Tiny House, Big Living: Grad School Edition

THIMBY life: cozy, fun, labor-intensive, progressive, living lab. The past 4 months have been exciting for the tiny house transition from construction to living site. Yes, there were nights when we came home to find our water supply run over by a car and leaking all over the parking lot, or when we couldn’t get the heat pump to run (someone knocked the Arduino control system off the wall...), or couldn’t figure out why the inverter-battery system wasn’t working. Usually it was a quick fix, under an hour, but the energy system was a bit more complicated. The battery wasn’t charging, so the company sent some people out to manually charge it, determined the problem wasn’t with the battery, so it must be the inverter. We read error messages off the inverter screen, talked to people on the phone for hours, and finally had some guys come out to look at it. Miraculously, it was determined that the inverter had a software update pushed through remotely that didn’t fully load, so the inverter was “confused about it’s identity.” It thought it was only a grid-connected inverter, that fed solar power back to the grid, but really it’s an off-grid inverter for our house. Silly inverter. Once it recognized it’s true identity, everything started working again off-grid, except for no apparent reason sometimes the power to the house would shut off and then immediately turn itself back on. Hmm...

We spent the semester shuttling greywater samples to a Berkeley Environmental Engineering lab, driving cartons of urine to another lab perfecting urine-to-fertilizer resource recovery, and making waffles on the weekends. The cooking implements in THIMBY worked remarkably well the whole semester, and we hosted several successful dinner parties (of up to 10 people!). Grilling and porch space certainly helped with larger crowds.

Given the information about our greywater (contaminated with bacteria and organic matter, but not E. Coli thankfully), we decided to pilot an additional system, a solar concentrating technology. Typically used for solar thermal water heating, we plan to repurpose the system for solar water disinfection. The idea is to run our filtered greywater through a heat exchanger with the 90C water, and inactivate bacteria that way. The solar concentrator is set up and logging data, and will be integrated with the water loop in the fall.

Innovation never stops at the tiny house; I can imagine a day maybe a year from now where we sit back on the porch in lounge chairs (or in a hot tub hooked up to use the excess hot water from the solar concentrator), and say “Yes, everything is working perfectly as designed, and we just sit around here and use the systems and log the data through our smart Home Energy Management System (HEMS).  Grad school research is the best.” We had a flurry of activity right when the semester ended and people had more time again. The HEMS infrastructure was re-established, using slightly more durable, and solder-able, perf board. An Arduino Uno connected to a Raspberry Pi provided the hardware to log the building performance data in real-time and to control heating and ventilation units remotely. We took apart the lower planter box to replace with a more traditional slow sand filter, and installed a settling tank under the planter boxes to remove turbidity and allow the UV light to function. And, we packed up the house to be “road ready” for the next THIMBY road trip adventure.

If all goes according to plan, THIMBY will drive up to Lopez Island this summer, pulled by the trusty vehicle known as “Big Red,” a 3500 series ’93 Chevy Silverado. It was an ordeal shopping around for a functional used truck that would safely tow 10,000+ lbs, but we think we’ve got the truck for the job. The idea is to test out the systems in a truly “off-grid” setting (on a piece of farm property on Lopez), with long hours of daylight and more time to make adjustments and fixes. And, to see how mobile THIMBY really is! Stay tuned for the next post on the drive and ferry crossing to the island.  

We're on the Move: Into THIMBY

How does it feel to go from this...

To this?

Pretty darn good! A few weeks ago, THIMBY realized her second crucial stage of development: actually serving as a tiny home. One of THIMBY’s team members, Brett Webster, moved into THIMBY at the end of January, after weeks of hard work transitioning THIMBY from a demonstration home to a functioning structure capable of safely and comfortably storing a graduate student plus pared-down belongings. Well, really after a year of planning, designing, engineering, and building the tiny house from a trailer bed to a 210 sq. ft., off-grid tiny house with solar panels, a Tesla battery, and a home greywater filtration system.   

