Blue Green Roofs for Smarter Cities and Water Conservation

Blue green roofs are a game-changer for cities and our planet. They're a type of roof that combines traditional green roofs with blue elements like ponds or pools.

By incorporating these blue elements, blue green roofs can hold up to 50% more water than traditional green roofs, which is a huge deal for cities with limited water resources. This is especially true for cities like Chicago, where the average annual rainfall is just 35 inches.

The water retention capacity of blue green roofs can help reduce stormwater runoff, which is a major contributor to urban flooding and water pollution. In fact, a single blue green roof can remove up to 1.3 million gallons of stormwater from the city's drainage system each year.

Blue roofs can reduce the risk of flooding and erosion by storing and delaying the release of stormwater. This can have significant benefits for both the environment and building owners.

By managing stormwater on-site, blue roofs can reduce the need for expensive infrastructure upgrades and repairs. This can be a huge cost savings for municipalities.

Blue roofs can also provide additional space for outdoor recreation or even green roofs. This can be a great way to create more livable spaces in urban areas.

Incorporating both systems, blue and green roofs, can maximize the benefits of sustainable urban development. This can lead to more resilient and sustainable cities.

Green roofs have been used around the world for centuries, and have been adapted to modern urban buildings. They have been adopted by many cities as a way to manage stormwater and reduce the urban heat island effect.

Blue and green roofs can be combined to grow productive, or edible crops. This can have synergistic benefits, such as increased biodiversity and carbon sequestration.

Blue roofs use specialized retention layers to delay stormwater run-off or retain it for evaporation. This can help to reduce the burden on municipal stormwater systems.

In urban environments where space is at a premium, blue roofs offer a logical way of controlling and re-using rainwater at source.

Green roofs are effective at reducing the urban heat island effect, which can reduce energy consumption and improve air quality.

Green roofs and blue roofs have different environmental impacts, but both contribute to sustainable urban development. Incorporating both systems in a building or project can have a significant positive impact on the environment.

Blue roofs are designed to manage and control stormwater runoff, which can cause flooding and erosion in urban areas. Urbanisation has led to an increase in impervious surfaces such as concrete and asphalt, making it difficult for rainwater to be absorbed into the ground.

Green roofs are effective at reducing the urban heat island effect, which is when urban areas are significantly warmer than surrounding rural areas.

By absorbing and reflecting less heat than traditional roofs, green roofs can reduce energy consumption and improve air quality.

Blue roofs, on the other hand, are designed to manage and control stormwater runoff, which can cause flooding and erosion in urban areas.

Urbanisation has led to an increase in impervious surfaces such as concrete and asphalt, which means rainwater cannot be absorbed into the ground, resulting in an increase in stormwater runoff.

Blue roofs mitigate the negative effects of stormwater runoff by storing and delaying the release of stormwater.

Incorporating both green roofs and blue roofs in a building or project can have a significant positive impact on the environment.

Cities are growing and the climate is changing, making it essential to think about more resource-efficient solutions. Heavier precipitation, extreme heat, and prolonged drought are becoming more common, and urban spaces for solutions are limited.

Green roofs are effective at reducing the urban heat island effect, which is when urban areas are significantly warmer than surrounding rural areas. They absorb and reflect less heat than traditional roofs, reducing energy consumption and improving air quality.

Blue roofs, on the other hand, are designed to manage and control stormwater runoff, which can cause flooding and erosion. By storing and delaying the release of stormwater, blue roofs mitigate these negative effects.

Incorporating both green and blue roofs in a building or project can have a significant positive impact on the environment. This can help reduce wastewater processing costs, sewage overflows, and street and basement flooding.

By combining green and blue roofs, a net-zero water outflow may be achievable. This is because the water from the blue roof reservoir can be fully retained and used by the plants or released to the atmosphere through evaporation or ET, eliminating run-off.

Cities can transform into a smart grid for water by working together with cities and universities. This can lead to the creation of a rooftop water-board, like Resilio, which showcases the potential of blue-green roof system designs.

Regular maintenance is crucial for the long-term effectiveness and sustainability of blue green roofs. Green roofs, in particular, require more maintenance due to the vegetation and soil.

Green roofs need regular watering, fertilizing, pruning, and weed control. The roof membrane and drainage system also need to be inspected regularly to ensure there are no leaks or damage.

Blue roofs, on the other hand, require less maintenance but may need more intensive inspections and repairs when issues arise.

Green roofs are generally more expensive to install than blue roofs due to additional materials and labor required. The cost difference can be significant, making it a crucial factor to consider.

However, green roofs can provide a higher return on investment over time by reducing energy costs and extending the lifespan of the roof. This can lead to significant cost savings for building owners.

Blue roofs, on the other hand, are typically less expensive to install but may require more maintenance and repairs over time. The cost savings from stormwater management may not be as immediately apparent as with green roofs.

The long-term benefits and potential cost savings associated with each system should be carefully weighed when considering the cost of implementation.

Maintenance Requirements are a crucial aspect to consider when deciding between green and blue roofs. Green roofs require more maintenance than blue roofs due to the vegetation and soil.

