In addition to retrofitting buildings, some asphalt is going to have to be torn up. It will be too expensive to maintain, causes runoff and the urban heat island effect, and the space/land can be better used to grow edible and other trees and plants.

And precedents exist: years ago, Ecocity Builders in Berkeley ripped up a parking lot and planted fruit trees.
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www.ecocitybuilders.org

http://www.findarticles.com/p/articles/mi_m0JQP/is_313/ai_30243559

Fruit-tree guerrillas and de-developers - Ecocity Builders adopt an aggressive policy towards urban ecology
New Internationalist, June, 1999 by Jade Saunders

Berkeley, US

Rolling back North America's urban and suburban sprawl - a million acres are sacrificed to it each year - may seem like a hopeless task. But not to activist and fruit-tree planting guerrilla, Richard Register. And the movement he has mobilized, Ecocity Builders, has a flair for effective and eye-catching campaigns.

For example, there's the time when 400 people dug up part of Berkeley to release, from under its concrete grave, a river. Other eco-feats have included planting urban orchards overnight as well as depaving parking lots.

In recent years, however, Ecocity Builders have taken a more `legal' approach. They are going for `a strategic legislative attack on the misuse of urban and suburban land,' says Register. This involves getting local authority planners to stretch their thinking - and their imaginations. They are currently campaigning for `de-development' rights. This means that if developed land - which has, say, a natural creek running under it - were offered for redevelopment, it would be possible to buy those rights but to `de-develop' it back to its natural state. The development planning permission could then be transferred to another, more suitable location.

Another campaign aims to overturn the Berkeley planning rules that insist that all new residential blocks need parking spaces. Not so, says Register. Why not have car-free apartments, inhabited by people who agree not to have a car, and who are repaid by cheaper rents?

www.ecocitybuilders.org