TechPractices: Baycliffs, Johnson's Island, Lake Erie, OH

TechPractices are outstanding housing projects throughout the U.S. where innovative technologies are implemented. Builders and remodelers can use these examples as models for projects of their own.

Summary

Talk about environmental limitations. Picture an island joined to Lake Erie's mainland by only a narrow causeway. There's no gas or oil service, and with only a small, volunteer fire department on the mainland, propane or natural gas delivery is a fire risk. There's a power line under the bay, so geothermal heat pumps are possible, but electric rates are the highest in the state and there's solid limestone just below the soil. How can you keep homes comfortable and economical when the thermometer can plunge to -10° F in the winter and soar to100° F in the summer? The developer of the planned 375-unit development solves the problem using a steel/rigid insulation panelized system with airtight, superinsulated walls, conditioned by a highly efficient geothermal heat pump drilled into rock.

Details

Baycliffs is being developed on over 140 acres of 285-acre Johnson's Island (the site of a Civil War prison built for confederate officers) in Sandusky Bay, Lake Erie. Of the 375 units planned, 175 will be detached single family homes and 200 will be condos. There are seven models to choose from, but the builder will accommodate changes as minor as offsetting partitions to complete customization. As of September 1999, four homes were built and two were under construction, with contracts signed for several more. According to Roberta Intihar of David Allen Builders (DAB) of Strongsville, OH, the keys to making Baycliffs possible are the exterior envelope by Techbuilt Systems, Inc. which uses light gauge steel framing, geothermal heat pumps and a radiant heat floor system. The techbuilt system is used for both exterior walls and roofs, and provides both structure and insulation. To minimize deflection, however, DAB uses gluelam ridge beams and purlins to support the roof.

The Techbuilt wall system includes a galvanized steel-tube stud frame screwed to upper and lower tracks, with 7.25 inches expanded polystyrene (EPS) rigid insulation in the walls and 12 inches in the roofs. To minimize thermal bridging (heat flow through the steel), studs and tracks are laid out in pairs. The opposed outer and inner studs are separated by 5.25 inches of EPS. A small amount of thermal bridging may occur through long screws holding the studs together. Studs (and rafters) are 1 inch by 2 inches, 18-gauge tubes 24 inches on center. The bond that is formed between the steel frame and the EPS is usually strong enough to withstand loads without sheathing, unless walls are to support stonework or exceed 30 feet in height. Rough window and door openings are cut and wood headers are installed in the fabrication plant, where the finished panels are marked for ease of assembly.

DAB chose a geothermal heat pump/radiant floor combination to condition the homes of Baycliffs. Each 100 foot deep well accommodates about a ton of heat exchange, drawing on a below-grade temperature of 57° F year-round. An added advantage of the geothermal system is virtually free domestic hot water year-round. Waste heat from the compressor is coiled to the domestic hot water tank. During unusually high hot-water demand, the backup electric water-heating element kicks in to keep the tank hot. The water heater also has space-heating capability. One-inch, flexible aluminum pipe with copolymer elastic coating is buried in the slab, heated by a domestic hot water loop from the tank to create the radiant floor system. The geothermal loop supports forced air heating, domestic hot water, and radiant floor simultaneously.

The mainland county of Ottawa plans to extend municipal water supply to the island by 2001, but for now, much of the drinking water is trucked in to fill cisterns. (As on many islands, fresh water is not abundant, particularly since limestone is not the most permeable substance.) Some of the drinking water comes from wells, so any chemicals, such as herbicides, used on Johnson's Island must be certified by the Environmental Protection Agency so as not to pollute the water supply. The development employs xeriscaping, a technique involving native vegetation that is adapted to the amount of rainfall in the region, so it doesn't need watering. The typical hardiness of xeriscaping also works to the advantage of the EPA regulations, since native plants typically don't require strong insecticides.

Installation/Construction

Since it is not cost effective to excavate limestone, the homes are built with frost protected shallow foundations supporting a slab-on-ground (this created the opportunity for the radiant floor). Once the slab is in place, panels are delivered by truck, ready to erect with a crane. Although the walls are light enough to tilt up, the roofs and beams are too bulky to place by hand. Techbuilt has its own panel erection company or can instruct a builder.

Once the panels are erected, the structure is inspected from inside. Any gaps are plugged with spray foam to reduce air infiltration. Techbuilt also recommends a building wrap for its energy-sealing value and ability to shed water behind vinyl siding. Siding can be fastened directly to the steel frame with self-tapping screws, although Techbuilt uses a fastener gun such as Paslode to drive high-pullout nails. Millennium vinyl siding by Wolverine is used, which features a "flexible hem" to enable tight installation with less rippling. Wiring is routed through built-in chases. Contractors use a "hot wire" device to slice out blocks of EPS to chase wiring up to switch boxes as needed. Although the finished nature of the panels limits the extent of construction changes, windows can usually be added or subtracted from the panels without a large upcharge. Since this can cause delays, Roberta Intihar of David Allen Builders likes to "spend time going over prints with customers."

