Near Net-Zero on a Community Scale: Page 2 of 3

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Half the ecovillage
Twenty-two of the 36 high-efficiency homes in the Belfast Cohousing & Ecovillage already have PV systems that provide most of their energy needs.
The other half of the ecovillage
Twenty-two of the 36 high-efficiency homes in the Belfast Cohousing & Ecovillage already have PV systems that provide most of their energy needs.
Homes are clustered, leaving much of the property as open space; wide vehicle-free pathways for walking, biking, playing, and socializing connect the houses.
Eco-village community event
Traditional folk music and arts are embraced by many in the community and create lively social gatherings.
New members are eagerly greeted by volunteers to help unload the moving truck.
Through a community effort, paths are being beautified with fruit trees.
Builders from GO Logic erect the 8.25-inch structural insulated panels that form part of the exterior wall.
Interior of SIP wall panel
Inside the SIP wall is a 2-by-4 framed wall filled with blown-in cellulose, bringing the total insulation value to R-45.
One of the ecovillage homes
All of the homes are duplexes and share a common wall, which reduces heat loss through the building envelope. While the styles and details vary slightly from building to building, each was constructed on a strong premise of energy efficiency and livability. This made achieving net-zero-energy achievable, even with relatively small solar-electric systems.
One of the ecovillage homes
All of the homes are duplexes and share a common wall, which reduces heat loss through the building envelope. While the styles and details vary slightly from building to building, each was constructed on a strong premise of energy efficiency and livability. This made achieving net-zero-energy achievable, even with relatively small solar-electric systems.
One of the ecovillage homes
All of the homes are duplexes and share a common wall, which reduces heat loss through the building envelope. While the styles and details vary slightly from building to building, each was constructed on a strong premise of energy efficiency and livability. This made achieving net-zero-energy achievable, even with relatively small solar-electric systems.
All but one of the PV systems installed on BC&E homes use Enphase microinverters, which were mounted on the racking prior to installing the PV modules.
Installing the PV array
BC&E community members and a Capital City Renewable crew member (also a BC&E member) install a 5-kilowatt PV system of Axitec 250-watt PV modules on the author’s home.
Installing the PV array
The first 11 systems at BC&E were installed by ReVision Energy, using Canadian Solar modules (see the schematic above, which reflects a typical system).
PV modules arrived in bulk
Kiril Lozanov organized the bulk PV module purchase to help keep costs down.
Half the ecovillage
The other half of the ecovillage
Eco-village community event
Interior of SIP wall panel
One of the ecovillage homes
One of the ecovillage homes
One of the ecovillage homes
Installing the PV array
Installing the PV array
PV modules arrived in bulk

Even so, Gibson estimates that a 1,500-square-foot ecovillage home (without a PV system) uses $300 for heating each year (2,000 kWh at $0.15 per kWh), while a standard Maine home costs more than $2,500 to heat, using an estimated 680 gallons of fuel oil.

What makes the homes so energy-efficient is the attention to details, like insulation and air-sealing. The outer walls are a hybrid system: blown-in cellulose in 2-by-4 framed interior walls and 8.25-inch structural insulated panels (SIPs), achieving R-45. The load-bearing portions of the slab are 12 inches thick, with 4-inch-thick floors. The concrete slab is insulated with 6 inches of EPS rigid foam, slowing heat loss to the ground, and the ceilings have 24 inches of loose-fill cellulose for R-80. The house-wrap seams were taped to complete an air barrier, significantly reducing heat loss due to infiltration.

The triple-glazed wood-aluminum Unilux windows have an SHGC of 0.5 and a U-factor of 0.09. The R-7 windows and doors help keep the homes virtually airtight, and promote ventilation and summer comfort when open. The windows can swing inward on two hinges or be hinged on the bottom to tilt inward, opening at the top. The latter offers draft-free ventilation and prevents rain from entering the home.

PV-Ready

Despite being clustered, the ecovillage houses shade each other very little, and only in the early morning and late afternoon. All of the homes are oriented either due south or within 30° of south, making them well-suited for PV and solar water heating systems.

