Openings in the building envelope can dissolve or reinforce the boundary between inside and out. They control the access of people and light into the building and of views out of the building. They enliven the mass of the building, and give it character — whether playful, formal, or eccentric. At the Safe Haven Animal Shelter, windows and openings are grouped into large areas, and light and views are carefully controlled through the use of overhangs, light shelves, and orientation. Horizontal mullions define datum lines that continue throughout the building.