The sustainable design approach relied on close collaboration between the client, design team and construction partner, in order to understand opportunities, risks and agree targets that were realistic and measurable. A primary goal was to implement passive measures, ensuring the concourse is filled with natural, glare-free north light, and natural ventilation and cooling, which filters through the canopies that protect the platforms above. Secondary drivers include active energy-efficient measures such as lighting controls, geothermal energy piles and intelligent escalator/ lift controls.

Above all, Network Rail committed to implement sustainability into the construction of the programme. This was manifested in the Thameslink Programme Sustainable Design and Construction Strategy. The document set out sustainability objectives with several targets under each objective, one of which was to achieve a CEEQUAL Excellent award for the project.

Key

1. Comfort / natural daylight and ventilation – The naturally ventilated concourse does not require heating or air conditioning and allows for good levels of natural daylighting, resulting in significant energy savings. The design target of the station was not to exceed external temperatures by more than 5 degrees and the station’s ventilation was determined to be enough for this criterion to be met throughout the next century. Overheating was further reduced through a dual-layered platform awning to limit the effect of radiant heat from exposed roof surfaces to platform occupants. The designed geometry of platform canopies also ensured the concourse could be top-lit, filled with natural glare-free northlight.

2. Prefabrication – The use of prefabrication across the project canopies, façades and cladding provided an inherent cost, energy and time saving in the reducing of interface with other trades; an improved quality associated with the working environment; a reduction in defects, rework, revisits and labour. Factory assembly allowed the roof, soffit and cable containment to be installed at ground level. This reduced the need to work at height; required fewer deliveries to site; reduced crane lifts, logistics and traffic management; reduced impacts on local communities, and; improved materials management and waste minimisation. It also provided the ability to mock-up, test, inspect and amend the product prior to delivery.

3. Sustainable construction materials – A Materials Use Plan was created to enable the sourcing of environmentally and ethically friendly materials while reducing the usage of unsustainable materials. Recycled materials contributed to lowering the project's embodied carbon. For example, by producing reinforced steel with a 98% recycled content, the project reduced the embodied carbon content of the top ten materials used by 15.6% against the industry standard baseline. Where possible construction materials were locally sourced, with 87% of deliveries to site from within 35 miles.

4. Heritage and reuse – A significant carbon saving was achieved through the decision to adapt and reuse 52% of the existing Victorian brick viaducts to accommodate the station's operational infrastructure, which included plant rooms, station storage and staff offices.

5. Enhanced urban realm and ecology – Rainwater is collected off all roof surfaces and stored on grade in the carpark area in a 500-gallon greywater tank; this rainwater is then used for HVAC make-up. The cooling tower makeup water consists of at least 50% non-potable water from harvested rainwater, and metering equipment has been installed to measure the makeup water quantities used from non-potable and potable sources. Excess rainwater overflow, 90% of the average annual rainfall, is sent to on-site injection wells to recharge the local aquifer. Greywater from basins, showers and building services is treated and reused for toilet flushing (80% of the flush fixture load is supplied from greywater).

6. Growing sustainable transport – The increased capacity of the station results in estimated savings of 24 million kg of CO2 per annum from the modal shift towards new and improved rail services. This is the equivalent to the energy use of 10 office buildings the size of the Shard.

7. Geothermal piles – Geothermal piles provides a continuous, reliable and sustainable energy source. These piles generate 126 tonnes per year in carbon savings for the operational station, delivering a 6.1% carbon reduction. They provide ground-source heating and cooling in the form of a series of chillers which feed into the main condensing loop of the retail spaces.

8. Low-energy fixtures – The station integrates a number of low-energy fixtures into its design. Intelligent control escalators allow reduced energy use during station off-peak hours and have annual savings of 36.46 tCO2e. DALI controlled LED lighting in the station concourse provides annual CO2e savings of around 235t. The inclusion of other active energy-efficient measures in the final build include high efficiency heat recovery, efficient air and water distribution and efficient control gear systems for lifts.