13 November 1998

Ridge revamp

A VENTILATION system used by pig and poultry producers 30 years ago is now being advocated for dairy cattle houses.

The venturi ridge is being promoted by Dutch firm Weelink, and Rinse Andringa from the company said the system was much more efficient than the curved ridge found on modern dairy sheds.

"A curved ridge asks warm air to go downwards before it escapes whereas the venturi ridge allows air to be sucked out much more effectively," he told the Auchincruive conference.

The system consists of two transparent roof sheets with turned up edges, extending downwards from an open ridge. A transparent skylight covering the opening completed the chimney.

"Wind constantly blows over the barn. When it enters from one side, the airstream is accelerated because of the narrow opening under the skylight, so warm air is pulled out of the barn. The wind stream going over the skylight reinforces the process by creating a vacuum on the leeward side." &#42