Posted: Monday 4 February 2013
by Adam Pasco
Research now shows that in addition to its aesthetic and wildlife value, ivy and plants trained against buildings help screen and insulate them from the cooling effect of cold wind.
Could garden plants reduce your winter heating bills? Some interesting research has been conducted at the University of Sheffield and by other organisations around the world that highlights the value of trees and plants surrounding buildings in reducing air temperatures during summer and insulating them during winter.
I've always been cautious about recommending planting climbers like ivy against buildings, although I enjoy the sight when others do it. Provided walls are sound and ivy is kept clear of gutters, windows, and so on, it's a valuable evergreen plant. Research now shows that in addition to its aesthetic and wildlife value, ivy and plants trained against buildings help screen and insulate them from the cooling effect of cold wind.
Shrubs and evergreens in the surrounding garden do the same thing, reducing wind speed, cutting down on draughts, and by doing so keeping buildings warmer through winter. Some researchers claim energy consumption could be reduced by up to 25per cent, but more research is needed to really quantify the value of plants in different situations.
During summer we all appreciate trees and green spaces that provide shade and shelter from strong sun, and research confirms that green environments are cooler than concrete and tarmac city and urban landscapes. Plants help keep walls cooler in different ways, preventing sunlight reaching and warming brickwork, and reflecting heat away. They reduce both surface and air temperatures, so planting round air conditioning units significantly cools the air they draw in, reducing energy consumption.
Green walls and green roofs have received much attention in recent years, particularly in cities where plants cannot be put straight in the ground. Calculating the effect of these on air temperatures is complex, but indicate that increasing the amount of vegetation planted in either traditional or new ways will reduce air temperature. I won't get into a discussion about global warming here, but suffice it to say that rather than simply concentrating on carbon taxes perhaps greater emphasis should be put on plants.
Well, gardeners know the value of plants, and in addition to their numerous benefits to local wildlife and me I'm now inspired to consider how I can use them to keep my home warmer in winter and cooler in summer. Now that really will be a benefit, and put pounds back in my pocket too.
Gardening Grandma
05/02/2013 at 09:07
This is very interesting. The opposite issue would be that plants can hold damp into walls. Not sure I know what I am talking about here, but i believe that older houses were built with very thick walls and small windows to provide maximum insulation in winter. Modern houses are more vulnerable to changes in temperature and need modern heating. They are also less well suited to having climbing plants grow on them, I should think. Between this and problems with roots undermining the foundations, any insulation using plants would have to be done very carefully, presumably. Are we just talking about windbreaks?
Adam Pasco
07/02/2013 at 10:05
Interesting thoughts Gardening Grandma. There are several different ideas and issues wrapped up together here, so in addition to understanding the physics involved in insulation/wind chill/draft proofing/heat transfer/summer cooling/shading/etc there are many practical considerations to take on board.
In many situations our properties benefit from the warmth direct sunshine provides, warming brick walls, or solar panels on the roof to warm water or produce electricity.
We know building construction also plays a part in controlling warming/cooling, from building a entry porch before getting to the front door to having a conservatory or lean-to against the property, double glazing, cavity wall insulation, and so on.
So, moving beyond the construction of the house, and the costs involved improving their insulation/heat loss and so on, it would be interesting to see more research on the influence of the outside environment, including our gardens, on our homes.
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