Commercial Benefits to The Building Owner & Client

Why have major retailers driven air tightness levels down to best practice level in the last 10 years?

One reason only – there are substantial commercial benefits to having an airtight building & retailers are accruing those benefits for the lifetime of the building stock. A typical example of the real benefits that can be realised can be illustrated by an existing store that was sealed in Feb 1997.The ambient temperature in store was raised by 5°C after store had been air sealed.

Typical air permeability rates of 3m³/(h.m²) have been obtained on new retail stores 5m³/(h.m²) on existing stores. These levels of air tightness have been achieved & by incremental improvement over a number of years, by all parties involved with the projects. Additional costs to clients on new build retail stores is <0.5% of the total spend.

Benefits obtained from achieving a good air tightness level can be summarised as:

  • Lower energy costs for the lifetime of the building.
  • Lower initial capital costs due to downsizing of plant and equipment.
  • Air tightness tests act as performance tests for fire compartments as well as external envelopes.
  • The environment within the building becomes less draughty and potentially warmer. Productivity of staff could be raised significantly - a happy worker is a productive worker!
  • The risk of interstitial condensation within the building fabric is minimised, if the building fabric is built to an air tightness standard. Degradation should therefore be reduced in the long term.

Different types of buildings require different levels of air tightness. Air conditioned buildings should be tighter than naturally ventilated ones. Archives, cold rooms and museums will all require much tighter specifications to ensure necessary levels for the control of humidity, heat loss and the ingress of pollutants are met.

Good Practice Guidelines For Different Building Types

 

The following figures are recommended air tightness specifications for various building types as set out in ATTMA TS1.
Building Type Air Permeability

 

m³/(h.m²) at 50 Pascals

 

Best Practice

Normal
Offices: Naturally ventillated

3

7
Offices: Mixed mode 2.5 5
Offices: Air conditioned / low energy 2 5
Factories / Warehouses 2 6
Superstores 1 5
Schools 3 9
Hospitals 5 9
Museums & Archival Stores 1 1.5
Cold Stores 0.2 0.35
Dwellings: Naturally ventillated 3 9
Dwellings: Mechanically ventillated 3 5

 

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Air Tightness - Flagship Projects

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Air test result

Tightest building in UK Air test result <0.5 m³/hour/m², HRS involved throughout

Air Tightness Consultancy

IKEA employed the UK's largest fan to check the air tightness of its Glasgow store

Poor Building Envelope Performance - Case Studies

A Complete Solution For Investigating, Analysing Problems and Providing Solutions