Prepared by Mohammad al-Asad and Majd Musa in association with Richard Brittain, 2002
In 1993, the Desert House demonstration project opened to the public. The project, which consists of a three-bedroom single-family home and an adjoining information center, is located at the Desert Botanical Garden in Phoenix, Arizona (figures 6 and 7). The location of the project is ideal since about 200,000 persons visit the Desert Botanical Garden each year. The Desert House also draws additional visitors to the garden through the publicity associated with it. The house was perceived as an example for improving residential water and energy efficiency. Its objective was to achieve a 40% reduction in water and energy use in comparison to the typical three-bedroom single-family house in the Phoenix area.
The Desert House is about 149 square meters in area. It cost about 125,000 $US to build, which was the cost of the average home in the Phoenix area at that time. It was designed with the main axis running along the east - west direction, and it had a minimal number of windows along the eastern and western facades to reduce heat gain from the morning and afternoon sun. The southern side of the house was provided with the highest window area since that side would collect solar heat in winter but could easily be shaded during the summer. Moreover, a ramada was built along that side and deciduous vines were planted next to it (figure 8). The ramada and vines provide protection from the sun in the summer, but the vines lose their leaves in the winter and allow the sunlight to enter and heat the house. A minimum number of northern windows were included in the house to minimize heat loss in the winter. Instead, the rooms located along the northern side of the house were provided with clerestory windows along their southern side so as to let the sunlight reach them.
Graywater and rainwater storage tanks were located in the basement of the house. Brittain mentioned that the basement in this particular project was referred to as the "research basement" because it houses all the plumbing equipment, water meters, control-valves, storage cisterns, and pumps. The water meters also are connected to a computerized monitoring system that monitors the resident family's use of water. Two 18 cubic-meter tanks were assigned for graywater storage and one 18 cubic-meter tank was assigned for rainwater storage. Brittain mentioned that the Desert House project team benefited from the knowledge they had gained in the Casa del Agua project. Consequently, they knew that significant graywater storage was needed in order to get through the dry period between the two rainy seasons of winter and summer, and that rainwater harvesting, although necessary, would not be enough. Each of the storage tanks for graywater and rainwater storage consists of four pre-cast concrete sections, which were connected together and sealed. The tanks are accessible through manways in their lids.
The Desert House was provided with a water-conserving landscape design. The house was surrounded by a path network so that visitors would be able experience the landscaping and to look at some of the features that were used for shading the house. The soil was mulched and low-water-use plants were used so as to contribute to the reduction of water use at the house. The garden plants were irrigated with graywater or rainwater, depending on the type of plants. The landscaping incorporated a small lawn area in the backyard, which served as an activity zone. Each of the plants, as well as the components of the irrigation system, were labeled so as to be identified by visitors.
In addition to the exterior pathway, the project incorporated two interior display areas. The first is the technical exhibit that is housed in the garage attached to the home; the second is the information center that is housed in a separate building. The technical exhibit deals with the technological aspects incorporated in the project, as well as other equally appropriate alternatives. These include items such as the showerheads, toilets, faucets, drip irrigation, as well as graywater recycling and rainwater harvesting systems. The exhibit also deals with the building materials used in the Desert House. These include appropriate types of glass, insulation materials, walls, and heating and cooling equipment. The idea of exhibiting a variety of materials aimed at illustrating to the public the multiplicity of water and energy efficient designs that can be used. This technical exhibit also is provided with an interactive computer that features a three-dimensional model of the house. One would select an area in the house featured on the model, and the computer would display how much water or energy is being consumed in that area (figure 9).
On the other hand, the information center illustrates the goals of the project, why one needs to conserve water and energy, and how one can design water and energy efficient structures and landscapes. It contains a model of the Desert House and a simulation of the positions of the sun at the different times of the year and the day. This allows visitors to better understand the importance of orientation for a given structure, and the importance of shading devices and of the correct placement of windows (figure 10). The information center is also equipped with a seating area for lectures and presentations. After all, the project addresses the community, and "... is designed to educate the community about the importance of wise water and energy use, and about the practicality of creating more resource-efficient housing at an affordable cost without significantly impacting today's lifestyle expectations." (8)