This article was originally published in the November/December 1998 issue of Home Energy Magazine. Some formatting inconsistencies may be evident in older archive content.


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Home Energy Magazine Online November/December 1998


A Technology Showcase with Southern Charm

by Jeff Tiller


Southface's annual energy costs are significantly less than those of a typical office building in the region. Southface's costs include electric vehicle recharging and are somewhat offset by an experimental photovoltaic 
electric system.
Large, south-facing, low-e windows light up the spacious living area with its thermal mass floor.
This attractive bathroom was designed for wheelchair accessibility. It has low VOC paints and a powerful exhaust fan that vents to the outside.
The Southface Energy and Environmental Resource Center demonstration home opened two years ago, just before the 1996 Summer Olympics in Atlanta. Since then more than 15,000 visitors have toured the 6,500 ft2 showcase of state-of-the art energy-efficient technologies, allowing Southface to meet one of its primary missions: educating the public about sustainable building technologies. In these last two busy years the center has also functioned as a technological classroom, a networking hub for the sustainable building technology industry, a center for the evaluation of new technologies, and a meeting facility for a variety of organizations, including utilities, private manufacturers, environmental groups, and other nonprofits. Building Features While the center's many sustainable features are awe-inspiring, most visitors at first are more impressed by the center's beauty than by its energy efficiency. Opening the front door, visitors walk into a wide entryway and pass into a large living area daylit by south-facing argon-filled, low-e windows that focus sunlight onto the thermal mass floor. Other visible features that invariably provoke comment are the toilet with two flush levels--one for liquid and one for solids--the porous exterior pavement (in particular, the ceramic floor tiles composed of 70% recycled materials from the feldspar industry); the deck floor and carpeting made from recycled plastic; the paving stones made from old concrete slab debris; the efficient side-by-side refrigerator and high-tech dishwasher; and the remote-controlled compact fluorescent lighting. Although these flashier features capture the initial attention, it's the internal features--the insulation products, the air sealing methods, and the mechanical systems--that provide most of the comfort and lie closest to the heart of Southface's mission.

Southface's construction process resembled controlled chaos at times. Yet the building opened on schedule with an amazing array of sustainable technologies, many donated by the manufacturers. (See Southface Technologies for a list of all the sustainable technologies found at Southface.) The demonstration technologies themselves have had varied success. However, in general they have worked well.

Internal Construction Features The basement insulating concrete form (ICF) system features a termite-treated foam, which we find helpful in Georgia. The R-16 ICF panels hold 8 inches of poured concrete. Before construction of the basement began, we had heard of problems others had had with blowouts during the pouring process. To avoid similar difficulties, the construction supervisor was careful to order concrete with the proper slump and to closely monitor the pour. There were two very minor blowouts, but they were an inconsequential price to pay for a continuously insulated, solid concrete wall ready for drywall on the interior and brick veneer on the exterior.

Construction of the next two floors was delayed for weeks due to problems with our original framing crew. Structural insulation panels (SIPs), were slated to be used as the construction material for the walls and roof. The walls went up easily enough, but the building's complex roof structure seemed to baffle the crew. Happily, we found and hired a local energy-efficient builder who successfully completed the roof in about a week. Because the SIP's built-in insulation ultimately reduced actual construction labor time we were able to meet our construction deadline in spite of the initial setback.

Southface staff took care of air sealing the building, using a foam gun to seal leaks, and putting up an airtight drywall gasket on the stick-framed roof section housing the integrated PV shingles. The results are impressive. The average air leakage rate in new Georgia homes is about 9 air changes per hour when measured with a blower door at 50 Pascals depressurization (ACH50). Southface has 2.3 ACH50-about one-quarter the average. For those who measure air leakage per unit of exposed surface area, the Southface building has .74 CFM50 per ft2 of surface area.

Mechanical Systems The mechanical systems had an interesting evolution. The building makes use of a variety of technologies, including a gas-fired heat pump, two ground source heat pumps, and a central dehumidification system. The gas-fired heat pump and just one of the ground source heat pumps were used initially. Together, they provided satisfactory comfort levels during the hot summer months and cool winter. It was not until the outdoor temperature dropped to around 15 °F during an unusual cold spell that the building became at all uncomfortable. After a small problem with the underground circulation loop of the second ground source pump was fixed, the building was restored to its usual state of comfort.

A few of the demonstration technologies remain under development. In the rush to complete the building before its scheduled opening, the solar electric (photovoltaic) system and the solar water heating system were installed, but not fully connected. The Uni-Solar PV shingles have been working incredibly well, cranking out the watt-hours of electricity. However, the inverter that converts the direct current produced by the solar modules to alternating current has never worked properly. Southface staff have now installed a new inverter to enable us to benefit from a supplemental off-grid source of electricity.

Southface staff finally had the time to connect the solar water heating system this summer, so there has not been much operating history. This active solar system features two solar collectors, and an indoor heat exchanger and storage tank. An antifreeze-water mixture circulates to the solar collectors and transfers the heat it picks up to potable water in the indoor heat exchanger.

