Native plants on green roofs reduce building management costs

Native plants on green roofs are often seen as a difficult option. This is primarily because they do not fit into the industrial systems often promoted by companies. However, a recent article in the USA highlights that native plants could, and maybe should, be the way forward. Not only because of the intrinsic value to biodiversity, but also in reducing costs.


Native plants - biodiverse green roof Switzerland
Native plants on a green roof in Switzerland


Native plants or non-native plants on green roofs – what are the costs?

Whilst there as been a move towards the use of native flora in the UK, this has been lead in the main through policy. Architects, who lead green roof specification tend be to look for a product.  Ecological systems and approaches are often hard for architects to embrace. . They change year in year. Yet these products that may use a lot of non-native flora, perhaps have a hidden downsize – cost. Not the cost of installing but the cost of maintaining. Furthermore, the cost is not only financial but also environmental.

LEED and native flora on green roofs

The article written by the Leonardo Academy states:

‘Whether supporting native plant species within your buildings site, on your roof, or on an offsite land trust or conservation, for LEED certification or general sustainable building management, building owners and managers can reduce their operating and certification costs by supporting native plant species and local biodiversity.’

As LEED awards  points for onsite native vegetation and green roofs, this is better route to take. And in doings so the cost saving opportunities associated plants can impact on inputs. In the case of green roofs that is the use of fertiliser, water and labour for maintenance.

The article also highlights the fact that new building sites can also score by offsetting elsewhere. Obviously in the UK, there is a move to offsetting biodiversity. Surely though by delivering green roofs onsite with native plants is a much better option? Not only do the green roofs provide benefits for nature onsite but also complement activities for reducing carbon and water run-off as well

Green roofs in the UK – BREEAM scoring system

Yet how effective is BREEAM in ensuring native plants are used on green roofs in the UK?  Wendy McFarlane of the Ecology Consultancy says: ‘BREEAM is fairly effective. However, for whatever reasons, there are still many projects that are going head that do not use a native approach. This is down to the design. BREEAM inherently points to a more ecological and native approach though. There is a frustration that architects and landscapes architects are not viewing BREEAM as a means enhance buildings ecologically.’

Therefore, though tools are available and planning policies/conditions require a native approach, many designers are still tending towards generic green roof systems. And therefore they may not score as well as they could or should.