelope per hour, under a pressure difference of 50 Pascals. This artificially induced pressure difference simulates higher wind conditions, helping to assess the integrity of the building’s air tightness layer. The rate of air leakage is expressed as Xm³/hr/m²@50Pa, a standard measurement defined by UK Building Regulations.

Alternatively, the rate at which the building’s air volume changes per hour at 50 Pa is another measurement method. This is noted as Xach/hr@50Pa and is the preferred metric used in Passivhaus air test certification.

The most common way to conduct these measurements is through a ‘blower door’ test. A membrane frame is installed in a doorway, and a large fan is positioned within the membrane. The fan blows air into the building, and the air flow is then measured.

To generate a controlled pressure difference, a calibrated fan is placed within the building’s external envelope. This fan either pushes air into or extracts it from the property. Calibrated equipment is used by the air tightness tester to measure the airflow, providing accurate readings of the building’s air tightness.

Does your project need an air tightness test?

The air tightness test, also known as air permeability test, air leakage test, air pressure test, or just simply Air test, is a mandatory requirement of the latest Part L 2022 Building Regulations. 

Applying to ALL newly built dwellings, new commercial buildings over 500m2 and commercial extensions with a floor area greater than 25% of the current building, the air tightness test is a crucial part of how a building fabric performs and an integral part of the as built SAP, EPC and the final sign off process.

Approved Document L: Changes and Impact on Air Tightness

In June 2022, a revised version of Approved Document L came into effect, introducing important updates to energy efficiency standards for buildings in the UK. The document is split into two volumes:

  • Volume 1: Dwellings (homes)
  • Volume 2: Buildings other than dwellings (commercial and public buildings)

These revisions are designed to achieve a 31% reduction in carbon emissions from new buildings as part of the transition towards the Future Homes Standard in 2025. Several areas, such as insulation, fuel types, and air tightness, have been significantly impacted by these changes.

Key Changes for Air Tightness Testing:

  1. No Sampling – Every Unit Must Be Tested
    Previously, a sample of units in larger developments could be tested for air tightness. Under the revised regulations, every unit must undergo air tightness testing, ensuring consistent performance across all properties.
  2. Lower Maximum Air Permeability
    The maximum allowable air permeability has been reduced from 10 m³/h.m² @50Pa to 8 m³/h.m² @50Pa. This change means buildings must be less draughty and better sealed to reduce energy loss.  However, the average test design figure specified tends to be less than 5 to ensure SAP compliance.
  3. New Test Standard (CIBSE TM23)
    Air tightness testing must now also adhere to the CIBSE TM23 standard, a new approach designed to improve the accuracy and consistency of tests.

Air Permeability Targets and Testing

The specific air permeability target for each property is calculated based on the design rate allowed for in the SAP calculation. It is essential to know this figure from the beginning of the project to ensure compliance with the air tightness requirements.

Testing and Competency Requirements

To comply with Part L, testing must be conducted by a competent person. Our team of experienced test engineers are all registered with the ATTMA (Air Tightness Testing & Measurement Association) competent person scheme, which is referenced in Part L, ensuring that your air tightness tests are carried out to the highest standard.

By adhering to these new regulations, you not only contribute to the UK's long-term sustainability goals but also improve the energy performance of your buildings, resulting in lower energy costs and better overall building quality. For more information, request a no obligation quotation, or to book an air tightness test, get in touch with our team today!

Why choose Melin for your Air tightness requirements?

Choosing a reliable provider for airtightness testing is crucial for ensuring that your building meets the necessary energy efficiency standards and regulations. Here are some reasons why you might consider us for your airtightness testing service:

  • Nationwide Coverage – We cover the whole of the UK.
  • Expertise and Experience – We have a team of highly trained professionals with extensive experience in performing air tightness tests across a wide range of building types.
  • Competency - Fully ATTMA Accredited Level 1, Level 2, EA and PassivHaus test engineers using state of the art fully calibrated testing equipment.
  • Consultation – including;
  • Desktop design reviews
  • Architectural drawing reviews
  • Pre-test site inspections
  • Pre-test sample building area testing
  • Air tightness test services
  • Online design reviews and design workshops
  • Full diagnostic service – Should the building fail to meet targets, we are able to perform smoke test diagnosis and thermal imaging
  • Same Day retesting – If your building fails the initial air test, we will advise and recommend straight away, and if remedial works can be conducted on the day, we will stay on site and retest in the same visit.
  • Competitive rates – We offer very competitive rates as standard, and additional discounts are available for multiple unit sites and when combined with our other services such as SAP, Part F testing or sound testing
  • Large Volume testing – Being one of the largest independent testing companies in the UK we are able to test in excess of 30 units in the same day.
  • Additional Services - Services such as SAP, SBEM, Part F testing, indoor air quality or sound testing can be integrated, especially for larger or multi-unit sites.
  • Flexibility - We understand that construction timelines are tight. That’s why we offer quick scheduling and turnaround times, helping you keep your project on track without delays. We’re also flexible in terms of working around your schedule to minimize disruption.
  • Out of hours testing – To minimise disruption and help clients meet deadlines we offer out-of-hours testing upon request.

Our Process

Answer Queries

We are happy to discuss the entire air tightness testing process with you, including what’s involved, important considerations, and the best time to conduct the test. We can also provide helpful guidance and checklists to ensure a smooth experience.

