Overview
Air permeability testing measures how much air leaks through the building envelope under controlled conditions. Excessive air leakage is one of the largest sources of energy waste in buildings — it drives up heating costs, reduces comfort, and makes it harder to achieve target energy ratings.
Synavo provides UKAS-standard air permeability testing for new builds, conversions, and refurbishments. Using calibrated blower-door equipment, we deliver accurate, repeatable results that demonstrate compliance with Part L of the Building Regulations.
Our Process
1. Pre-Test Preparation
We work with your site team to ensure the building is in a suitable condition for testing. This includes confirming that all external doors and windows are fitted, service penetrations are sealed, and mechanical ventilation is temporarily closed off.
2. Equipment Setup
Our technicians install a calibrated blower-door fan in an external doorway. The fan depressurises the building to a standard test pressure of 50 Pascals, allowing us to measure the total volume of air escaping through the envelope.
3. Pressurisation & Depressurisation
We conduct both pressurisation and depressurisation tests to account for the effects of wind and stack pressure. Multiple readings are taken to ensure accuracy and repeatability.
4. Leakage Identification
While the building is under pressure, our technicians can identify the location of significant leaks using smoke pencils or thermal imaging. This information is valuable for remediation if the initial result does not meet the target.
5. Certification & Reporting
You receive a detailed test report including the measured air permeability rate, compliance status against your Part L target, and any observations about leakage points. The report is suitable for submission to Building Control.
Key Benefits
- Part L compliance — Demonstrate that your building meets the air tightness requirements of Approved Document L, a mandatory element of Building Regulations sign-off.
- Energy performance — A tighter building envelope reduces heating demand, improving EPC ratings and reducing operational costs.
- Occupant comfort — Eliminating draughts creates a more comfortable internal environment and reduces condensation risk.
- Defect identification — Testing under pressure reveals construction defects such as poorly sealed service penetrations, gaps in insulation continuity, and incomplete vapour barriers.
- SAP and SBEM inputs — Accurate air permeability data improves the precision of energy models used for EPC calculations and design-stage compliance.
Who It's For
- Housebuilders needing to demonstrate Part L compliance on new-build dwellings.
- Commercial developers testing office, retail, or industrial buildings.
- Main contractors managing Building Regulations sign-off on large developments.
- Architects and designers wanting to verify that their airtightness specifications have been achieved on site.
- Housing associations testing properties undergoing deep retrofit as part of PAS 2035 programmes.