Given the unprecedented extremes in climate change that the UK has experienced in the past few years, local and national planning policies have been developed to ensure that developers, architects and engineers take into account the impact of climate change on the performance of buildings.
For example, the recently revised London Plan requires developers to incorporate “urban greening” into new developments and consider stormwater reuse as a priority in managing surface runoff. This has seen a significant increase in specifications for blue roof attenuation systems, which are seen as an ideal way to manage both ends of climate change in conjunction with green roofs, as they control runoff and can help mitigate the effects of summer storms and storms. It can cause flash floods. Blue roofs also provide the added benefit of enabling water reuse either as a passive irrigation system or as a more conventional rainwater harvesting system.
However, the design of blue roof relief systems is not governed by any specific standards, and it is important to understand the differences in the function of a flat roof system and a blue roof relief system. Flat roof systems design is subject to a well-established set of British and European standards, as well as building regulations. These standards promote the rapid and effective removal of rainwater from the roof surface, the longer the rainwater remains on the roof, the greater the risk of water entering the building.
On the other hand, the blue roof attenuation system is designed to do the opposite explicitly, since the intent, for very good reasons, is to retain and hold water for specific periods of time to control flooding and the potential for water to be retained on the roof structure for later reuse.
Almost all blue roof systems available today are based on a roof waterproofing system and a roof drainage system that has dual functions. They start from the premise that you’re designing a roofing system when what you should be designing is a rooftop attenuation system.
If you see that you are designing a roofing system, there are a number of design issues that need incredibly careful consideration, for example the number, position and size of roof vents, the gradient of roof fall, the type of roof construction, and how long water is retained on the roof. Using this approach, you are designing two opposing roof functions that will require design compromise, non-compliance with known standards and accepted best practices, and therefore will increase the overall building design risk.
Given the novelty of blue roof systems, it should come as no surprise that developers and building insurers do not easily place these attenuation systems on top of residential developments or critical infrastructure, but this should not be the case if a more sensible design approach is adopted.
Unlike a normal flat roof that is visible and open to the elements, a blue roof system is often a covered structure that may have hard or soft landscaping above it, making it difficult to tell if the system is working. In the event of a system blockage, water will be retained in a semi-permanent manner if there is no early warning system or regular maintenance system.
Designing for flexibility requires not only compliance with standards, but also full consideration of worst-case scenarios: what if the system is not serviced and becomes clogged, how do we want the roof drainage system to function in such a situation? What if climate change is so much worse than expected that the system regularly outperforms, how would you want the system to work in that case? These are expected events that require design solutions.
The patented ACO RoofBloxx blue roof attenuation system responds to these design challenges by ensuring that function and form are not confused. It creates a separate open attenuation system that sits and operates independently of the rooftop waterproofing and drainage system.
By creating a separate system, ACO ensures that the roof can drain slowly during design precipitation events, and can hold water for reuse, but that in extreme and unexpected events, for example, the system is blocked or a design event bypassed during storms, it can The roof drains quickly to all recognized building standards. Importantly, water is not encouraged to remain in contact with the waterproofing of the roof for longer than acceptable design practices allow.
Giving designers, developers, insurers and building owners peace of mind, the ACO system increases the flexibility of the overall roofing structure and thus eliminates unnecessary risk. In addition, by separating the responsibility for design, there is a clear separation between the disciplines of engineering and design.
Flexibility, sustainability and net zero are standard words for a new generation of designers seeking to increase the functionality and lifespan of buildings. Understanding the function of the system is critical to designing an appropriate solution. ACO RoofBloxx meets building regulations and planning requirements and allows for the installation of a flexible climate system that helps mitigate surface run-off and does not damage the building fabric.
To find out more, please register here for a Blue Roof Certified CPD – Creating Sustainable Urban Environments on September 29, 2022 at 12:30 PM. Register for a CPD by clicking on the link
To visit our blue roof page, please watch the animation of our system, click over here