18 C
London
Thursday, June 30, 2022

Question Time May

 

In our steadily expanding urban environments, are sustainable living walls the way forward?

 

Our cities are growing and there has been a steady increase in housing developments in recent years, as the population boom takes an effect. With buildings taking over green space should we consider living walls as the way forward and a solution to bring in sustainable, green space into a built up environment? In areas of high air pollution, such as London, Manchester and Birmingham, living walls are an effort to counter poor breathing conditions and also create a striking display for the building. We are asking how achievable is such an installation? Water collection and distribution for the plants, working on listed buildings and the impact upon the building itself are just a few issues to be considered, how can these be overcome to install an environmentally friendly living wall, which will benefit those living in an urban space?

 

 

Gary Coetser, Senior Project Architect, SHH

 

Whilst the premise of cities swathed in green walls is an attractive utopian ideal, I believe it would be very difficult to implement in major cities such as London, Manchester or Birmingham.

 

The issues are twofold. The first concerns implementation and maintenance and the second is the nature of our cities in terms of buildings being listed or unlisted, together with the overriding planning policies that govern our urban landscapes.

 

One question always comes up when proposals with a wide-reaching impact on the public domain are made; namely, who??s going to foot the bill? It??s a valid question, of course, especially considering that the large-scale installation of green walls would require mutual agreement and investment by both councils and private building owners, in order for there to be vested interest in maintaining the installation. This in itself would take years of negotiation.

 

Green walls are not cheap and, whilst low maintenance, they still require some post-implementation upkeep. Then there is the structure required to hold them up against the buildings. For the installation of green walls to make any significant impact within the urban realm, they need to be at scale. Scale creates weight and weight increases structure ?? as well as cost. 

 

Let??s take London as an example. The city is dominated by historic built fabric and is known for this throughout the world. The installation of green walls in London would result in a quagmire of committees and negotiations. It??s hard enough sometimes to get permission to replace a rotten single glazed sash window in a listed building; how would we decide which buildings to cover with a green wall and which not?

 

A more optimistic avenue might be to look up at our roofs. Toronto and Chicago have implemented initiatives where the installation green roofs are either mandatory or incentivised. London has a large number of flat roof buildings, making this a particularly apt solution. Perhaps London should be incentivising the provision of shared green spaces on top of existing buildings in the form of maintained rooftop allotments? 

 

To benefit properly from green spaces, people need to be able to enjoy them physically and not just look at them from their office window. If you engage, you take on ownership. Green roofs also mean increased biodiversity, adding to the case for adding green places to an existing dense city fabric, where you can escape your office to a shared rooftop park above the hustle and bustle of the city, move up out of the shadows and into the sunlight and take in the air ?? with the odd bee or two for company.

 

 

Olivia Kirk, Landscape & Garden Designer, KKE Architects

 

Ask anyone what is a garden and the first thing they will describe is a horizontal space with grass, plants and trees growing upwards, from earth to the sky, but in our increasingly populated country should this always be the case?  

 

We have all heard of green roofs but the relatively new concept of green walls is developing rapidly. These are not ivy-covered buildings but specially designed kits that offer the opportunity of landscape design on the vertical plane. Many living wall systems come in modular form allowing experimentation at a small scale which can evolve as required. These modules can be planted in a nursery then fitted to a vertical framework once the plants have established, it also allows experimentation on the ground before committing to the finished panel. The felt pockets and rockwool system used by the father of vertical planting Patrick Blanc, is backed with a PVC sheet, supported by a metal frame. Water and nutrients are fed through a mechanical irrigation system which can also be set up to harvest rainwater or re-use grey water.  

 

Living walls are a useful solution to a variety of situations, they can screen ugly walls, act as both acoustic and thermal insulation as well as filter air-born pollutants. As with trees in the larger environment, vertical walls cool the surrounding air-temperature by as much as 4 degrees, providing shade from summer sun and insulation in winter.  They also have real benefits to wildlife providing habitats for birds and insects, creating mini ecosystems which wouldn??t otherwise exist.  

