Aquaten Fleece – Water attenuation and living roof passive irrigation system
The weather cycle of hot/dry then very wet is becoming a common pattern, one which standard living roofs find difficult to cope without relatively expensive irrigation systems, which is why the team at Aquaten developed a solution – Aquaten Fleece.
Aquaten Fleece is a geo-composite mesh made of 100% recycled material including AquaSAF absorbent polymer. It is designed to reduce rainfall runoff and/or to provide a valuable reservoir for living roof plants.
Aquaten Fleece can be installed onto any roof as a standalone solution or work on flat or sloping roofs and, via proprietary technology, AquaSAF, is designed to hold over 600% of its mass in water, significantly reducing run-off.
Aquaten Fleece can be incorporated into:
- the designed build-up of a living roof system or a landscape design to support a natural and ecological urban habitat without the need for expensive irrigation systems;
- retrofitted failing living roofs where lack of water has caused plant die back.
What’s more, because of it’s ability to hold more water, Aquaten Fleece can reduce the traditional costs of construction through reduced labour and reduced substrate requirements which ultimately reduce weight and logistics.
The essential function, to act as a water reservoir and water feeding to root systems, is based in the collective functionality of the component elements within the AquaSAF material, which is a highly absorbent and retentive fibre blended with low absorbency but high ‘wickability’ fibres.
This high absorbency provides two critical functions:
· Increases rainfall attenuation – reducing rainfall runoff
· Captures water to keep substrate hydrated for longer periods
Aquaten Fleece allows yearly rainfall attenuation to be more scientifically calculated and plays a major benefit in reducing stormwater run-off off roofs.
1. Longevity re performance, lifespan
While there is no specific test data available the product when buried will last for 20 years or more. The recycled Polymer fibre is very slow to degrade although the polypropylene will break down sooner, however this will not significantly reduce its absorbent capabilities.
Where the Aquaten is exposed to UV and the elements it is anticipated a life time of 4-5 years will be expected. Again this can be extended with the use of a sacrificial upper layer as we propose with our panel product.
2. Water availability for plants.
Tests we have carried out with Warwick University and the University of East London are demonstrating a 30% improvement in plant available water when using Aquaten Fleece in green roof builds. (Test data from UEL and Warwick are available.)
3. Water retention capacity
Tests done on random sampling have yielded a water absorption of between 5 litres and 6 litres/m2. The type of water that is used will also affect the result. Unless extreme pressure is applied then the Aquaten holds this volume and releases it slowly to the plants. It must be noted that by increasing the SAF (Super Absorbent Fibre) content then more absorption can be achieved as well as doubling layers etc.
When the fibre is converted into fabrics it becomes very much an integral part of the fabric itself; not just a superabsorbent stuck onto it.
- It provides a much more even distribution of the superabsorbent.
- It allows very specific placement of the superabsorbent.
- In roll form it is easy to simply roll it out over the required area.
- Moreover, a fabric presents a more versatile option. It can be used for applications such as wrapping around root balls to keep most during transportation, rolling out on a greenhouse bench to stand pots on to provide water to the pots etc…. these types of things cannot be done with a powder.
4. Other outcomes such as heavy metal absorption, carbon capture etc. We are investigating a carbon capturing geotextile.
The inability of excess rainwater to drain into the ground because of the introduction of man-made hard surfaces such as roads and roofs increases the
likelihood of flash flooding. The average daily rainfall in London is 1.8mm, however we see yearly rainfall patterns becoming more monsoon like, where short bursts of heavy rainfall are becoming the norm and this is creating significant flooding and pollution problems. This problem is particularly severe for cities and specific mention of this is made in the London Mayor’s Plan for London where planners are encouraged:
“To help deliver more living roofs and combat climate change the most recent alterations to the London Plan now ‘expect major developments to incorporate living roofs and walls where feasible.’”