BY The Conversation
THE secret to a cooler home this summer could be growing in the backyard, with research showing strategically placed plants can significantly reduce the amount of heat absorbed by buildings.
Trees, shrubs and climbing plants can provide a natural barrier against direct sunlight, shading walls, windows and hard surfaces before they have a chance to heat up and radiate that warmth into and around the home.
Plants also cool their surroundings through evapotranspiration, releasing water vapour through their leaves, while some species can reflect a portion of incoming solar radiation rather than allowing it to be converted into heat.
University of Sheffield Professor of Environmental Horticulture Ross Cameron and fellow researchers found plants positioned in front of brick walls could reduce surface temperatures by as much as 25C under the conditions studied.
The research has particular relevance for Queensland households, where walls, windows, driveways, patios and other hard surfaces can spend hours exposed to intense summer sun.
Rather than relying entirely on air-conditioning once a house has heated up, strategically positioned greenery can help stop some of that heat reaching the building in the first place.
The western and north-western sides of Queensland homes are particularly vulnerable to afternoon sun, making them prime locations for carefully positioned trees, shrubs, screening plants or climbers.
Homeowners do not necessarily need a large backyard to take advantage of the effect either.
Climbers grown over pergolas or freestanding trellises can provide shade without requiring significant ground space, while potted plants can be positioned around exposed windows, balconies, courtyards and paved areas.
Professor Cameron’s research also found different plants cool in different ways.
Dense foliage can provide an effective physical shield from direct sunlight, while other plants rely more heavily on transpiration to cool their immediate surroundings.
