Biodiversity Net Gain and Living Roofs

Biodiversity Net Gain doesn’t have to be an obstacle in the pursuit of planning success. And with so many benefits to be gained, it makes sense for developers to embrace it and design it into their development plans from the early stages.

Trying to mitigate biodiversity loss and achieve the 10% gain required to secure planning approval can be challenging for developers” advises Matthew Fasham, Technical Director in our Ecology team.

With BNG now mandatory in England and still playing a big part in the future of development across the rest of the UK, we caught up with Matthew to find out more about one of the solutions he recommends to his clients in the pursuit of BNG.

“Onsite delivery of BNG is simpler for a developer, if it can be achieved” adds Matthew “Green infrastructure can deliver a significant number of credits to your scheme. Green and brown roofs, for example are especially useful on urban sites where there is limited space for landscaping at ground level due to other development constraints”.

What are green and brown roofs?

A green roof is a flat or pitched roof covered with plants (which can be as simple as mats of mosses, Sedum and a range of grasses and flowering herbs). It creates habitat for flora and fauna and can therefore play an important part in conservation or enhancing biodiversity, particularly in urban locations.

A brown roof is where space is left on the substrate surface to allow colonisation from windblown seeds or seeds brought in by birds. RPS has designed and successfully installed ‘Biodiverse brown roofs’ which have a mix of substrate, topdressing with translocated seedbank, dead wood, dew ponds and bee mini-banks to maximise botanical and invertebrate species richness. Brown roofs provide opportunities for different species to green roofs, and therefore a combination of both can increase the habitat diversity of a site. 

What are the benefits of green and brown roofs?

  • They help deliver BNG in urban environments where space is limited
  • They can help to balance surface water but retaining and slowing run-off which helps to reduce the risk of flooding
  • They can be a striking design statement, aesthetically pleasing and help blend a building into its surroundings
  • They improve air quality, trapping pollution and absorbing gases
  • Reduce the urban heat island effect through absorption of heat and the natural cooling effects of water evaporation from plants and soil
  • They can improve the thermal efficiency of a building, reducing its carbon footprint
  • Developers can enjoy cost savings by delivering their BNG requirements onsite
  • Their sustainability credentials help deliver BREEAM and make them popular with planning departments in local authorities



“It’s important to make your green space work hard and deliver as many credits as possible” concludes Matthew. “The inclusion of green/brown roofs can help to achieve net gain onsite and therefore avoid the need to seek a potentially complicated and expensive offsite solution”.

Project experience

  • Darwin Escapes

    Architect: NBDA

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  • Cambridge North

    Client: Brookgate

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  • Brighton and Hove Wastewater treatment

    Client: Southern Water Services Our multi-disciplinary team secured planning permission for this £300 million scheme which included a 18,000m2 green roof, the largest of its kind in the UK at the time.

    03 /03
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Watch now...How to approach BNG

The future of development is Biodiversity Net Gain (BNG) - failing to prepare could be a costly mistake. In this webinar Mike Barker, Director of Ecology, helps clients to prepare by demonstrating how to integrate biodiversity net gain into development plans, avoid costly mistakes and effectively and legally manage a site to achieve maximum value.


Use the form below to watch our webinar now

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Masterplanning and Green Infrastructure

Watch on demand 

Designing green infrastructure into your developments can tick a lot of boxes from both a planning and environmental perspective. With so many benefits to be gained, integrating Landscape, Ecology and Hydrology into the early masterplanning process is fundamental. In our free, one hour webinar, Director or Ecology, Mike Barker and Director of Urban Design, Jonathan Stewart share how to deliver truly integrated, multi-functional green space that adds real value to your project.

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The lessons we've learnt so far

We’ve been delivering BNG for some time and know how to integrate it into a project to achieve a sites maximum value. Over the years, we’ve learnt a number of lessons that have shaped our approach, how we assess it and how we deliver it for our clients.

We've summarised what we've learnt into eight key lessons to help you integrate BNG into your development plans effectively. 

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