The US Department of Energy Solar Decathlon 2015 team Texas/Germany — the University of Texas at Austin and Technische Universitaet Muenchen in Germany — has designed an affordable, net-zero energy, water self-sufficient home — NexusHaus — that has two 420-ft2 modules. One unit houses living, dining, and kitchen areas, and the other houses two bedrooms and a bath.
NexusHaus is envisioned as a prototype for Austin’s Green Alley Flat Initiative, which proposes sustainable, green, affordable housing in the city’s underused alleyways. A key for success is modularity and flexibility of design. The tremendous variety of conditions in the backyards of Austin single-family properties — including trees, garages, fences, easements, and setbacks — means the NexusHaus must be highly adaptable. The modules can be placed in a number of configurations, reduced in scale, or sold individually to meet the needs of the site, according to the team’s NexusHaus website.
Ernie Tucker, writing for the US Department of Energy Solar Decathlon communications team says the 5,500-mile distance from Austin, Texas, to Munich, Germany, melts away with NexusHaus. Decathletes have drawn upon shared interests — especially the energy-water nexus of sustainable practices — to create an ultra-efficient solar house.
It helps that Austin and Munich share cultural bonds. A wave of immigration around Austin gave the region German roots. These days, residents of both Austin and Munich enjoy outdoor beer gardens and relaxing in public spaces.
There are technological parallels as well. Germany’s electric system is rapidly moving away from fossil fuels and toward renewables such as solar energy and wind power, while Texas is a leader in developing wind energy and Austin has made some strong moves toward solar. Both grapple with integrating intermittent renewable power into electricity grids, and both are increasingly aware of the need to conserve resources such as water.
Wolfgang Vidal, a Technische Universitaet Muenchen student, says he became involved in the Solar Decathlon project because he shares a sense of responsibility for the global environment and wants to support “sustainable ways of designing and building and thus contribute to finding solutions for environmental issues.”
Charles Upshaw, a University of Texas mechanical engineering doctorate student and team co-captain, says the house’s name encompasses what the team is trying to address — a nexus of four interrelated elements: energy, water, population growth, and sustainable food production.
“The idea is to build a house that is water self-sufficient, is net-zero energy, and has thermal storage,” says Charles Upshaw.
Our design is composed of two equal-sized modules, with a clean division between day and night usage. These two house components come together through a central space, which we also call ‘nexus’ or the breezeway. It is an outdoor-indoor space which we integrate in our architectural and energy concept. –Eneida Lila, one of the Technische Universitaet Muenchen’s student leaders.
The European preference for clean architectural lines, big windows, and sustainable materials is evident in the 784-ft2 modular urban home.
Population in Austin is projected to increase by 80%, while water supplies will decrease by 10%. The point is to increase the housing density in the city without increasing the burden on water and electricity. –Charles Upshaw, an Austin native who also says that Austin’s reservoirs have only been about a third full for several years because of drought conditions.
To help conserve water, NexusHaus uses its modular multipurpose canopy to collect rainwater and direct it to the under-deck storage system. It is also designed to recycle greywater — defined in Texas as water from showers, bathroom sinks, and washing machines — to support outdoor urban farming. The team will pump greywater for vegetables such as tomatoes and okra, and an aquaponic system will support fish such as tilapia and water plants in a symbiotic system.
Technische Universitaet Muenchen students will head to Austin this spring to help with construction. The group will benefit from advice from University of Texas at Austin veteran decathletes. The school participated in Solar Decathlon 2002, Solar Decathlon 2005, and Solar Decathlon 2007.
As the team gets down to the serious work of building NexusHaus, the Europeans and Americans will probably also find time to relax in Austin, aware that two cultures — so many miles apart — can come together in a single place, in a single project, as one group and, as Wolfgang Vidal says, “can laugh about everything.”
The draft animated walkthrough of NexusHaus | Video Credit: NexusHaus 2015 UT-TUM Solar Decathlon 2015