Portfolio - Y Senedd
One of Wales' most prestigious buildings, located in Cardiff Bay
INTRODUCTIONOne of Wales' most prestigious buildings, located in the Cardiff Bay area, it was designed and constructed at the turn of the 21st Century, and forms a part of the everyday life for the people of Wales.
It's design, innovative for its time included many sustainable features, among which was a natural ventilation system to serve certain areas of the building. This system utilised an under croft plenum which transported outside air into the occupied spaces via attenuators and two stage motorised dampers through builders work trenches incorporating stainless steel floor grilles. Tempering of the fresh air was by means of a heat emitter fitted in the trench. This fresh air was introduced under the dictates of carbon dioxide and temperature sensors placed in the spaces, to ensure that good indoor air quality was maintained throughout the diverse range of occupation and climatic conditions.
PROBLEMSFollowing concerns raised by the building occupants a detailed survey was carried out and the single most important finding was the inadequacy of the heating emitter to provide tempering of the incoming air effectively, as most of the fresh air was able to by pass the heater in the trench and enter the space at almost outside ambient temperature levels. This meant that those occupants situated close to the floor grilles complained of cold draughts.
A secondary problem was that the originally installed motorised dampers were not efficient in shutting off completely and this allowed air flow into the space, even when closed. Coupled to this, given the area of dampers installed, the thermal properties of the dampers severely compromised the thermal properties of the overall building envelope.
SOLUTIONFollowing detailed study by the Engineering Consultants it was decided to replace the existing heat emitters in the trench with fixed heating elements mounted directly to the motorised dampers. This would ensure full contact between the incoming air and the heating medium. This would eliminate the cold blocks of air being introduced into the occupied space. In conjunction with this solution it was decided to replace the existing motorised dampers with high quality, double skinned, insulated dampers with guaranteed low leakage and excellent thermal properties. Additional changes and improvements to the existing control system was proposed and agreed.
THE WORKSThe works involved removing and replacing 21 No. existing motorised dampers with Ruskin Air Management Vengen insulated models all 930 mm high, comprising a 320mm high winter section with heating coil arrangement and a 630mm high summer section with no heating provision. The damper sections varied in length from 2000mm up to 5650mm long their installation involved the removal of the existing attenuators, removal of the existing motorised dampers, installation of the new Vengen motorised damper assemblies coupled with the heating coils. Finally, the existing attenuators were repositioned and fixed to the new dampers.
Practical difficulties with carrying out the works involved restricted access allowing works only during unoccupied times and the bulk of the work carried out in the under croft with a headroom of only 1000mm.
The heating coils were then connected to the existing low pressure hot water system and the completed installation commissioned.