Today, the Los Angeles Unified School District has a goal of converting at least 30 percent of every schoolyard to green space, a years-long project that it expects to cost $3 billion. By its own estimate, about 475 schools do not meet that standard and, of them, more than 200 elementary schools have less than 10 percent green space. This analysis does not include school parking lots or truck delivery areas — paved surfaces that are likely to remain that way and raise the temperature around schools.
Webster, after years of waiting, is now on the list of schools to be renovated by the Trust for Public Land. The nonprofit will work with a class of third-graders and landscape architects for the next year to design a new schoolyard. Projects like this can take two to three years to complete, at a cost ranging from $400,000 to as much as $2.5 million, said Danielle Denk, who directs the organization’s schoolyard transformation work. In Philadelphia, most of the money for these projects comes from the water department, which is trying to make the city more capable of absorbing storm runoff.
That's still effort every other year. Tbf I don't know what all is involved in "maintenance" of concrete - I presumed that one could ignore it far easier, but I have nothing with which to back that up:-).
Concrete is different from blacktop
Oh right, but that too - how much maintenance could that "need", compared to something constantly growing?
Not as much, but it breaks down a lot faster than concrete