TechPractices: Dunrite Construction Inc., Rolling Meadows Subdivision, Dover, DE

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

Over the last couple decades, builders and homeowners alike have developed a stronger awareness of how thermal performance and energy efficiency translate to conservation of resources, increased comfort levels, and most importantly, bottom line savings on utility bills. Paul Keeley, of Dunrite Construction, has taken his small residential construction firm a couple steps beyond a simple awareness of R-values, making energy performance a cornerstone of his company. Working in partnership with Gede Insulation LLC, Dunrite uses blown cellulose insulation combined with rigorously monitored air-sealing techniques to achieve a high performance envelope. In conjunction with efficient HVAC systems and thermal pane windows, the builder estimates that his homes typically use 30% less energy for heating and cooling than average homes in the area. Moreover, Dunrite buyers receive a written warranty of this performance through the Gede "Performance Home" Program.

Details

Background, Planning and Design Considerations

Dunrite Construction is based in Elkton MD, between the upper reaches of the Chesapeake and Delaware Bays, an area of rolling farmland separating longstanding communities and newer developments, not far from recreational areas along the Delaware shore. In a typical year, Dunrite Construction builds about 20 houses, from starter models to more elaborate custom homes. In the tradition of small independent builders, Mr. Keeley oversees all phases of construction and interacts personally with his customers. In large part, traditional wood framing methods are employed, but Mr. Keeley is not averse to emerging technologies that demonstrate sound advantages. He works hard to establish long-term relationships with reliable subcontractors who share his attention to detail.

Mr. Keeley partnered with Richard Harris of Gede Insulation, LLC, in Dover, DE. to maximize the thermal performance, cost effectiveness, and comfort level of Dunrite homes. Special emphasis is placed on air-sealing, quality of insulation, and energy efficient components. Since 1996, Mr. Keeley and Mr. Harris have demonstrated this added value to customers with the Gede "Performance Home" Program. The program guarantees that monthly space conditioning costs will not exceed a specified dollar amount for two years after the sale. The space-conditioning cost for each home is impressively low, grabbing the attention of buyers, and helping to draw attention to other quality details. The program succeeds both in marketing and in actual performance. Heating/cooling costs have never exceeded the estimated figures, so no payments have ever been required.

Mr. Keeley recently completed construction of 13 homes in the Rolling Meadows subdivision of Dover, DE, a pastoral site of about 40 single-family homes on half-acre lots. The houses were traditionally styled, ranging from 1,200 s.f. ranches to 2,000 s.f. two-story models, and all of them included the "Performance Home" guarantee. The construction details that allow this program to be offered are described below.

Precast Foundation System

For home designs that include basements, Mr. Keeley has found pre-cast concrete foundation panels to be both cost effective and faster to install than block foundations. Superior Wall precast foundation panels are provided to Dunrite by Weaver Precast, Inc. of Ephrata, PA. These panels are premanufactured in a variety of standard heights, and widths up to sixteen feet. They are constructed using 2 by 8 fiber- and steel- reinforced concrete studs with polystyrene insulation and a 2-inch concrete shell. This structural design provides sufficient load-bearing capacity at less than 1/3 the weight of a typical 10-inch thick concrete wall, allowing the panels to be placed on a bed of gravel, rather than concrete footings.

Another major advantage of precast panels is the speed of assembly. Panels are placed with a crane and bolted together so that most foundations can be installed on site in less than five hours, even in adverse weather. The manufacturer estimates that most builders can save 15% over traditional basement foundation construction. Superior Wall foundation panels also offer advantages if basement finishing is planned. The polystyrene insulation incorporated into the design provides an R-5 insulation value by itself, and fiberglass batts are easily added between the reinforced studs to achieve R-28. The interior concrete stud face includes a pressure-treated wood strip for easy attachment of drywall.

Tankless Water Heaters

Mr. Keeley offers customers the choice of conventional tank, or tankless water heaters. In recent years, about 75% of his customers have been choosing the tankless option. Traditional tank water heaters hold a fixed supply of preheated hot water. Keeping this water supply hot 24 hours a day can account for up to 14% of the average home's utility bills.

Tankless heating systems allow water to be instantly warmed as it flows through a small gas or electric heating element in the supply line. Energy is only consumed during the short periods daily when hot water is actually used. Mr. Keeley uses Microtherm's Seisco electric units designed for whole-house supply. This technology is especially appreciated in homes where several family members take showers within a short period, since it provides a continuous and unlimited supply of hot water, although flow capacity may be slightly reduced. The greatest savings are achieved by working families, whose homes are unoccupied through the day, eliminating the standby losses of conventional tank heaters.

