Most summer heat gains come when the sun is low enough to shine directly through windows. A tree in full leaf can block 70 to 90 percent of solar radiation. Shade trees on the east side of the house prevent heat build-up in the morning, while those on the west and southwest side shield afternoon rays. Trees planted to shade paved areas reduce the heat-island effects from parking lots. Vines provide shading and cooling; vines on trellises can shade windows or the whole side of a house.