This paper attempts to evaluate the positive effects of vegetation with a multi-scale approach: an urban
and a building scale.
Monitoring the urban heat island in four areas of New York City, we have found an average of 2 C
difference of temperatures between the most and the least vegetated areas, ascribable to the substitution
of vegetation with man-made building materials.
At micro-scale, we have assessed the effect of surface albedo on climate through the use of a climatological
model. Then, using the CO2 equivalents as indicators of the impact on climate, we have
compared the surface albedo, and the construction, replacement and use phase of a black, a white and
a green roof. By our analyses, we found that both the white and the green roofs are less impactive than
the black one; with the thermal resistance, the biological activity of plants and the surface albedo playing
a crucial role.