Cohousing and Renewable Energy: Leading the Way toward Zero-energy Homes

At Wild Sage Cohousing in Boulder, CO, “alleys” between south facing buildings allow solar access to each unit, treat rain water, and create a matrix of outdoor spaces that offer the sort of casual elective interaction that makes communities thrive. (Photo by Bryan Bowen)

This year’s National Cohousing Conference was a treasure trove of useful information for established cohousing communities and forming groups. One of the more visionary, yet practical, sessions was a presentation on renewal energy led by Mark Daugherty, energy systems consultant and chief technology officer for Great Lakes BioFuels in Madison, WI, and Bryan Bowen, a Colorado-based architect, specializing in low-impact, environment-friendly housing design. Attendees learned about some sobering trends on peak oil and global warming, along with positive steps that cohousing communities are uniquely qualified to take.

Daugherty’s portion of the session came as no surprise to anyone who has seen Al Gore’s An Inconvenient Truth. By extracting and using every available ounce of fossil fuel, we are not only creating a hazardous environment, but also are depleting the finite supply of stored solar energy represented by oil, coal and gas. Sooner or later, out of sheer necessity, we will be forced to exchange our industrial approach (extracting energy from natural and human capital, with no economic incentive to restore or renew) to a sustainable one that will require investing energy to restore and renew natural and human capital. The question is: Will we do so soon enough to avoid major dislocations, suffering and injustice?

High-consumption vs. zero-energy homes

The ever-growing “ideal” single family home is typical of the current problem, according to Daugherty. Such a home in Wisconsin, for example, uses about 10,000 kilowatt hours of electricity (primarily from coal) and 100,000 cubic feet of natural gas per year.

Besides the ever-rising consumer cost – about $2,000 per year, or $40,000 over 20 years – the environmental impact is sobering. It takes 33 acres of forest to absorb this much carbon dioxide, and that’s only the amount produced by one single family home. Other fossil pollutants such as mercury, sulfur dioxides and nitrogen dioxides also make such homes a costly environmental burden.

As the world reaches “peak oil,” conservation and efficiency measures will be necessary to create a stable demand. Even if these measures are effective, however, sustainable energy technologies will be needed to take the place of fossil fuels by the end of the century.

A major part of the solution, Daugherty maintains, is the “zero-energy home,” (ZEH) meaning one that offsets the import of fossil energy by generating and exporting an equal amount of renewable energy over a year. The creation of such a home will evolve only in logical stages, but it does indicate a trend that ultimately will drive even mainstream housing development, as energy costs continue to rise and more people are faced with the repercussions of a finite fossil energy supply. (See table.)

Naturally, the technology for getting to ZEH has different price points. For those making construction decisions, some relatively inexpensive choices costing less than $2,000 include overall site planning, designs for passive solar heating and passive cooling, and creating buildings that are solar-ready. Moderately expensive technologies ($2,000-$5,000) include efficient appliances and solar water heating. On the expensive side ($5,000-$25,000) are technologies such as solar water space heating, ground source heat pumps, solar (photovoltaic) electricity and wind turbines.

Offsetting the “sticker shock” factor is the reality that such systems are becoming more efficient and less costly as they gain wider public acceptance. While the return-on-investment for today’s systems is longer than many projects can afford, it will get shorter. For example, the cost of photovoltaic (PV) systems will start to decline significantly in three years’ time, according to Bowen. With such changes on the horizon, now is the best time for communities to plan their energy strategy.

Cohousing’s potential

Most likely it will take many years for mainstream developers and their allies in the professional design, financial and governmental worlds to apply ZEH principles to North American housing. Cohousing communities, on the other hand, are in a unique position to do so much sooner because they include a high proportion of motivated, socially conscious problem-solvers, which is exactly what’s needed to pioneer these ideas.

Perhaps the single greatest factor that makes cohousing ideal for ZEH is the fact that cohousing developments are not isolated households, but rather, deliberate, forward-thinking communities. While the time and money required to implement non-fossil energy systems is still a challenge, even for highly motivated groups, many cohousing projects are well suited to implement sustainable principles – and can do so in a manner that will influence public policy. This can be as simple as the use of shared walls, shared mechanical systems, energy-efficient design and green building techniques. Many cohousing projects already include sustainable energy as a major component of development, while others include it in their plans for the near future.

Practical steps

Bowen offered many practical steps that cohousing communities can take toward developing zero-energy homes. The first and most critical step is to design buildings and sites which emphasize conservation first and incorporate renewable energy systems to achieve net-zero energy. He suggested that cohousing projects start with simpler systems, such as solar water heating and space heating, before considering more complex systems, such as PV electrical systems.

PV systems have become far more efficient in recent years, Bowen noted. Battery-dependent PV systems often are more problematic (and expensive) than those connected to the local grid, so he recommended a simple grid-connected system using a DC-to-AC inverter. A battery system and charge controller could be added later, if desired. As PV technology becomes more efficient, and silicon suppliers catch up with the growing demand, not only will such systems drop in price, but they will become more feasible in regions with fewer direct sunlight hours.

Regional differences will dictate what systems are appropriate. For example, cloudy regions such as Seattle have made surprising progress with solar power, yet other alternatives such as ground source heat pumps might be more immediately useful, Bowen suggested. Each cohousing project’s energy plan should be designed on a case-by-case basis, according to weather patterns, site location and other variables.

Installed in 2003, a photovoltaic system at Muir Commons in Davis, CA, offsets approximately 21,500 pounds of carbon dioxide emissions each year.

One piece of encouraging news not raised directly in the session is the beginning of a public policy shift on alternative energy’s relationship to the public power grid. Washington State recently enacted legislation requiring public utilities to buy excess power from alternate sources. Colorado recently passed Amendment 37, which is rekindling public interest in PV and stimulating the industry. With rolling blackouts continuing to make the news, this trend is likely to continue – making a flexible, “on the grid” energy plan for cohousing projects more viable. It’s important to note that the shift is coming both from policy makers and growing public support, which means that individual votes have the potential to make an impact at a local and regional level.

Conclusions

Without a doubt, Americans lead the world in over-consumption of energy, with our buildings leading the way in total energy usage. As individuals, we are increasingly concerned about this, but usually are blocked by the very practical question: “What can I do? I’m only one person.” Members of cohousing communities can more effectively address these issues on a practical basis, and can apply emerging energy technologies in a manner that influences public policy. All Americans ultimately are responsible for their energy addiction, but change is more likely when their neighbors set a good example.