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Material Matters 5Could the typical ranch home, split level or four-bedroom colonial be a thing of the past? The way homes are designed and built is rapidly evolving. Modular systems, flexible space concepts and energy-efficient materials that contribute to sustainable living are quickly gaining in popularity. In this issue of Material Matters, we look to the 2007 Solar Decathlon for an early read on emerging trends in sustainable residential dwellings.
Sponsored by the Department of Energy’s Office of Energy Efficiency and Renewable Energy, the Solar Decathlon challenged 20 college and university-led teams from the U.S. and three foreign countries to find the wave of the future in energy-efficient abodes. The specific goal: an attractive, marketable home, no more than 800 square feet in size, but able to generate enough hot water and electricity from solar panels to perform day-today functions, from cooking to powering home electronics and maintaining comfortable temperatures—all while having enough “juice” left over to run a street-legal electric car.
We looked at prototype homes by seven teams.
Not surprisingly, American hardwoods were well-represented among the appealing, energy-efficient materials in the homes, with student designers using white and red oak, ash, birch, cherry and maple, for interior millwork, flooring, furniture, shelves and cabinetry. In each project, traditional hardwoods combine with exciting, new spatial configurations and high technology to showcase what’s in store for green-conscious homeowners in years to come.
Plug and Play
Carnegie Mellon University takes the computer industry’s concept of “plug and play” to a new level. The Plug and Play House, sheathed in wood and fitted with hardwood cabinets, flooring and furniture from western Pennsylvania, allowed occupants to reconfigure their living areas, or “pods,” by plugging or unplugging them to a central spine or power source. More prefabricated rooms can easily be placed alongside the existing structure and “plugged in” to gain additional living space.
Metals or plastics were used on or within the core, providing an excellent opportunity to incorporate recycled materials. The technological and mechanical aspects of the core are deftly juxtaposed with livability and warmth of the pods. The pods accommodate modular wall shelving, furniture and ceiling panels, all of Pennsylvania white oak that was locally grown and sustainably harvested to ensure regrowth and reduce shipping costs. Finishes chosen for the house include environmentally-friendly and sustainable materials.
In keeping with the competition’s green mandate, Carnegie Mellon art students incorporated plant sculptures into the architecture. Plants were grown on sections of the roof and in bogs around the house. A stepped structure, overloaded with plants, included a tank to collect water from the rooftop for use in irrigation.
In keeping with the competition’s green mandate, Carnegie Mellon art students incorporated plant sculptures into the architecture. Plants were grown on sections of the roof and in bogs around the house. A stepped structure, overloaded with plants, included a tank to collect water from the rooftop for use in irrigation.
Built with 32 solar panels and 24 lead-acid batteries, the house featured floor-to-ceiling windows facing south to gather heat and light, along with a system to draw in cool air from below and vent hot air through windows high on the walls. Hot water lines in the floor produced radiant heat. “This group of students has raised the bar so high that they have spoiled me completely,” said Carnegie Mellon architecture Professor Stephen Lee, the project advisor, noting that the house could serve as a prototype for a prefabricated line of quality, handsome solar houses.
Green Design in Native Materials
In the MorningStar, Pennsylvania State University students combined standardized, high-tech mechanical solutions in a “house next door” prototype that can be fully integrated into the character of any community. Its green features included an “outdoor vegetation carpet” on the roof to filter pollutants and absorb excess rainwater.
MorningStar is built around the “brain” of the structure, a prefabricated mechanical core, including heating, cooling, and water systems that can be mass-produced and shipped to any location. As the “lungs” of the home, the breezeway adds to solar collection and aids natural ventilation. The living space, seen as the home’s “heart,” is open and airy, and incorporates several features to make the space appear larger. The roof, for example, slopes up toward large clerestory windows opening to exterior views; and most window and door openings are glazed from floor to ceiling to further extend the space. Both the breezeway and living area can be customized, and are intended to incorporate local materials and building traditions.
Students used materials characteristic of central Pennsylvania, including Pennsylvania Black Slate, Pennsylvania Bluestone, recycled steel and native hardwood. Built-in furniture—dining room table and chairs, as well as closets and shelves—was crafted from a fallen 100-year-old elm, which was harvested from the University’s Allen Street Mall, one of the oldest and largest American elm groves in the world. An interior moveable wall of native cherry separates bedroom and dining/living quarters, and shifts to adjust room size to occupants’ preferences.
