ASHRAE LV-11-C040-2011 Reducing Plug and Process Loads for a Large Scale Low Energy Office Building NREL’s Research Support Facility.pdf

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1、Chad Lobato is a researcher at the National Renewable Energy Laboratory, Golden, Colorado. Shanti Pless is a researcher at the National Renewable Energy Laboratory, Golden, Colorado. Michael Sheppy is a researcher at the National Renewable Energy Laboratory, Golden, Colorado. Paul Torcellini, PE, Ph

2、D is a group manager at the National Renewable Energy Laboratory, Golden, Colorado. Reducing Plug and Process Loads for a Large Scale, Low Energy Office Building: NRELs Research Support Facility Chad Lobato Shanti Pless Michael Sheppy Paul Torcellini, PE, PhD Associate ASHRAE Member ASHRAE Associate

3、 ASHRAE Member ASHRAE ABSTRACT The construction of the National Renewable Energy Laboratorys (NREL) new 220,000-ft2 (20,438-m2) Research Support Facility (RSF) was completed in June 2010. The projects Request for Proposals (RFP) set a whole-building demand-side energy use requirement of a nominal 25

4、 kBtu/ft2yr (78.8 kWh/m2yr). The RSF baseline plug and process loads (PPLs) were 35.1 kBtu/ft2yr (110.6 kWh/m2yr). To meet the building energy goal, PPLs had to be reduced by approximately 50%. This paper documents the methodology NREL researchers developed to identify and reduce PPLs as part of the

5、 RSFs low energy design process. They examined PPLs, including elevators, kitchen equipment in breakrooms, and office equipment in NRELs previously occupied office spaces to determine a baseline. This, along with research into the most energy-efficient products and practices, enabled these researche

6、rs to formulate a reduction strategy that should yield a 47% reduction in PPLs. The building owner and the design team played equally important roles in developing and implementing opportunities to reduce PPLs. Based on the work done in the RSF, a generalized multistep process has been developed for

7、 application to other buildings. INTRODUCTION The Research Support Facility (RSF) is projected to achieve annual net zero energy use with on-site renewables and be one of the largest U.S. net zero energy office buildings. The projects Request for Proposals (RFP) set a whole-building demand-side ener

8、gy use requirement of a nominal 25 kBtu/ft2yr (78.8 kWh/m2yr) (Pless et al. 2010) that sparked an investigation into benchmarking current plug and process loads (PPLs). Overall, PPLs in residential and commercial buildings account for almost 12% of U.S. primary energy consumption (McKenney et al. 20

9、10). Minimizing these loads is one of the primary challenges in the design of an energy-efficient building. PPLs are not related to general lighting, heating, ventilation, cooling, and water heating, and typically do not LV-11-C040330 ASHRAE Transactions2011. American Society of Heating, Refrigerati

10、ng and Air-Conditioning Engineers, Inc. (www.ashrae.org). Published in ASHRAE Transactions, Volume 117, Part 1. For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAES prior written permission.provide comfort to t

11、he occupants. They use an increasingly large portion of the building energy use pie because the number and variety of electrical devices have increased along with the efficiency of building systems. Reducing PPLs is difficult because there is a limited understanding of energy efficiency opportunitie

12、s and equipment needed to address office space PPL energy use. Typically, no single decision maker can specify all efficiency strategies for PPLs, which makes centralized educated decisions about possible strategies difficult. The owner, tenant, engineer, architect, information technologies (IT) pro

13、curement staff, and facility operator all can make decisions about efficient PPLs. Furthermore, most PPLs are not included in ASHRAE 90.1 and are typically not addressed by building codes. This paper outlines reduction strategies that were developed for the RSF. These can be used in any building, bu

14、t are most effective at the beginning of the design stage. DEVELOPMENT, IMPLEMENTATION, AND RESULTS OF PLUG AND PROCESS LOAD STRATEGIES This section includes an overview of RSF PPL strategies. The results from a survey of NREL campus PPLs are presented with proposed energy saving strategies. Energy

15、savings predictions are made based on the strategies and recommended equipment. Plug and Process Load Survey The RSF posed a unique challenge. The design team was contractually required to meet a whole-building energy use goal that included PPLs. To accurately account for PPLs, the team required inp

