Green Parasites, or How We Can Learn to Take Advantage of Nature

By Rafael Longoria, ACSA Distinguished Professor of Architecture

Before air conditioning became ubiquitous, designing with the local climate in mind was not a virtue but a necessity. Passive design – taking advantage of the cyclical nature of the sun and maximizing natural ventilation – was widely practiced centuries before that phrase was coined. In Houston and similar climates, cooling southeasterly breezes were encouraged to flow through the inhabited section of buildings during the hot months, while northerly winds were blocked during the colder months. And solar orientation had to be carefully considered in order to live more comfortably.

That gradually fell out of favor as air conditioning – so comfortable, at the touch of a button – took over. But growing environmental concerns and simple economics are bringing a renewed interest in passive design.

Every spot on the earth receives sunlight at a particular angle that changes continuously following a fixed pattern, repeated every year as our planet revolves around the Sun. These recurring angles are easily predicted for any given day and time, simply by knowing the latitude of a particular place.

Project Row Houses (Latitude 29.731855°N) has provided a living laboratory for marrying art, sustainability and utility. The organization, a community-based arts and culture nonprofit in Houston’s Third Ward neighborhood, has hosted many artists in their house-galleries over the past 20 years; in 2001 it invited architects from around the country to make installations that reflected on their built environment.

Felecia Davis, now an architecture professor at Penn State University, conceived a memorable project, “One Week, Eight Hours,” that recorded the movement of sunlight along the interior surfaces of one of the row houses over the length of a week. Making graphic the patterns that most people rarely notice, the project highlighted not only natural phenomena, but also the history and experiences of those who once lived there.

Kim Tanzer and I included Davis’ project in our book, “The Green Braid: Towards an Architecture of Ecology, Economy, and Equity.” As Davis wrote: “The houses are very small, 31 x 17 feet wide typically, with front and back porches that are cut out of the main volume. … The name ‘shotgun house’ was coined because it was said a bullet could pass through the clear view from the front door to the back door without hitting any interior walls. They are quite simply built and recall a housing building type in Western Africa brought to the United States as a remembered building method by African slaves.”

We can learn much from these modest buildings. The window placements of traditional shotgun houses encourage cross ventilation that functions well even when the interior doors are closed. The close proximity of the row houses to one another, while a significant challenge to privacy, shade the neighboring walls and create narrow airflow corridors that accelerate the wind at precisely the right place to pull out air through the side windows, thus creating a cooling breeze across any room when the windows located on opposite walls are open.

During the Fall of 2016, University of Houston graduate architecture students were challenged to design what eventually came to be labeled as Green Parasites — devices that can easily be attached to existing buildings to improve their energy efficiency by maximizing the potential benefits of sunshine, wind or rain. Since the Project Row Houses galleries on Holman Street have large front windows facing southwest — and facing southwest is the most challenging orientation for windows in places with exceedingly hot days, like Houston — these buildings are ideal to demonstrate the performance of the sun-shading devices designed by the architecture students.


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