THE LIGHTWAVE BLOG

The Green Wall Phenomenon – a vine frame for a commercial building

The notion of greening buildings and the urban landscape can be difficult to achieve. Personally, I have found people’s attitudes toward greening a city very positive. When asked about greening the city the general response is “yes it’s a great idea, we should be doing more of it” however, when delivering projects, the attitude of professionals towards implementing the idea can be very negative. The competing interests affecting attitude may include ‘doing what is easiest’, loss of gross floor area, ongoing maintenance, structural constraints and most often, the budget.

Through the course of one project (the Synergy building located in Brisbane’s Kelvin Grove) persistence has brought great reward. By employing a series of sustainable and technical solutions a significant portion of the building’s facade has been ‘greened’.

The following is commentary of my experience with a vine frame system. The image below is of a successful vine frame 50m long and 3 stories high. The vines were installed in 2008 and have been exhibiting health and vigour. A new apartment building has recently been built beside the wall and is now shading out the lower portion, so supplementary planting of a shade loving vine is now required.

The design parameters for the project are below:

• Design life – building life for supporting structure, 20-25 years for soil and vines.
• Design scale – to provide a curtilage of the building that is of a meaningful scale within the urban environment.
• Australian Green Building Rating (AGBR) = to achieve a nominated sun shading of the glazing wall and contribute to the buildings AGBR rating at commissioning of the building, vines were pre-grown and arrived on site as a series of mats 1m wide and 4m long to provide instant shade to the first floor.
• Soil volume to ensure vine growth can be sustained into the future. The soil volumes are 1.2m deep 2.2m wide and 50m long, in a self contained reinforced podium planter with carpark and rainwater tanks below.
• Structural frame is separated from the glazing line by 1.2m and braced for high wind events.
• Structural horizontal posts are connected to reinforced concrete at each floor level of the building.
• Structural system’s basic load weight is supported by the planter walls and transferred to columns in the basement of the building.

• Wire spacing/aperture – wind vortices will affect the health of the vines, both in terms of evaporation and physically cutting the new growing tips if the wire aperture is to open. Also wind will pose an increasing challenge the higher you go, or if the vine frame is located between buildings or if it located close to the coastline. A good rule of thumb is a 100-200mm spacing.
• Species selection – multiple species can be selected to “hedge your bets” or select a long living species that grows like a weed and won’t die if the irrigation isn’t working.
• Contract grown stock – vines are pre-grown in bags to best prepare them for the final on site position. They should be grown for a full growing season in advance, in conditions similar to what they will experience on site, for eg NW façade will be grown facing NW on frame rows in the nursery. If the vines are grown on frames they can be brought to site using hangar clips in the nursery truck and then zip tied to the vine frame on site.
• Irrigation – 2 x 50,000L irrigation tanks are directly underneath and easy to access as they are adjacent a carpark.
• Maintenance access – the frame was set off the wall so an abseiler can prune from the inside and keep the vines off the glass.
• Aspect – north western aspect allows the vines to receive full sun during the hottest part of the day and protect the facade.

For more information on living walls featuring vine frames click here.. www..

Written by Steve Dunn
(Whilst employed at Gamble McKinnon)