 

The range of planting options available is surprisingly diverse – as with traditional landscape design the maxim ‘right plant right place’ holds good.  An initial assessment of the amount of light, space, orientation and exposure to water amounts informs the type of planting.  Soil is not a necessary commodity, it is the water and nutrients held within soil that keeps these planting schemes thriving together with light and carbon dioxide to conduct photosynthesis. Plants with lightweight leaves and either a cascading or mound forming habit close to the roots are the best choices as large and heavy leaf varieties will put pressure on the area where the root joins the plant as this is angled when grown in a pocket type system. Plants with highly textured or decorative foliage give the best scope for creating vast sweeps of visual interest. 

 

The big question however is just how sustainable are these living walls in the UK? Seen by many as expensive to install and difficult to maintain there is a large gap between the rapidly growing ?green wall?? industry and UK specific scientific research. Studies have shown that the greening of urban environments results in an improvement in air quality, aesthetics and wellbeing, however most of these studies have taken place in climates significantly warmer than ours.

 

A research programme is now under way at the University of Sheffield in collaboration with living wall systems specialist Scotscape and will for the first time provide some UK specific technical data enabling the researchers to clarify the benefits of living walls in improving a building??s energy performance and the indoor thermal comfort of its occupants as well as looking at the consumption of irrigation water required for each system. 

 

This research information which should be available this year will help architects and landscape designers to make informed decisions and choices when they consider specifying a living wall in the UK.­

 

 

Sean Farrell, Managing Director, Mobilane

 

Green screens have the potential to have an enormous impact on improving the air quality of our environment. They are a tool for tackling pollution that delivers an instant result.  

 

At the start of April we experienced an air pollution spike across England and Wales that led to an increase in media reports about health related illnesses alongside articles on how to survive the smog, which generally indicated we should all stay indoors with the windows tightly shut. Now I am genuinely not wishing to be flippant here because in the UK alone 50,000 deaths are attributed each year to air pollution. These are mostly people who are asthma sufferers, have a heart condition or a chronic lung disease. Air pollution is deadly serious. It has been classified by the World Health Organisation as a carcinogen and there are many credible studies published that reveal the level of harm to people that it poses.

 

 Under the EU Air Quality Legislation all member countries are required to meet a target for particulate matter (PM10) and nitrogen dioxide (NO2) however, the actions taken in the UK such as introducing congestion charging and encouraging alternative methods of transport are still painfully slow in addressing the problem and the reality is we are failing to hit our targets.  If we are to truly tackle pollution and achieve measurable improvements we need to deploy a far wider range of weapons. It makes sense to harness nature??s own method for cleaning up and generating air.  

 

Green screens represent a tool for tackling pollution that delivers an instant result. Quick to install, cost effective and long lived, green screens are made of ivy, which has the ability to absorb high levels of PM10s. These are the tiny air borne particles (less than 10 microns in diameter) that make up dust, soot and smoke.  Green screens also have a huge effect on nitrogen dioxide pollution.

 

To really put the impact of a green screen into context is to highlight that a 17-23 sqm green screen removes the same number of pollutant particulates from the air as an average sized city tree its effectiveness is due to ivy??s natural ability to absorb PM10s.  Our own collaboration with the University of Staffordshire, which has a dedicated Green Wall Centre, is finding health improvements can be generated rapidly by strategically positioned green screens near our busy roads and pollution hotspots.  We know that a 50% reduction in our streets?? pollution levels through the intelligent use of green screens can be achieved.

 

Air pollution also damages eco-systems so as well as absorbing harmful particulates, green screens boost biodiversity levels by providing a habitat and source of food for birds and insects ?? including vital pollinators like bees and butterflies.   

 

While urban pollution is mostly man-made it??s perhaps somewhat oxymoronic to think that nature has provided its own remedy in green screens.

 

Related Articles

Stay Connected

  • – Subscribe –

Latest Articles