In 2002 the U.S. Department of Energy launched the Solar Decathlon, an international college competition where students refine and present their best ideas in solar-powered home design. The Solar Decathlon’s interdisciplinary challenge requires students to design, build and operate a cost-effective, energy-efficient home from the drawing board up.
The Solar Decathlon challenges participating students to break new ground, figuratively and literally, on sustainable home design. Held every two years, a top contender at the 2013 Solar Decathlon was Stanford University’s Start.Home, leading the pack in market appeal, affordability and engineering.
Getting to the core of energy efficient home building
Reflecting the holistic nature of sustainable design, the Stanford team comprised a broad range of disciplines, from design and architecture to computer science, product design, business and social science.
Led by Derek Ouyang, the 50-member Stanford team built the Start.Home around the idea of the Core, a modular unit designed as the nerve center of the building, around which a customized home is built. A Core includes the kitchen counter and appliances, one or two bathrooms, a laundry room and a mechanical “engine” room integrating electrical, HVAC and plumbing with automation and monitoring systems.
“It’s not just about engineering the perfect home,” says Ouyang, “it’s about designing a product that people love and empowering people to actually lead more sustainable lives.”
Power to the people: don’t build for sustainability
Ultimately, the design philosophy behind Start.Home isn’t about building for sustainability; it’s about building for agency.
A home built for sustainability includes lots of good things: net-zero energy use, sustainably-sourced materials, passive heating and cooling, graywater recycling and automation system to manage energy use. That’s all well and good. But at the end of the day what you’ve created is a couple thousand square feet of sustainable habitat. If Donald Trump lived in it, what would you have? A sustainable house with a clueless man living inside, with no notion of how his slovenly ways impact energy and resource use inside the house. A nice, energy-efficient house, but with no real impact on human behavior.
Building for agency puts the power back to the people living inside the house (we’ll drop our Donald Trump analogy for now). Creating a home system that relies more on information and flexible human interaction than simple automation gives homeowners the knowledge and “nudge” they need to truly understand their energy use and therefore act on it. They then go out and impart this awareness to their friends and neighbors, spreading the idea of sustainable living through agency and active engagement, not through home automation systems running unseen in the background.
“…our philosophy,” Ouyang says, “was that in the end, it’s not about smart homes; it’s about smart people. And with good design we can actually empower homeowners to make the decisions instead of the house making decisions for you. This, over the lifetime of the homeowner, can actually change behavior”
Building this system of agency was a primary challenge and goal for the team. Ouyang’s team quickly discovered that using off-the-shelf components for the human/home interface wouldn’t work. Integration is a key ingredient for Start.Home, and making the process of monitoring and understanding energy use must be seamless.
“Home automation systems today are difficult for the homeowner to implement because they typically require multiple integration of multiple products from multiple companies, few of which are designed to work together effectively.”
Based on extensive research into behavioral psychology done at Stanford, much of it in the Design school, the team built human interaction into Start.Home by answering two principle questions:
- How to we identify interaction points throughout the home at exactly the moment when an energy decision is being made?
- Once that is done, how do we redesign these interaction points to nudge users toward more energy-efficient behavior?
As the “brains, heart and muscle” of Start.Home, the Core is the central hub for recording energy and resource consumption, presenting that information to the user and providing a human-focused interface to control anything – lights, outlets, windows, shades and ceiling fans. Using smartphones and tablets works to a degree, but integration points are much more intuitive when they are part of the physical home itself, “like light switches, sinks, or even art,” says Ouyang.
Ouyang’s team designed and built what they call “Pods,” built on the Raspberry Pi and Arduinos platform, to link up various off-the-shelf and custom built devices. Each Pod can control up to 14 different switchable elements, eight dimmable elements and one HVAC element. “We designed our own relay panels with custom PCBs that could turn low-voltage signals into relay commands, and could handle dimming and HVAC protocols,” says Ouyang.
Using the low-voltage protocol of the Pods allowed for designing beyond physical switches. Homeowners can control elements based on programmable swipe-based gestures we already use on our tablets and smartphones. A tap could turn on a light, a swipe right could turn a dimmable fixture up, a circle motion could turn on a ceiling fan – it’s up to whatever the homeowner is comfortable with.
Instead of inadvertently leaving the lights on all evening as you rush out the door, a simple three-fingered gesture down could turn off all the lights. This is the sort of human-based interaction with automation that Ouyang and his team believes can empower people to easily adapt habits of sustainability.
Like the Core, Pods are modular, and can be distributed throughout the house in locations where they are most relevant to what is being controlled. In this way, tracing wiring back to the core is reduced. Pods are easily added if more are needed. The structure and control of the Start.Home grows and adapts to the user.
