TechPractices: EcoVillage at Ithaca, Ithaca, NY

PATH's Technologies in Practice are large scale housing projects throughout the U.S. where innovative technologies are being installed and used. Information is presented from the viewpoint of builders and remodelers who can use these examples as models for projects of their own.

Summary

As a PATH website visitor, you probably know something about sustainability, taking into account future generations when building homes today. By using an inventive arrangement of distribution systems, homes can be designed and constructed to generate low energy bills but maintain high indoor air quality. Internal home wiring systems also can economically accommodate future communication innovations such as high-speed internet and intranet.

Details

In upstate New York, a group of families got together to build an environmentally responsible community that would use advanced energy systems while keeping home prices modest. There are a total of 15 duplex houses (30 units) located close to town to reduce transportation time and costs. By including a large, extra community house with spaces all residents could use--such as woodshop, soundproof music room, and kids' playroom-- individual houses could be slightly smaller. This common house has its own climate system, featuring geothermal heat pumps with the heat exchange piping in a pond instead of the earth, and a radiant floor heating system.

The group felt it was important that each household be responsible for its own energy use. This is a common issue in multi-family housing, and the experiences of EcoVillage have important implications for shared systems in clustered housing and apartment buildings. The standard way to assess energy responsibility is to individually meter each apartment. The group realized, however, that this would negate some of the energy savings because the utility would charge each homeowner a monthly metering fee. So the designers devised a "mini-district" submetering system that would use only five metered utility connections and measure each of the 30 residents' energy use internally. Each metered connection serves a pair of small gas-fired boilers, which feed space heating and domestic hot water coils for six to eight households in each "cluster."

Since the boilers would provide for both space heating and hot water, the designers saw an opportunity to further reduce equipment costs by sizing the boilers according to peak domestic hot water demand. The homes are so efficient that, even in upstate New York, energy needed for space heating is less than that for domestic hot water. The maximum combined load of showers and space heating is 500,000 BTU per hour per boiler. By taking advantage of slow heat loss due to thick insulation, the designers specified boilers with 320,000 BTU per hour capacity, considering it rare that everyone would shower at the same time on the coldest days. An economical submeter system that measures only run time of individual residents' pipe circuit was designed and installed. The meters measure total energy use as well as the use of energy specifically for domestic hot water.

Densely-packed cellulose wall insulation, vapor barrier, and triple-glazed windows help create nearly airtight homes. Thus, indoor air quality (IAQ) is an important issue. By incorporating a fresh air intake into the return air ducts, the air distribution system provides filtered fresh air in every room, even if doors and windows are closed. In addition, placing boilers in separate, insulated sheds keeps combustion away from living spaces.

Installation/Construction

To take advantage of the rapid technological development in HVAC and communications distribution, the community opted for an "open systems concept." Pipe chases connecting houses through crawl spaces contain plumbing and heating, electrical, telephone, and cable service, and allow easy routing for future repairs and upgrades. The designer/builder considers the chases to result in cost savings by eliminating trenching. The residents had the opportunity to take advantage of the open systems concept soon after it was installed by adding an ethernet local area network and high speed Internet wiring, which they installed themselves. Some residents chose the Category Five Wiring system.

The designer/builder developed an exterior wall that uses the performance advantage of dry blown cellulose insulation under compression. Although 2 by 6 studs are used, the assembly resists heat loss almost as well as 8-inch thick walls. This is accomplished with 2 by 2 horizontal strapping along the 2 by 6 studs, which is separated by a durable vapor barrier. The cellulose is overblown through holes in the barrier to create a pillowed effect. It is held back by the strapping, which becomes a wire chase. Therefore, approximately two-thirds of the wall is insulated to 7.25 inches instead of 5.5 inches. Some air space is created between the vapor barrier and the sheetrock so wiring does not penetrate the vapor barrier. The combination of tight construction, densely-packed insulation, and triple-glazed windows also decreases sound transmission, resulting in a sense of privacy -- an important issue in clustered housing.

Benefits/Costs

In the beginning, the local bank would not consider cooperative financing because officials there were unfamiliar with it. However, with persuasion from the developer and a requirement for 20% down payment, they approved financing. At $90,000 to $170,000, these homes are slightly below the area median. Energy bills, however, are much lower than average homes in the area, making it economical to live in EcoVillage.

It is generally recognized that making households accountable for energy use results in significant savings. EcoVillage’s mini-district heating system reduces metering costs. Submetering also saves each household roughly $15 per month, up from $7 per month a few years ago due to deregulation.

Code/Regulatory

Local code considers houses of three stories or more to be multiple dwellings (which would activate fire/egress restrictions), prompting the decision to limit EcoVillage to two-story buildings. Therefore, a first floor mezzanine was provided above the kitchen to offer additional living area within two stories.

The open systems method complies with code, but the municipality would not allow the builder to run sanitary lines through the large diameter pipes in the crawlspace walls. This would have saved considerable excavation, particularly since each house is double plumbed for greywater/blackwater separation. They were, however, allowed to branch to each pair of buildings through a shared sewer connection (15 instead of 30), and to limit clean outs to one per group of buildings due to the linear site plan.

Feedback

Monitoring system performance after move-in proved instructive. For example, specifying even smaller boiler pumps and timer controls on fans would have further reduced energy consumption. The small boilers proved adequate, though there have been some complaints on cold mornings when multiple showers occur just as the heat is timed to turn on. This was resolved by resetting the timer earlier.

The domestic hot water submetering system tracking run time was thought to be adequate. It was chosen based in part on cost, but it turns out to be less than accurate, because it assumed similar setpoints among households. The problem is, households set their hot water thermostats at different temperatures. In addition, the sensors have proven to be maintenance intensive. The energy consultant plans to retrofit the community with a new set of submeter sensors that measure temperature drop as well as run time, and cost much less than conventional BTU submeters. The sensors will also enable zoning between the north and south sides of the houses -- important to making homes with high solar gain more comfortable. These sensors include software that automatically produces energy bills for each house.

In the winter, there is some warm air stratification due to convection under the 16-foot high ceilings at the mezzanines. Locating the cold air returns high at the mezzanine and low at the ground floor could have reduced temperature extremes. A big advantage of the high ceiling is the cooling stack effect it creates. Not one resident has bought an air conditioner. They keep cool with ceiling fans and window exhaust fans, with just a few very hot summer days driving them to the air conditioned "common house."

Despite high controlled ventilation rates in the houses of almost 2.5 air changes per hour, designers believe they could further improve IAQ by installing low-pressure exhaust ports in closets, under sinks, and in garbage cabinets.

The project has received a good deal of press, and has been featured on CNN, Nickelodeon, and National Public Radio. Feature articles on EcoVillage have been published in the New York Times and Popular Science. The community has been covered in numerous other publications, including American Demographics, the Washington Post, and the Wall Street Journal. It also won a Building Innovation for Homeownership award from HUD in 1996.

Contact(s)

Do you have a specific question? Try the contacts listed below:

Building Performance Contractors Association
121 Rachel Carson Way
Ithaca, NY 14850
gthomas@buildingperformance.com
607-277-6240

EcoVillage at Ithaca
607-255-8276
www.ecovillage.ithaca.ny.us