Commercial air leakage testing fan installed in doorway — Commercial Air Leakage Testing Fan — doorway pressurisation setup.

Commercial Air Tightness Testing

Our commercial air leakage testing (blower door test) covers schools, shops, factories, multi-storey and other non-domestic buildings. Air tightness testing NSAI Certified.

NSAI Certified

Fan Pressurisation Systems

Single fan in single door used for small buildings
Multiple fans used in single door for small – medium buildings
Multiple fans used in double door for larger buildings
Trailer or lorry mounted fans for medium to large buildings

Building Envelope Calculations

Unconditional areas e.g. plant rooms, escape stairs, bin stores & external stores should not be included in the calculations of the total surface of the building (building envelope).

Lift shaft vents on external walls remain open and the internal surface of the shaft is not included in the envelope calculations.

Riser openings to external walls should not be included in calculations.

Fan System Selection

Adequate Fan Capacity must be available to perform the test. The fan flow supplied should be no less than 100% of the required flow @ 50 Pa to achieve the worst acceptable building specification.

Determine fan flow required

TSA
──────  ×  (required air permeability)  =  flow (m/s)
 3600

Location of the fan equipment — decide prior to site meeting:

Access for fan equipment to be delivered and installed
Air flow restrictions around the fan location to be free
Acceptable route for the air to flow unrestricted around the building

Multi Occupying Buildings

Apartments over retail units: There is a defined boundary between the apartments and the retail unit in the form of a concrete floor slab. The retail unit is tested separately and a representative sample of the residential accommodation should be tested in accordance with the current Building Regulation Requirement.

High Rise & Multi Storey Buildings

To achieve equal pressure throughout different storeys, it may be necessary to employ multi-fans at different locations. For buildings above 15 storeys, by opening the lift shafts door, air flow will circulate equally around the tested area. Health & Safety restrictions are implemented during this procedure. Ideally test when the building is empty.

Potential testing scenario (by floor)

Ground floor: Test the ground floor and pressurise the first floor simultaneously to produce the same test pressures. Analyse using the envelope area of the ground floor slab and external wall area only. If the first floor plan area is less, include any ground floor roof areas.
Intermediate floor: Test a selected intermediate floor while pressurising the floors above and below at the same pressures. Analyse using the area of the external walls of the test floor only.
Top floor: Test the top floor and pressurise the floor below; take the envelope area as the external walls of the top and the roof area.
Provide sufficient open area between the test floor and adjacent floors along with a route to feed the outside differential pressure tube.
The number of intermediate floors tested should be at least 10%, unless construction methods differ substantially between levels.
Final value if any element fails: Q50 (ground) + Q50 (top) + highest Q50 (intermediate) × (number of intermediate floors), divided by the envelope area of the building.

Most triple fan blower door systems will deliver a total of > 6 m³/s.

An intermediate floor area of 4,000 m² and a height between floors of 4 m would require a flow rate of around 2.8 m³/s per floor at an air permeability of 5 m³/(h·m²).

The top floor would potentially require two triple fan blowers with one double fan blower door on the floor below. Ground floors often have a footprint greater than the main high-rise portion; large portable fans are typically used at this level.

If the cross-sectional area changes dramatically after the second floor level and above, apply extreme care and diligence to methodology and airflow requirements. More floor levels may need testing.

Large and Complex Buildings

Large buildings like hospitals or airport terminals (80,000 m² and greater) with different air permeability requirements can be part-tested during construction (phased handover).

Recommendations in phased handover

Method designed to achieve the required air permeability during design stage
Hire professional contractor to install the air tight system
Liaise with project manager on progress
A thorough quality management procedure is required. Nominated contractor should oversee the project with regard to air tightness issues, inspect detailed air sealing drawings, inspect the building at intervals during construction, require robust QA site auditing procedures from main and package contractors, recommend full scale mock ups of sections of the building be tested and/or recommend air tightness testing of components
Monthly inspections carried out and tool box talks organised to inform all contractors on the site the importance of the air tightness layer
Nominated sections of the building tested during construction and results recorded. Where the required target is not achieved, remedial works are carried out and retested until required air permeability is achieved. A log of the results and the sections of the building tested to become part of the Hand Over File.
Constant monitoring of the air tightness system
On completion the entire building is tested

Zone / Sample Testing

Phased handover or occupancy may preclude testing of a whole building. A representative sample may be reasonable and should represent at least 20% of the building envelope area, representative of the external envelope construction for the building as a whole.

Where samples are used to prove compliance of larger areas, it is necessary to achieve a test result 10% below the target specification, giving comfort that workmanship/detail issues elsewhere will not compromise the envelope performance.

Consider internal walls or temporary screens isolating test zones; leakage through these elements will impact the result even though they may not form part of the final building envelope.

Building Extension Testing

Where the extension can be tested as a separate entity, this is straightforward. If not practicable (e.g. a sales floor extension), test the existing building (or part) before works commence to characterise performance; then test again after works.

Derived permeability of the extension:
(Air quantity required to pressurise existing + extension) − (Air quantity required to pressurise existing only) ÷ (Envelope area of the extension)

An air tightness test on the original building should be carried out.

Plan & book your commercial air tightness test

Share drawings, envelope take-off, target permeability, and access constraints. We’ll confirm fan strategy and schedule.