Explore: Environment and Sustainability

Future stations should be self-sustaining and have a positive impact on the environment. Sustainability must be core to the design brief, not an afterthought.

In the first round of engagement you told us that:

• You support the environmental and sustainability principles behind of the HUB Station and believe the environment should play an important role in future stations. • You wanted to see more detail on how station designs will reduce energy use and be more energy efficient, for example through insulation, low energy use and solar lighting and infrared radiant heating.• You asked for more detail on the planting and biodiversity strategy, including the specification of native species that are attractive to pollinators; links to other habitats such as rail embankments; and the integration of plants into the overall station design, such as on platforms and green roofs and walls.

What has developed since?

• Interrogating the brief to create stations that do more with less
• Detailed analysis to build the case for self-sufficient stations
• Carbon and energy modelling to inform environmentally conscious design decisions
• Developed landscape proposals to increase biodiversity 
• Rigorous testing of options including discounting options that are not beneficial to the stations or environment.

Interrogating the briefSketch showing a typical Category D,E and F Stations, courtesy of 7N Architects. 

From the outset, the ambition of HUB has been to offer a better passenger experience and facilities than is typically found in the smallest stations. To do this in a way that is sustainable, it is critical not to overdevelop the station.

Network Rail and 7N architects have been working to investigate the brief for stations. They are developing a functional brief for delivery of the 'HUB' station which will:

• Enhance the passenger facilities that are included in stations as a mandatory requirement.
• Establish a consistent standard of facilities across all stations
• Streamline the delivery of stations, allowing local station design teams to focus on site specific issues. 

This is still in progress, but in practice, it would mean that for HUB stations key aspects of the design such as a canopy and 'Welcome Mat' would become mandatory. More stations would receive enhanced passenger facilities such as an accessible WC with baby change, WIFI and electric vehicle charging as standard.

Energy resilient

HUB Station visualisation produced by Pillar Visuals, courtesy of 7N Architects

On-site renewable energy can meet up to 60% of the HUB station’s energy demands. 

Photovoltaic Panels
Standing on the platform on a sunny day, you might notice the dappled light filtering through the solar photovoltaic (PV) canopy. The PVs are embedded in the canopy glass and silently generate between 40-60% of the station's energy demands. Category D stations generate a higher proportion of energy due to their larger canopies. 

PV panels help the station to support the energy goals set out in the Network Rail Environmental Sustainability Strategy 2020-2050. Alongside the cost saved from purchasing energy from the national grid, this helps build the case for building platform canopies even at the smallest stations, where previously this would not have been a priority. 

The carbon saved through generating renewable energy on-site can balance the embodied carbon (the carbon stored within the materials and expelled in their manufacture) within 6 years. 

Carbon conscious decisions

Cross Laminated Timber offers a 65% carbon reduction in comparison to a typical steel frame.

Carbon and energy analysis has been used throughout the design process to assess the different options and make conscious design decisions. This allows the design team to specify materials and products which balance carbon with the robustness required in station environments.

Choosing the right materials isn't as simple as identifying the materials with the lowest embodied carbon. Materials also need to be robust enough to ensure they can last the lifespan of the building. It's important to consider how easily the structures are constructed, maintained and if they can be re-used or recycled at the end of the building's life. Life-cycle carbon and energy thresholds will be set within the design guidelines that apply to future stations.

Building with Timber

The station uses sustainably sourced FSC certified structural timber in place of steel or concrete. The design uses glulam for canopy structure and cross laminated timber for the tower structure. 

What is laminated timber? 
Cross Laminated Timber (CLT) is a wood product produced by glueing together timber panels under pressure and heat. By gluing layers of wood at right angles, the panel has a more robust structural rigidity than standard timber panels.

Glulam beams are produced using a similar process, but with the laminated panels oriented in the same direction.

When a tree grows, it absorbs carbon dioxide from the air, and the carbon stored in the timber becomes part of the structure. When this is considered in carbon analysis, CLT is potentially a carbon negative product - in other words, it stores more carbon than is used in its processing.

Timber is light and therefore easier to transport, and it can also be easily assembled on site. Classing can be pre-attached to reduce construction time, which is particularly important to limit the impacts on passengers during station construction.

Enhancing biodiversity

HUB Station visualisation, produced by Pillar Visuals, courtesy of 7N Architects.

Each station includes planting with a focus on local species. In addition to incorporating sustainable drainage where possible, the landscape will also aim to address biodiversity loss and encourage pollinators such as bees and butterflies.

Find out about Network Rail's commitment to improving biodiversity in their Biodiversity Action Plan.

Discounted options 

Following feedback from the first round of engagement the design team researched many different options, below are some of the systems discounted as not being suitable for the HUB Station. 

Rainwater Harvesting 
Rainwater harvesting was considered to minimise surface water run off and reduce carbon emissions associated with accessing potable water and sewage treatment. 

This approach was discounted following a detailed review for several reasons, including: 

• The space required for water storage 
• The ongoing maintenance requirements for tanks and pumps - particularly as stations are often unmanned
• It was found that the system, at this scale, would increase the stations carbon emissions due to the carbon expended from pumping the water

Green Roof 

The design team considered green roofs to reduce the discharge of rainwater from the roof to the drainage network and to enhance biodiversity.

However, this approach was discounted for this design for several reasons, including:

• It was found that a green roof would offset only a small proportion of the stations Greenhouse Gas emissions through carbon sequestration
• Although a green roof appears to offer a positive option from an embodied carbon perspective, it provides limited carbon offset (approximately 5%)
• Unlike PV panels, there is no reduction in carbon emissions caused by importing electricity, and no financial payback

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