BAIHP Partnership with
G.W. Robinson Builder Inc.
Gainesville, FL

G.W. Robinson home in Cobblefield neighborhood.

This builder, a leading member of the BAIHP program, takes care to incorporate features and measures that enhance not only the energy and resource efficiency, but also the indoor air quality, safety, durability, and comfort, consistent with the spirit of Building America.

Cobblefield Development

G.W. Robinson committed to building the first “green homes” community, as designated by the Florida Green Building Coalition (FGBC), and to achieving Building America standards in each home built (Table below). Individual home performance testing by Florida H.E.R.O. ensures that the homes meet both program specifications. G.W. Robinson proudly refers to these programs in weekly newspaper ads. (Figure above).

Initial discussions between Florida H.E.R.O. and the builder, sales manager, project manager, and mechanical, insulation, and solar system subcontractors resulted in the original decision to include batch solar water heating and hydronic heating systems.

Florida H.E.R.O. undertook a redesign of the air distribution system for the Cobblefield homes to insure that ducts are properly sealed with mastic and that the air handler closet (or mechanical room) is sealed from the attic. Field tests showed that leaks on the return side of the air handler depressurized the mechanical rooms. When the ceiling was not properly sealed, air from the attic was introduced to the home, which diminished indoor air quality, increased summer latent loads, decreased comfort, and increased the home’s operating costs.

In response to an ongoing challenge to achieve a reasonably air tight mechanical equipment closet, a new protocol shifted installation of ductboard adjacent to the ceiling to rough-in instead of finish mechanical, which allowed maximum accessibility for the field technicians. Once the main supply and return trunk line were stubbed out, the ductboard was custom cut and installed over the ducts, then affixed to framing members with nails or screws and plastic grommets. The duct line seam between the ceiling and duct was sealed with pressure sensitive tape and mastic and perimeter seams were caulked after sheetrock installation. A flow hood CFM test on a Cobblefield model found less than a 5% deviation from the anticipated design flows.

Initially Florida H.E.R.O. recommended using hydronic heating systems for the Cobblefield Development. Since the original decision to include these systems, additional County requirements for anti-scald mixing valves and automatic air vents have added to the difficulty and precision of system installations. Larger models also required bigger water heating units which proved difficult to locate and costly. Installation irregularities and inconsistencies, despite repeated training attempts, exacerbated the situation and compromised the envelope tightness. While the hydronic system offers many benefits, Florida H.E.R.O. decided that the benefits did not justify the costs and problems associated with installing these systems in this development. Instead, a cost effective line of high efficiency (90% AFUE) condensing natural gas furnaces will replace the hydronic systems in all 17 models. This furnace style uses PVC for the exhaust flue and to deliver outside combustion air directly to the unit. This eliminates the need for high and low outside combustion air vents in the furnace closet and insures the maximum amount of system location flexibility. Changing the heating system type did not affect the model duct designs.

Reducing Home Moisture After Plumbing Leaks

Florida H.E.R.O. surveyed, performed diagnostic tests, and made recommendations to G.W. Robinson on how to prevent moisture-related problems in several water damaged homes. Two homes had significant moisture problems with one home flooded several days before it was scheduled to show in the 2002 Gainesville Fall Parade of Homes. The "flood" in this home was likely a result of a material failure in a kitchen sink supply riser. The large plumbing leak, however, did provide researchers with the opportunity to initiate and monitor the "drying out" process.

Interior, exterior, and internal ambient moisture readings enabled the monitoring of this situation with a goal of preventing mold growth. To begin the process, all carpets and cabinets were removed from the home and discarded. Two commercial dehumidifiers and several fans were installed to reduce the home's humidity. After 24 hours, moisture readings were taken at a variety of points throughout the home. Wall surface moisture readings ranged from 45% to 99%. After five days of continuous drying, no surface moisture reading exceeded 10.9% at any point in the home. The process and procedures employed seem to have been successful.

Eliminating the effects of a plumbing line leak and the resulting water damage proved more difficult in the second home where the lasting effect of the water damage was mostly odor. Based on recommendations from FSEC and Florida H.E.R.O., the home’s water heater was disconnected, all water-damaged sheetrock, wood, and insulation removed and replaced, and the water heater reconnected. Though initially this fix seemed to work, the smell eventually reappeared. Because the odor was evenly distributed through the home, further investigation determined that the odor source was most likely airborne. The air handler, distribution system, and carpeting were fogged with “May-Clean” solution, whose active ingredients include "cleaning solutions and caustic acids.” For now, this appears to have eliminated the home's odor problem. The home was sold and now is occupied, so additional data collection may be difficult.

High Bill Complaint

G.W. Robinson's sales manager expressed concern that the model center's monthly utility bills were significantly higher then they expected - more than $300 a month! To locate the source of this high electric usage, Florida H.E.R.O. arranged a site survey with the mechanical contractor and conducted a two-week temperature/humidity study. Since the home had been individually performance tested for both whole house infiltration and duct leakage rates, the detective work was fairly simple. After determining that the mechanical equipment was correctly functioning and properly charged, researchers tested the flow rate of the outside air intake with an Energy Conservatory exhaust fan flow meter. Higher than anticipated readings, led researchers to test the return air plenum temperature. With an indoor temperature of 77° and an outdoor temperature of 93°, the air temperature in the plenum measured 84°. The in-line damper was adjusted to reduce the volume of outside air introduced.

While investigating this problem, researchers also noted that sales staff continually overrode the programmable thermostat, typically after returning from lunch. Indoor temperature readings as low as 71° were recorded in the model. All findings were reported to the builder and subsequent measurements have indicated that utility bills have dropped.

Standardized HVAC Installations: Florida H.E.R.O. Duct Designs

Prior to this, the distribution system was field “designed” by the duct mechanic. Florida H.E.R.O. developed duct designs for all of the community models. To insure that mechanical design specifications are correctly interpreted by the HVAC installer, Mr. Robinson has agreed to allow the mechanical contractor to conduct a final review of all architectural CAD drawings before each house project begins. With the designer and installer in agreement on installation parameters, placing the design emphasis on performance excellence and standardization of supply and return register size, HVAC installation has proven to be more timely and the installer’s profits enhanced.

Florida Green Building Certification

Florida H.E.R.O. researcher Ken Fonorow met with University of Florida Urban Horticulture Extension Agent, Wendy Wilber, at the Cobblefield model center to survey and complete the FGBC checklist required by the green certification process. Green Features are listed in Table 13.

Fluorescent Lighting

Florida H.E.R.O. used an infrared thermometer to demonstrate to the builder the operating temperature differential between an incandescent and compact fluorescent bulb. After viewing operating temperature differentials of 75°, the builder indicated an interest in replacing as many bulbs as possible with CFL bulbs. The incandescent bulb measured 158°, while the CFL bulb measured 83°.

For More Information

• For more BAIHP Partnerships and Projects see: http://www.baihp.org/casestud/index.htm
• G.W. Robinson Builder, Inc. Website
• BA DAY: http://www.baihp.org/casestud/baday/index.htm