Green roofs are a criminally under-utilised resource in the UK.
Whilst the UK green roof market is growing at around 17% annually, it’s not enough. In a time where we need to drastically cut pollution, lower our emissions and manage biodiversity better than ever before, green roofs continue to be overlooked.
Despite the fact that core living roof benefits are a cost-effective way to manage the impact our cities have on the world, there are no real policies in place to support their implementation.
UK Policies that could affect Green Roofs
The benefits of a green roof – insulating properties, emission reductions, noise insulation, habitation… – mean there are multiple options available to try and leverage. Any policy relating to:
- Energy saving measures
- Biodiversity – see biodiverse green roofs.
- Rainwater management
- Mental wellbeing
Could all be improved with the use of green roofs.
But without the price of green roofs reducing through market maturity and green roof demand increasing, we are unlikely to see government policies put into place.
The German green roof market is arguably the most mature and an excellent example of how government policies create notable product demand. Stuttgart has subsidised green roofs since 1986, with over 60% of the city classed as a green area and 39% protected, they have become a global green roof leader.
As urban living evolves and 68% of people are expected to live in cities by 2050, it’s of the utmost importance that we encourage urban roof farms or intensive green roof systems. Intensive living roof demand is expected to see CAGR of 17.5% from 2020 to 2027. If we don’t keep pace with this in the UK, our cities and urban spaces will be left even further behind.
UK Pollution Laws and Green Roofs
The UK government’s pledge to reach net zero emissions by 2050 and reduce GHG emissions by 68% by 2030 (based on 1990 levels) is incredibly ambitious. Really they need all the help they can get.
And green roofs must have a significant part to play.
Studies in the USA have shown that green roofs collected 137g of carbon per metre squared. Whilst research from Singapore suggested the substrate and vegetation captured 37% of SO2 from the air.
Given the UK probably only has around 5 – 7 million square metres of green roof coverage (extrapolated from UK Green Roof Market 2017 Assessment) – 0.003% total coverage – there’s a huge amount of wasted, otherwise unusable, roof space that could significantly reduce GHG emissions.
UK Insulation Policies and Green Roofs
Whilst the Green Homes Grant is a fantastic initiative, green roofs don’t specifically feature under the primary and secondary home improvements measures.
However primary insulation measures do cover:
- Solid wall insulation
- Cavity wall insulation
- Loft insulation
- Flat roof insulation
- Pitched roof insulation
And as every voucher must include one primary method of insulation, we think green roofs are well placed to feature as part of this voucher. We have asked for feedback from the government as to whether this is possible.
UK Biodiversity and Wildlife Protection Policies and Green Roofs
There are a number of wildlife protection acts in the UK designed to create environments where species can thrive.
As urban areas continue to grow and our impact on the world around us increases, taking care of our native species is pivotal. You only need to look at the plight of the honey bee to understand how damaging wildlife loss can be.
And that’s where green roofs can help. By significantly increasing intensive and extensive roofs across the UK, we open up safe, community spaces designed with specific species in mind.
UK Water Management Policies and Green Roofs
Runoff – particularly the stormwater variety – is a real issue in urban areas. Without permeable soil or ground to absorb much of the rain, cities are more prone to flooding. But this is where green roofs come in.
According to a GSA report, green roofs can reduce the rate of runoff by 65%. Even extensive roofs intercept and retain the first 0.5 – 0.75 inch of rainfall.
So local authorities concerned with urban water management absolutely need to consider green roofs as part of the solution. Their ability to reduce the amount and rate of runoff is a scalable solution. And an environmentally-friendly way to mitigate runoff and flooding concerns.
Social Measures and Green Roofs
With less than 1% of London currently covered by green roofs, there’s ample, otherwise unusable space up for grabs.
Intensive green roofs in particular can take the form of fully fledged gardens that operate as habitats, social spaces and community centres.
One Danish study with over 1,000,000 participants found that people growing up with the least green space next year had as much as a 55 percent increased risk of developing psychiatric disorders such as depression, anxiety, and substance abuse in later years.
London and Green Roof Policies
London’s size, density and comparatively archaic infrastructure have led to reliance on resources outside of it’s capacity.
For example, Londoners use 167 litres of water per day – 14% more than the England and Wales average. When it rains heavily, London’s sewer interceptors overflow 60 times a year. 60 times!
Much like the rest of the UK, London has no policies specifically aimed at green roof construction. Crazy considering the above.
According to Governmental green roof planning advice, major development proposals should include:
- Roof, wall and site planting – on roofs and walls where possible
- Adaptation to climate change
- Sustainable drainage
- Enhancement of biodiversity
- Accessible roof space
- The potential to create rooftop agriculture and garden space
And when it comes to sustainable design, the mayoral office published supplementary planning guidance (SPG) which includes:
- Energy efficient design
- Meeting CO2 reduction targets
- Decentralised energy
- Retro-fitting measures
- Offsetting GHG emissions
- Resilience to flooding
- Urban greening
- Pollution control
Alongside a host of other measures that suggest London and the mayoral department want to take green roofs seriously. They see them as a legitimate response to climate change and urbanisation.
Boris Johnson's 2020 Plan
In 2020, Boris Johnson set out ambitious green targets. Ones we believe are ideally suited to green roofs, including:
- An overall reduction in Co2 emissions of 60% by 2025 compared to 1990 levels
- 25% of heat and power used generated through localised, decentralised energy systems by 2025
- Increase the amount of surface area greened in the Central Activities Zone by at least 5% by 2030
- Increase tree cover by 5% by 2025
- 95% of construction, demolition and excavation waste is recycled / reused by 2020
- That there is no net loss in the quality and quantity of biodiversity