Best Practices for Air-sealing and Thermal Efficiency

The centerpiece of Dunrite's focus on energy efficiency is the care taken to insulate and airseal these homes. During the framing process, each plate and sistered stud joint is fully and carefully caulked with siliconized latex sealant. Special care is taken to thoroughly seal window and door framing, such as header joints, and between jack and king studs. By making sure no minor gaps exist between these adjoining members, air-sealing is better assured with minimal efforts. Although these simple caulking procedures are recommended as "best practices" for all residential construction, it is careful monitoring in the field by builders like Mr. Keeley that assures follow-through on each home constructed.

Tyvek® barrier wrap is used to provide a moisture barrier and second drainage plane over the exterior sheathing. Dunrite's standard windows are Andersen's dual pane Narroline® double hung.

Another area of focus is installation of ductwork. Thermoply^TM rigid ¼-inch polyiso material with a foil surface is used to form duct enclosures in cavities between studs and floor joists, with each joint carefully caulk-sealed. Where boots or fittings are used, careful attention is paid to proper attachment, taping, and sealing. Mr. Keeley states that duct blaster testing typically shows leakage rates of under 5% in Dunrite houses. Emphasis is also placed on proper calibration of furnaces and air-conditioning equipment to achieve maximum performance efficiency. York® high-efficiency equipment is used, with the buyer choosing between a gas furnace or electric heat pump. Return ducts are provided for most rooms for best air flow and system balance. The willingness of H&R Heating and A/C Inc., Mr. Keeley's HVAC subcontractor, to rigorously maintain high standards is important to their relationship, as Dunrite must rely on high quality workmanship to facilitate the Performance Home program.

Blown Cellulose Insulation

Mr. Keeley and Mr. Harris feel that another critical factor in the thermal performance of Dunrite houses is blown cellulose, an insulative material that contains up to 90% recycled paper. The remaining properties include additives for fire, infestation, and mold resistance, and for adhesion and desiccant properties. Manufacturers state that cellulose insulation in its spray-applied form is three times denser than fiberglass batt insulation, resulting in less thermal transfer and greater insulating efficiency. The density of the applied product is also a factor in its fire resistance within wall cavities. Oxygen, needed to fuel a blaze, cannot transfer through the cellulose fast enough to allow studs or other flammable materials to keep burning. Slight modifications to framing details assure that the spray cellulose can be used most effectively. For instance, where interior wall framing meet exterior wall sections, they are fastened to horizontal "ladder" spacer blocks so that the insulation can easily flow behind the interior wall stud, maintaining a consistent insulative barrier throughout the structural envelope. The spacers are affixed in pre-designated positions so that the drywall crew knows where to place fasteners.

Gede maintains several trucks and crews with specialized equipment for the application of spray cellulose. Crews begin the application by taping over outlet boxes and other areas that need to remain clear. Certain unsheathed partitions, such as the wall separating the living space from an unheated garage, need to have a netting material stapled onto the framing, to provide an adhesion surface for the insulation. 50 lb. bags of compressed cellulose material are dumped into a hopper that separates and aerates the material. Flexible tubing carries the insulation to the application site, which incorporates a misting device to moisten both the structural elements and the cellulose itself for proper adherence. The correct moisture-adhesion balance helps the cellulose retain its shape as the mist evaporates, and resist settling that might lead to the loss of long-term insulation performance. Current formulas require minimal moisture, and include dessiccants to quicken the drying process, so that drywall may be installed as soon as the insulation crew is finished. Some manufacturers perform vibration testing to assure that normal settling does not lessen the insulative value over time.

Applying the insulation under pressure helps the insulation fill the interior wall space with the efficiency of a liquid filling a void, packing insulation tightly throughout interior wall spaces, even into small fissures or gaps that might be missed when cutting batt insulation. The sprayed insulation is also densely packed around plumbing lines and electrical boxes that might otherwise be difficult to reach.

The material that oversprays onto the stud faces, floors, or adjacent surfaces is removed 10 to 20 minutes after application. A special roller device, powered by a variable-speed drill, cleans the stud surface and lightly compacts the insulation into cavities, creating a smooth, plumb surface. Excess insulation is recycled into the hopper. The standard recommended density is 1.3 lbs. of cellulose per cubic foot of wall space.

