Stipulating that walls should be screened with plants should be part of Government building policy, University of Sheffield landscape management researchers Jane Taylor and Ross Cameron have suggested.
They have produced research demonstrating that walls and shrubs can provide "significant passive cooling" and are working on evidence to show the warming effects of green walls in winter (HW, 24 January).
PhD student Taylor said: "Vertical greening should be considered in a policy review since it not only offers the opportunity to insulate a building but also provides other vital functions in urban areas such as improving air quality, reducing rainfall run-off, well-being benefits and wildlife habitat provision.
"While vertical greening could certainly have a role in new-build developments, the major opportunity is in the retrospective fitting of existing housing stock, around 80 per cent of which was built prior to 1980, with little focus on energy efficiency in the Building Regulations.
Landscape management senior lecturer Cameron said the HTA, which funded the research, will use it when lobbying appropriate parties. "We will publicise through conferences and seminars, targeting the architects, building engineers and green wall companies as well as local and national government officials."
Cameron said there is less work published on winter insulation but one study in Scotland suggested there could be a 17 per cent reduction in heating bills, with trees being used as shelter belts around office blocks.
Taylor's work with replicated block units using ivy suggested an energy-use reduction of up to 25 per cent during the coldest periods.
Cameron added: "The arguments in practice tend to centre around whether plants are better than artificial insulation materials and facades used on buildings. Some data suggest plants are comparable to these, others that they are not as good. The results are affected by type of green walls, building material, orientation and weather factors, so the jury is still out.
"The point that should intrigue policymakers is that unlike artificial materials, plants provide a range of additional 'ecosystem services'. There is quite a lot of current research trying to put more accurate economic values to these services."
Taylor and Cameron are working on a paper for winter warming potential. This is expected to be complete in a few months.
"BREEAM is regularly updated to take into account new research and standards where relevant. Where there is a scientific basis for making changes to the criteria within the scheme we do so through the update process. We will therefore review the research you refer to when next updating the scheme."
Sarah McCarrick, education sector manager, BREEAM