Urban and industrial water management faces big challenges, as the recent floods in cities like Toronto have demonstrated. Such extreme volumes of rainfall over a short time period overload stormwater infrastructure that was not originally designed to handle the capacity of current rainfall intensities. When overloaded, stormwater systems overflow and are bypassed, causing flooding. As a result of the flood damage, water damage claims are rising, increasing the financial impacts of major floods.
The good news is that blue roofs are a new rainwater harvesting technology that can be key in managing stormwater, especially for manufacturing and warehouse facilities as they often have large flat surface areas ideal for storing rainwater. By attenuating stormwater, they can slowly release rainwater to the municipal sewer systems at a manageable rate.
As a plus, blue roofs do more than just hold water. The retained rainwater can be used for irrigation, flushing toilets, non-contact cooling, non-potable cleaning, and cooling buildings (through the cooling effect of the evaporating water). Plus, since the foam underlaying the top TPO (Thermoplastic Olefin) layer has better insulative properties than conventional built-up roof (BUR) and modified bitumen roofing, they help save energy for building owners and landlords and reduce the urban heat island effect due to the white colour of the TPO.
Key Takeaways
- Blue roofs are key in attenuating the impacts of heavy rain and flooding.
- They use commonly available roof construction materials.
- They save energy by making buildings more insulated.
- They help save water by reusing the stored rainwater.
- They help cool cities in hot weather due to the stored water and the white TPO roof material.
- They can be made affordable with government help.
What is a Blue Roof? Understanding the Basics
A blue roof is designed to manage stormwater in urban and industrial areas, and it can also reduce building heat load through the evaporation of the stored rainwater.
Advantages of blue roofs over conventional ones is that they support sustainable living and offer economic benefits. The main sustainability advantages are managing stormwater and reducing energy use. Since a blue roof captures rainwater and releases it slowly, it reduces the strain on stormwater sewage systems and mitigates flooding risks.
As mentioned, blue roofs also cut energy costs by insulating buildings naturally (due to the thick foam layer) during the winter and through the cooling effect of evaporation during summer months. In certain applications, the rainwater can be used for non-potable uses, such as flushing toilets or first rinses (e.g., vehicle washing stations).
Recognizing these benefits, some international governments are starting to provide funding for them. For example, the UK government supports them through funds like the Green Infrastructure Fund. As their implementation becomes more widespread, it is likely that other jurisdictions (including those in North America) will provide funding opportunities as well. For example, some regions in Ontario, Canada, like the City of Kitchener and the City of Mississauga, offer stormwater credits for activities such as improving the quality or quantity of stormwater runoff. Kitchener’s non-residential stormwater credit program includes “rooftop storage” as an eligible best management practice (BMP), which is an excellent fit for a blue roof.
| Feature | Benefit |
| Stormwater Management | Controls runoff, reducing flood risk |
| Sustainability | Supports water reuse, energy efficiency, and aids urban cooling |
| Economic Incentives | Reduces water and energy costs, potentially eligible for green funding such as stormwater credits |
The Role of Blue Roofs in Urban Flood Prevention
Urban areas face more flooding due to climate change and poor stormwater management. Blue roofs are a key part of solving this problem. Since they hold rainwater, less water flows into stormwater systems (as a portion of the stored rainwater evaporates) and the flow to the stormwater systems is attenuated by releasing the stored rainwater slowly, and lowering flood risks during storm events.
Blue roofs use smart systems to manage water flow, such as valves that can be operated remotely and set to drain the roof at various flow rates.
- Reduction of flood risks via controlled water release
- Stormwater management improvement through delayed runoff and reduced peak flows
- Enhancement of urban resilience and adaptation to climate change impacts
- Sustainable urban environments with multi-functional roof spaces
When designing blue roofs, it’s important to think about rainfall, runoff, and how much water they can hold–so these systems need to be carefully designed. As cities and industrial areas grow and face more environmental issues such as more intense storms and hotter temperatures, blue roofs can play a key role in keeping them cool and sustainable.
The Cost-Benefit Analysis of Blue Roof Installation
When evaluating blue roof technology, one should consider both the upfront costs and long-term savings. At first, blue roofs might seem expensive. But they can save a lot of water if there are opportunities to reuse the stored water, as discussed previously. This translates into long-term environmental and economic benefits.
The ideal time to install a blue roof is for a new build or when a roof is due for replacement already, since there is already a planned investment in a new roof and the incremental cost to upgrade it to a blue roof may be worth the additional installation costs. Large, flat roofs that are common for manufacturing facilities and warehouses are ideal, as they provide significant surface area for water storage.
Ready to transform your business with sustainable water management solutions? Contact Enviro-Stewards to learn more about how blue roofs can help your company achieve its sustainability targets.