About
Architect: RSHP
Contractor: Taylor Woodrow
Sector: Government
Overview
The Welsh Parliament Senedd provides natural ventilation and daylight into the debating chamber 30m below the glazed roof lantern and rotating wind cowl. Daylight passes through the lantern and is reflected of a large, inverted mirror cone that directs the natural light through the funnel to light the central circular debating chamber at ground floor level. The wind cowl weighing over 2000kg naturally rotates at winds above 2m/s adjusting to changes in the prevailing wind direction. Fresh air is provided into the chamber at floor level and extracted through the wind cowl at the top using hot air passive air stack assisted by the negative pressure created as the wind passes around the wind cowl causing a natural draw as you get with traditional chimneys only much larger.
The Brief
For over 15 years the wind cowl has been routinely serviced with minimal cost and has not had any performance issues. However, in the last year we noticed that the rotation of the cowl had become more resistive and was difficult to rotate during the maintenance schedule. The internal support structure being exposed to coastal weather conditions was also showing signs of corrosion. It was decided that to preserve the wind cowl and its natural ventilation performance that the main bearings needed to be serviced and the rusted components treated to stop further corrosion.
Our Solution
Vision Ventilation outlined the need for a complete bearing refurbishment. The cowl sits on a central spike located into a thrust bearing that takes the main weight of the cowl and keeps the unit central. At the base of the cowl is a large circular bearing ring with eight bearing cassettes that the cowl rotates on and prevents lateral and vertical movement under high wind speeds. All the bearings have corrosion issues, and many had completely rusted away. All the lower bearings were replaced with high quality replacement bearings. The top thrust bearing had completely collapsed so we designed a new machined bearing housing to accept a better thrust bearing that was designed to easily enable future replacement and maintenance. On completion the internal rusted steel structure was treated to neutralise the rusting and marine grade paint applied to protect the structure for the next 15 years.
