Bennetts Associates has set new benchmark in sustainable office design.
The refurbishment of Elizabeth II Court (formerly Ashburton Court) in the centre of Winchester represents an innovative transformation of a tired, dilapidated1960s office block into a modern, efficient, highly sustainable and award-winning working environment for Hampshire County Council (HCC).
Undertaken in two main phases, the 12,600m2 building replaces the previous institutional working environment of corridors and cellular rooms with stylish, flexible open-plan office space. An area of car parking has been cleared to create a welcoming new entrance that transforms the Council’s public interface and fosters a vibrant new social heart to the organisation. A 200 seat auditorium, meeting rooms, a café and restaurant are laid out around new landscaped courtyards and linked by a new internal ‘street’. Externally, the building’s outdated appearance has been modernised using local materials and is now much more in harmony with its historic context. The redesign contributes significantly to the city centre and responds to comments from local residents and amenity groups at the planning stage.
The new building is predicted to be BREEAM ‘Excellent’ and to produce one of the lowest levels of CO2 emissions of any building in the UK based on the results of extensive early design modeling and analysis. As such it is well on the way to meeting the government’s 2050 target for carbon reduction and represents a remarkable achievement given the constraints of the existing building and the challenging urban context.
The design solution has reduced the carbon emissions level for the transformed building from 90kg CO2/m2/annum to a targeted level of 39kg CO2/m2/annum. This was always recognised as a realistic target and over time the project team is confident that the building could achieve around 30kg CO2/m2/annum, or possibly even lower. Such levels would represent an annual reduction of around 70%, equivalent to the output of 200 average UK households. The Carbon Trust is using Elizabeth II Court as a case study to evaluate reductions in carbon emissions that can be achieved through refurbishment.
The building is predominantly naturally ventilated via a carefully engineered and innovative solution. Acoustic studies indicated that open windows were not feasible on the street facing elevations due to traffic noise levels, so a system was devised whereby air is drawn from the internal courtyards across the floorplates and expelled through ducts or ‘chimneys’ along the street façades. The ducts have devices at the top called ‘wind troughs’ that use ‘renewable’ wind energy to create the suction force that drives the system. The new street elevations self shade the building and break up the massing of the façade in a way that relates to the character and materiality of the historic Winchester townscape.
Retention of the concrete frame saved 50% of the embodied energy normally required to construct a building and use of local bricks and a timber based window system helped to significantly reduce related CO2
emissions. A large proportion of demolition materials were recycled through the contractor’s supply chain, including former pre-cast concrete cladding panels that were crushed offsite and re-used as aggregate in other Hampshire projects.
Waste heat from the cooling plant required to service the Council’s Data Centre will be recycled to heat areas of the building in winter.
Solar shading (sun control devices), intelligent lighting systems that switch off when not required, exposing of the concrete soffits for thermal mass and a new energy efficient building envelope all contribute to achieving very significant energy savings. Water saving devices in toilets and washrooms have also been installed to keep consumption within previous levels despite nearly doubling the occupancy. The new working environment is flexible and stimulating with a very positive reaction from staff and users thus far.
Source: Bennetts Architects' Press Release
Photos: Bennetts Architects