National Assembly for Wales, Cardiff, UK

Overview

The design of the new seat of the Welsh Parliament – the Senedd – comprises of a central Debating Chamber, Committee Rooms, supporting offices and public concourse areas located above the secure private functions, all enclosed by a single glazed box and topped by a large undulating and oversailing roof plus a rotating wind cowl, to assist with the natural ventilation strategy of the inner spaces

Key Design Features

The disposition of the architectural spaces was directly informed by the environmental concept of ‘layering’ spaces or ‘zones’, with differing environmental conditions, resulting in over 75% of the areas being fully naturally ventilated with no back-up cooling.
The Debating Chamber is served by a mixed-mode ventilation system - majority of the time it operates in natural ventilation mode, with back-up mechanical ventilation provided in extreme summer conditions. A very large rotating wind cowl on top of the Debating Chamber assist with wind driven natural ventilation from floor outlets and extract at cowl/roof level.
An inverted mirrored cone reflects daylight into the deeper corners of the Debating Chamber, and daylight levels can be controlled by adjusting the disposition of the cone.
Extensive daylight studies undertaken to configure most appropriate skylight/roof design openings, as no vertical windows were permitted in the private spaces, for security reasons.
Heat rejection from the heat pumps is via ground source heat exchangers. These also operate in reverse mode in winter, as a low-grade heat generator, with top-up heating provided by means of a biomass boiler.
The large undulating roof provides a large catchment area for rainwater harvesting, covering majority of non-potable water demand.
Post completion data has demonstrated that the building has not activated its cooling systems, serving all main spaces, in the first 10 years in operation.