A grand tiny house

Trying to fit all of one’s possessions inside 170 square feet is tough. But designing and building a tiny house of that size in less than two years is a challenge of an entirely different magnitude.

Yet that’s just what a team of Berkeley students accomplished. Just a few weeks ago, they placed second overall in a collegiate tiny house competition organized by the Sacramento Municipal Utilities District (SMUD).

“We built exactly the house we wanted to, which was incredibly ambitious,” says Ian Bolliger, the team’s project manager and Energy and Resources Group doctoral student.

The team thought carefully about how to design a house that embodied sustainability, affordability and durability — key components of the tiny house movement in particular.

The house — which won the competition’s Best Craftsmanship, Sustainability and Water Conservation categories — is an off-grid structure that incorporates cutting-edge green technologies such as Tesla’s home energy storage battery, insulation made from cork, a photovoltaic solar array and a “living wall” of plants that filters greywater for reuse.

A rendering of THIMBY’s tiny house. (Image courtesy THIMBY)“The approach the Berkeley team took towards sustainability was outstanding,“ says Suzette Bienvenue, SMUD energy education specialist who organized the competition. “Their house showed excellent craftsmanship and attention to detail.”

SMUD’s building competition is the first focusing  focus on tiny houses, Bienvenue says.

Building a house that’s sustainable, affordable and durable is a balancing act, as these qualities can be at cross-purposes — for example, the most durable materials or sustainable technology aren’t always the cheapest.

“From the first day, we wanted to build the house that we felt best reflected the intersections of these tensions and showcased what the tiny house movement is all about — doing more with less,” Bolliger says.

To stay within the competition’s requirements, which included a maximum $25,000 material budget and complete off-grid functionality, the Berkeley team, calling themselves Tiny House in My Backyard  (THIMBY), had to make some tough decisions early on.

“We had clear priorities — design a house that was first and foremost as sustainable as possible,” Bolliger says. “Given that constraint, we wanted to ensure the house would also last and be as affordable as possible.”

Because THIMBY was composed of students from 12 different disciplines — including architecture, engineering, environmental design, law and communications — the team was able to make decisions that took into consideration each of those angles, he added.

Every step of the way presented challenging decisions, according to Kenny Gotlieb, a doctoral student in applied science and technology and lead designer of THIMBY’s electrical system. Though the knowledge he needed to accomplish his task was outside of his academic background, Gotlieb was confident that he’d be able to figure out a way to make it work.

“Having designed, debugged and successfully implemented many experiments in my lab by asking for help, I knew not to be too intimidated,” he says. “With the enthusiastic support of other students and industry partners, we were able to incorporate the latest photovoltaic, battery and related technologies.”

SMUD’s tiny house competition was scored in four areas: energy, architecture, home life (comfortable living space for two) and communications (how well the team shared their vision to the public through video, online and print materials). Each team was required to design their house with a specific end user and environment in mind. THIMBY designed its house for a real-life couple who will be living at Unity Park, an urban park in Richmond.

The competition’s winner, Santa Clara University, built its tiny house for Operation Freedom Paws, a Central California-based organization that works with disabled veterans to train their own service dogs. That house will likely be placed in the group’s parking lot and veterans will live in the house for two weeks at a time while they work with the dog to prepare for service, Bienvenue says.

Since a main purpose of the competition was to educate the public about new ways to conserve energy at home, teams opened their houses for public tours at Cosumnes Community College in Sacramento on October 15.

While Bienvenue says she initially expected 4,000 attendees, approximately 15,000 visitors showed up by the end of the day, including a camera crew for the popular cable TV show Tiny House Nation.

“That shows just how popular tiny houses have become,” she says. “We’re looking forward to putting together the event again next year.”

WATER HEATING: A new eco-friendly and energy-efficient heat pump uses CO2 as a refrigerant, instead of standard synthetic refrigerants, to raise water temperature. ENERGY STORAGE: Using Tesla’s new lightweight and compact “Powerwall” lithium-ion battery, the house can store 6.4 kWh of energy and provide 3.3 kW of power. RADIANT HEATING: The heat pump works with a heat-exchange system to circulate water through the subfloor in a radiant heating system. ENERGY PRODUCTION: Eight photovoltaic roof panels collect enough sunlight to generate between 5-12 kWh per day. LIVING WALL: Water drained from the kitchen sink and shower flows through a “living wall” of plants and two feet of soil to remove organic contaminants before being filtered by activated carbon and disinfected by UV light. Processed greywater is then collected for bathing and non-potable reuse.