Environmental design and energy strategy
Design strategies that have been utilised to reduce and manage the overall impact of the operational energy demands are summarised below:
Daylight in the Hall has been improved through the lantern design, which will help to reduce regulated energy consumption from artificial lighting. Development of the lantern design through daylight modelling has allowed a balance to be made in terms of glazing area, to ensure adequate daylighting while limiting heat loss. The Atrium, with glazed curtain walling and rooflight, will also bring daylight deep into the building.
2) Thermal performance:
Improved thermal performance will help to reduce energy consumption from heating systems. The Atrium itself also provides a thermal buffer to the Sherlock Library and Armitage Room, greatly reducing heat loses from existing spaces.
Heating options were considered early in the design including use of a ground or air source heat pumps to eliminate the use of fossil fuels and future proof the scheme in relation to future gas security. However, ground that would be available for ground source heat pumps is located too far away and roof space, and for air source head pumps is very constrained. Switching to a heat pump would also result in recently installed gas boilers becoming redundant or running at reduced loads, which would affect their delivered efficiency. The current design is therefore based on re-using existing central plant, although the College is planning to install new kitchen equipment that would enable a switch from gas to electric power.
4) Ventilation and overheating:
The ventilation strategy has been developed for comfort and energy efficiency, and the spaces make use of natural ventilation where possible, such as to the Atrium and Hall. There is improved natural ventilation to the Hall using the lantern for stack effect and the Atrium provides a natural ventilation route from the basement. Mechanical ventilation with heat recovery (MVHR) is provided in other key spaces.
Overheating modelling of the Hall, against hours exceeded criteria, has concluded that the current mechanical ventilation can be removed. To assist the natural ventilation for summer time overheating, cooling will be provided via embedded capillary cooling mats in the acoustic plaster at high level.
5) Catering energy consumption: Catering
Energy use will be reduced through new highly efficient equipment and the possible use of induction hobs to enable the switch to an all-electric kitchen. Peak electrical demands have been analysed and it has been confirmed that an all-electric kitchen can be accommodated; this will also help towards future proofing the College.
Improved metering of systems will allow monitoring, analysis and feedback, to deliver a reduction in energy consumption in practice and help the building to perform as designed.
The overarching approach for the development will be to provide efficient systems and services that mitigate excessive demand at point of use, while still meeting the expected demands of the users.
The project is aiming to achieve a 40% reduction in water demand against baseline levels, achieved through use of efficient fixtures, which can help reduce site water consumption and as well as demands on waste water services, while requiring no behaviour change by the user.
The increase in roof area of the garden room is replacing hard landscaping and therefore there is no increase in pressure on surface water infrastructure. Due to the constraints of the project in terms of site restrictions and existing foundations and structure, it is not considered possible to retrofit Sustainable Urban Drainage Systems (SUDS).
Landscape and nature
The design incorporates new planting as part of the landscape works to Chapel court and a green roof over the Hall. The softened landscape to Chapel Court brings biodiversity enhancements and allows rainwater to percolate, so reducing rainwater drainage system load, and the green roof over the Hall shall provide further site biodiversity enhancement, scent and storm water attenuation – as well as a vastly improved outlook for surrounding Study Bedrooms. All planting will be native, adaptive and drought resistant.
External lighting design is predominantly aimed at providing safe movement around the site by illuminating circulation routes. Upwards lighting will be minimised.
The selection of materials with strong environmental credentials will be encouraged with preference given to robustly manufactured, high performance products that are flexible and resilient. Once in the construction stage, the contractor will be encouraged to procure products responsibly, including but not limited to:
- All timber products will be responsibly sourced from FSC / PEFC accredited sources.
- All other key materials (concrete, steel, metals and insulation) will be responsibly and locally sourced where possible, using leading industry standards.
- Recycled, responsibly sourced materials will be employed to help reduce the whole life environmental impacts of the project.
- Low VOC paints will be used.
Waste will be managed in a sound environmental and cost-effective manner throughout the lifetime of the project.
Construction impacts, including energy usage, will be monitored and managed in order to reduce negative impacts during the construction process.