If we were to listen to the old adage – ‘friends with benefits’ – we’d be led to believe that it’s possible to have your cake and eat it too. All the pros and none of the cons.
But of course we know that isn’t true. Everything comes with a downside and sustainable development is no different.
Living walls, or vertical gardens, are beautiful, personal impressions of the outside world in. Your opportunity to build your own little shrine to mother nature without using any extra space and reducing your impact on the world around you.
But ultimately there are some ‘cons’ associated with living walls. But I find some of the cons are just a part of the process and something to enjoy.
Pros of Living Walls
1. Positive Health Benefits
- Decreased stress and improved mental wellbeing
In a sweeping nationwide study, researchers from Denmark’s University of Aarhus found that childhood exposure to green space – parks, forests, rural lands, etc. – reduces the risk for developing an array of psychiatric disorders during adolescence and adulthood.
- The scientists found that citizens who grew up with the least green space nearby had as much as a 55 percent increased risk of developing psychiatric disorders in later years.
- And using data from 25,518 people, researchers have found out that Londoners who live within 300m of green space have significantly better mental wellbeing.
- And just proximity to green space was more important than lifestyle factors such as employment, income and general health.
"Contrary to popular opinion, up until now the evidence for the link between green space and mental wellbeing has been pretty circumstantial. By combining advanced statistical and mapping methods, we've shown that the effect is real and substantial. Basically we've proven what everyone has always assumed was true."
2. Reduces Energy Bills
- Living walls reduce heat loss and improve the heating-cooling cycle
Numerous studies have demonstrated the effectiveness of living walls in mitigating heat loss and improving both heat absorption and heat reflection.
- In Athens, the external surface temperature difference between the bare wall and the covered wall changed from 12 ◦C to 20 ◦C, during sunny days in this study
- The nighttime temperatures for the vegetated walls proved to be higher by around 3.5 ◦C in Bari as the façades also act as a thermal screen
- A research study in the Mediterranean climate found that energy-saving during the summertime was as high as 36% with a LAI (Leaf Area Index*) of 3.5 – 4
Of course the thermal performance of green walls depends on its orientation, the climate, the plant type used and the total coverage.
*The Leaf Area Index is dimensionless quantity that characterises the size of plant canopies vs the ground area.
3. GHG Emissions Reduction
- Plants act as natural air purifiers filtering carbon dioxide through photosynthesis
- In the same study that took place at the University of Kansas, they investigated the effectiveness of the living wall in reducing carbon dioxide (CO2) concentration levels indoors
- Results showed that the living wall reduced CO2 concentration rates by 56% and reduced the amount of CO2 being returned to the recirculation system
- And when comparing green walls to green roofs...
- Living walls have the capacity to mitigate CO2 output, but the amount of CO2 accumulated is less than that of green roofs
- Indoor living walls could be more environmentally sound if recycled materials, renewable energy and sustainable design and maintenance practices are applied
- For example, by adopting recycled materials (such as HDPE), the building’s total energy production can be reduced by 4–49%
- And the carbon footprint can be reduced by 6–19%
4. Sound Absorption
- Green walls have significant sound absorption potential
Do you happen to live by an airport? Or you moonlight as a garage DJ? Then a living wall could be your answer.
- Multiple studies have found that a green wall can reduce sound levels by 15db
- This provides a potentially significant option to improve urbanites quality-of-life.
5. Food Production
- Vertical gardening is getting more and more commonplace and the ability to grow herbs and vegetables in an otherwise unusable space is revolutionary
6. The Urban heat Island Effect
- Living walls cool the surrounding air through evapotranspiration
The findings of 19 living wall studies clearly demonstrate the cooling effect of living walls during summer and their ability to reduce heating and cooling cycles in different climates.
- In some cases room temperature reductions of 6 degrees have occurred
- With 4 degrees being the norm in summertime.
As cities continue to grow in size, it’s absolutely vital problems like this are tackled head-on.
7. House Price Increase
- Living walls have been known to increase property value by up to 20%
Cons of Living Walls
1. Mess
- Indoor living walls can lead to muddy spillage
If you thought normal gardening could be messy wait until you try and water plants 10 feet high in your own living room.
We joke of course, as there are drop irrigation systems that bear the brunt of the watering, you may just need a careful top up every now and again to avoid soil spills.
2. Maintenance
- Green walls, like any living thing require maintenance
This can be in the form of:
- Watering
- Drainage
- Trimming
- Periodical plant replacement.
Even root replacement – which obviously requires some green fingered skills – as root balls that begin the growth. But DIY home living wall projects can be setup and maintained relatively cheaply.
3. Cost
- Living walls can cost £300+ / meter squared
The initial cost can be prohibitive and it takes time to recover the cost in the form of energy bill savings etc – and there is a certain cost attributed to upkeep every year.
This is without taking into account things like supplementary UV lighting or additional irrigation.
4. Misadventurous Growth
- Plants can creep a little too quickly towards the sunlight
Plants grow towards the sun. In the unlikely event you don’t have a roof or your roof is made of glass of seethrough plastic your wall will likely extend towards your window(s).
5. Wall or Floor Damage
- Water damage can cause pretty significant, costly issues in the home
Excessive watering pretty commonly leads to mould.
So be careful with your irrigation setup and your lackadaisical watering capabilities. Make sure your wall is waterproof and you apply waterproofing matting to the floor if required.
6. Pets
- Toilet training
Do you have a dog with a strong bladder? Good. It takes a well-trained, sturdy-bladdered pooch to not pee all over the low level plants.
Additional Things to Consider
It’s important to note there are different types of living walls, and each type has its own slight variations on the aforementioned pros and cons.
- The different creative procedures all interact with the world around them differently
- Certain plants require more watering, irrigation and maintenance than others
- Succulents require minimal maintenance and watering and are perfect for the less avid gardener
- Edibles are a bigger challenge, but ultimately the goal is slightly different as you’re trying to feed your family through a wall. Well not quite, but you get the idea. The type of wall you decide on has ramifications – both positive and negative – and you need to pick the right one
