Footprint

Arup and Sky-Garden have launched Pocket Habitat, a modular planting bag designed to promote biodiversity on roofs. Last week, AJ Technical Editor Felix Mara attended the launch at Arup’s new HQ at 8 Fitzroy Street  London and wrote the following report:

Each bag is a standalone unit made from ‘green’ material, containing recycled substrates and wildflower seeds. The bags link together to form continuous vegetated surfaces, which may be moved when required. This is an adaptable way to create rooftop environments that can be tailored to area postcodes, using locally sourced aggregates, thus promoting
localised biodiversity. Pocket Habitat overcomes the manoeuvrability and maintenance problems of conventional systems.

Developed as a way of retrofitting buildings with green roofs, it can also be used on brownfield sites, wasteland or balconies. Installation and removal is easy, requiring no expert knowledge. These bags create stepping stones, facilitating movement and dispersal of wildlife.  They may also provide habitats for rare, protected and otherwise important species. Humans benefit, too. While cities are generally dry, impoverished of soil, impermeable and hot, vegetation returns elements of the natural world into the urban realm.

All the usual arguments for green roofs apply. Vegetation and soil retain water but also, through evapo transpiration, they return water to the atmosphere.  The procedure takes heat away from buildings, providing significant savings in terms of air conditioning costs. At the same time, it helps tackle rising urban temperatures and reduces rainfall run off which may over burden urban drainage systems.

It can can act as a filter for air pollutants and add additional noise insulation and protecting waterproofing membranes from the effects of UV and frost. This is why vegetation at roof level in particular is increasingly being seen as key to changing cities from hot concrete jungles into flourishing, cool, green spaces.

Pocket Habitat emulates the natural living conditions of plants, aiding seed germination by providing shade and shelter from the wind, while offering large open areas for maximum exposure to the sun. It offers flexibility to host plants, flowers, grasses, bushes, shrubs and vegetables, enabling users to personalise modules. When installed it already looks established,
so no unsightly growing periods.

This product is particularly interesting because of the collaboration between Sky-Gardens Greenroofs, a supplier and installer of green roofs, and multi-disciplinary consultant Arup.  Arup product designer Rebecca Stewart explained that generally ‘it is a logistical nightmare getting stuff up onto the roof.’ The 20kg  Pocket Habitat bags help to overcome this. She emphasised the textiled, crafted nature of the product and the importance of ‘having an aesthetic from day one.’

Mike Cottage, founder director of Sky-Gardens Greenroofs, noted that ‘being bio-diverse’ doesn’t mean being sustainable.’ The bags could have been manufactured in China, but Stroud was chosen instead.

Green roof authority Dusty Gedge rounded off the presentation by recalling the days when people interested in biodiversity wanted to create roof gardens. ‘We were considered nutcases’, he reminisced.

I’m glad I attended the launch because Pocket Habitat really is a product which you have to see to appreciate. The zip-up bags, with their grey felt outer layers, are covetable objects and they form attractive groups of planting which is available in a range of specifications, with six pick and mix substrates. Rather like the iPod, you might say ‘is that all it does?’ But it does it very well, it looks great and it rocks.

Drawings of Pocket Habitat which explain the system well can be found here and here.

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