Green, Greener, Greenest: Page 2 of 3

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Active and passive solar
Active and passive solar pair up to offset this home’s energy needs.
House’s narrow footprint
The house’s narrow footprint makes the best use of the small lot.
South-facing windows
Well-placed windows on a south wall let in sunlight for warmth. Honeycombed shades slow heat loss through the windows at night.
Energy Star appliances
Energy Star appliances are part of the whole-house approach to efficiency.
Custom-cut structural insulated panels
Custom-cut structural insulated panels go up fast, and insulate well with little air leakage or thermal bridging.
SIP wall provides room for additional insulation
A nonloadbearing 2-by-4 wall inside the SIP wall provides room for additional insulation.
SIP roof is placed by crane
The 12-inch-thick SIP roof is placed by crane.
Efficient washer and dryer
An efficient washer and dryer help save water and energy.
Drying rack
Linda and Brad routinely use the drying rack for even greater energy savings.
Space-saving fold-down desks
Space-saving is part of energy savings. Linda and Brad have matching fold-down desks in one bedroom, which also functions as an office.
T8 fixtures
LEDs are used throughout the house, including in these T8 fixtures in the utility spaces.
Thermal blinds
Even the most efficient windows lose heat. Thermal blinds help keep it in.
A minisplit heat pump
A minisplit heat pump that helps heat and cool the home with minimal energy input. (Outdoor part shown).
A minisplit heat pump
A minisplit heat pump that helps heat and cool the home with minimal energy input. (Indoor part shown)
Wall-mounted minisplit air handler
The wall-mounted minisplit air handler in the guest bedroom is unobtrusive.
Aurora solar thermal collectors
Two 4- by 8-foot Aurora solar thermal collectors provide as much as 85% of the homeowners’ hot water needs.
Solar hot water components
Peeking up into the thermal closet at the expansion tank, drainback tank, and Grundfos circulator pump.
A single-tank drainback system
A single-tank drainback system is ideal for small spaces. This utility closet was sized specifically for the system.
PV array
Part of the 12 kW PV array.
PV AC disconnect
At ground level, the PV AC disconnect is the only evidence of the system.
utility kWh meter
The well-labeled utility kWh meter.
Low-flow fixture
Water conservation is a key design element: Low-flow fixtures reduce usage. A greywater system distributes the used water in the landscape.
Underground 11,000-gallon rainwater cistern
Perforated black poly pipe is the inner supporting structure for an underground 11,000-gallon rainwater cistern.
Gutters feed directly into the cistern
Gutters feed directly into the cistern.
The garden sits above the rainwater storage tank
The garden is planted in topsoil that sits above the rainwater storage tank.
Linda and Brad
Linda and Brad cozy up in their high-performance home.
Active and passive solar
House’s narrow footprint
South-facing windows
Energy Star appliances
Custom-cut structural insulated panels
SIP wall provides room for additional insulation
SIP roof is placed by crane
Efficient washer and dryer
Drying rack
Space-saving fold-down desks
T8 fixtures
Thermal blinds
A minisplit heat pump
A minisplit heat pump
Wall-mounted minisplit air handler
Aurora solar thermal collectors
Solar hot water components
A single-tank drainback system
PV array
PV AC disconnect
utility kWh meter
Low-flow fixture
Underground 11,000-gallon rainwater cistern
Gutters feed directly into the cistern
The garden sits above the rainwater storage tank
Linda and Brad

Brad and Linda selected level three—the “greenest” option, which is closer to Passive House standards or for clients who are contemplating a net-zero annual energy use home. This design uses an insulated nonbearing stud wall constructed with 2 by 4s along with an 8.25-inch SIP, resulting in a 12-inch-thick wall. Separated from and on the interior side of a SIP, this construction method eliminates almost all thermal bridging. The space created by the inner wall provided easy access for plumbing and wiring runs. After the mechanicals were installed, it was packed with cellulose insulation. We used a 12-inch SIP roof and placed the structure on an insulated slab with R-20 around and under the slab, which was double the code requirement.

When building with R-48 walls, it is always disappointing to install R-2 or even R-3 windows, since that draws down the envelope’s overall thermal performance. Brad and Linda specified Andersen E-Series/Eagle double-hung, double-pane, low-e windows with R-values ranging from 3.33 to 3.7. We “tuned” the windows for passive solar gain, specifying a higher solar heat gain coefficient (SHGC = 0.39 to 0.44) for the south-facing glazing.

Conservation + Solar Solutions

It is great when clients come to the table knowing they want to use the sun to help maintain the thermal comfort of their home. We often have clients who say they want to design a passive solar home, but then prioritize orienting the home for the view rather than solar access. For this project, Brad and Linda had actively sought out a property that was in alignment with their solar goals.

It is fairly easy to get sunlight and solar gain into a building; the challenge is to keep it in the building once the sun sets. This is where the structure’s insulation and thermal mass (in this home’s case, a concrete slab floor) come into play. Another vital element of a passive solar structure is involving the occupants in the home’s management. In the winter, this might include closing thermal shades at night and opening them in the morning. In the summer, it might be opening windows at night and shutting them in the morning.

Beyond passive solar, this home’s narrow, long design made daylighting much easier to accomplish. To minimize the energy used for artificial lighting, Brad and Linda installed LED bulbs in almost every fixture.

An efficient, well-insulated envelope is much easier to heat and cool, requiring minimal energy inputs. When supplemental heating or cooling is required, Brad and Linda rely on a small minisplit heat pump. Because they are ductless, minisplits avoid the energy losses inherent in conventional ducted central heating systems. And because each interior unit has its own thermostat, homeowners can choose to heat or cool only when rooms are occupied.

Solar Hot Water

Brad and Linda were interested in using the sun’s energy as much as possible, and turned to active solar systems once they had maximized its passive aspects. They had met solar water heating (SWH) system installer Luke Frazer on a solar home tour and had decided, early on, that they wanted an SWH system for their home. With the relatively mild climate in Ashland, Frazer specified a drainback system for the couple. It was sized for an “average” household and designed for the amount of space available for the equipment. Because the system was planned before the home’s construction, Frazer was able to work closely with the contractors to keep pipe runs short and properly sloped. He also worked closely with their photovoltaic (PV) installer, coordinating the placement of the collectors with the rooftop PV array.

Comments (2)

DawnLarisa's picture

We have magnesium anode in our solar heater. Corrosion inhibitor decreases the corrosion rate and protects the metal tank.

Marc Fontana's picture

The article mentions that the Solar Water Heating system uses water with a corrosion inhibitor as the heat transfer fluid. What is this corrosion inhibitor? How frequently does the fluid need to be changed?

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