This is La Casa de Tierra, or “The House of Earth”
La Casa de Tierra is an exploration into sustainability and environmental response within the context of a southwestern medium. It takes advantage of the inherent need for sustainability in extreme environments such as the Sonoran Desert. The site is a generic flat site with natural desert vegetation in rural North Phoenix, with distant neighbors and low traffic. The sensory experiences of the desert are all present, and the connection between the site and the open landscape it looks onto is deep.
The house forges a strong cultural and visual connection to the surrounding desert, something that is held in high regard in this part of the country. The Sonoran Desert in general has long been known to many as being a place of great spiritual and cultural connection with the natural world. The relationship between man and desert is an ancient one, going back to the ancient Hohokam and Sinaguan peoples of Central Arizona, and they mastered early sustainable and passive strategies. It is sensible that we begin using their resourceful architectural concepts as inspiration towards contemporary design in the Sonoran Desert region. Ancient inhabitants used local materials and learned how to use the earth beneath their feet and the plants they grew as an architectural medium. Ancient Hohokam architecture thus had a strong sense of materiality and context, and these qualities show up in important archaeological sites such as Casa Grande in the city of Casa Grande and Pueblo Grande in Phoenix.
Today, we have neglected many of the lessons that our desert ancestors had long understood. Only a few notions of ancient ideas show up in modern southwestern architecture, often as kind of this faux sense of sustainability, a faked relationship with the desert. I understand the desire to have huge windows on the west side to soak in those spectacular Arizona sunsets. I also understand the desire to build as many cheap homes as quickly as possible. After all, it is incredibly difficult to keep up with the pace of growth in the Phoenix area. But in the end, we all live in an extreme, and beautiful, environment that demands respect. And the truth is, we sadly lost our connection with the landscape long ago. Hopefully, with a recent resurgence in sustainable practice and a growing desire for efficient and environmentally responsive architecture, we have an opportunity to add value to the natural environment rather than destroy it. We must capitalize.
I believe in applying sustainable principles to their furthest possible architectural, social, and economic extents, even beginning with something as broad as building orientation. The house is oriented in the east/west direction to take advantage of warm low winter sun angles and protect from the hot setting sun in the afternoon. Thick rammed earth walls on the south facade protect the house’s interior spaces from the extreme heat of the summer and will keep the house warm on cold nights during the winter. The material for the wall would be sourced on and near the site and constructed in place, significantly reducing transportation costs and utilizing on site material resources. Additionally, the decision to use rammed earth as a contemporary adaptation of adobe and earth architecture stems from its efficiency as thermal mass and its unique aesthetic value. The south face thus becomes an important visual feature, weighing heavily on the eye yet gently disappearing into the surrounding desert environment. The tall, narrow openings in the wall act as closely controlled apertures which selectively allow south light into the home, and create dynamic shadow movements across the great room. The wall’s thickness combined with inset glazing blocks direct south light during the overheated period of summer, mitigating solar heat gains.
On the north face, a bank of floor to ceiling, and in some cases double height, windows allow plentiful cool north light into the home’s interior spaces throughout the year. When outdoor temperatures permit, windows on both faces can be opened to allow for full cross ventilation through the entire building. NNW prevailing winds would be used for natural ventilation during most of the year, and the building is situated far enough outside the urban heat island to where nighttime temperatures during the summer can cool down enough to allow for night flush cooling.
A large 50 square foot evaporative cooling tower supplies cooled air throughout the home, with registers both on the second and ground floors of the home. The tower takes advantage of hot dry summer breezes through the principle of evaporative cooling. The cold air sinks and is directed into the second floor lounge and the first floor bedroom/kitchen areas. The home also features a backup mechanical cooling system and a radiant heating system, as well as a solar hot water system. Photovoltaic panels on the roof heat water for domestic use as well as in the radiant system, which is built into the floors. In the desert, where water is the key to the survival of any organism, water collection and recycling is important. Graywater is collected, filtered, and recycled for use in toilets and irrigation of the home’s outdoor garden and native landscaping. Rainfall is collected on the roof, filtered, purified, and stored in an underground cistern for domestic use. Plentiful daylighting mitigates the use of daytime electric lighting during much of the year, and the photovoltaics aid in offsetting the rest of the home’s electrical needs.
Wrapping around parts of the south, west, and north facades of the building is a shading system constructed of locally sourced mesquite wood louvres and steel. The screen has an innate sense of materiality that directly connects it to the site, and its horizontality, contrasted with the verticality of the rammed earth walls, brings to mind the lure of the desert horizon. The windows behind can be opened during periods of good weather to allow for better ventilation flows through the building and for unobstructed views. The house then effectively becomes an indoor/outdoor space. The desert, as you might imagine, also has a strong relationship with the sun, and watching shadows move through the house evokes an image of the sun and shadows moving across the mountains and canyon landscapes of the greater southwest. During the afternoon in particular, the sun shines through the screen just enough to leave a beautiful, continuously changing shadow pattern on the floor and walls of the great room.
The house features one bedroom and one bathroom on the ground floor for long term use. The bedroom can be opened almost completely to lessen the feeling of isolation bedrooms often give off if desired. A short hallway opens into a luxurious modern kitchen and a spacious double height great room. These spill out onto a shaded covered patio underneath a large cantilevered space above. On the second floor, overlooking the great room, is a more formal lounge space that acts as the main entry into the home. Guests generally would enter this space on the second floor before going downstairs. Also on the second floor, off the lounge, is a generously sized indoor/outdoor patio enclosed by the mesquite wood screen. Views of the desert mountains are preserved throughout the home and often framed by rammed earth.
This was a side project that took me about 3 days to design to completion. I intend to do many more side projects to strengthen and diversify my portfolio (and because its fun). Practice makes perfect and now summer will allow me to devote even more time to personal design projects.