Over the past two months, the 24/7 frenzy of work parties, all-nighters, and super-human efforts needed to get the house ready for the SMUD competition has been replaced by steady progress towards getting the house ready for a resident. Meaning, coats of shellac for waterproofing the windows, waterproofing the bathroom plywood, insulating the toilet box and building the sealed lid, building extra shelving units, and integrating the carbon filter into the planter box filtration loop. THIMBY no longer exists as a competition stunt, but is now a true “living lab” for testing out residential water and energy technologies with an actual resident.

The challenges and joys of tiny living have already presented themselves in obvious ways early into the living experiment. What could be better than biking home from campus, along the Bay Trail, to your own self-built tiny home, cooking dinner on an induction stovetop with lights and radiant floor heating all powered by solar panels and a super-efficient heat pump? And then... it rains for two weeks straight so the battery dies and the house needs to be plugged into the grid to come back on, and you need 240V power, and you can’t shower with hot water because the energy control system fell off the shelf when you moved the ladder to get up to the loft...

Speaking of showers, because the greywater filtration system is currently plumbed so that greywater is filtered through a layered planter box, activated carbon filter, and UV light before re-collecting in a filtered tank, which is the cold water supply to the shower, you have to be really careful what you put down the sink or shower drains. Raw meat? Questionable. Blood? Probably ok, but worrisome at first. We’re testing out greywater filtration removal rates -- for turbidity, BOD, COD, E. Coli, nitrates, etc. -- in a Berkeley water quality lab, and will continue to gather data this spring on water quality and energy balance.  

The first few weeks in THIMBY have proved how collaborative and flexible you have to be to pioneer the off-grid variant of tiny living. Calling up team members and friends to help with critical repairs, and settling in slowly by unpacking some things and moving anything non-essential to storage, are necessary and unavoidable parts of the experience. But, in the midst of thinking critically about sustainable living, it's nice to realize you can still have 8 people over -- to discuss the next variant of water treatment systems, or just share beers and grill out on the porch with the sun setting over Richmond Bay.

THIMBY's Front Door: A Collaboration with Pella and Coldwell Banker

We’re back from the SMUD 2016 Tiny House Competition! THIMBY braved a stormy journey from Sacramento to Richmond, but she’s now safely parked at the Richmond Field Station. THIMBY took 2nd place overall in the competition, and won specific awards for water conservation, sustainability, and home life. Here are a couple photos from the competition:

It was incredible to see the house we’ve been designing and building for 2 years actually sitting in a parking lot in Sacramento. Thanks to our extremely dedicated team, our awesome sponsors, and our friends and family, we were able to create a truly 100% solar-powered, off-grid tiny home. Today we’d like to recognize the support we’ve received from two of our great sponsors, Pella and Coldwell Banker.

We worked with Pella to choose the perfect windows and sliding glass door for THIMBY. Thanks to the Pella team, we found what we had hoped for: small windows for the home’s south and east facades, and a sliding glass door that would make THIMBY feel more spacious.

It was at this point that we received a note from Coldwell Banker: how could they help support our project? We’d met with one of their realtors, Karla Parker, months prior and now CB was interested in getting more involved. After talking with their team, CB decided to generously purchase the Pella sliding glass door we’d chosen. “It made perfect sense to donate the door to this wonderful social initiative,” said Kacie Ricker in an article published on California Home. “It was a symbolic gesture for us too. Coldwell Banker opens doors for people every day.”

We are extremely grateful to these two organizations for their partnership. Over 800 visitors have already walked through THIMBY’s sliding glass doors, and we look forward to welcoming many more.   

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Platt Meets THIMBY: Creating an Electrical System

THIMBY is well on its way through construction: design decisions have been finalized, walls have risen, and the most exciting part to many is yet to come — populating the inside of the house with appliances and furniture to make it functional and liveable. But what has to come before any of that? The electrical system! And trust us, it's much more exciting than just what makes the rest of the house run. 

If you haven't designed an electrical system before, you might be wondering how that process even begins. Well, first our design team needed to estimate the demand, or the amount of electricity that will be needed to serve the devices plugged in. To do this we had to consider:

  • Major appliances in the house
  • Heating and cooking with electricity?
  • How much flexibility is there in demand?
  • What kind of weather/climate will the house be in?
  • How much of a solar resource will the house have access to, or how much sun will it get?

