The trees at Kapolei are very young. We have information on tropical species and we know how they will grow. We can 'grow' them over time on the computer and know how they'll look in 20 years. The program is not specifically trees, but trees are the largest things growing and you can't grow big trees without good soil. Even the colors of the roofs and the surface of the roads affect heat.
Light colors reflect, dark colors soak up heat.
Light colored roofs make a difference, and guys keep telling me that macadam roads don't have be black. The computer technique was developed five years ago, and has been refined and downscaled in price since then. If the right trees are planted in appropriate places, they won't have to be hacked through for utility wires or shed slippery flowers on the sidewalk that invite lawsuits. There are all kinds of good reasons to plant trees. Psychologists say that they soothe and relax us, and enhance our sense of privacy and solitude.