In partnership with the Florida Solar Energy Center (FSEC), two manufactured homes were located on North Carolina A&T State University’s campus in Greensboro, NC and used in a side-by-side energy consumption comparison. One of the homes was built to the basic HUD code standard and the other was constructed with features expected to produce a home that was 50% more energy efficient. FSEC and NCATSU began monitoring energy performance in both homes. In addition, the performance of each unit was evaluated using a DOE2 based computer energy analysis program developed by FSEC. A comparison of the performance of the units shows a measured energy savings in the more energy efficient unit of 52% for the Heating, cooling, and DHW energy use. This compares well with the energy savings predicted by the FSEC Energy Gauge program of 57%, even when accounting for the warmer than usual winter experienced during the testing period. 1.0 INTRODUCTION As part of a project funded by the North Carolina Department of Administration Energy Division, and as Part of the US Dept of Energy’s Building America Program, researchers in the Center for Energy Research and Technology (CERT) at North Carolina A & T State University evaluated technologies to improve the energy efficiency of manufactured housing. The partnership effort described by this report required CERT researchers to monitor the energy use of two side-by-side manufactured housing units on the campus of North Carolina A & T State University in cooperation with the Florida Solar Energy Center (FSEC). One of the units monitored was designed and built to basic HUD code requirements [HUD, 1999] and the other was designed to use at least 50% less energy (Building America compliant). As part of this study, both units were also analyzed using the FSEC developed ENERGY GAUGE software program. This program predicts building energy consumption using the DOE 2 analysis engine with a user friendly front end that develops DOE2 input files and models that are more appropriate for residential building systems. In addition, in this second year, modifications were made to the solar hot water heating system in the energy efficient housing unit to help improve the performance of this system. Further, a number of the incandescent light bulbs in the energy unit were replaced with compact fluorescent bulbs. These changes were staged to allow an evaluation of the effect each of these measures had on the energy use in the homes. The following report summarizes the results of the second year of the effort described above (the first years results were previously reported) [McGinley, 2002]. 2.0 STANDARD (HUD CODE) AND ENERGY (ENERGY EFFICIENT) MANUFACTURED HOME DESCRIPTION Each of the two manufactured homes used in this study have 1,528 ft of living area, 3 bedrooms and 2 baths. Each of the two housing units had identical floor plans. The homes were oriented on the site with the front facing east. Both houses were furnished. Exterior finishes were of medium color, with dark roofs. See Figures 1 through 3. Each home unoccupied; however incandescent lights on timers were used to simulate occupancy loading. One of the homes was constructed using conventional HUD code provisions and the other was designed to be 50% more energy efficient. Construction differences between the two homes are listed in Table 1. The Standard housing unit used a perimeter ducting system, while the Energy housing unit used a central trunk line. The higher thermal resistance of the energy home building envelope allows this more efficient central distribution system and a reduction in compressor tonnage, which reduces initial costs and duct losses. See Figures 1 and 2. It should be noted that the Energy housing unit incorporated the use of a solar hot water heater, with a 66-gallon hot water tank, while the “Standard” home used an electric hot water heater with a 40gallon tank Table 1 Summary of Construction of the Two Homes *(Note that the Energy House values for Duct Leakage and House leakage were based on retests done after August 2001 repairs) NCATSU Side-by-Side Study of HUD Code Homes Specifications of Standard and Energy Construction Characteristic Standard Home Energy Home Floor Insulation R-11 R-22 Wall Insulation R-11 R-13 Ceiling Insulation R-20 R-33 roof deck radiant barrier Windows Single Pane with Interior Storm Windows Low-E Thermopane Windows Exterior Doors Storm Door on Front door only Storm Door on All doors Marriage Wall Seal Fiberglass Pad SOF-Seal Gasket Heating System Electric Resistance Furnace Heat Pump HSPF7.5 Cooling System Central Air Conditioning SEER10 3 ton Central Heat Pump SEER12 2.0 ton Water Heater Electric Water Heater 40 gallon capacity Solar Water Heater – 66 gallon capacity Duct Joints Industry Standard Sealed with Mastic Duct System Perimeter Duct System Main Trunk Line House Leakage ACH50 = 10 ACH50 = 9 Figure 1 Floor Plan and HVAC layout for the Base HUD Code (Standard) Housing Unit (Courtesy of Palm Harbor Homes) Figure 2 Floor Plan and HVAC Layout for the Energy Efficient (ENERGY) Housing Unit (Courtesy of Palm Harbor Homes) 3.0 MONITORING PROGRAM A computerized data logging system was used in each house to monitor: 1. The interior temperature and relative humidity. 