Thriving On Low Carbon

Another Tight One by Habitat

Habitat for Humanity of Martha's Vineyard is really getting the superinsulated, energy efficient home down pat. Last Saturday, accompanied by job super extraordinaire Lee Taberner, I did a final blower door test on the second house they've built at the end of Bailey Park Road. The result - 203 CFM50. Real tight, well under 1 ACH50. Along with this, the HVAC system is a minisplit heat pump, a heat pump water heater, and a heat recovery ventilator.

HfHMV has made the connection between energy efficiency and permanent affordability. So has the Island Housing Trust (South Mountain is currently building two new homes for IHT, also in West Tisbury). It's heartening to see the two most significant affordable housing providers on MV so committed to high performance homes.

Variations in energy use

Last year, during November and December 2011, our net energy with the grid was 98 kWh - we imported 98 kWh more than we used. This year during the same period that figure was three times higher, 299 kWh net import. Why so different?

For one thing, it was cloudier. The PV system made 68 kWh more last year during this time. The larger difference is that we used more - 947 kWh this year, vs. 814 kWh last year. How come? I can think of three things:

- It was colder this year - 1,580 heating degree days (base 68F) vs 1,296 in the same period last year, mostly in a colder-than-average (yes, we still have those occasionally!) November. So the heat pump ran more - 98.5 kWh more, in fact. That's the big one.

- Jill is working three long days a week instead of going to work five days/week, so she's home more, using lighting, a higher thermostat setting, the computer. A small impact, but it's likely real.

- Jill's Christmas cookie marathon, in which she made 16 different types of cookies. Lotta oven usage, plus kitchen appliances and lighting, plus dishwasher, plus more hot water cleaning up. This extra usage of energy is very well appreciated by many cookie recipients!

You can see that the big difference is weather-related - colder and cloudier. The lower energy use a house is, the larger these year to year variations will be, on a percentage basis. Yet the benefit of  solar-driven, energy efficient building is that the percentage variations may be high, but the absolute difference in dollars is small. So the difference in our net energy flow over those two months year to year is about $37 total.

MA Construction Supervisor License

Not long ago I got a bee in my bonnet about getting my Construction Supervisor's license in MA. Working as I now do for a company that is quite diverse, but is fundamentally still a design/build company, it feels right to join a number of my colleagues, mostly but not entirely our foremen, in holding a construction supervisor's license.

It was an interesting process. You have to show at least three years experience, and take a test. The three hour multiple choice test has 75 questions and is open book with these books: The 2009 IRC, 2009 IECC, 2009 IBC; MA amendments to these; the MA Architectural Access Code, and the OSHA regs governing construction. Obviously a test like this doesn't really test one's ability to supervise construction - it's really testing how well you can quickly find stuff in the code books. Most of this is more suited to those in the design professions than the construction profession. Nonetheless, it plays to my strength as a standardized test-taker, so I can't complain. When I began prepping for the test I was a bit cynical about the process, but was surprised to leave the test center with a very positive feeling about the process. It forced me to look at aspects of the code and regulatory environment that I wasn't really aware of, which was good.

MA is implementing a requirement for continuing education units for a CSL, so I actually will have to do something in the next couple of years to retain the license. Hopefully that will also feel worthwhile.

Greed Ate Winter

Jill and I went out to Santa Fe for a Zen Buddhist retreat called Rohatsu, which celebrates the Buddha's enlightenment and is Dec. 1-8 every year. It was quite warm this year, and I could be outdoors in a tee shirt in the afternoon sun. My teacher, Roshi Joan Halifax gave a Dharma talk in which she noted how Rohatsu in Santa Fe used to be really cold and snowy (I recall her leading us in walking meditation outdoors in the snow). As she touched on climate change, her pithy assessment of the change in the weather was "greed ate winter".

A foundational aspect of Buddhist teaching is that suffering comes from greed, hatred, and delusion, hence the reference - our collective greed leads to excess consumption, and therefore emissions, and therefore climate change.

6000 kWh

After a stunning amount of sun in April, May has been cloudy and has brought much-needed rain. Yesterday at Island Cohousing Lynn Weber, our garden guru, marshalled a dozen of us to do the semi-annual move of the hoop house from the winter location where it protected greens to the warm season location where the seedlings now in the cold frames - tomatoes, eggplants, peppers, cukes - will get a head start on the season. The compost bin was dug out and new piles of compost built. The last of the collards got pulled and it took me close to an hour to pull leaves off the plants - ending up with a heaping wheelbarrow of collard leaves (chiffonade the collard leaves, saute garlic in a pan, remove, saute collards, throw the garlic back in, eat). It was cool and cloudy, a great day for garden work.

Meanwhile, the House 5 PV system quietly passed the 6000 kWh output milestone. With 5 weeks left to go in year one of operation, we may exceed 6,500 kWh. This would be 1.37 kWh/W of DC rating, an exceptional output, especially with the mild amount of shading present.

Habitat for Humanity MV, energy, and affordability

The Town of West Tisbury recently passed the Stretch Code at Town Meeting. It's a more stringent building code and in essence it speeds up the adoption of the next iteration of the International Energy Code. Debate was spirited. Aginners (as in, I'm agin it) made impassioned pleas about how it was just another gubmint imposed tax on those that could least afford it, the working folks. My opinion is exactly the opposite - Martha's Vineyard's tax on the working people is $4+ per gallon oil and propane, and almost $0.20/kWh electricity. A tougher energy code is the worker's friend in the long run.

