green or living wall

‘Living walls’ reduce heat loss by over 30 per cent

Image credit: university of Plymouth

A University of Plymouth study has found that retrofitting masonry cavity walled buildings with green or living walls can reduce the amount of heat lost through its structure by more than 30 per cent.

The study was centred around the university’s own Sustainability Hub, an unremarkable pre-1970s building on the university campus. It was conducted by academics associated with Plymouth’s Sustainable Earth Institute.

The researchers compared how effectively two sections of its walls retained heat. Despite being on the same west-facing elevation, one of the walls had been retrofitted with an exterior 'living wall' façade comprised of a flexible felt system with pockets for soil and planting. The other part of the wall was left plain.

Following five weeks of measurements, the Plymouth researchers found that the amount of heat lost through the wall retrofitted with the living system was 31.4 per cent lower than that of the unchanged wall. They also discovered that daytime temperatures within the flora-bestowed section of the wall remained more stable than the area with exposed masonry, requiring less energy to heat it.

The study is among the first to ascertain the thermal influence of living-wall systems on existing buildings in temperate scenarios. In their Building and Environment paper, the researchers said that while the concept of living walls is quite new, many benefits have already been demonstrated, such as increased biodiversity.

Buildings account for 17 per cent of UK greenhouse gas emissions, largely due to heating requirements (space heating accounting for over 60 per cent of all energy used in buildings). The government is under pressure to cut emissions from buildings by improving energy efficiency and switching to low-carbon heating, such as electric boilers, heat pumps, and hydrogen, while phasing out gas boilers. In the meantime, these new findings could be a game-changer in helping the UK achieve its net-zero commitments.

 “Within England, approximately 57 per cent all buildings were built before 1964. While regulations have changed more recently to improve the thermal performance of new constructions, it is our existing buildings that require the most energy to heat and are a significant contributor to carbon emissions,” said lead author and sustainable architecture expert Dr Matthew Fox.

“It is therefore essential that we begin to improve the thermal performance of these existing buildings, if the UK is to reach its target of net-zero carbon emission by 2050, and help to reduce the likelihood of fuel poverty from rising energy prices.”

Another report author, Dr Thomas Murphy, added: “With an expanding urban population, 'green infrastructure' is a potential nature-based solution which provides an opportunity to tackle climate change, air pollution and biodiversity loss, while facilitating low-carbon economic growth. Living walls can offer improved air quality, noise reduction and elevated health and well-being. Our research suggests living walls can also provide significant energy savings to help reduce the carbon footprint of existing buildings. Further optimising these living wall systems, however, is now needed to help maximise the environmental benefits and reduce some of the sustainability costs.”

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