Trees save energy

As the cost of fossil fuels continues to rise, concerns turn not only to how to replace these resources, and how to buy time by minimising the amount we use now. According to our research, the average UK home could save up to a tenth of its annual heating and cooling expenditure with the natural winter insulation and summer shade provided by trees.

How does that work?

In the winter months, houses inevitably lose heat to their surroundings, and in exposed areas, this heat is whipped away by fast-moving winds, drastically reducing the efficiency of the house’s insulation. The problem is most acutely felt in buildings which have no windbreaks outside, in mainly rural locations. And in towns and cities, streets act as wind tunnels, channelling cold wind as it takes with it the warmth from the houses it passes.

In America, the trend for natural windbreaks has already caught on. Evergreens are planted on the north side of a house, far enough away that they don’t obstruct views and their roots are not hazardous to the foundations, but close enough, and tall enough, that they divert cold wind over or around the house.

Evergreen trees are well suited to this task: they can grow together easily, and their branches grow even from the base of their trunks, both features boosting their ability to block wind.

Conversely, for the summer months, deciduous trees can be planted to provide shade on the southern aspect of a building, cooling it additionally by evapotranspiration, the removal of water from the surrounding air. And because these trees are deciduous, their leaves fall in autumn, allowing sunshine to warm the house during the winter months.

How does this affect the work you do in cities?

Cities require a special mix of trees to take full advantage of the benefits they can offer: the spread of the branches should be enough to break up fast-moving winds, but not to block out light; they should be large enough to absorb moisture from the air during the summer months, but not threaten nearby buildings with their roots.

“I'm going to give the charity Trees for Cities £25 for every goal West Brom score between now and the end of the season. That won't buy a forest, but it might make a difference.”

Adrian Chiles - TV Presenter

© 2011 Trees for Cities. Registered Charity no. 1032154