By continuing to use the site you agree to our Privacy & Cookies policy


400 SYSTEM 600 SYSTEM 800 SYSTEM 1000 SYSTEM 1200 SYSTEM Size of system 400mm square or circular 600mm square or circular 800mm square or circular 1,000mm square or circular 1,200mm square or circular Size of core 120mm diameter 200mm diameter 200mm diameter 200mm x 400mm 530mm diameter Number of fans 1up to 140 l/s 1up to 285 l/s 1up to 540 l/s 2up to 790 l/s 3up to 1,050 l/s Windcatcher ventilation rate (at 3m/s wind speed) Additional ventilation rate (from fan) 50 l/s 195 l/s 260 ...

Subscribe to the AJ from £3 per week


for less than 46p a day

Join thousands of professionals who already subscribe to the Architects' Journal.
You’ll get instant access to read this article - and 50,000 others like it.

  • Trusted industry news & analysis, wherever you need itUnlimited online access and weekly magazine delivery – now also available on iPad/iPhone
  • Get ideas, get inside buildings and check precedentsBuildings Library – images, drawings and plans for exemplar projects in British architecture
  • Planning & regulation – what you need to know Protect your practice - the AJ keeps you up-to-date with changes to regulations and legislation

Already subscribed? Sign in here

For less than the cost of a pint you can have the magazine, iPad edition, full access to and the amazing Subscribe now and experience architecture from a British perspective. The AJ - it's your journal.

Architects' Journal Subscribers:

If you are an AJ subscriber please sign in with your email address and click submit:

Our records show you are already a registered user. Please sign-in with your password...

By continuing to use the site you agree to our Privacy & Cookies policy

Not an AJ subscriber?

Subscribe today for immediate access at a special introductory rate

Subscribe today

Subscribe today

Need help? Call 0844 848 8859 and our customer service team will be happy to assist.

The searchable digital buildings archive with drawings from more than 1,500 projects

AJ newsletters