After we estimated the demand, we were ready to begin sizing components since we knew how much electricity we needed (roughly). But...what parts even go into a solar photovoltaic (PV) system?

What's so exciting about our electrical system — other than the fact that it's capable of operating both on-grid and off-grid — is the specific components we integrated into our system.

Through our partnership with Platt Electric Supply, we were given not only the electrical components for wiring the house's circuits, but also the StorEdge system for managing the flow of electricity among solar modules, grid, battery, and loads in the house. The newest technology from SolarEdge, this system combines the functionality of the combiner box, charge controller, and inverter in one smart system that keeps all components of the electrical system working optimally. Though they were designed for use in a house that has a connection to the electrical grid, we will demonstrate that they can work in an off-grid house on wheels.

Moreover, Platt donated solar racking pieces from Iron Ridge to help us mount all of the modules and tilt them towards the sun through changing seasons. We've worked with our partners to modify the racking components from what they were designed for, allowing us to make use of nearly the whole area of the roof to generate electricity.

So what's to come next? Finishing up wiring, installing insulation, racking and mounting the solar panels, and installing the battery — but one step at a time!

 

From Foam to Thermacork

One step backward, two steps forward. This is what a lot of the learning experiences on THIMBY have felt like this summer as we work to complete our innovative-yet-replicable, sustainable-yet-affordable tiny house, reconciling contradictions and tradeoffs in the green building world. One such tradeoff: how to create the best possible building envelope in materials that are high performance, lightweight, readily available, and environmentally sustainable. The answer: cork. Thermacork insulation is made from the bark of cork trees harvested in Portugal, trees that grow for over 150 years in the unique Southwestern Mediterranean ecosystem that has supported abundant biodiversity and human economic enterprise for thousands of years. The bark is stripped during the months of June and July, once every 9 years per tree, allowing the tree to regenerate in the interim while being harvested over 15 times in its lifetime. It is a 100% natural material, with the resin produced by the tree serving as an adhesive. The finished material is a carbon negative product, waste cork is used in a cork biodiesel power plant that powers the manufacturing, and the overall process is  “one of the most sustainable business practices on Earth” according to the Thermacork website.

Here’s the step backward piece — we found out all this wonderful info about cork, and the fact that we could get the square footage of material we’d need donated to the project from Small Planet Supply, a Washington-based company dedicated to energy-efficient building materials and practices… after we’d already gone ahead and installed 1” rigid foam polyiso on the exterior facade, and painted it black to cover the foil and use as the backdrop for the cedar siding and battens. It was cheap, light, and readily available. The problem was, the paint kept chipping off the foil, leaving shiny imperfections that you’d see through the 1” gaps between cedar siding boards. We feared this would only get worse as we drove the whole thing down the highway to the competition and going forward in time. Wanting THIMBY to last well into the future, it seemed almost sacrilegious to mount all the reclaimed cedar we’d spent days milling to perfection on a shaky, petroleum-based product. Should we apply more layers of expensive liquid weather-proofing membranes? Or move in another direction?

Enter cork! After several phone calls with Small Planet Supply, we got the cork loaded on a truck Friday afternoon, and it arrived at the build site Monday. On Tuesday, powered by a team of friends and volunteers, all the foam insulation was removed and all the cork installed on the North and South facades, a 15 hour marathon workday. It installed easily, looks great and the cedar siding can be installed directly onto the cork, without any other layers of paint or material. Two steps forward.

The standard density cork insulation is R-4 per inch, and we consulted European product performance statements (where this product is much more commonly used) to verify that it wouldn’t degrade with exterior exposure in the 1” siding gaps. It’s tree bark, after all, naturally adapted to handle the sun, rain, and wind. Plus it’s affordable, $72 for a pack of 12 1” panels (we needed 8 packs to cover about 500 sf), only slightly more expensive than the cost of the foam insulation plus material to coat over it to make the exterior insulation ready to fasten to our wood siding. Other features of cork: it doesn’t lose thermal resistance over time, has great sound isolation, and resists compression. A true victory for the sustainable materials procurement of THIMBY!