2. The power consumption of the whole house. 3. The power consumption of the air conditioning/heat pump compressor. 4. The power consumption of the air handler fan. 5. The power consumption of the electric resistance heat (primary heating in the standard house, secondary heating for the energy house). 6. The power consumption of water heater and electric water tank coil. 7. The exterior temperature and relative humidity, solar radiation (both parallel and at the solar panel angle), and wind speed. The data-loggers were connected to FSEC’s mainframe computer via modem, and downloaded automatically. Data were sampled at 6 second intervals and recorded in hourly intervals. All appliances in the home were unplugged except for the hot water heater, HVAC system and some incandescent lights. There were also a few miscellaneous devices such as the data logger, phones, and controls that show as a minor electrical load. The incandescent lights were used to simulate an occupancy load of 1.5 persons and were run on the following schedule; 500 watts of lights were on 24 hours a day 7 days a week, 500 watts of lights are switched on by timers from 4 pm to 12 pm, 200 watts of lights are switched on by timers from 6 am to 9 am. In addition, on weekdays, there were two hot water draws of 40 gallons each, one in the morning and one in the late afternoon for each of the houses. This water draw was used to simulate an average weekly water use of a typical residence. A comparison of the performance of the units over the period from January 2001 to March 2002 was made and reported in the first year report. This report summarized the initial poor performance of the Energy housing unit that resulted from an excessively high air-handler fan speed that significantly reduced the efficiency of the system, a very large duct leak resulting from an improperly set Y-connection coming off the main supply duct trunk line, a supply duct collar failure and a poorly sealed opening around the refrigerant line and drain between the return and supply side of the coil plenum creating a return air bypass around the coil. These items were repaired by September 2001 and “good” data were obtained from September 1, 2001 to August 16, 2002. Both homes were on cooling only mode from September 1, 2001 through October 26, 2001 at 7:00 pm. After this time, both homes were on heating only mode until, April 16, 2002 at 2:40 pm, where they were switched over to cooling only mode again until October, 2002. It should be noted that one of the critical findings of the first year of the investigation indicated that current manufactured home set up procedures may not be adequate to ensure predicted performance of the energy efficient home units. As a result, Palm Harbor, one of the industry partners in this investigation, has instituted steps to improve installation/setup procedures. It was also found that the standby losses in the solar hot water heater in the Energy Unit were significant and on long idle periods were sufficient to make the overall efficiency of the solar hot water heater less than the standard electric unit. To help alleviate these stand-by losses, the solar water tank piping insulation was upgraded on March 6, 2002 and its effect on the water system performance was evaluated. The solar hot water tank had a significant amount of copper and plastic tubing exposed in the original installation configuration. Additional pipe insulation was applied to all accessible pipe surfaces and the effects of this upgrade was evaluated. On May 1, 2002, in an effort to further improve the performance of the solar hot water heater, the solar hot water tank in the energy unit was wrapped with a R5 foil bubble wrap insulating blanket over the sides and most of the top of the tank. Figure 3 shows the tank with the foil insulation and additional pipe insulation applied. The final modification made to the Energy Housing unit was made on June 4, 2002. At this time, three of the light fixtures that were on evening 4 hour timed duration were changed from 100 watt incandescent lamps to 25 watt compact fluorescent lamps. Figure 3 The Solar Hot Water Tank with R5 Insulating Blanket and additional Pipe Insulation Located in the Energy Efficient Manufactured Housing Unit 4.0 RESULTS AND DISCUSSION 4.1 Energy Use Results and Discussion The measured total energy used by each of the housing units for cooling and heating are shown in tables below. Table 2 shows the energy used for heating and cooling the Standard Housing Unit over the period of January through August in 2002. The Standard Unit data logger was struck by lighting in mid August, 2002 and all data after this point was not included since on