Savings and Benefits The thermally efficient, airtight envelope and efficient mechanical systems have paid off with considerable savings on energy bills. Southface staff project that the heating and cooling bills are 25% to 40% lower than comparable new construction in the Atlanta area. Over the last year, Southface used 7.06 kWhrs per ft2 per year (including electric vehicle recharging) compared to a national average energy usage for office space of 16.5 kWhrs/ft2/year. Hopefully, the charts showing the center's low energy bills will continue to make the hidden energy efficiency features more visible.

A wonderful side benefit of the high-quality construction at Southface has been the control of noise pollution. The building is unusually quiet. Although we're located about one-quarter of a mile from the interstate running through downtown and about one-half of a block from another busy road, the interior of the building remains a peaceful refuge from the din of urban life.

Educating for the Future As an educational center, we know we are successful because we are not just preaching to the converted. Of the 15,000 visitors over the past two years, many have had little connection to organizations supporting energy efficiency. Southface has had visits from national affordable housing groups, local home-building associations, state legislators, condominium associations, and a wide variety of organizations conducting independent training seminars or holding private parties. Southface also opens its doors for tours to local schools. The staff's daytime hours are often enhanced by the bright faces of eager young people learning how to build a more sustainable future.

Of course, there wouldn't have been a center to tour if not for the hard work of its volunteers and the many resources donated by its sponsors. Although the various contributors to the building are too many to name, Southface has had strong support from the U.S. Department of Energy (DOE), which jump-started the project and provided funding for many of the resources in the building. Continuing support is being provided by the DOE, the Turner Foundation, and the Environmental Protection Agency.

The Southface Energy and Environmental Resource Center looks forward to many more years providing
information on sustainable building technologies to an ever widening

Southface Technologies

Insulation, Air Sealing, and Moisture Protection Technologies 

  • Basement walls built with R-16 insulated concrete forms. Walls have a membrane for waterproofing and a drainage plane made of rigid fiberglass insulation.
  • First and second floor walls built with SIPs, which include termite-treated polystyrene foam insulation.
  • Airtight drywall approach augments other air sealing steps.
  • Garden cottage built using straw bale construction.
  • Variety of insulation types in cathedral ceilings, including high-density R-30 insulation, blown-in cellulose, and SIPs.
  • Air sealed and insulated band joist.
Windows and Passive Solar Design 

  • Argon-filled, low-e windows and door glazing.
  • Passive solar design with thermal mass floor.
  • Minimal east- and west-facing windows for optimal performance during Atlanta's hot summers.
  • South- and north-facing windows provide for cross ventilation and natural daylighting. South-facing windows shaded by 2-ft overhangs and additional interior shading.
Mechanical Systems and Indoor Air Quality 

  • Safe and efficient, direct-vent, natural gas-fired fireplace.
  • Ultraquiet, energy-efficient, exhaust fans.
  • Ductwork designed using Manual D sizing techniques.
  • Geothermal and gas-fired heat pump.
  • Central dehumidification system.
  • Three-zone HVAC design.
Appliances and Lighting 
  • Multitude of innovative, energy-efficient lighting fixtures, including remote compact fluorescent dimming.
  • Efficient kitchen appliances include a side-by-side refrigerator without CFC or HCFC-based refrigerant and a dishwasher with sensors that adjust the water heating and cycle time.
Sustainable Building Materials 

  • Variety of materials made from recycled products including floor tile, carpeting, deck flooring, interior wood flooring, paving stones, and landscaping mulch.
  • Sustainable building products, including birch shelving certified to be harvested in an environmentally sustainable manner and engineered wood products.
  • Recycling center in laundry room.
  • Compost bin.
  • Termite bait and monitoring system to reduce risk of infestations.
Water-Saving Features 

  • Toilet with dual-flush trip lever (1.1-gallon and 1.6-gallon flush).
  • Horizontal axis clothes washer.
  • Xeriscaping design, minimum turf, graywater irrigation system, porous concrete that allows rain penetration, and rainwater capture into a cistern from which a PV-powered pump pushes water through drip irrigation lines.
Indoor Air Quality 

  • Formaldehyde and radon test kits. 
  • Carbon monoxide alarm.
  • Low VOC paints.
  • Natural fiber carpeting in bedroom.
  • Controlled ventilation system in building with airtight construction.
  • Electronic air cleaners and cartridge filters on HVAC systems.
  • Subslab radon mitigation system.
  • Carbon dioxide monitors.
Transportation Efficiency 

  • A home office for the telecommuter with Energy Star computer equipment.
  • Electric vehicle with electric vehicle charging station.
  • Hydrogen fuel electrolyzer to provide fuel for a hydrogen-powered vehicle.
Solar Energy Technologies

  • PV shingles with battery storage and inverter to produce household current.
  • PV-powered outdoor lighting and motion detector.
  • Solar water heating system.
  • Central control system for security, mechanical, and lighting.
  • Original shade trees saved during construction to lower cooling costs, increase comfort, and enhance building appearance.
Other Features 
  • Full wheelchair accessibility--ramp, doorways, bathroom fixtures, roll-in showers, water fountain, kitchen sink, lower kitchen cabinets.

Jeff Tiller is an associate professor at Appalachian State University in Boone, North Carolina, and is staff engineer at the Southface Energy Institute.

For more information on the Southface
Center, call (404) 872-3549. Web Site:


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