Bigger factors in passive house design are siting and orientation, building envelope air sealing, continuous insulation, and correct window placement and shadin

Bigger factors in passive house design are siting and orientation, building envelope air sealing, continuous insulation, and correct window placement and shading - usually with purpose designed shade structures - not trees. It's not that trees can't provide the shade, but they take a while to grow enough to achieve the immediate effect of an awning. If you have a mature tree on a site, however, you could design a house that takes advantage of the shade it already provides.