Air pressure n50 test
The n50-value over one hour is used by the Passivhaus standard to describe the number of air changes that occur within a building's envelope at a pressure difference of 50 Pascals (Pa). The Passivhaus standard is based on a building physics principle that a building can be heated only by the occupants' activities and solar gains. As such the standard is primarily interested in the volume of air that needs to be heated and thus the rate at which that volume of air would be replenished through uncontrolled ventilation or minimised through air tightness.
This is measured through an n50 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 change rate. The standard (or n50) requires a test result which is less than 0.6 air changes per hour @ 50 Pascals expressed as < 0.6h-1@50pa. Note that the volume of the building is based on the sum volume of all individual rooms rather than the total volume within the envelope.
[edit] Related articles on Designing Buildings
- Accredited construction details ACDs.
- Air change rates.
- Air permeability testing.
- 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
Quality Planning for Micro and Small to Medium Sized Enterprises
A CIOB Academy Technical Information sheet.
A briefing on fall protection systems for designers
A legal requirement and an ethical must.
CIOB Ireland launches manifesto for 2024 General Election
A vision for a sustainable, high-quality built environment that benefits all members of society.
Local leaders gain new powers to support local high streets
High Street Rental Auctions to be introduced from December.
Infrastructure sector posts second gain for October
With a boost for housebuilder and commercial developer contract awards.
Sustainable construction design teams survey
Shaping the Future of Sustainable Design: Your Voice Matters.
COP29; impacts of construction and updates
Amid criticism, open letters and calls for reform.
The properties of conservation rooflights
Things to consider when choosing the right product.
Adapting to meet changing needs.
London Build: A festival of construction
Co-located with the London Build Fire & Security Expo.
Tasked with locating groups of 10,000 homes with opportunity.
Delivering radical reform in the UK energy market
What are the benefits, barriers and underlying principles.
Information Management Initiative IMI
Building sector-transforming capabilities in emerging technologies.
Recent study of UK households reveals chilling home truths
Poor insulation, EPC knowledge and lack of understanding as to what retrofit might offer.
Embodied Carbon in the Built Environment
Overview, regulations, detail calculations and much more.
Why the construction sector must embrace workplace mental health support
Let’s talk; more importantly now, than ever.
Ensuring the trustworthiness of AI systems
A key growth area, including impacts for construction.