
Blue-Green roofs for future-proof cities.
Multifuntional roof systems allow people to live in a healthy environment, while enjoying the ecological and economic benefits of blue-green infrastructure.
Solution
From grey to healthy green.


Space for green infrastructure is disappearing in ever denser cities all around the world. Yet, cities feature vast areas of unused and unexploited rooftops. These empty spaces can be reclaimed for stormwater management in combination with plant growth by creating blue-green roofs and roof gardens.
Rooftops can be transformed into functional landscapes or roofscapes, designed to conserve and generate energy, manage rainwater, create space for biodiversity and space for people to enjoy or any smart combination thereof.
With this approach, roofs are no longer just there to keep out the rain. They become an integral and functional part of the building they are on and the city they are in. A transformation from unexploited capital to functional space.
Process
How does it work?
In order to deliver ecosystem functionality, vegetated roofsystems need water. Too often water is missing in conventional green roofs during prolonged dry spells in summer; exactly when the urban cooling capacity of vegetated roofs is needed most. Based on scientific peer reviewed research by KWR Water Research Institute we have evolved the conventional green roof to a naturally functioning blue-green roof. By incorporating significant stormwater retention volume and capillary functioning in the design, full smart water management is now possible. Improving ecosystem functionality in water sensitive design.
System functionality

The hollow Permavoid subbase makes it possible to store more rainwater in lightweight geocellular units underneath the soil in podium decks, blue-green roof systems and roof gardens. This stored rainwater is made available to the plants by capillary rise through capillary fibre columns in the Permavoid units. This nature- based solution of capillary irrigation eliminates the need for drip lines, valves, hoses, pumps and the associated maintenance requirements. Water is available for the plants when they need it, naturally, on-demand, and most importantly without the use of energy; just like in nature.
Water is the key to successful green infrastructure at any level, in every green design. Keep rainwater out of the sewer and put it to work to support, biodiversity and help cool the urban environment.
Benefits
Strong benefits for rooftops.
Water is available for the plants when they need it, naturally, on-demand and most importantly without the use of energy. Just like in nature.
Irrigation water savings
The total amount of water needed for irrigation can be reduced without hampering plant growth, because capillary irrigation does not experience surface evaporation losses. Independent research by STRI in Australia, the UK and the Gulf region showed irrigation savings up to 60%.
Versatile mounting platform
A reliable connection to attach complementary elements to the Permavoid capillary system is available with the addition of the PermaLock in which bolts can be screwed. No more drilling into the roof to attach fencing, solar panel systems or wooden decks.
Plant growth & biodiversity
The reliable capillary availability of water for vegetation enables the landscape architect to choose from a wider array of plant species. Permavoid Project Smartroof 2.0 in Amsterdam scored highest on flower count and bee-species diversity in an ecological study including 21 different green roofs and roof gardens in the summer of 2018 and 2019.
Cooling down
Stored water can be used for a myriad of functions, from drinking water generation to flushing toilets and grass irrigation or synthetic turf cooling, conserving water, keeping water out of overloaded sewer systems during peak events and at the same time creating a valuable urban cooling effect.
Water is key to successful green infrastructure in every design. Keep rainwater out of the sewer and put it to work to improve city life.