ECO-STRUCTURE recently caught up with Sarah Miller, project architect for INhome, the Purdue University’s entry for the U.S. Department of Energy’s 2011 Solar Decathlon.

How is your solar paneling unique?

Although the INhome’s solar system is a commercially available product, the system is unique because it’s a photovoltaic system with no evacuated tubes for producing hot water. Our home uses a heat-pump water heater to produce hot water run-off of electricity. The main reasoning behind this decision was cost. During the competition, we had few sunny days. This worked in our favor, because a solar hot water system cannot produce hot water in cloudy weather, while our all-electric system was able to produce plenty.

What other sustainable features have you incorporated into your design?

The exterior of the INhome is composed of Structural Insulated Panels (SIPs). Instead of building with traditional wood-stud framing, which allows for increased thermal bridging, pre-manufactured SIPs allowed us to construct the exterior shell of the INhome in two days.

Passive design was incorporated in the INhome as well. Vaulted ceilings allowed for a feeling of grandeur but also contributed to passive ventilation. A series of operable clerestory windows sit at the peak of the vault and when both clerestory windows and front façade windows are open, the chimney effect occurs allowing hot air to escape through the peak and cool air to enter the home. Natural day lighting is utilized in the home as well. With 73 percent of the home’s glazing facing south, solar heat gain reduces the reliance on mechanical systems in Indiana’s cold winter months. A 2-foot overhang creates shading however, when the sun is higher in the sky, preventing unwanted solar heat gain in Indiana’s humid summer months.

What was the inspiration for your design, and does it display any regional influences?

The inspiration for the INhome’s design was to combine practicality with innovation. Many technologies and efficient systems behind the walls enable this home to be net-zero energy, however it is our belief that in order to see solar living more mainstream, home still has to feel like home. Purdue intentionally designed a conventional and comfortable home with products right off the shelf. You could take the INhome and place it in any neighborhood in America. We want people to see themselves living in the INhome and understand that solar living is accessible to the masses. We want to show people that the transition from traditional living to solar living is simple and that you don’t have to sacrifice the comforts and amenities you’re used to in order to be net-zero.

How has the new affordability criteria affected the design of your house?

The affordability contest was a welcomed addition to the competition by our team. The goal was to show that net-zero homes are possible right now, and that they can be done in a way that is familiar to the public. We believe that if there is broad appeal for our design, it will be more likely to be adopted by a wider audience and therefore have more of an impact on energy usage in the future. Affordability seems to be one of the major reasons why homeowners are not adopting solar technology into their homes. We maintained a detailed budget broken down into different sections for the home, and we had to make sacrifices at times. The affordability contest made the design process more realistic and more of a challenge. 

What will happen to the house after the Solar Decathlon?

The house has already been placed in a neighborhood in Lafayette, Ind., that is going through redevelopment. The home is scheduled to be finished in the next month and then will be open for tours. Early next year, a subsidized homeowner will move in and our team will be able to remotely monitor its technical performance for further research. This is exciting for the team because we’re able to share something we put our hearts into with an actual family. We’ll continue to monitor the home’s performance for five years gathering a realistic depiction of how the INhome’s design lives up to the use of a family.