Updated: Aug 11
Renderings designed by Zauben for urban master plan for 2,000 net-zero affordable housing to absorb 167 tonnes of CO2 over 25 years.
The positive effects of an interior living wall on a person’s health and well-being have been widely documented. In recent times, however, studies are also turning their attention to the large-scale impact an exterior living wall can have on a building as a whole.
From moderating heat transfer and improving the performance of HVAC systems to boosting the efficiency of solar PV systems — the results may surprise you.
In this article, we examine each of the positive impacts an exterior living wall can have on an entire building, from the inside out.
A Reduction in the Need for Heating and Cooling Energy
Living walls are an innovative building envelope technology that attempts to solve a variety of challenges related to sustainability in our built environment.
Green living walls vary from other forms of botanical wall coverings in that they incorporate the planting substrate into the construction of the building’s surface. In doing so, studies have found that living wall facades have the potential to enhance the thermal performance of the building envelope.
Photography credit by Zauben
The building envelope (also referred to as an enclosure) is the physical barrier that separates a building's interior and exterior environments. Therefore, this envelope is responsible for creating a building's resistance to outside air, water, heat, light, and noise transfer.
There are several reasons that a living wall enhances the thermal performance of a building envelope. Most notably, this is due to the fact that a living wall requires a substrate system, which often contains a growing medium, for the plants to be attached to the wall.
One study has found that some living walls offer as much as a 68°F air temperature difference between the surface of the building envelope and the ambient air.
It’s not just a reduction in heat transfer that has researchers excited about the energy-reducing effects of a living wall on a building’s facade. During cold weather, living walls also limit the flow of heat from inside the building to the outside.
Research by the University of Plymouth has discovered that swapping an existing wall featuring a masonry cavity to one containing a living wall can lower the amount of heat lost through its structure by over 30 percent. This study found that the areas within a building that contained an exterior living wall remained more stable in temperature throughout the day. This meant that less energy was required to heat them.
When living walls on the facades of buildings are having such a significant effect as a buffer against both hot and cold weather, they allow a building to require less artificial heating and cooling, therefore lowering its energy usage.
The Ability to Pre-Cool Intake Air
Living wall facades also play a key role in pre-cooling intake air to improve the performance of HVAC