Among the many projects that Mithun worked on for Miraval are the guestrooms, which make use of simple, natural and durable materials suited for the desert environment. The buildings are constructed of rammed earth, which serves as thermal mass keeping the interior cool during the day and emitting heat at night. Clay adobe bricks were made on site with local materials and used to build the outdoor showers, while branches from local saplings were used to screen in the mechanical areas. Decomposed granite paths meander throughout the resort and aid in drainage during the rainy season.
Facing south and the Catalina Mountains, the guest rooms take advantage of solar passive design and the views in one fell swoop. Large overhangs provide shade for the interiors and operable windows allow for natural ventilation. The roofs are coated with a high-albedo roof coating, which decreases solar energy absorption, and at the same time, solar hot water systems soak up the energy to provide hot water for guests.