ASHRAE Journal - March 2011 - 40

Lighting

Climate Location The ambient average lighting power density (LPD) was reduced from 1.44 W/ft2 (15.5 W/m 2) in the Figure 4: Energy savings and simple payback for complete EEM package by climate zone. baseline to 0.83 W/ft 2 (9 W/m 2) in the low-energy case by using high performance lighting Table 7 shows a more detailed breakdown of the simulasystems. Occupancy sensor control, improved lighting tion results for Houston, Baltimore, and Chicago in terms of power management, and daylighting with dimming con- end-use EUIs, savings percentage and simple payback period. trol further reduced consumed lighting power at different The impact of climate zone is most evident in the variation times of the day. between cooling and heating savings in these cities. The lighting EEMs also include the reduced exterior lightFigure 5 presents the breakdown of the savings by end-use ing power levels, according to the allowances prescribed by category for all of the 16 cities analyzed in the TSD. It shows Standard 90.1-2010. The total exterior lighting power is re- that the largest energy savings was achieved in the cooking duced from 4,333 W to 2,687 W. Photocells and timers were end-use with the largest energy savings of 39% attributable selected to further reduce exterior lighting energy during un- to the gas cooking equipment or 45% for all of the cooking occupied hours and after dark. equipment. The next largest group of end-use savings is observed in the heating, cooling and fan categories, which comSavings and Cost Analysis bine for 37% of the savings. These savings are the result of In the TSD, energy performance of the baseline and various EEMs associated with the rooftop HVAC systems and low-energy buildings with the complete EEM package also include the interactions of other measures such as the heat was simulated for 16 representative climate locations gain to space from the appliances or by moving the ice mausing EnergyPlus. Figure 4 presents the energy savings chines outside. from the complete EEM package for all of the climate The interior and exterior lights savings accounted for 7% locations. The savings averaged 45% nationally but the of the total energy savings. Although this is a relatively lower savings in climate zones 7 and 8 were more than 50%. energy savings compared to some of the other end-uses catFigure 4 shows that the simple payback varied from 1.5 egories, the costs for implementing the lighting measures is to 3.5 years. lower than the baseline lighting costs, which results in an im-

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ASHRAE Journal

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tion of the runaround loop heat recovery system with two heat exchangers, one installed in the kitchen exhaust airstream and the other in the DOAS unit. Because of the energy penalty resulting from the increased fan and pump energy, the heat recovery EEM was found only beneficial in cold climate zones such as 5A, 6A, 6B, 7 and 8. The economizer use complies with Standard 90.1-2004 and 90.1-2010 in the baseline and lower-energy buildings, respectively. The baseline DX coil efficiency meets Standard 90.1-2004; and they are listed in Table 6 along with high efficiency coils. The mechanical efficiency of fans in the advanced model is improved from 55% to 65%. 60% The baseline model uses a standard gas-fired water heater with a 100 gal50% lon (379 L) storage tank.The minimum required thermal efficiency 40% established by Standard 90.1-2004 is 80%. In the advanced cases, a single 30% gas-fired condensing water heater with 95% thermal efficiency was 20% selected. Besides the thermal efficiency improvement, the low-energy 10% design recovers the waste refrigerant heat to preheat incoming city water 0% before it is heated in the service hot water heater.
Percentage Savings

Size Category <65,000 Btu/h 65,000 ~ 135,000 Btu/h 135,000 ~ 240,000 Btu/h 240,000 ~ 300,000 Btu/h

Efficiency (SEER/EER) Baseline 13.0 SEER 10.1 EER 9.5 EER 9.3 EER Efficiency Case 15 SEER 11.5 EER 11.3 EER 10.5 EER

Table 6: Efficiency of packaged unitary air conditioners.
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March 2011
ASHRAE Journal - March 2011

Table of Contents for the Digital Edition of ASHRAE Journal - March 2011