Next to those designed and built by South Mountain Co., the most energy efficient houses on MV are being built by Habitat for Humanity. They are dedicated to permanent affordability for their owners. In the past, HfH often was the recipient of donated products that were sometimes on the low end of energy efficiency, such as inexpensive windows and low efficiency heating and hot water equipment. On MV, the forward thinking folks who operate HfH are, with some detailing help from SMC, building super insulated homes that are very airtight. I help with QA, testing the houses with blower door and fog machine or IR camera. The first house at Bailey Park Rd. was 175 cfm50 at the stage of windows and doors installed and most of the roughing done, but no drywall. In the next month they'll be ready for a final test. Today we tested the shell at the second house they are building there, with window and door openings poly'd off. It was just about 300 cfm50 with the air barrier being one layer of taped polyiso foam on the walls and roofs. The house is a kit, which is all T&G pine inside, a potentially very leaky strategy.

With volunteer workers, they're building a house tighter than almost all the pros do here. The beneficiaries will be the owners. The mechanical system is mini split heat pumps, far less costly to operate than fossil fuel equipment. Thanks, Habitat, for leading the way to permanently affordable housing.

 

 

 

PVs and credits and bills (Oh my!)

This morning we reached a new high for the credit we've built up in terms of net exported energy - 1,753 kWh. The previous high was 1,738 on December 3rd, then it dropped to a low of 1,477 on January 28th. This winter we were net importers in December and January, and I discovered to my dismay that even though I'd built up a credit of over $300 with Nstar, I was getting billed for the energy we imported. Looking closely, I learned that I had Nstar as my energy delivery company, and Coned Solutions, via Cape Light Compact, our municipal aggregator and default supplier, as my energy supply company. Having two separate companies is part of the deregulation process - you get a choice of who supplies the energy, but not who delivers it (owns the wires). It turns out that Nstar credit doesn't offset Coned supply charges. The simple solution, that doesn't make Cape Light Compact happy, is to switch to Nstar as the energy supply company. The rates are within hundredths of a cent per kWh, but that actually doesn't matter if we are net exporters - in fact, a higher rate allows us to build up a larger credit, which we could allocate to another meter.

Le cheque du SREQue

SREC - solar renewable energy credit. The MA government under Deval Patrick set a goal to dramatically increase solar electric generation and jobs, and the increase has been dramatic - from under 4 MW in 2007 to 118 MW installed or in process currently. The state has used multiple tools, including tax credits and outright rebates from the MA Clean Energy Center, yet the one that will put the most green in my pocket is the SREC.

The utilities are required to have an increasing % of their generation from renewables and a portion of that from solar electricity. If they don't have it, they can purchase credits from those who do own systems producing solar kWh. Small systems like mine are pooled by aggregators (not to be confused with Republican presidential candidates, who are aggravators) who sell them into the open market quarterly at auction. The latest auction went for $540/mWh, or $0.54 per kWh (an SREC is 1,000 kWh or 1 mWh). That's almost three times what I pay for electricity from Nstar here on MV. My net after fees and such was $502 for my first SREC. My system should make 5-6 SRECs annually.

This golden goose doesn't last forever. I'm signed onto this for 40 quarters. Once the utilities hit the required targets the price will drop, but it's fairly likely that I'll be clearing over $250/SREC. So my SREC income over the next decade should be over $15,000. I should be installing solar electric systems wherever I can, it's a way better investment than any other I can make :-)

I'm not really a fan of subsidies. I wish for an economy where all subsidies are removed - if the effects of oil, gas, nuclear, etc. were accounted for, solar wouldn't need subsidies to compete. However, unlike a flat tax credit or a rebate, paying per unit of produced energy at least directs the subsidy towards lowering the cost of the technology - my motivation is to make as much energy as possible at the least cost, and that's the right form of incentive. If you live in MA, you should be putting solar electricity on your roof (or mounted on the ground) - get guaranteed dividends while cleaning up our energy supply.

Sunshine!

January so far has been incredibly sunny. PV Watts, the NREL software that estimates the output of PV systems based on location, tilt and azimuth of the array, and array rated power, estimates an average of 10 kWh/day for my location in January, assuming no shade. I have some mid-day shading from an oak tree. The first ten days this month have averaged about 17 kWh/day. This means that we've actually increased our net export credit, because our use of energy, in what has been a mild weather period, is below that number. Won't last - tomorrow is supposed to pour - but this must be what living in Colorado is like :-)

Fossil-fuel free at last

While I was in the Big Apple teaching a couple of days in the Passivehouse Consultant training, Vineyard Propane came by and took away my propane tank. I had recently sold our last remaining fossil fuel burner, the VT Castings gas heater (the dryer and kitchen range preceded it). I checked when I called them what it would cost for a current delivery - $5.09 per gallon. On a strict BTU basis, that's equal to $0.19/kWh for electricity, about what we pay here on MV. But that's figuring the propane at 100% efficiency. Since we're seeing a pattern when we do energy use assessments here of high summer propane and oil usage with boilers heating DHW, and warm season efficiencies that appear to be as low as 20% or lower, I'm beginning to think that as we design solar hot water systems we should just disconnect the entire DHW system from the boiler and use electricity for the back-up energy.

I'm supposed to get a refund for the propane in the tank, which had about 80 gallons according to the tank gauge. They filled it last fall even though I didn't want it done, and assured me then that I would get refunded for the propane left in the tank. We'll see!