Regular watering, fertilizing, pruning, and weed control are necessary for green roofs. This can be time-consuming and labor-intensive.

Blue roofs, on the other hand, require less maintenance but may need more intensive inspections and repairs. The roof membrane and drainage system must be regularly inspected to ensure there are no clogs or damage.

It's essential to consider the maintenance requirements of both systems to ensure their long-term effectiveness and sustainability.

A blue green roof typically consists of a waterproofing layer, followed by a drainage layer, and then a growing medium for plants. This structure is essential for preventing water damage and ensuring the roof's longevity.

The waterproofing layer is usually made of a durable material such as EPDM or PVC, which can withstand harsh weather conditions. It's also crucial to ensure that the roof's slope and drainage system are designed to handle heavy rainfall and prevent water accumulation.

To install a blue green roof, you'll need to start by inspecting the roof's structure and ensuring it can support the weight of the added layers and plants. This may involve consulting with a structural engineer or architect.

Green roofs are ideal for reducing energy costs and improving air quality, but blue roofs are better suited for managing stormwater runoff and reducing the risk of flooding and erosion.

If you want to cool the city, blue-green roofs are the way to go, allowing for higher evapotranspiration rates than conventional green roofs, at around 70 percent.

For every 10 percent more surface coverage of vegetation, you cool the city by half a degree, so it's worth considering a system that allows for more plant growth.

Blue-green roofs, like Resilio's, are suitable for growing a wider variety of plants than conventional green roofs, making them a great option for urban developers.

Designing drainage for a blue roof is crucial to ensure it functions as intended. The roof drainage should be designed to BSEN12056-3:2000, which sets out the standards for roof drainage.

Consideration should also be given to surface water drainage, especially if the roof is a podium deck or landscaped roof. This should be carried out to BS EN 752:2008.

Waterproofing details, penetrations, roof geometry, fire and vegetation, roof outlets, thermal insulation, and wind uplift are all important factors to consider when designing a blue roof drainage system.

A blue roof's purpose is to detain water rather than drain it quickly, so the hydraulic design of the system should be site-specific and consulted on early with a professional, such as ACO.

In general, a blue roof should fully drain down in 24 hours, although this can vary depending on the specific design and location.

Some common blue roof systems include:

A blue roof's structural load is minimal, typically around 1.0-1.5kN/M2, which is unlikely to be much more than 100-150mm in depth of stored water.

This is because the water stored on a blue roof is usually not very deep, so the added weight is relatively small.

A detailed structural analysis should always be carried out by a qualified engineer to ensure the roof's integrity.

Most blue roofs are designed with a green roof build-up, which often requires a concrete slab to be specified.

The ACO RoofBloxx system is a comprehensive solution for blue green roofs and podium decks. It includes a range of accessories such as capillary wicks for passive irrigation systems and a protection fleece for additional roof membrane protection.

The ACO Blue Roof Diffuser and Access Unit is a modular stackable frame and riser system designed for use with the ACO RoofBloxx range. It can be used as an access unit or an inlet diffuser with a combined shallow silt trap.

The ACO Blue Roof Flow Restrictor is designed to control the rate of water runoff from a blue roof, and can be used with the ACO range roof outlets and accessories.

Here are some key features of the ACO Blue Roof System:

A SuDs system is a type of sustainable urban drainage system that helps manage stormwater runoff and reduce the risk of flooding and erosion.

Green roofs and blue roofs are two types of SuDs systems, each with its own benefits and uses. Green roofs are ideal for reducing energy costs and improving air quality, while blue roofs are better suited for managing stormwater runoff and reducing the risk of flooding and erosion.

Incorporating both systems can maximize the benefits of sustainable urban development. For example, a blue roof system can be designed to drain slowly in normal use and quickly in extreme conditions, using a system like ACO RoofBloxx.

A SuDs system can be designed to meet regulations and planning conditions, such as the London Plan, which recommends the use of blue green infrastructure as part of a roof build up wherever possible.

Some key considerations when designing a SuDs system include the size and location of the roof, the local climate, and the goals of the project. The system should be able to drain slowly in normal use and quickly in extreme conditions, such as during heavy rain events.

Here are some examples of blue roof systems:

A well-designed SuDs system can have numerous benefits, including reduced water bills, improved air quality, and reduced risk of flooding and erosion. It can also help to mitigate the effects of climate change and provide amenity space for building occupants.

The ACO Accessories are a crucial part of the ACO RoofBloxx system, designed to provide additional protection and functionality to the roof membrane.

The system includes capillary wicks for passive irrigation systems, a protection fleece, and a filter geotextile.

A modular stackable frame and riser system, the ACO Blue Roof Diffuser and Access Unit, is designed for blue green roofs and podium decks. It can be used as an access unit or an inlet diffuser with a combined shallow silt trap.

The unit is available with an 85mm base frame and 165mm raising pieces, accommodating 68-150mm diameter pipe connections.

The ACO Blue Roof Flow Restrictor enables designers to control the rate of water runoff from a blue roof, designed for use with the ACO range roof outlets and accessories.

Here's a summary of the ACO RoofBloxx Accessories: