A word on...blue roofs
Increasing water scarcity in the UK has dramatically ramped up the need for inventive water management solutions. One potential answer to the dilemma is blue roofs, which provide a sustainable method to manage stormwater and mitigate sewer system stress. Here, Neill Robinson-Welsh, Consultant at ACO Building Drainage, analyses the impact of blue roofs on tackling water shortages.
Unlike traditional roofs that quickly drain water, blue roofs are modern drainage systems designed to temporarily hold rainwater and release it slowly. These systems help manage stormwater run-off, specifically in dense urban environments, reducing the risk of flooding and decreasing the load on sewer systems. This is an especially important feature as climate change increases the amount of stormwater and urban areas continue to expand.
Blue roofs also play a crucial role in enhancing urban climate resilience by reducing the risk of flash floods and mitigating the impacts of drought. When paired with green roofs, which feature vegetation nourished by stored rainwater, blue roofs help to combat the urban heat island effect, offering cooling benefits and improving environmental conditions in cities.
The UK’s water scarcity crisis
Projections suggest that by the mid-2030s, water demand will surpass supply unless significant infrastructure improvements are made. Since the privatisation of water services in 1989, underinvestment has left the UK’s water infrastructure ill-prepared to meet rising demand and manage stormwater adequately.
During 2024, urban sewer systems were often overwhelmed during heavy rainfall, resulting in combined sewer overflows (CSOs) where untreated sewage spills into rivers and seas. A blue roof’s ability to retain rainwater on site and release it gradually can therefore reduce the volume of water entering already stressed sewers. In turn, this helps prevent CSOs and environmental damage, providing a sustainable solution to the growing problem of sewer system overload.
Unlocking blue roof benefits
In addition to managing stormwater, blue roofs support water conservation efforts. Captured rainwater can be used for irrigation, which is particularly important given the UK’s increasing water scarcity. This reuse of rainwater minimises reliance on conventional water supplies and promotes self-sufficiency for buildings. But for blue roofs to function effectively, they need to be meticulously designed and seamlessly integrated. This is where building services engineers, specifiers, contractors and architects will play a vital role in implementing the systems properly into the UK’s urban infrastructure.
Other key considerations include the positioning of outlets, the roof’s slope and the choice of suitable attenuation systems.
ACO currently provides a solution that is purposefully engineered to operate independently of the roof’s waterproofing and drainage infrastructure, allowing for precise water retention management. The modular design of ACO RoofBloxx enables straightforward maintenance and provides reliable performance over time, even under severe weather conditions.
This system is also fully compliant with building regulations, enabling roofs to efficiently manage stormwater while improving the overall resilience of the structure.
