Virginia Tech’s Solar Decathlon houses of 2002 and 2005 were invaluable learning experiences for the process of the 2009 house. The third Solar Decathlon Competition presents further opportunities to challenge the ideals of solar housing design, integrate technology and architecture, and ultimately promote solar power for the modern homeowner and workforce. A collaborative of students, faculty, and staff from the departments of architecture, industrial design, interior design, building construction, mechanical, structural, and electrical engineering, computer science and the college of business have come together to design, build, communicate and operate a unique solar house that demonstrates a viable and comfortable living and working environment, excellence in sustainable construction, and strong architectonic expression.
While various interpretations exist, the Virginia Tech Solar Team places major emphasis on the duality of sustainability through a “responsive architecture;” not sacrificing a quality through aesthetic value for affordability or sustainability in the architectural context. Homeowners should not have to make this sacrifice, as all of these objectives can be achieved through thoughtful, innovative design. The Virginia Tech house, named lumenHAUS, proposes solutions to current issues of affordability, sustainability and architectural quality. Prefabrication methodologies drive these solutions through: innovative transportation techniques, flexibility and multiplicity of design models, architectural responsiveness and an automation of building assemblies. Our methods of prefabrication are designed to increase access to broad markets and demographics, while also promoting solar power as a viable option for today’s home.
The lumenHAUS design was originally modeled after the Farnsworth House, a modern icon through its open plan, abundance of light and its strong ties to the outdoors and nature. The 700 square foot house instantly triples in square footage and utilizes zero energy for a good part of the year both day and night. Large sliding-glass doors with screens allow full cross ventilation and a dark grey, polished concrete floor offers thermal massing for the incorporation of a passive solar energy strategy. Otherwise, an opaque screening system closes tightly to contain and insulate against loss of energy.
The mission of the Virginia Tech Solar Decathlon Team is to inform and educate the public about issues of energy (particularly solar), promote the diffusion of important and innovative technologies, enhance student education, through a design-build, educational process, and engage in innovative research and testing through application. The breadth of expertise incorporated into the design, engineering and construction of the 2009 home exemplifies multidisciplinary excellence and consideration.
An innovative transportation system allows the house to be transported easily without expensive permitting and very little on-site construction or assembly. The system, which is inspired by the double drop lowboy trailer, is made up of removable components (axle/wheel assembly on the back and hitch hookup on the front) allowing for simple truck transport, flexible suspension, and higher height clearances than conventional modular transportation methods. Low cost and efficient transportation is a critical component to the future of pre-fab, modular construction.
Our team’s market viability plan utilizes this transportation system with the many advantages of prefab, factory built assemblies that include higher quality control, lower construction cost and less construction waste. Further, manufacturing technologies present economic opportunity through local workforce development (both skilled and unskilled) and sustainable productivity solutions.
The design also accounts for community and lifecycle solutions through multiple units that connect or stack with plug-in stairs and entryways, making a holistic system and viable product for variable and changing markets. The home incorporates major parts, such as screens, which require remote assembly and can easily be attached to the home’s main structure. Each additional item attached to the home is therefore customizable for the locality, environment or desires of the homeowner. A sustainable community, an extension of the lumenHAUS concept called lumenCITY, has been developed by the team which models different affordable housing schemes and envisions neighborhood growth through a trading of modules to one another, accommodating growth or the modern aspect of shrinking community.
An Engineering Solution
The home is “intelligent,” containing a computer that collects information and utilizes it to operate house controls, ensuring energy efficient operation and user comfort. The computer can open and close sunshades, moveable insulation panels, and curtains; it can adjust the thermostats and control humidity. The computer also controls lighting, house music and security. The home’s engineering design also responds to its environment through the following controls:
- The house is equipped with a weather station that monitors temperature, wind speed, humidity, and daylight which can be disseminated as localized data;
- Through the internet, the house can also gather weather forecast information;
Sensors inside the house can monitor interior environmental conditions: temperature, humidity, day lighting and house occupancy.
During initial occupation, the interface offers a set of questions to the new owner to translate daily routines and schedules, comfort levels, even preferred lighting levels at different times of day to insure its operation at the most efficient energy level. The computer further programs background music for atmosphere and comfort. Still, overrides and daily custom operations can easily be achieved through the use of the interface device: the iPhone. Virginia Tech’s computer science department is developing such an iPhone application which enables one to operate all house systems remotely. This remote operation includes access to power management displays (above), providing the home’s energy production and consumption, with detailed information on specific components consuming energy. Additionally, the iPhone will facilitate the ease of turning on and off lights, moving automated, exterior insulation or shading panels, or opening and closing curtains. RFID coding in the phone will lock and unlock your front door; occupancy sensors and daylight sensors will add an additional level of energy management.
The Heating, Ventilation and Air Conditioning (HVAC) system utilizes the latest geothermal heat pump technology. With an earth-tied water-to-water heat pump, low energy hot water is produced which supplies hot water for the hydronic radiant floor system and for domestic hot water. An additional earth tied water-to-air heat pump provides hot and cold forced air and humidity control. An efficient air-to-air heat exchanger is also incorporated into the system. Finally, the thermal massing of the concrete floor increases re-use of solar energy, either via heating of the hydronic system (integrated into the slab) or storage of radiation.
Home energy is obtained by an 8.4-kilowatt photovoltaic array consisting of 43, 195-watt Sanyo Hit Double-bifacial photovoltaic (PV) panels. This innovative new technology utilizes both sides of a silica wafer to increase the panels’ outputs up to 15%. In other words, the roofing membrane (a white PVC rolled-roofing) reflects energy back up to be collected on the reverse side of each solar panel. Depending on how much ambient light may be reflected onto the panels’ backs, the array could potentially be a 9.4-kilowatt array, more than enough energy to power the home and offer excess energy back into the grid-tied power infrastructure. The entire array will be mounted on a sun tracking rack system, for increased efficiency, allowing the array to shift from a 17-degree angle in summer to a 35-degree angle in winter.
The above image illustrates the various pools surrounding the home. Rainwater is collected by a roof drainage system and is filtered and reused inside the house and for irrigation. Greywater (house water from the shower, bathroom sink and clothes washer) is filtered through a water-land plant system and also reused to fill the toilet basin or for irrigation.
Moveable translucent insulating walls (pictured above behind, and shorter than, the metal panels) utilize polycarbonate panels and Aerogel insulation to generate an r-24 insulation rating, well beyond the efficiency of most home wall assemblies without windows. The house therefore has the ability to adapt to the exterior conditions: if the weather is good, you have the ability to open the house up to the outdoors and expand your interiors or insure a well-insulated assembly when desired. Edges of the panels include inflatable gaskets for a tight fitting closure to ensure the capture of all energy produced during the hours of optimal radiation. With a low energy lighting system included in these walls, lighting can be easily provided for both interior and exterior spaces when desired. A similar system of shade panels will also slide across the north and south facades to provide shading and privacy as needed.
Finally, low energy L.E.D. lighting is engineering throughout the home with the latest technology to minimize draw on the power source. As you see above, the ambient and task light provide a desirable atmosphere for any home, day or night. The lighting levels are, again, easily controlled using the iPhone interface and allow numerous options for lighting solutions.