Air pressure q50 test
The q50-value over one hour is used to describe the air leakage (or air infiltration rate) of a building envelope at a pressure difference of 50 Pascals (Pa). This standard is related to the rate that air infiltrates the whole envelope of a building when doors and windows are closed thus the volume is calculated to include everything within the envelope or the air tightness line.
This is measured through a q50 pressure test which is carried out by closing and sealing doors and windows and installing a door blower to create a pressure differential of 50 Pa (equivalent to a 5 mm water column) between the inside and outside, to measure the air leakage. The standard (or q50) and the UK building regulations requires a test result which is less than 5m3 of air per hour per m2 of floor area @ 50 Pascals expressed as < 5m3/hm2@50pa. Note that the volume of the building is based on the total volume within the building envelope as opposed to the sum of the volume of all internal rooms as is used for the Passivhaus standard.
[edit] Related articles on Designing Buildings
- Accredited construction details ACDs.
- Air change rates.
- Air permeability testing.
- Air pressure n50 test.
- Air tightness in buildings
- Airtightness of energy efficient buildings.
- Draughts in buildings.
- Energy audit.
- Floor plenum airtightness.
- Indoor air quality.
- Indoor air velocity.
- Passivhaus.
- Site inspections.
- Thermographic survey.
- The history of non-domestic air tightness testing.
Featured articles and news
Costs and insolvencies mount for SMEs, despite growth
Construction sector under insolvency and wage bill pressure in part linked to National Insurance, says report.
The place for vitrified clay pipes in modern infrastructure
Why vitrified clay pipes are reclaiming their role in built projects.
Research by construction PR consultancy LMC published.
Roles and responsibilities of domestic clients
ACA Safety in Construction guide for domestic clients.
Fire door compliance in UK commercial buildings
Architect and manufacturer gives their low down.
Plumbing and heating for sustainability in new properties
Technical Engineer runs through changes in regulations, innovations in materials, and product systems.
Awareness of the Carbon Border Adjustment Mechanism
What CBAM is and what to do about it.
The new towns and strategic environmental assessments
12 locations of the New Towns Taskforce reduced to 7 within the new towns draft programme and open consultation.
Buildings that changed the future of architecture. Book review.
The Sustainability Pathfinder© Handbook
Built environment agency launches free Pathfinder© tool to help businesses progress sustainability strategies.
Government outcome to the late payment consultation, ECA reacts.
IHBC 2025 Gus Astley Student Award winners
Work on the role of hewing in UK historic conservation a win for Jack Parker of Oxford Brookes University.
Future Homes Building Standards and plug-in solar
Parts F and L amendments, the availability of solar panels and industry responses.
How later living housing can help solve the housing crisis
Unlocking homes, unlocking lives.
Preparing safety case reports for HRBs under the BSA
A new practical guide to preparing structural inputs for safety cases and safety case reports published by IStructE.
Male construction workers and prostate cancer
CIOB and Prostate Cancer UK encourage awareness of prostate cancer risks, and what to do about it.