An Old House Gets A High-Tech Efficiency Upgrade

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Inside this Article

The bungalow after rehab.
The North Seattle bungalow as purchased in 1991—ready for efficiency upgrades.
Jack and contractor friend George Walter get down and dusty adding batt insulation to the attic for R-50+.
Air-sealing and additional insulation were some of the first improvements, including a new subfloor over old leaky boards and lots of spray foam.
A high-efficiency Coleman forced-air gas furnace was installed in the attic.
The air-sealing and new windows and doors paid off in an air-exchange rating of 0.31 ACH.
The kitchen brightens up: Before (left) and after (right) the installation of just one tubular skylight. A second was installed, creating abundant natural light and further reducing the need for electrical lighting.
Eighteen Sanyo HIT 190 W PV modules provide 3,264 kilowatt-hours per year—enough to meet their electricity needs before the addition of electric vehicle charging loads.
An SMA 3 kW inverter with SPS backup ties the PV array to the house and grid.
A 20-tube Thermomax evacuated-tube thermal collector provides up to 75% of the household’s yearly hot water needs.
A Caleffi differential controller is the brains between the collector and the 60-gallon storage tank.
A outdoor-mounted Rinnai natural gas on-demand water heater provides backup when solar isn’t enough.
A hot water pre-circulator was added to eliminate temperature spikes caused by the Rinnai’s reaction time.
Drought-tolerant ornamentals and rainwater-irrigated food crops grace the backyard.
One of three rainwater storage tanks.
The rainwater irrigation system’s pump box, with filter, and input and distribution shutoff valves.
Sheila and Jack with their electric car and electric bike.

Jack and Sheila Herndon’s 1910 single-story, 850-square-foot home north of downtown Seattle, Washington, is an unassuming structure, typical of its neighborhood. For the Herndons, its draw was affordability and a reasonable commuting distance to Sheila’s job.

The couple purchased the home in 1991, and immediately realized its potential for energy upgrades. “Restructuring the house to be greener was more of an evolution than a goal from the top,” says Jack. “We addressed remaking the home in convenient pieces each year, starting with structural integrity. It made managing costs affordable without the need for construction loans. Plus, we didn’t need to be displaced or disturbed for extended periods of time.”

Getting to Work

Sheila, a medical lab technician, first worked on tearing out patchy grass and low-growing juniper, developing a low-maintenance yardscape for drought resistance, eye appeal, and for shading the southern front of the home. The backyard is their “personal oasis” and organic vegetable garden.

Jack, a retired facilities and environmental research laboratory manager with the University of Washington Civil & Environmental Engineering department, put his energy into mechanical and structural upgrades. “I have been an avid believer in the benefits of renewable energy and efficiency for the greater part of my life,” says Jack. “I like to experiment at the house with new materials and processes toward that end. My passion is being a general handyman, inventor, and, to a lesser extent, an artist.”

Tightening the Envelope

Once the structure was secure with earthquake reinforcements, they increased insulation throughout. Infrared photos and a smoke gun revealed air leakage and areas that needed additional insulation. First, ceiling penetrations and the tops of wall cavities were sealed. After that, paper-backed fiberglass batt attic insulation (R-21) was cross-laid over an older 3 inches of blown cellulose. This was topped by R-5 foil-backed fiberglass batts for a total of R-50+. The cross-pattern of batts helps block air movement through the insulation.

External wall cavities were filled with blown-in cellulose funded partially by a rebate from Puget Sound Energy. An exterior overlay of faux antique brick siding with an inch of wood-fiber insulation backing provides another insulative layer. Because it is interlocked, it also serves as a moisture- and air-infiltration barrier.

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Comments (6)

jeh@w-link.net's picture

One MPPT feed is from the two strings of six panels panels (12 total) along the top of the roof and the second is from the single string of six panels lower on the roof. The lower string gets shaded first by the neighbors roof. That is why the lower string is on a separate input.

Oz Baeza's picture

I didn't understand how there are three strings feeding with 2 MPPT inputs.

jeh@w-link.net's picture

Sorry for the delay in responding. I thought I would be notified when questions appeared. Not the case.

One MPPT feed is from the two strings of six panels (12 total) along the top of the roof and the second is from the single string of six panels lower on the roof. The lower string gets shaded first by the neighbors roof. That is why the lower string is on a separate MPPT input.

Oz Baeza's picture

It's all clear now, thanks!

Peter Gruendeman_2's picture

Hi: What did the solar thermal DHW system cost, parts only if owner-installed, or total cost?

Also, my own program of air sealing, insulating the foundation, adding storm windows and lastly, a 200ft2 solar thermal heat system has in seven years in this house seen the annual heating bill go from 700 gallons of propane to 270 gallons. This includes a modest bit of propane for the clothes dryer and for cooking. DHW is solar. The house measures 1,680 ft2 on the main floor, single story. 270 gallons of propane is not a lot of energy for a whole year.
thanks,
Pete Gruendeman, La Crosse, Wisconsin

jeh@w-link.net's picture

Sorry for the delay in responding. I thought I would be notified when questions appeared. Not the case.

Cost of the SHW system as initially installed in 2010 was $5,880. I don't have the parts cost. There were additional cost later to add extra insulation to the storage tank for a longer hold time, upgrade to a proportional controller for better heat generation, and to have the collector removed and reinstalled when the metal roof was put on the house.

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