The same cellulose material is also used for attic insulation, but in an 8" layer that provides R-30. Traditionally, no misting is used for this horizontal application, as adhesion is not required. Manufacturers now recommend adding a minute amount of moisture to control the amount of dust created during installation, and later as homeowners access the attic. The builder uses blown cellulose wherever possible, but fiberglass batt insulation may be installed where construction details make it the most practical option.

The high-performance cellulose insulation system, and Mr. Keeley's attention to other air-sealing and quality details, allows Dunrite to confidently stand behind the Gede "Performance Home" program.

Gede "Performance Home" program

To accurately track heating and cooling costs, separate meters for the HVAC systems are installed in Gede Performance Homes. Prints for each layout are sent to Charles Bowles at The Energy Consortium in Doswell, VA. who establishes the maximum monthly dollar amount for heating/cooling utility bills used for each home. If the homeowner's bill for any month were to exceed this amount, Dunrite would pay the difference. As of this writing, no homeowner has ever presented a bill that exceeded the guarantee. As an example, costs for a 1,500 square foot home, with cathedral ceilings, were warranted not to exceed $51 in any month. The homeowner's largest actual bill during the two-year period was $45. Delmarva Power supplies electric service to the area at a rate of $0.08 per kilowatt hour.

Buyers at Rolling Meadows can choose between HVAC systems using gas-fired heating or an all-electric heat pump, a factor that was included in the maximum cost calculations (the selection of a heat pump typically reduced the monthly figure by several dollars). Customized postcards are provided to buyers, along with information on the warranty program. Homeowners are asked to record space-conditioning costs from their utility bills (facilitated by separate metering) on the postcards and return them to Dunrite. Although not every owner participates, the information allows Mr. Keeley keep tabs on the performance of his products long after the sales transaction has been completed.

During the marketing process, handled through local realtors, the Gede "Performance Home" program gets the attention of potential buyers, who are impressed with Mr. Keeley's willingness to stand behind his product. It can also be of value as buyers negotiate with lenders, since the cost of space conditioning is a significant factor in the long term outlays required for home ownership. Knowing this cost in advance helps potential buyers budget more effectively, and to qualify for the highest amount of financing possible.

Mr. Keeley has found the costs of providing an energy warranty program to be reasonable, given the advantages it earns. He pays an about $500 per house for the calculation and testing services required, $125 for the additional meter and wiring, and $200 in costs to Gede to administer the warranty program. Depending on the house size, the upgraded ductwork and sealing adds $300 to $400. Costs for cellulose insulation are another factor. The material is highly cost-effective for attic applications where R-30 is specified, but more expensive for the blown cellulose application for 3½" wall assemblies. Dunrite's overall costs for insulating a two-story home are about 25% more than the cost of using fiberglass batts.

Overall housing prices in this market are reasonable, with the Dunrite homes in Rolling Meadows selling for between $130,000 and $150,000. With the builder's costs shown above, and the higher costs for efficient HVAC equipment and better performing windows, the Performance Home concept added $2,500 to $4,000 to the price of each house. However, the program also created strong selling points, with buyers convinced that the long-term low maintenance costs insured by the Gede Performance Home warranty, and other quality details, fully justified the slightly higher initial price tag.

Conclusions

Dunrite Construction demonstrates that a traditional small builder, by paying attention to detail and thinking creatively, can help meet the PATH goals of increasing the energy efficiency, value, and durability of housing. But Mr. Keeley's energy warranty helps his company in other ways as well. It creates a strong internal quality control incentive as Mr. Keeley monitors the work of his subcontractors, and provides a positive selling strategy, drawing buyers who appreciate Dunrite's overall commitment to quality workmanship.

Contacts

If you have further questions about the technologies described above, try the contacts listed below:

Dunrite Construction, Inc.
546 Nottingham Road
Elkton MD 21921
410-398-5360

Andersen Windows
Andersen Corporation
100 Fourth Avenue North
Bayport MN 55003-1096
651-264-5150
www.andersenwindows.com

HVAC Equipment
York International Corp.
5005 York Drive
Norman OK 73069
877-874-7378
www.york.com

Precast Concrete Foundation Panels:
Superior Walls of America, Ltd.
937 East Earl Rd.
New Holland, PA 17557
800-452-WALL (9255)
Fax: 717-351-9263
www.superiorwalls.com

Tankless Water Heaters:
Microtherm, Inc.
Seisco
223 W. Airtex
Houston, Texas 77090
940-498-9700
www.seisco.com

Tyvek Home Wrap:
By Dupont
4417 Lancaster Pike
Wilmington DE 19805
800-448-9935
www.tyvek.com