Monday, July 12, 2010

Completion Celebrations

Hello again,
This was another action packed week of details. The end of most projects seem to go in slow motion and the days turn into weeks.

The interior trim and door details and built-ins are finished. We got our new water meter three days ago and completed the hook up to both houses. Most of the solar thermal (solar hot water) is complete. Next week we will fill the tanks and let the sun take over and Blue2 will enter a 90% fossil fuel free hot water mode for the next 50 years. On Tuesday the 5th we had an Open House to celebrate the completion of Blue2, at least that was the plan a month ago, instead it was the near completion of Blue2. The event was so moving and cool that no one seemed to care we were not yet done. I am intending to go on holiday for a week starting next Friday, assuming it will be finished enough for me to leave, so the race to finish is still on. See you next Thursday.
Enjoy .... Terry

Here Rae Levine is giving her final blessings and praise to the ~100 people who came to celebrate Blue 2's completion. Two days later Rae left West Marin to her new home in Seattle. How sweet and perfect that her last act after leaving her position of executive director of CLAM was to celebrate the vision and wisdom of CLAM, it's board members- now and past, and the dozens of other dreamers and volunteers who birthed Blue2 into West Marin. Thank you, Rae, for your years of holding onto the vision. You were the Pied Piper and we followed your enthusiasm. Blue2 will always be one of yours. CLAM's new executive director, Sam Leguizamon Grant (not pictured), officiated the July 5 Celebration event.

Daniel, on right, and Derick of Sebastopol Heat and Cool doing the final balancing of the ERV's fresh air and exhaust. Below them (sorry no face shot) is Aran Collier of Sun First who's crew did the solar thermal system. The first Passive House in California required a lot of fine tuning to synchronize all the systems. We had some of the best minds and skills in the Bay Area to bring it all together. They assembled out here at the Blue2 house not because it was lucrative (many donated time and materials), but because they wanted to be part of something that was cutting edge, smart and ultimately good for the planet. Blue2 could not have happen with out their belief, heartfelt contributions, and skills. Thank you all for your efforts and trust.

On Thursday after the workers went home we set up for the last tour. Here James Bill and I are fielding technical questions from the attendees. This crowd of 75 was from the green building, energy performance, professionals, sector. Our keynote guest speaker was Cathleen Fogel from the California Public Utility Commission, an energy efficiency planning analyst. She understands the potential of the Passive House for mitigating climate change.

It got pretty tight in the mechanical room trying to fit in all the hot water production stuff. The two large tanks linked together with copper piping are 80 gallon storage tanks. They have over 2" of foam insulation around each tank, so they will retain the hot water longer than a typical tank. We are expecting to get up to 90% of the hot water requirements from this system. It will also produce most of the space heating for the house. In the right corner is a conventional electric hot water heater that will go on when the houses tap water is lower than 120 degrees. For full explanation of solar thermal system, see description at end of post by James Bill.

Nancy Stein and Jim Campe are formulating a landscaping plan that will use native and drought resistance plants. This view it is about to be transformed with designated parking and plants and paths and lights.

Seldom Seem Lowell Moulton. (Up until this photograph, many people were not sure if he really existed.) This is the guy that did Blue 2's passive house energy modeling(PHPP). He is one of the the kingpins of this project.
He was in on hundreds of emails and spent hundreds of hours with a keyboard in some undisclosed location or at a conference in Dresden gathering PHPP technology. So far all he has required for payment was some Menghai Beencha Puer tea and possibly a backpacking trip in Point Reyes.
Thank you Lowell.........

By James Bill, Licensed Architect, LEED™ AP, CGBP
(see 4th photo of mechanical room for reference)

Most solar thermal systems are used to heat domestic hot water, and they use a closed plumbing loop filled with glycol. The glycol captures the heat in the solar panels and brings that heat down to heat the water in the solar storage tanks. But glycol breaks down when it gets hot. To keep the glycol from getting too hot, most closed loop systems use energy consuming methods to cool the glycol.

Instead of a typical system, we used a drain back water loop system. These are filled with water, not glycol. The water only flows through the panels when the sun is providing heat and the solar storage tanks can absorb more heat. So when the panels get sunshine, even if the sun is behind a thin layer of fog, and the solar storage tank water is colder than the solar panel temperature, a pump turns on, filling the pipes and panels with water that is circulated to the heat exchangers at the bottoms of the solar storage tanks, thus heating the water in those storage tanks. When the pump turns off, the water drains out of the panels into a small drain back tank.

We have two 80 gallon solar storage tanks. The number of gallons is determined by the amount of heat that needs to be stored for the periods of time there is little or no solar radiation. The solar storage tanks have heat exchange coils at the bottom and at the top. The bottom heat exchangers are hooked up to the solar panel loop, and provide the heat from those solar panels.

The heat exchanger at the top of tanks is for heating the air in the ducts, thus supplying space heating. The water at the top of the solar storage tanks is hotter than the water at the bottom, as hot water rises. There is a loop of water that goes through the top heat exchangers and up to a radiator located in the ventilation supply duct. When the thermostat calls for more space heat, and there is sufficient heat in the top of the solar storage tanks, then a pump will turn on and run water from the heat exchanger up though the radiator heat exchanger, delivering heat from the storage tank to the air in the duct. If there is a need for heat, and the top of the tank is less than 100 degrees, then an electric resistance heating element in the duct will turn on to add heat when there is no solar heat stored up. This duct element is the backup source of heat for the space heating.

Also at the top of the solar storage tanks, there are plumbing lines coming out that go to a small 20 gallon domestic hot water heater. It is small as it is just meant to top off the domestic hot water temperature to 120 degrees, not create vast amounts of hot water. As the occupants use hot water, it will pull water out of this hot water heater. The water that refills this water heater comes from the top of the solar storage tanks. If it is greater than 120 degrees, as it will be much of the year, the water heater element will not come on. If it is colder, the element will come on. But as the water coming in will always be somewhat hot, it will use less electricity than a regular water heater. The water that is removed from the solar storage tanks will be replaced at the bottom of those storage tanks from the cold water supply line.

As you can see in the photo, all of the plumbing seems to have been equally spaced between the two solar storage tanks. This is because the two storage tanks are plumbed parallel. This means that there are equal lengths of plumbing to each tank so that the pressures are equalized. Thus, each tank will get the same heat from the solar panels at the bottom, draw the same amount of water from each tank for the water heating tank, and will have the same draw for the duct heating loop.

The solar system modelers predict the sun will provide almost 90% of the space heating and the domestic water heat. When there is not enough stored solar heat, we have two backups. The domestic water backup heat is supplied by the 20 gallon electric water heater, and the electric resistance element inside the supply air duct supplies the backup space heat. Because we have separated the space heating backup from the domestic hot water backup heating tank, and because we can use cooler temperature water for space heating than we need for domestic hot water, we can use the stored solar heat more efficiently.

There you have it, the integrated solar thermal space and domestic water heating system.

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