A New Vision for Homes in the Sonoran Desert
With a focus on passive systems first and efficiency in both mechanical systems and design, Casa Donante sets a new standard for how new development in the Sonoran desert could look and function.
The home's name indicates how it gives back to the neighborhood by contributing electric energy to the grid and thermal energy to the SunBlock district energy system.
Casa Donante uses best-practice passive building techniques to achieve an exceptionally low EUI. This allows the house to share electric and thermal energy with its SunBlock neighbors.
Passive Design Strategies
The design team believes that a sustainable house has the least possible negative impact on the environment. So how is it designed? The team considered orientation, size, layout, optimized insulation and window performance, and specified Energy Star appliances.
The team also took into consideration the hot-arid Sonoran climate, which has large temperature swings between night and day throughout the year. In conjunction with an optimized and airtight envelope, natural ventilation and thermal mass help to provide a comfortable environment for much of the year.
The living and kitchen spaces are cooled with a solar chimney, which pulls of warm air up and out of the home.
As the sun heats the exterior space, it creates a pressure differential that causes air to rise inside the house. As that air leaves, outside air moves into the space below. By opening windows near the thermal sink, entering air is tempered as it moves in to replace the exhausted air.
Building on a precedent from Randy Williams of Wilson Inc., we developed a slabless foundation which reduced our concrete usage by 60.7%. This is significant because concrete typically has the highest embodied carbon of any building material. The stem wall is made of recycled engineered foam block. At window and wall openings, the design uses a proprietary foam window buck to improve thermal and energy performance of the wall assembly.