The following checklists are available for download and can assist you in managing the air testing process, from planning and design stages to construction and test preparation:

  • [Download - Site readiness Checklist]
  • [Download – Guidance document]

Date & Price

We offer an indicative price based on the building size and location before providing a formal quote. To create the formal quote, we use PDF drawings of the property. We can work with you to schedule a test date that suits your project timeline, with typical lead times of 1–2 weeks. However, we can often accommodate single tests at shorter notice.

Preparation

Once a test date is confirmed, our engineer will contact you ahead of time to walk you through the preparation process and discuss the test schedule. At this point, we will also confirm the air permeability target outlined in the energy model (SAP) if this hasn’t already been addressed. Achieving the required air tightness is crucial for building control sign-off, as the results are a key factor in calculating the building’s overall energy efficiency.

On the Day of Testing

For smaller houses and flats, we typically handle any temporary sealing required for the test upon arrival at the site.  For our larger commercial or multiple unit sites we may require an additional day for preparation works.

We will then conduct the pressure test by installing fan/s in a doorway to create a measurable pressure difference between the inside and outside of the building. The amount of air needed to maintain this pressure helps indicate the volume of air escaping through the building fabric, which would translate to draughts in everyday use.

If the building doesn’t meet its target on the first attempt, our equipment can help identify the points of leakage. If these can be addressed quickly, we can retest on the same day. As air tightness standards become more stringent to meet higher energy performance targets, careful attention must be paid to air permeability in the building design, including the use of membranes and tapes to maintain the air barrier. For more information, refer to our guidance document.

Paperwork

We can provide ATTMA certificates for each test within 24 hours of completion, but same-day issuance is available upon request.

Don’t just take our word for it, if you would like to get in touch to discuss your air tightness requirements, request a quotation or would just like to test our knowledge (we don’t charge for this 😊) please call us on 01554 571010 or email admin@melinconsultants.co.uk.

What are the benefits of Air Tightness Testing?

Air testing is conducted for several key reasons including regulatory requirements, building performance, energy efficiency and occupant comfort;

  1. Energy Efficiency
  • Reduce Heat Loss: Air leakage through gaps, cracks, and holes in a building’s envelope allows heat to escape in the winter and cool air to leak in the summer, increasing the energy needed for heating or cooling. Air testing helps identify these leaks, allowing for improvements in insulation and sealing, which reduces energy consumption.
  • Lower Energy Bills: By minimising air leakage, a more airtight building consumes less energy, leading to reduced utility costs for heating and cooling.
  1. Comfort
  • Improved Indoor Comfort: Air leakage can lead to drafts, cold spots, and inconsistent temperatures inside a building. A tighter building envelope helps maintain a more stable and comfortable indoor environment, ensuring even heating and cooling.
  • Better Control of Indoor Climate: In buildings with good airtightness, HVAC systems work more efficiently because the conditioned air (heated or cooled) stays inside the building.
  1. Regulatory Compliance
  • Meet Building Regulations: Part L of the Building Regulations requires an air test to be carried out on every new build dwelling . The testing is necessary to demonstrate compliance through the as built SAP and EPC, which the air test result directly feeds into.
  • Energy Performance Certifications: buildings must meet certain air permeability standards to qualify for energy certifications like LEED, BREEAM, or Passive House. Air tightness testing provides the data needed for these certifications.
  1. Sustainability and Environmental Impact
  • Reduced Carbon Footprint: A more airtight building uses less energy, which in turn reduces the demand for fossil fuels, resulting in lower greenhouse gas emissions. Air testing helps promote sustainability by identifying areas for improvement in building efficiency.
  • Supports Green Building Initiatives: Testing helps buildings qualify for green certifications, which are essential for promoting environmentally responsible construction practices.
  1. Moisture Control and Durability
  • Prevention of Moisture Issues: Uncontrolled airflow can bring moisture into a building, which can lead to condensation, mould growth, and damage to building materials. Air testing helps identify potential moisture paths, allowing builders to seal them and prevent future problems.
  • Increased Building Durability: By minimising air leakage, buildings are better protected from issues caused by moisture ingress, which can damage materials like wood, insulation, and drywall, extending the building’s lifespan.
  1. Improved Air Quality
  • Control of Pollutants and Allergens: Air leakage can allow dust, pollen, and other outdoor pollutants to enter a building. A well-sealed building can help keep these contaminants out, leading to better indoor air quality.
  • Improved Ventilation: Airtight buildings can be paired with controlled mechanical ventilation systems to ensure a constant supply of fresh air, improving indoor air quality while avoiding the uncontrolled entry of outside air through leaks.
  1. Performance Validation
  • Quality Assurance for Builders: Air tightness testing provides verification that a building has been constructed according to the design specifications and meets performance standards. This helps builders identify areas that need improvement and demonstrate their work quality.
  • Enhanced Customer Satisfaction: For homeowners and building occupants, airtightness testing ensures they are getting a building that performs well in terms of energy efficiency, comfort, and durability.
  1. Noise Reduction
  • Reduction of External Noise: A more airtight building reduces the amount of external noise that can enter the space, improving acoustic comfort, especially in urban or noisy environments.

Get in touch

Melin Energy Consultants

Swansea

01792 002085

Bristol

01172 356512

London

020 3725 8399

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