BioTecture Ltd is the UK’s first dedicated green walling company. Run by richard Sabin, a sustainable building consultant and Mark Laurence, a sustainable landscape designer, BioTecture’s new patented product, the BioWall™, brings to the field of green walling a commercially robust, reliable and economic design, install and maintain package.

the BioWall™

The BioWall™ is the main component in any Biotecture green wall. This patent-pending, modular unit is designed to be installed in the same manner as any commercial rain screen cladding system, using standard caldding rails and fixings. Plants are watered and fed via a hydroponic-style computerised irrigation system, tuned to deliver precise, minimal amounts of water to the wall. This would use harvested rainwater whenever possible, with mains only as a backup. Standard module size is 300mm high by 600mm wide, with a saturated weight of 60kg/m².

Green wall benefits

There are many potential benefits to using green walls on buildings, either to new developments, or as retrofit to existing structures.

• Reduction of thermal loading on building fabric, reducing the need for heating and air conditioning
• Potential to offset building carbon footprint
• Mitigation of “Heat Island” effect (reduction in reflected light and heat)
• Air filtration, to counter pollution (plants remove carbon dioxide and VOC’s (volatile organic compounds) from the air. Potential to reduce “sick building syndrome”.
• Noise attenuation, either inside or out
• Creation of ecological microclimates of benefit to urban ecology
• Stormwater attenuation and rainwater harvesting potential
• Potential for building greywater filtration as part of the wall nutrient cycle
• Potential for edible, vertical landscapes
• Striking aesthetic, positive “green” message
• Uplifting environment for building users and passers by.
• Adds a “WOW factor!”

There are, as yet, no reliable figures to quantify the obvious benefits that green walls can offer. BioTecture Ltd will be funding research projects with a number of universities during 2008 to further understand the potential thermal values and behavioural characteristics of green walls. Currently green walls cannot be considered as part of the overall thermal U value calculations required to prove Building Regulations compliance which mean that any wall on which they are used is likely to perform better than the calculated design values! Sustainability by stealth, perhaps!

Applications

From large scale installations to individual domestic applications there are many walls and façades that are ripe for greening. A green wall can be grown in many different situations, even indoors, and will enhance any environment. Green walls provide tremendous artistic potential either as stand alone structures or with the addition of waterfalls, lighting & sculpture. They can be single or double sided and offer the unique reward of bringing greenery into an urban setting. Examples of potential locations include:

• New build commercial developments
• Retrofitting existing building facades
• Schools & community buildings (excellent educational benefit)
• Private dwellings and gardens
• Lightwells
• Building foyers, atriums and internal courtyards
• Retaining Walls
• Motorway sound barriers
• Temporary hoardings and moveable or fixed screens for shows and exhibitions

Planting

Many plants can be used on a green wall, but some plants adapt better than others. The main criteria are that they are evergreen (or predominately so) to give all year round coverage, create good, bushy foliage without too much woody top growth (ie not large shrubs or trees), are tough enough to stand the wind exposure and are not short-lived species. The aspect of the wall will determine light levels, as will their position vertically. These criteria inform the planting design; a few of the suitable species are shown below.

Maintenance

Walls are maintained on an on-going contract basis and usually involve three visits per year by BioTecture staff to prune, tidy and replace any plants as necessary. Fertilisation is by means of liquid feed which is performed as part of the operating duties of the building. This is simply a matter of changing over containers once empty, which might only be two or three times per year. As the wall is a modular system, it is possible to remove and replace any individual panel as required, a new one being pregrown to the same pattern as the original.