Drilling into solid limestone is difficult, so Intihar first considered using the nearby lake for a water-to-air heat pump. However, the water was not deep enough to provide for an unobstructed piping loop. Fortunately, they found a local driller who specializes in geothermal wells. Unlike soil, consolidated stone does not tend to fill the space between the geothermal piping and the inner well surface. This gap must be packed for an efficient exchange of heat. So the installer injects bentonite, a naturally-occurring, expansive material, into each well, where it expands to fill the space.

Benefits/Costs

According to DAB, an alternate version of the $167,000 homes can be built for $95,000, or $53/sf hard costs, by omitting options and high end materials. (Baycliff homes often include features such as granite countertops, and ceramic tile.) Although materials for a Techbuilt exterior cost more than those for a wood frame house, construction is faster and HVAC can be downsized due to the tight, superinsulated envelope. The panels are typically delivered within 30 days of contract signing, and erection takes less than a week for most homes. The steel-framed panels do not support rot or termites, and have a higher ignition point than wood in a fire. The panelized system reduces onsite waste, since there is no excess insulation or scraps from cut framing members.

A further benefit of the Techbuilt system is wind resistance. With closely-spaced screws tying the roof to the wall to the slab, the exterior acts as a continuous skeleton. The system was used for condominiums on the mainland shore 30 miles from Baycliffs. In 1998 a tornado hit the condos without inflicting significant damage, although adjacent wood frame houses were destroyed. The Techbuilt system has been tested to withstand 130 mph winds.

Drilling for the geothermal loop is expensive, about $10/ft, nearly double the cost of soil drilling. However, DAB estimates that homeowners will save 50% on their electric bills due to the combination of tight walls and the geothermal system. As a result of testing the first two homes, each 1,650-sf unit will not exceed $130/yr in heating costs. DAB says envelope sealing on current homes will yield even lower bills. Homes have been blower door tested at less than 0.3 air changes per hour -- so tight they require mechanical ventilation to meet ASHRAE recommendations for indoor air quality. An air-to-air exchanger, or heat recovery ventilator, is timed to keep ventilation at a constant level, but residents can override the timer for extra fresh air.

Code/Regulatory

The Techbuilt system is approved by model building codes, and can be used for both detached and attached housing in most areas. For the condos, DAB wanted to maximize the energy and cost benefits of the panels by incorporating them into multiple dwellings. However, the existing "residential development" zoning rigidly divided the land into a grid of evenly-spaced, single-family homesites. So DAB took the township to court, which ruled that planned unit development is permissible, mandating township zoning to allow clustered housing and more traditional site planning. DAB then planned a "triplex" condo arrangemen -- large Victorian houses that fit the historical context, but containing three dwelling units. DAB then revised the condo plan to include a combination of triplexes and clusters with cul-de-sacs to preserve plenty of open space around them.

Feedback

The two prototype homes won the 1997 Governor's Award for Energy Efficiency in Ohio, and are rated by the Home Energy Rating System for ENERGY STAR Homes' highest label. According to DAB, they attracted "an unending parade" of curiosity while they were being built, with the older crowd in particular asking many questions. Their subsequent success has most residents regarding the home system as a good value.

The Techbuilt system makes for a very quiet home. This may be a disadvantage. When one of the homeowners first installed a burglar detection system, he did not correctly disarm it before going out. The siren blasted for hours before he, or his neighbors, suspected anything. If you install an alarm in a Techbuilt home, make sure it has external speakers.

Contact(s)

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

Energy Star Homes Program
US Environmental Protection Agency
401 'M' St., SW
Washington, D.C. 20460
888-STAR-YES
www.epa.gov/energystar.html

Office of Ground Water and Drinking Water
US Environmental Protection Agency
26 West Martin Luther King Drive
Cincinnati OH 45268-1072
(513) 569-7562
www.epa.gov/ogwdw/protect.html

Paslode
888 Forest Edge Dr.
Vernon Hills IL 60061
800-682-3428
www.paslode.com

David Allen Builders
Sandusky OH
440-572-0214
robertaatdab@msn.com

Techbuilt
941 Clark Avenue
Cleveland OH 44113
216-621-4340
www.techbuilt.com

Wolverine Siding Systems
750 East Swedesford Road
P.O. Box 860
Valley Forge PA 19482
888-838-8100
www.vinylsiding.com