White oak is particularly important to MorningStar, and serves as a beacon marking the site entrance. White oak also comprises much of the interior furniture and storage units. Exterior sliding panels of white oak and local recycled steel grace the south facade, described as “an occupant-operated mobile energy membrane between the interior and exterior,” through which residents can regulate light penetration and solar heat gain. In addition to being native to Pennsylvania, another fallen white oak used at MorningStar from outside Penn State’s Pattee Library, reflected the renewable aspects of wood construction. “We really liked the contrast between old and new, natural and man-made. They both fit so well together, and make the house more livable,” commented fifth-year architecture student Kyle Macht.
Redirecting Expectations
The Kansas Solar Project, a collaboration between Kansas State University and the University of Kansas, went “low labor,” with an extensive use of structurally insulated panels. The long, narrow structure, which can be built in a matter of hours, had a south side facade of solar panels that can be easily attached to the metal roofing and tilted at 64 degrees to capture maximum winter sunshine. Additional roof-mounted panels enhanced energy capture.
Reclaimed barn wood was used in interior cabinetry and exterior screening. The floors in the house were white ash, finished with a clear VOC-free satin finish. “The interior wood finishes all looked great,” said R. Todd Gabbard, LEED AP, assistant professor of architecture. “The students’ selection of ash flooring and cabinet veneers created a clean, calm, understated look that was the perfect backdrop for casual living.” Gabbard noted that the wood’s sustainable harvest was an important aspect that was in harmony with student goals for the house—namely to “redirect expectations.” Or, as Gabbard put it, “showing that homes today can have all the design features and quality we’ve grown accustomed to with less impact on the environment, less energy expended, and higher-quality interior environments.”
Other “redirected expectation” features included a centrifugal clothes dryer that uses a fraction of the energy of a conventional heated dryer and an induction cook top that heats only the cookware and the food inside it, never getting hot to the touch. The home’s monitoring and control system knows what systems to turn off first if the energy supply is tight—and batteries hold three days’ worth of energy, just in case. Biodegradable trays, rather than recycled plastic, was used on the roof; after two years, the biotray will completely degrade, leaving the roof covered in vegetation.
A House for Our Times
The Lawrence Technological University team christened its house ALOeTERRA, evoking the curative properties of aloe vera, the gel from the leaves of the aloe plant, which soothes and heals. While reaching out for sustainable materials, particularly those available to the general public and locally sourced, Team ALOeTERRA kept the focus decidedly low tech, while including innovations like electrochromatic windows and a unique solar chimney.
“This is not the house of the future. This is the house of now,” said Philip Plowright, assistant professor of architecture and faculty advisor to the project. “We are using well-vetted products and technology, and the focus has been on keeping it simple. As a team, we made a conscious decision not to go for the ‘wow’ factor.”
Instead of conventional stick frames and truss roofs, the team opted for structurally insulated panels consisting of two layers of structural boards laminated to opposite sides of insulating foam. They provide the building’s main structure without additional framework. Examples of the team’s commitment to sustainable, low-cost materials: decking material made of rice hulls and exterior panels made of paper so thick even a hammer wouldn’t break the surface.
For its hardwood applications, the team was drawn to American hardwood manufacturers because they practice environmentally responsible harvesting methods, such as selecting individual trees for harvest, instead of clear-cutting acres of land—a practice that allows forests to easily regenerate and reduces the chance of adversely affecting wildlife. Another plus for hardwood selection was modern saw technology that enables nearly every section of a log to be used, minimizing the number of trees needed to fulfill harvest demands.
ALOeTERRA’s wall partitions and furniture are made of formaldehyde-free hardwood plywood that is nontoxic to indoor air quality and has a finish grade that allows the wood to be exposed without using a veneer or additional layer.
A Beach House Gets Smart
With technology capable of recognizing a homeowner’s preferred settings based on a fingerprint scan, New York Institute of Technology’s (NYIT) OPEN House is a smart house on the beach. OPEN House architects envisioned a place where people could live in a healthier way, more in tune with the ecosystems that sustain us, without sacrificing the daily comforts. Flexibility is key, and OPEN House is designed for adaptable, customizable beachfront living that enables a range of lifestyles, from starter home to vacation getaway.