Most of the homes have enough roof space for a grid-tied PV system large enough to offset the home’s electricity using net billing. Some roofs also have room for a couple of solar collectors for water heating. The roof pitches vary—30° on the smaller units and 40° or 45° on the larger units. These angles are well-suited for year-round PV system performance and ease of winter snow removal. All of the homes are PV-system ready, with a junction box on the roof, concealed conduit running from the roof to the load center, and dedicated breakers in the electrical panel. To date, 22 of the 36 ecovillage homes have PV systems installed. One home also has a solar water heating system.

“It was nice to work on a project where there are a large number of folks who are interested in solar power,” says John Luft of ReVision Energy, which installed the first 11 systems. Homebuyers were given the option of a PV system as part of the homes’ feature selection process, and the option of including the system cost in the mortgage. GO Logic provided estimates of energy usage and a variety of solar options drafted by ReVision Energy that were customized to each home based on house size and number of occupants.

In the summer of 2014, residents organized a collective purchase for 11 additional PV systems, which were installed by Capital City Renewables (CCR). To receive wholesale rates on the PV modules and components, all of these systems used Axitec 250-watt PV modules with Enphase microinverters. The systems range in size from 2 to 5 kilowatts. Two BC&E members were trained and helped install the systems with the CCR crew.

With so many PV systems, Central Maine Power was concerned that the transformers couldn’t handle the back-feed, and the utility required BC&E to commission a study. It was determined that numerous PV systems could be supported without upgrading the transformers, although CMP imposed a limit—no more than 150 kW of PV capacity. There was also concern about the “resiliency” of BC&E’s all-electric homes when the utility grid goes down, considering that all the PV systems are grid-tied without battery backup. But so far, residents have—literally—weathered the winter storms with relative ease. Even without mechanical heating during a winter snowstorm and several-day utility outage, indoor temperatures remained relatively constant.

The ecovillage homes are all electric, in part because the 36 units are clustered on 6 acres of a 42-acre site. “There were a lot of discussions of whether or not to have wood heaters,” says Alan Gibson, a principal for GO Logic. Because of air-quality issues and the heating loads of the buildings being so low, it made sense to install inexpensive electric-resistance baseboard heat.

Gibson estimates that using electric baseboards in every room, controlled by individual thermostats, instead of a conventional oil-fired forced-air central furnace, saved $15,000 in each 1,500-square-foot home, although other energy-saving techniques—such as the heat-recovery system ($3,000; see “Heat-Recovery Ventilation” sidebar); increased insulation ($17,000); and triple-pane windows and doors ($8,000)—added to the construction costs.

The mission of the ecovillage includes sustainability, so solar energy was part of the initial vision as a major source of energy for the community. “We didn’t want to truck in deliveries of fossil fuels, so oil and propane were out,” says Gibson. “If you can afford a PV system to meet all of your annual electricity needs, [electric heat in a super-efficient house] can be a greener alternative.”

Comments (2)

Sarah Lozanova's picture

That's a great question David. We joined Belfast Ecovillage during the development phase, after a core group was established. The community resonated with us because the mission is in line with our values. We visited or met with several communities, both established and forming, and this one seemed to be the best fit for us. I was more interested in joining an established community because it can often take 5 years or more to form an intentional community.

Conflict is inevitable, but I think what is more important is if it can be worked through productively. Belfast Ecovillage is experimenting with the use of dynamic governance, with distributed leadership. This is helping to reduce the time spent in general meetings, while striving to make create more productive meetings.

Before joining Belfast Ecovillage, I read a couple books on intentional communities. I recommend:

Creating a Life Together: Practical Tools to Grow Ecovillages and Intentional Communities by Diana Leafe Christian and Patch Adams

Finding Community: How to Join an Ecovillage or Intentional Community by Diana Leafe Christian

Visiting communities is a great way to get started. IC.org has a directory of forming and existing communities. You can also advertise that you are forming a community, to help attract potential members.

All the best in your endeavor!

david congour's picture

Thanks for the great article on your community, I wish you all success!

I'm starting to think about starting an ecovillage in Colorado, and was wondering how you managed to get together a group of people that would be compatible, and also, how you manage to resolve the inevitable conflicts/disagreements that arise in a community?

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