16、ut from NREL on previous and proposed equipment and use. A team of NREL researchers was assigned to be PPL champions, and began by performing a thorough survey of NRELs equipment use. An equipment inventory was developed from the PPL survey. A representative sample was then metered to develop use pr

17、ofiles and determine peak and standby energy use. The metered data revealed a baseline PPL energy use of 35.1 kBtu/ft2yr (110.6 kWh/m2yr), which would have made it impossible to meet the energy goal. Therefore, RSF PPLs had to be reduced by approximately 50%. The strategies and resulting reductions

18、are discussed in the following sections. Implementation of Plug and Process Load Strategies Data Center. NRELs previous data center used a number of servers that typically had a utilization of less than 5%. When the total data center power draw was divided among all users, the continuous power consu

19、mption rate per person was 65 W. The uninterruptible power supply (UPS) and room power distribution units were 80% efficient. The RSF data center uses blade servers running virtualized servers. When the total data center power draw is divided among all users at NREL, the continuous power consumption

20、 rate per person is 35 W. The current UPS and room power distribution are 97% efficient. Copiers, Printers, and Fax Machines. The initial PPL audit revealed that many workstations had their own single-user machines (copiers, printers, fax machines, and scanners). All-in-one copying and printing stat

21、ions had approximately 40 users on average, and many operated in an always-on mode. In the RSF, each all-in-one printing station is used by approximately 60 occupants. Through better space planning and understanding of common space utilization, the design team was able to reduce the total number of

22、shared all-in-one printing stations by a third. IT and management put in place policies that have eliminated shared and personal single-function machines wherever possible. Using fewer shared multifunction devices reduces capital and maintenance costs, as well as wasted energy when the machines sit

23、idle. The standby features are activated and used to reduce night and weekend energy consumption from 175 W to 20 W continuous. By using centralized print stations, people with significant printing needs face some limitations, as they previously had personal machines at their workstations. Some view

24、 the shared devices as an inconvenience because they can no longer retrieve printouts at their desks; further, some people objected because they did not want to send sensitive print jobs to a shared device. To keep such materials private, shared devices feature password protection. In addition, many

25、 of the NREL business processes are going toward electronic approvals limiting the need for printers substantially. Computers and Monitors. The PPL audit revealed numerous opportunities to reduce PPLs from workstation 2011 ASHRAE 331equipment. Approximately 90% of employees used desktop computers. W

26、hen idle, these computers went into a screensaver mode or displayed an idle desktop screen. Monitors were typically either fluorescent backlit LCD or CRT displays. To reduce computer energy consumption, 90% of the RSF occupants use laptop computers with LED backlit LCD monitors. Figure 1 shows the m

27、easured load profile of a laptop computer and two 22” (56 cm) LED backlit LCD monitors. Figure 1 Laptop computer and monitor load profile The average power draw for this laptop and display combination was 53.9 W during occupied hours and 4 to 5 W during unoccupied hours. Further savings during unocc

28、upied hours are achieved with a controlled outlet on a power management surge protector to eliminate the parasitic load of the docking station and battery charging (see Figure 1). One commonly expressed concern involved the perception that laptops cannot always provide the computing power required.

29、This may be true when substantial computing is needed, but most employees perform only standard business functions. Desktops are issued to those few employees who are truly limited by laptop capabilities. The previous strategy for dealing with idle computers was to lock them out after 15 minutes and

30、 to display a security screensaver. The screensaver increased average power by 5 W compared to an idle state (30 to 35 W for a laptop locked out in the security screensaver versus 25 to 30 W for a laptop in use). Setting the monitor into a standby state while the computer runs the screensaver reduce

31、s power draw, but is not an optimal solution. Setting both the computer and monitor into standby produces the most energy savings, reducing power to 4 to 5 W. Task Lights, Phones, and Power Management. Additional equipment in the previously occupied workstations included a task light, a phone, and m

32、iscellaneous items such as cell phone chargers, lights (decorative or functional, or both), mini refrigerators, coffee pots, electric teapots, fans, personal heaters, label makers, and radios. The task lighting used traditional linear fluorescent lamps and fixtures and the phones were standard model

33、s. The items received power from standard six-plug surge protectors. Workstation area lighting, especially task lighting, was a challenge for the RSFs unique design. In conventional office buildings, occupants are accustomed to lighting levels that far exceed the minimum requirements. The RSF is des

