Western Power Distribution’s new 650m2 depot in Spilsby, Lincolnshire, recently achieved a BREEAM Outstanding rating of 100.5% at design stage under the BREEAM New Construction 2011: Simple Building’s scheme, making it the highest scoring BREEAM project in the world to date - with an anticipated 101.9% post-completion score. Main contractor Speller Metcalfe - an approved contractor for Western Power Distribution - has now completed the tenth in a series of mainly fast-track, BREEAM projects for the national client.

Together the project team has worked to consistently review previous experience and fine tune their design and build approach, enabling construction of high quality buildings that deliver the best in environmental performance and value.

Lead designers B3 Architects developed a data rich 3D model for the scheme through use of the specific BIM component families and design base library that has been established following a standardised specification for approaching 40 new build depots and refurbishments. Overall this led to an estimated 40% in time savings of getting the project to planning versus traditional methods.

By integrating the 2D MEP design schematics within the 3D model, Speller Metcalfe created a Level 2 integrated model, which was used to inform accurate, high quality construction and service routing and avoidance of structural clashes.

Energy Use & Zero Carbon

During design development, it became apparent that zero carbon energy performance could be achieved without exceeding budget.

By taking a fabric first approach, excellent U value and airtightness enhanced the energy performance while value engineering identified that thermal comfort and building regulation compliance could be achieved through natural ventilation. Consequently MEP systems were simplified and mechanical ventilation and comfort cooling removed, reducing energy demand.

Capital freed through value engineering was then shifted to invest in photovoltaic installations which, along with the energy efficient design, resulted in a net zero carbon performance rating.

The depot maximises use of renewable energy and energy efficient technologies in its design and operation; use of refrigerants is limited with only a small, efficient system provided for the IT server room, and space heating / hot water provided by a high efficiency gas boiler with NOx emissions <39mg/kWh at 0% O2.

Unnecessary water wastage is prevented by using solenoid valves in each toilet block, with complete sanitary fittings meeting 55% improvement beyond performance. Overall, at least 80% of materials were sourced from suppliers with ISO14001 or BES6001 certification.

Biodiversity Protection & Enhancement

Through various measures the landscaping scheme enhanced biodiversity on site compared with the ecological value prior to development, which included extensive planting of native plant species and installation of bat and bird boxes to create new habitats.

Delivering a ‘BREEAM Outstanding’ Building and Transferrable Sustainability

Working alongside BREEAM Assessor Greenbuild Consult to devise a detailed BREEAM action plan from an early RIBA stage, the contractor achieved 15/15 BREEAM credits under the Ene-1 Energy assessment – a key driver for Western Power Distribution and demonstrating their commitment to environmental excellence. A further two innovation credits were achieved for energy performance - delivering a 106% improvement beyond the compliance requirements of Building Regulations Part L2a (2010).

The value of Western Power Distribution Spilsby to the wider UK construction industry is a legacy of delivering zero carbon energy performance without exorbitant cost. With an emphasis on low energy M&E services and natural ventilation, BREEAM Outstanding was achieved at a cost of £1,074/m2.

Speller Metcalfe believes that such affordable performance is what the UK desperately needs to meet the stringent Government carbon reduction targets, move away from reliance on high cost forms of energy and deliver construction methods accessible to the majority of the UK construction industry - SME’s.

Project Team Details

• Client: Western Power Distribution,
• Contractor: Speller Metcalfe
• Building Services: Halligan Associates
• Structural Engineer: Nolan Associates
• BREEAM Assessor: GreenBuild Consult Ltd