> They also block light.

The lack of old trees that block like is why all those new developments you see are so miserable. You'll be blasting your A/C to keep the house comfortable if you live in a warm climate precisely because there's no big enough trees blocking the light.

Being outside around your house without shade is also miserable in the summer.

Those developments will be livable in 15-20 years when the trees mature. That's why I bought a house in a 25 year old neighborhood with mature trees. Any added maintenance of the trees is worth the shade they provide.

In, or rather around, passive houses they are meant to block light during summer. That's why it's recommended to plant trees that will shelter your house from the sun thus lowering temperature inside (and your cooling energy requirements, if you've got air-con, etc.). During winter they shed their leaves and let the sun in, providing the opposite effect. Of course that's in climate zones that actually have summers and winters. Granted, you don't need entire forest for that.

Naturally, that works for most kinds of houses, not just passive ones. It's just especially important for those, if you want to achieve their stated (very low) energy requirements levels.