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TechPractices: 21st Century Townhomes, Bowie, MD


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.

21st Century Townhouses Snapshot
Location: Upper Marlboro, Maryland
Builder: NAHB Research Center
Project Scope: 4 Townhomes
Price: $180,000+
Financing: Market
Innovations: Energy Efficiency and Alternatives to Lumber


Photo of the four 21st Century Townhouses in Bowie, Maryland

In 1996 the NAHB Research Center, Inc. built four 21st Century Townhouses to test, demonstrate, gain experience, and disseminate information about innovative home building products, systems, and technologies. The objectives of the project were to demonstrate energy efficient construction using alternatives to lumber.

Through a competitive process, sponsors from the private sector were selected to donate products and services to meet the project goals. Many also contributed funds to help cover construction costs. Other companies and public organizations donated products, services, or funds to help build the 21st Century Townhouses.

Through research, demonstration, and evaluation, the NAHB Research Center, Inc. is trying to help move promising new technologies into mainstream construction, and to help home buyers get the highest quality and greatest value available.


Each of the four townhouses featured different foundation and structural systems, energy-efficiency features, and lumber alternatives. The systems and technologies incorporated into each of the homes are summarized in the following table.

System House #1 House #2 House #3 House #4
Foundation Insulated concrete form basement with uninsulated slab floor Insulated concrete form basement with uninsulated slab floor Insulated concrete form basement with uninsulated slab floor Pre-cast concrete foundation
Structural System Structural insulated panels (SIPs) containing 3.5 inch EPS (walls) and 7.5 inch EPS (roof) Insulated concrete form walls. Blown-in fiberglass roof insulation. Light gauge steel framing with spray-in foam insulation. Lightweight autoclaved aerated concrete block (R-10). Blown-in fiberglass roof insulation.
Attic/Roof Structural insulated panels. Standing seam steel roof with high recycled content. Raised-heel wood roof truss. Standing seam steel roof with high recycled content. Steel-framed raised-heel roof truss. Standing seam steel roof with high recycled content. Wood-framed, raised-heel truss. Standing seam steel roof with high recycled content.

Solar electric roofing material covers part of roof.

Exterior Finish Exterior insulation and finish system (EIFS) Exterior insulation and finish system (EIFS) Exterior insulation and finish system (EIFS) Fiber-reinforced concrete stucco.
HVAC Gas engine heat pump Gas furnace that also produces hot water. High efficiency air conditioner. Ground source heat pump for heating, cooling, and domestic hot water. Gas furnace that also produces hot water. High efficiency air conditioner.
Other Engineered wood I-beams, low-e glazed argon filled windows, insulated steel door. Drainwater heat recovery system. OSB sheathing, argon-filled low-e windows, insulated steel door. OSB sheathing, foam-core steel door, argon-filled low-e windows, insulated steel door Engineered wood I-beams, insulated doors, low-e glazed argon filled windows, insulated steel door.


The townhouses in the framing phase of construction
Contractors install a standing seam steel roof with high recycled content

The evaluation of construction was not intended to be quantitative. Qualitative information was gathered on "Buildability" with respect to the large number of new and innovative materials and systems incorporated into these homes. During construction, materials and systems were evaluated on the basis of technical performance, capability of the average contractor to install, and infrastructure for the adoption of the technology such as availability of technical information and code. A report detailing the construction of the townhouses is available from the NAHB Research Center, Inc.


The construction of the 21st Century Townhouses provided a lab for the evaluation and collection of valuable information on many innovative products and systems. The project confirmed that a large variety of innovative systems could be successfully integrated to produce quality homes. Construction costs for this demonstration project were not documented due to the large amount of donated products and services.


Compared to conventional construction, far less information was available for the innovative structural systems used in the townhouses. There were substantial delays in obtaining permits for the homes due to the lack of supporting data on the many new technologies used in the project. The lack of data was most pronounced in the area of fire protection. Compliance documents were developed by the NAHB Research Center, manufacturers and the local fire department to satisfy the regulatory requirements. A major challenge facing the manufacturers and suppliers of innovative materials is the development of sufficient information and data to support the widespread use of their products.


Energy performance of each townhouse was modeled for and monitored during the heating and cooling seasons. Simulated energy use for each home exceeded Model Energy Code simulated energy use by between 22 and 58 percent. Actual energy use for the monitored year (homes were unoccupied) closely matched simulated use. Focus groups were conducted for the sponsors to provide a qualitative assessment of the technologies. After the townhouses are open to the public for a one- to two-year period, they will be placed on the market and sold. The selling of the homes is the final, and perhaps the most important test that innovative products face, that of consumer acceptance.


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

NAHB Research Center, EVHA Coordinator
400 Prince George's Boulevard
Upper Marlboro, MD 20774-8731

American Iron and Steel Institute
1101 17th Street, NW, #1300
Washington, DC 20036

Armstrong World Industries
P.O. Box 3001
Lancaster, PA 17604

Benjamin Moore and Company
51 Chestnut Ridge Road
Montvale, NJ 07645-1862

Hearth, Patio & Barbecue Association
North Kent Street, #1001
Arlington, VA 22209

5805 Whittle Rd, Suite 110
Mississauga, Ontario
Canada L4Z 2J1

Maryland Energy Administration
45 Calvert Street
Annapolis, MD 21401

U.S Head Office
1 North Dale Mabry, Suite 950
Tampa, Florida 33609

National Ready Mixed Concrete Association
900 Spring Street
Silver Spring, MD 20910

Portland Cement Association
5420 Old Orchard Road
Skokie, IL 60077
708-966-6200 x348

Superior Walls
937 East Earl Rd.
New Holland PA 17557

Therma-Stor Products
1919 South Stoughton Road
P.O. Box 8050
Madison, WI 53708

iLevel by Weyerhaeuser (formerly TrusJoist)
33663 Weyerhaeuser Way South
Federal Way, WA 98003

United States Gypsum Company
125 South Franklin Street
P.O. Box 806278
Chicago, IL 60606

U.S. Department of Energy
1000 Independence Ave. SW
Washington, DC 20585

U.S. Environmental Protection Agency
Ariel Rios Building
1200 Pennsylvania Avenue, N.W.
Washington, DC 20460

U.S. Department of Housing and Urban Development
415 7th Street SW
Washington, DC 20410