Frank Lloyd Wright once said "a doctor can bury his mistakes, but an architect can only advise his clients to plant vines." It turns out he could have been a mechanical engineer, for it is surprising how effective vines are at keeping a house cool. With the new weatherization grants, the salesmen are out peddling ground source heat pumps to keep you cool for less, but really, free is better.
Vines such as ivy, russian-vine and virgina creeper grow quickly and have an immediate effect; according to Livingroofs.org.
Climbers can dramatically reduce the maximum temperatures of a building by shading walls from the sun, the daily temperature fluctuation being reduced by as much as 50%.Together with the insulation effect, temperature fluctuations at the wall surface can be reduced from between ?10°/14°F to 60°C/140°F to between 5°C/41°F and 30°/86°F. Vines also cool your home through envirotranspiration, described in our post Be Cool and Plant A Tree.
Surprisingly, they also work in winter to keep you warm, by maintaining a pillow of air and reducing wind chill. Heating demand can be reduced by 25%.
Some say that vines damage a building, but if the masonry or siding is in good shape they should be fine. Others claim that it actually protects the building from very heavy rainfall and hail, and shields the building from the effects of ultraviolet light, which can degrade paints and some sidings.
Top that off with the fact that it absorbs pollutants and offers a habitat for insects, spiders and birds.
So it is another low-tech, energy free way of shading your home and keeping cool, perhaps even eliminating the need for air conditioning in many climates.