Green facades – a case of Sustainability being only skin-deep?
Paul Godfrey examines the case for green facades and whether they could impact the way buildings are being designed and built in the region
In 1927, the acclaimed architect Le Corbusier published his Five Points of Architecture, destined to become the core blueprint for the Modernist movement. The second of the ‘Five Points’ was the requirement to have a roof garden, which could be either a kitchen garden or a sun terrace.
It would be on a flat roof, which should have a humus layer covered with vegetation – which, Le Corbusier observed, ensures constant moisture and serves as a perfect heat and cold insulator. He also shrewdly commented that a garden of this type can dramatically reduce the building’s footprint on the ground, effectively putting what would otherwise be the surroundings up on the roof instead.
Today, architects and planners alike use a very similar language to sing the praises of ‘green facades’ – living walls of vines and plants that maximize a project’s green space with a minimum-sized footprint, creating a vertical landscape and becoming an eye-catching feature that can distinguish an otherwise-bland property
They can also bring environmental benefits to the local community and the building’s occupants alike – providing acoustic buffering (reducing noises from the streets below), lowering ambient wind speeds around the structure and – as Le Corbusier observed – insulating the property and reducing its carbon footprint by lessening dependence on heating or air conditioning.
All important factors, because as Benjamin Beer, Head of Facades, Ramboll, comments: “We tend to spend more than 90% of our time in buildings, so the façade is of key importance for human wellbeing, providing shelter from the external environment.” Moreover, it appears that even the external environment itself can be modulated and improved by green facades.
Micha Pawelka, Managing Director, Priedemann, explains: “There are project studies from Asia to Europe showing that ground air temperature can be decreased by around four degree Celsius, which is a significant number. However, it’s important to note that this improvement can only take place when the green facades are provided in an area of busy pedestrian circulation – a situation we have challenges with in the GCC.”
Are there any other regional challenges that could limit the practicality and benefits of green facades? Benjamin Beer believes that the sheer costs of upkeep can often be detrimental: “The harsh Middle East climate means there are very limited natural resources of sweet water. So, with green facades you need to cost in not only the higher maintenance requirements but also the sweet water consumption of the plants and the associated carbon footprint. In the Middle East, most sweet water is gained from seawater desalination plants and the CO2 emission per cubic meter of sweet water is between 0.4 and 6.7kg CO2 eq/m3 – so green facades tend to have little effect on the overall energy consumption of a building.”
Micha Pawelka adds another chastening note, this time in terms of the structural impact: “Remember, the normal structural challenge is to drain water out of the façade – but here, we are intentionally inviting it in. That’s a risk and it needs to be considered and dealt with from the very early stages. This also necessitates a thorough and convenient maintenance strategy. Imagine your living wall is part of your overall U-value calculation. How much value remains if your irrigation system is not maintained and the living plants in your façade die?”
While green facades can reduce utility bills for the building itself (if not for its total down-stream consumption), they may not be the ‘silver bullet’ that architects and town planners foresaw.
As Agnes Koltay, CEO, Koltay Facades, remarks: “Of course, pollution needs to be closed out, but any facade that meets basic airtightness requirements is able to do that. So, we are really talking about protection from pollution, not combatting it. Plus, pollution will still come in through the door or window the second you open it. The reality is, if you want to combat pollution, go to the sources of pollution, which are the old cars, aged public transport buses, low-technology factories and so on – rather than expecting a facade to work a miracle and cure the city.”
Standards and Regulations
While it may be true that green facades have their limitations – and the GCC’s harsh climate poses extra challenges – the regional authorities were quick to see the potential benefits that green facades can have. The first steps towards regulation have already been taken by the Middle East building authorities, most notably in the Dubai Green Building Code.
Benjamin Beer adds: “There is also the WELL Building Standard® being third-party certified by the Green Business Certification Incorporation (GBCI), which administers the LEED (Leadership in Energy and Environmental Design) certification program and the LEED professional credentialing program.”
These codes are particularly important given the harsh demands of the regional climate, with its ability to corrode and deteriorate materials that would have been perfectly useable elsewhere.
Micha Pawelka comments that: “It’s no accident that we tend to be most familiar with green facades from developments in South East Asia, with its more seasonal climate. In the GCC, green facades need to be developed specially for the local climate, which can limit their use. Of course, this comes at a cost and in a region where many markets are driven by ROI, it is always a challenge to introduce solutions which may be more expensive than standard ones.”
Not the Green icon we imagined?
“I’d have to say in summary”, says Benjamin Beer, “that green facades tend to have little effect on the overall energy consumption of a building; however, the local microclimate and occupant’s wellbeing can be enhanced by the greenery and plants.”
Perhaps indeed this is the greatest take-away with green facades, as Micha Pawelka adds: “We know how important interaction with nature is for human wellbeing. And we know also that a biophilic design can improve wellbeing, happiness and performance not only at the workplace but in our homes too.”
Yet if we’re looking for something more than that, we may be disappointed – or at least looking in the wrong place. A last word here from Agnes Koltay: “Why do we expect the building, with its tiny non-vision facade area to generate energy like a power station? Let’s build power stations to generate energy, and let’s build buildings to have a nice living environment instead.”