Two main structures were joined together along an east-west axis. The core contained the kitchen, bathroom and environmental systems. The 40-foot by 12-foot open-living space contains flexible furnishings that can be moved or adapted to create varied microenvironments for inhabitants. The floor in the expansive living space is solid hardwood. “We used 4-inch cherry flooring because of the richness and color. We also used cherry for the trim,” says Professor Thomas Rochon, NYIT Solar Decathlon faculty advisor. “Everybody loved it.”
OPEN house is in sync with its environment. It sits lightly on the ground on a raised, permeable platform. Ample windows on the south side connect the occupants to nature; windows allow natural light and warmth in winter, and a shading device keeps the house cool during summer months. Heat generated by OPEN House is stored and dissipated in the roof-top pool, and a waterfall allows water to cool and be recycled back to the roof pond.
Roof-mounted photovoltaic cells and evacuated tubes harness electrical and thermal energy from the sun; inverters and controllers in the core transform solar power into electricity to be stored in batteries outside the house for the competition.
And OPEN House is smart. Besides a biometric scanner that permits entry to the home via finger print, the intelligent dwelling features a screen that shows temperature, humidity, power usage and water deployment. Via an automation system, residents can electronically control windows, lighting, temperature and appliances—the system even teaches occupants how to properly maintain the house.
The groHome System
Rather than confine their efforts to a single prototype house, Texas A&M’s Solar Decathlon team adopted the groHome concept, a system for building homes, invented by team leader Pliny Fisk III. A sophisticated, high-tech approach to home building that draws from the best in engineering and business, groHome encompasses a kit of parts that are modularized, high-performance, lightweight, and can be transported to a site and easily set up.
Pedestal footings set the house above the ground to cause minimal damage to the earth. Prefabricated walls, floors and roofs can be added onto the frame—and because they’re coordinated dimensionally, they can be replaced or altered as desired. Rounding out the kit are prepackaged, or do-it-yourself, modular sub components, with integrated subsystems for energy, water, food, sleeping, dining and other functions, all of which are designed for simplicity of installation.
In the not-too-distant future, people may be able to construct their own house without the use of heavy equipment. According to the team’s web site, “A team of four can construct our home in a matter of days. Soon, people will head down to their local hardware store and walk away with an entire room, or log on to eBay and sell their walls.”
Solar generators are incorporated into walls and roofs, and geared to generate the required energy based on lifestyle and solar resource availability. High-efficiency appliances and advanced lighting systems that can be easily replaced when upgrades become available, further maximize energy efficiency.
In terms of building materials, substances that are durable and non-toxic throughout their life cycle are key. GroHome designers stressed flexibility and envisioned the use of steel, wood, and aluminum according to regional market dynamics. The team’s prototype home made ample use of wood. American hardwoods, including pecan and walnut, were used for front and back doors. The reasons, according to Fisk—“all were indigenous to Texas, all were long lasting and beautiful.”
Seeking Icarus
Georgia Institute of Technology students brought the best of high tech and nature together in their prototype home, named Icarus after the mythological figure that flew close to the sun. Inspired by the seeming paradox between lighter, more transparent buildings and those that promote energy conservation, Georgia Tech students used advanced materials technology and energy systems in their Solar Decathlon House.
The home embraced sunshine through a translucent roof and walls, while maintaining insulated comfort. Think light: light roof, light walls, light floors. Lightweight, light-emitting and thermally efficient, the roof featured building-integrated photovoltaic panels with shading devices and translucent skin that is inflated and filled with aerogel insulation—the lightest known substance. The floor used cost-effective “light frame” wood construction. Between the framing members is a light, sponge-like, biobased insulation to achieve an airtight assembly. Walls were white polycarbonate fitted with LED light strips that dim and brighten.
Can durable American hardwoods co-exist with such a light aesthetic philosophy? Georgia Tech architecture professor and team co-mentor, Franca Trubiano, admits hardwoods almost didn’t make it into the Icarus design. “Originally, we were going to make it an all-steel framed home with no wood at all,” she explained. “But I woke up one Sunday and said, ‘No! We need wood inside.’ To me, the introduction of wood is what makes it a home.” The rest of the team agreed. The walls are complemented by solid maple support beams, shelving and floors—a fittingly warm and homey touch for the team’s goal of making the house comfortable to the most rapidly growing population: mid-life empty nesters who desire an adaptive living environment.
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