Is it art, or energy-use feedback? (or both)
To demonstrate the flexibility of data management and feedback, the team designed a piece of “kinetic art” for Start.Home. A series of fan-like leaves curl in tightly or flatten out, giving an abstract representation of electricity consumption over the past hour. Two fans, each with 12 leaves, give a 12-hour history of energy production and consumption. Changing every hour, the leaves provide real-time visualization of net-balance throughout the day. “This was a big hit with people who came to see the home,” Ouyang said.
The point is to make monitoring energy use and net-balance production flexible, seamless and intuitive, keeping in mind the concept of human agency, not just sustainability. Changing human behavior was the goal. Maybe even Trump would turn off his lights if he saw exactly how it would save him money. Now that’s changing human behavior!
To help insure against wasting water from a forgotten or ignored open tap, the team designed a knee-activated bathroom sink. Leaning into the bar turns on the water, releasing it turns it off. We’d call it a kind of “deadman switch,” but that might not be in the spirit of the idea. Still, it is a simple and elegant design that reduces water waste. Graywater from the laundry room can be used to irrigate landscaping.
The team intended on installing water flow meters, but ran out of time. Nonetheless, this is easily included in future iterations of Start.Home
Manufacturing Start.Home: Inspirations from Henry Ford
Henry Ford built the Model-T around a core engine-drivetrain serving as the foundation for various chassis options depending on user needs. Sound familiar? Ford’s idea of using modular components to maximize efficiency was “our major inspiration,” explains Ouyang. The hard times suffered recently by the auto industry notwithstanding, Ford’s original inspiration for modularity and efficiency has allowed the industry to adapt to changing times, meeting consumer demand for cars that are more efficient and cost-effective.
Start.Home is Stanford’s answer to a largely stagnant home construction industry, creating a “smart, adaptable residential system that cuts up-front and use-phase energy emissions” built on an “energy-efficient framework that is modular and scalable, and does not sacrifice the freedom of the homeowner to build a custom home.”
Ouyang envisions a variety of Core configurations, varying in size and equipment specification based on end-use needs and location (the prototype was based on Stanford’s Palo Alto Mediterranean climate). Once fully developed, modular home Cores will be produced in an assembly line process and shipped as efficiently as possible to construction sites.
The power of BIM and visualization modeling
Integrating the basic architectural, structural and MEP (mechanical, electrical and plumbing) elements into a tightly coordinated configuration within the Core was a challenge. Without modern 3D modeling and visualiztion tools, making the Core work may have well been impossible, at least in any cost-effective manner. With BIM, clashes between studs and ducts or casework and pipes were quickly identified in the initial design phase. “We could fix mistakes in an iterative manner before actual construction,” explains Ouyang.
At every point in the design process the team employed a full suite of Autodesk BIM modeling and visualization tools, including the Autodesk Building Design Suite, Vasari for conceptual design, Simulation CFD for fluid flow and thermal simulation, and Green Building Studio for environmental analysis.
Bringing Start.Home to market
Solar Decathlon rules required the Start.Home be built entirely on-campus, preventing a real-world simulation of the factory-build process. The “manufacturing process is still undeveloped and needs further research,” says Ouyang. Even so, the task of building the prototype Start.Home revealed several lessons for the manufacturing phase:
- Prefabrication is only beneficial if it eliminates time-intensive materials and techniques. Drywall, for instance, takes the same amount of time whether set in a factory or a construction site. There is little advantage or efficiency gain in “prefab” drywall.
- Getting the most benefit of prefabrication in home building comes from using new materials and techniques using large tools not available onsite; materials the don’t require curing or drying, stud walls pressed together by a single machine, robotic welding arms assembling Core elements.
Clearly there is still a lot work sussing out exactly how factory-floor operations and distribution will work. But the concept is viable and ready for further development. The Stanford team received support and mentorship from BluHomes, a market leader in energy efficient prefab homes.
Adaptable and cost-effective
Market appeal and cost-effectiveness are among Start.Home’s strongest selling points. The adaptability of the modular design has appeal across the housing and economic spectrum
“…from high-end residential (think the kind of people who buy Teslas) all the way to disaster-relief and temporary housing,” Ouyang says. “I think it just goes to show how simple yet important the idea of a Core is, and I am confident that in the future they will solve lots of problems.”
Not only will Start.Home and its Core concept solve lots of future problems, but so too will bright, inspired designers like Derek Ouyang and his Stanford colleagues. They take the lemons my generation has given them and are making lemonade – all in their smart, interactive, resource-efficient kitchens.
Where is Start.Home now?
After the Solar Decathlon competition on October of 2013, the Start.Home was reassembled on Jasper Ridge Biological Preserve near Stanford campus. It is the home of Resident Ranger Brooke Fabricant, his wife and daughter.
All image credit: Dept. of Energy Solar Decathlon, courtesy flickr