34、igned to be 100% daylit, so supplemental lighting comes from efficient 6 W LED task lighting and overhead electrical lighting. RSF employees are provided with VOIP phones that consume a constant 2 W. 332 ASHRAE TransactionsPower at the workstation is managed primarily through new power management su

35、rge protectors that have low or no parasitic loads, manage power, and are aesthetically pleasing and cost effective. Each has four controlled outlets and four always-powered outlets. When power draw on the sensor outlet drops below a manually set threshold, power is cut to the controlled outlets. Th

36、ey are desktop mounted so the main power button is easily accessible. Typically, commercial building occupants are unaware of their energy use. In the RSF, occupant behavior and equipment are the driving forces behind energy use. All occupants need to be aware of how their energy use affects the RSF

37、s overall performance. This awareness drives people to eliminate items that waste energy and are unnecessary. Appliances. A key design team contribution to reducing PPLs included maximizing space efficiency in shared areas. The previously occupied NREL office buildings provided breakrooms with refri

38、gerators, microwaves, coffee pots, drinking fountains, and vending machines. The RSF features the same amenities, but each breakroom serves approximately 60 building occupants compared to 40 in previously occupied NREL buildings. This increase will reduce the number of energy-consuming appliances. F

39、urther savings are accomplished in the breakrooms by purchasing efficient refrigerators (48 W average load) and eliminating mechanically cooled drinking fountains. Every floor on each wing has two kitchens. They have ample refrigerator space, dishwashers, coffee makers, and microwaves to eliminate t

40、he need for personal equipment. Management and safety policies disallow the use of personal equipment at individual workstations. Special cases are considered for business or other justified reasons. Elevators. The RSF employs energy-efficient regenerative traction elevators rather than the standard

41、 hydraulic elevators that typically operate in low-rise office buildings. Each elevator has a potential annual saving of 7000 kWh (KONE 2006), depending on use, compared to standard hydraulic elevators. Each is equipped with energy-efficient fluorescent lighting and fans, which are turned off when t

42、he car is unoccupied. The stairwell design is inviting (to encourage their use), with wide steps, windows with mountain views, and a variety of art pieces at each floor. Miscellaneous Loads. The RSF offers the same amenities as do previous NREL office spaces, including a coffee kiosk, a gym, an ice

43、machine, and vending machines. The previous coffee kiosk provided a variety of hot and cold beverages and food to occupants in three of NRELs buildings. The espresso machine and water heater were left powered 24/7. The espresso machine had a continuous average load of 455 W. Multiple glass-front min

44、i refrigerators were used to store food and cold drinks. Overall, the previous coffee kiosk had an average continuous load of nearly 1400 W. The RSF coffee kiosk is significantly more energy efficient. The espresso machine goes into standby mode when it is not in use during occupied hours, and is tu

45、rned off during unoccupied hours. The manufacturer claims a 30% in-use energy savings (General Espresso Equipment Corporation 2009). It has an estimated continuous average load of 150 W. Food and cold drinks are stored in full-size refrigerators with nontransparent doors. All mini refrigerators have

46、 been eliminated. Timed outlets cut power to all items except the refrigerators, freezer, and cash register during unoccupied hours. Overall, the coffee kiosk has an estimated average continuous load of nearly 700 W. The ice machine is controlled by a timer to it turn off during unoccupied hours, wh

47、ich reduces continuous power draw from 327 W to 110 W. The RSF has two ENERGY STAR soda machines and one snack machine that feature efficient LED display lighting (the lighting is deactivated to achieve additional energy savings) (Deru et al. 2003). Results The innovative application of energy-effic

48、ient PPL equipment and design strategies result in overall savings of 47% for PPLs and 51% for the whole RSF building compared to the previously occupied NREL office space. By integrating the PPL strategies along with the other efficient building systems, the RSF has an expected whole-building energ

49、y use of 35.1 kBtu/ft2yr (110.6 kWh/m2yr) 10.6 kBtu/ft2yr (33.4 kWh/m2yr) of which is for data center equipment. Because of the goal of a Zero Energy Building (ZEB), additional loads must be offset with a photovoltaic (PV) system. These strategies resulted in a PV cost savings of more than $4 million. See Table 1 for a detailed description of each PPL energy-saving strategy, before and after EUIs, and photovoltaic (PV) cost savings. The reduced PPLs account for 55% of the total energy use in the RSF. Figure 2