Smart roof technologies mitigate blue roof risks
Blue roofs can play a crucial role in urban water management by collecting and storing rainwater for gradual release, thereby reducing urban flooding and easing the burden on drainage systems. Despite their significant benefits, blue roofs require careful design and regular maintenance to mitigate associated risks, such as leaks and moisture-related damage. Advanced smart technologies, like VILPE Sense, can be essential in effectively managing these risks.
In many urban areas, blue roofs have been introduced to address challenges such as stormwater flooding and heatwaves (Almaaitah, Drake and Joksimovic, 2022). Cities like New York and San Francisco have increasingly adopted blue roofs as a sustainable solution (Engle, 2017).
Purpose of Blue Roofs
While there are various types of blue roofs, each with distinct functional and technical features, their primary purpose remains the same: collecting and storing rainwater on the roof. This stored water is typically:
- gradually released into the drainage system
- used for cooling indoor air
- evaporated
- repurposed within the building, such as for flushing toilets
Benefits of Blue Roofs
The advantages of blue roofs extend beyond stormwater management. They can reduce the strain on drainage and sewer systems and lower energy consumption for cooling buildings. Additionally, the collected water can be used by building occupants, further enhancing resource efficiency. Some argue that blue roofs are more cost-effective and, in some cases, easier to maintain than green roofs, making them a viable alternative for mitigating climate-related stresses on buildings (reference).
Diverse blue roof solutions
While the core concept of blue roofs is consistent, their implementation varies widely. Local building codes and stormwater regulations significantly influence blue roof designs. Water collection techniques on blue roofs vary, including pools, standing water in cups or boxes, water-absorbing materials, tanks, and various drainage and pipe systems (Andeneas et al., 2021, p. 2). These features can either be visible on the roof or integrated into the roof structure.
Blue roofs generally fall into two categories: active and passive water collection systems (Engle, 2017). Active systems, or automated roof runoff management systems, systematically store, move, and distribute water. These systems range from highly sophisticated data-based setups to simpler mechanisms. In contrast, passive systems merely gather and hold water, and for instance, allow it to evaporate naturally (Engle, 2017).
Blue roofs are sometimes combined with green roofs to create “blue-green roofs,” which integrate vegetation and various substrate layers for enhanced stormwater management (Andeneas et al., 2021, p.11). These roofs are designed for significantly higher stormwater retention compared to traditional green roofs, thanks to the combination of plant layers and water storage containers, pools or porous materials.
Design considerations and risks
The retained water is the largest challenge for blue roof design. The biggest risk is the heavy weight of the water and the stress it poses on the roof structures. It is paramount to specify the amount of water weight that the roof structures can bear and making sure that the weight load does not exceed the capacity of the roof. Special care should be considered for unexpected weather and other nature-related phenomena, such as earthquakes and unusually heavy storms.
Another important aspect of the design is to specify what will happen to the retained water. Standing water is a risk for many reasons, for instance it provides a growing ground for fungi, bacteria and algae and the water needs to be purified and tested regularly (Engle, 2017). Commonly, the retained water is evenly distributed on the roof to be released in a controlled manner. The water releasing system on blue roofs can vary largely in sophistication. It is very important that the drainage system is maintained and that it is not for instance clogged by algae as clogged drainage can lead to water pooling, which in turn is associated with leaks, roof degradation, or even structural failure.
Most of the risks on the roof is moisture related. There is a consensus within the academic literature that moisture-related problems construct the largest challenge for roofs of all types. Some studies suggest that on flat compact roof 73 % of the examined defects and problems were moisture-related (Andeneas et al. 2021, p. 3). This risk is likely to be even bigger on blue roofs. Because blue roofs involve storing water on the roof surface or inside the structures, there is an increased risk of water infiltration into the building if the roofing materials or drainage systems fail. Therefore, extra care needs to be taken to the leakage risk already at the design phase.
Smart roofing technology to mitigate blue roof risks
Incorporating IoT and smart technologies into blue roofs significantly enhances their safety, performance, and longevity. For instance, real-time monitoring systems equipped with sensors can track critical factors such as water levels, flow rates, and roof temperature (reference).
These systems can often be managed remotely and include customizable alarms, allowing for prompt responses to potential issues. Some advanced blue roofs can even integrate with weather forecasts, automatically adjusting water retention and release to prevent overflow and flooding based on upcoming conditions.
Help in detecting moisture problems
Since blue roofs temporarily store water, effective moisture management is crucial. Smart technologies are pivotal in preventing moisture damage, particularly through smart systems like the VILPE Sense leak detectors. These detectors continuously monitor moisture levels within the roof structure and send real-time alerts if levels exceed safe thresholds. This early detection enables building managers to address moisture-related issues before they lead to costly repairs or structural damage. Proactively managing moisture helps maintain the roof’s integrity, preventing problems such as water infiltration, which could compromise the structure or drainage systems.
Additionally, VILPE Sense leak detectors improve the efficiency of the repair process by pinpointing the location of damaged areas. For example, if leaks occur under solar panels or other installations, the system facilitates more targeted repairs, reducing the need to dismantle large portions of the roof. This focused approach not only shortens repair times but also lowers maintenance costs, enhancing the overall efficiency of blue roof upkeep.
The VILPE Sense humidity control system, while sharing the leak detection features, adds a demand-based ventilation function. It is connected to a roof fan that ventilates the insulation layer as needed to, among other things, prevent condensation buildup. Water stored on blue roofs often results in colder roof surfaces, causing moisture to accumulate in the insulation layer. The system’s smart ventilation feature automatically adjusts airflow to reduce humidity, keeping the insulation dry and maintaining its thermal efficiency. This helps the building remain energy efficient while protecting the insulation from moisture-related damage.
Both the VILPE Sense leak detector and humidity control are suitable for use on roofs where the insulation layer needs to remain dry. For optimal performance, the insulation in the VILPE Sense humidity control must allow for adequate ventilation to ensure effective moisture management.
References
Almaaitah, T., Drake, J., & Joksimovic, D. (2022). Impact of design variables on hydrologic and thermal performance of green, blue-green and blue roofs. Blue-Green Systems, 4(2), 135-155.
Andenæs, E., Time, B., Muthanna, T., Asphaug, S., & Kvande, T. (2021). Risk reduction framework for blue-green roofs. Buildings, 11(5), 185.
Engle, John (2017, May). https://www.constructionspecifier.com/the-rise-of-the-blue-roof/
Blue Roofs, https://blueroofs.com/the-benefits-of-blue-roofs/
PHP Systems/Design, https://www.phpsd.com/blog/everything-you-need-to-know-about-blue-roofs
Sustainable Technologies Evaluation Program, https://sustainabletechnologies.ca/home/urban-runoff-green-infrastructure/low-impact-development/blue-roofs/detailed-design-and-implementation-of-a-smart-blue-roof/