ASHRAE Journal - January 2010 - 22

In addition, lighting contributes indirectly to the space cooling High performance construction projects are routinely achievenergy use. ing these levels and the use of daylighting controls applied to Combined, these three end-uses account for 62% to 68% of the building perimeter can help lower the “in use” LPD even the total energy use by commercial buildings and as a result, more. One example is the recently completed renovation of the a high performance low energy design needs to address the Exelon Corporation 200,000 ft² (18 581 m²) headquarters in components and technologies that will impact these end-uses. Chicago. The design earned a LEED CI Platinum certification Standard 90.1 is increasingly defining higher levels of thermal and achieved a low “in use” LPD of 0.6 W/ft² (6.5 W/m²).17 Still lower LPDs will be possible as white LED lighting performance and lower lighting power densities. As shown in Table 1, succeeding versions of Standard 90.1 offer increasingly efficacies continue to increase beyond the level of the best higher levels of thermal performance. The values shown are the fluorescent systems. Recently, one manufacturer of LED lightmaximum U-values for buildings in Zone 5 with heating degree ing reported efficacies of 129 lumens/watt in the laboratory for a cool white LED light. days from 5,400 to 7,200. The Researchers believe that LED European Union under the Office Equipment can achieve efficacies of 150 Energy Performance Building 7% to 200 lumens/watt and these Directive (EPBD) proposed Other 14% performance levels can potenin 2004 thermal performance tially lower LPDs further.18 levels that are significantly Space Heat The performance improvehigher than those of Standard 32% Lighting 24% ment of cooling equipment, 90.1-2007.14 DHW heating equipment and fan Similarly, Standard 90.1 14% power use outlined by the continues to define increasdifferent versions of Standard ingly lower lighting power Cooling 6% 90.1 are less than the improvedensities (LPDs) made posVentilation 3% ments achieved in envelope sible with improvements in thermal performance and conperformance of fluorescent DHW 9% Office Equipment nected lighting loads. The perlighting coupled with better 14% Ventilation Lighting formance guidelines of large understanding of the physiOther 1% 8% 10% tonnage centrifugal chillers, ology of the human eye and Cooling 6% natural gas boilers and the fan the importance of lighting power limitations defined in color. As shown in Table 2, Space Heat various versions of Standards LPD levels have decreased by 52% 90.1 are shown in Table 3. The approximately 20% to 30% full load performance requirebetween the 2001 and 2007 ment and integrated part load versions of the standard. The reductions shown in Figure 1a (top): 1995 Commercial Buildings Energy Consumption value (IPLV) for centrifugal Table 2 have been possible due Survey (CBECS). Table 2A, p 35.8, 2003 ASHRAE Handbook— chillers in the range of 300 to the increase in the efficacy HVAC Applications. Energy intensities of commercial buildings in a to 600 tons have not changed of fluorescent lighting sys- climate zone with 2,200 to 3,055 HDD. Figure 1b (bottom): Energy Use since Standard 90.1-2001, tems from approximately 65 Data Handbook, August 2006, Natural Resources Canada (NRCan). yet manufacturers of cooling lumens/watt for standard F34 Values shown are based on the total energy use by end-use for the equipment have continued to T12 lamps with electromag- entire commercial sector divided by the total floor area (pp. 48 – 49). improve equipment performance. Best-in-class products netic ballasts to 100 lumens/ watt for high performance T8 lamps with extra efficient instant capable of IPLV levels in the range of 0.45 to 0.5 kW/ton (1.58 start ballasts.15 to 1.76 kW/kW) at AHRI standard conditions are available in Improvements have also occurred with lamp phosphors and the market. Similarly, fan power limitations and boiler efficiency the quality and color of fluorescent lighting. Spectrally enhanced have not changed. fluorescent lamps produce light that is closer to daylight and allow further reductions in the connected lighting loads. This results in Future Performance Levels and Technologies a potential further drop in the LPD beyond what can be achieved High performance designs able to achieve energy savings from the improvement in the lighting efficacy alone. LPDs as above 50% will require performance levels beyond those outlow as 0.75 W/ft² (8 W/m²) in office environments are possible lined in the preceding section. Table 4 show the performance now with the best fluorescent technologies, while providing good improvements that can be achieved with different envelope, illuminance levels and ongoing research by the U.S. Department lighting and HVAC equipment performance levels based on a of Energy (DOE), supports these LPD levels.16 hypothetical building located in Chicago. ASHRAE Journal ashrae.org January 2010

ASHRAE Journal - January 2010

Table of Contents for the Digital Edition of ASHRAE Journal - January 2010