We are indebted to a number of retailers and building industry professionals for taking the time to provide equipment and construction cost estimates and to review our analysis assumptions and earlier versions of this report. John Priebe of The Abo Group arranged for the procurement of envelope construction cost data from Cumming Corporation and HVAC system cost data from RMH Group. Stefan Coca of Cumming Corporation provided us with an extensive set of envelope cost data for low-rise and high-rise large office constructions. Bob Stahl of RMH Group, with assistance from Phil Kocher and Jim Bradburn from RMH Group, provided us with detailed HVAC schematics, equipment lists, and overall system costs for our baseline and lowenergy HVAC systems. Bob also provided us with estimates for incremental costs associated with improved component efficiencies. Steven Taylor of Taylor Engineering and Fiona Cousins of Arup Engineering provided us very detailed review of both our analysis assumptions and our overall approach. David Okada of Stantec Engineering provided review of an initial list of possible energy efficiency measures (EEMs).We would like to thank all of the peer reviewers for their time and constructive feedback. NREL colleagues Anthony Florita, Andrew Parker, Rois Langner, Daniel Studer, Michael Deru, and Shanti Pless all reviewed the report during its development. Stefanie Woodward and Stephanie Price of NREL proofread and edited the document. Carol Kerstner assisted with final edits and prepared the document for publication.Several other NREL colleagues provided valuable guidance and information during the modeling process, either directly or through their past work. Eric Bonnema and Brent Griffith provided extensive modeling assistance. Ian Doebber and Kyle Benne provided modeling assistance and significant insight into the modeling process, especially in regards to the setup and control of the radiant heating and cooling system model. Jennifer Scheib and Rob Guglielmetti provided electric lighting and daylighting EEM data. Nicholas Long and Eric Bonnema provided Opt-EPlus assistance. Michael Deru and Kristin Field provided review of our code compliant high-rise baseline, including our schedule sets. Jenni Sonnen coordinated graphic design work by Joshua Bauer to provide us with figures for the report. Eric Bonnema, Brent Griffith, and Michael Deru shared their computing resources for the optimization process.ii Executive SummaryThis Technical Support Document (TSD) was developed by the Commercial Buildings Group at NREL, under the direction of the DOE Building Technologies Program. Its main goal was to evaluate the potential for new large office buildings in the United States to achieve a 50% net site energy savings compared to a baseline defined by minimal compliance with respect to ANSI/ASHRAE/IESNA Standard 90. 1-2004, Energy Standard for Buildings Except Low-Rise Residential Buildings (ASHRAE 2004c.The work presented here extends the 50% Energy Savings Design Technology Packages for Medium Office Buildi...

Until recently, large-scale, cost-effective net-zero energy buildings (NZEBs) were thought to lie decades in the future. However, ongoing work at the National Renewable Energy Laboratory (NREL) indicates that NZEB status is both achievable and repeatable today. This paper presents a definition framework for classifying NZEBs and a real-life example that demonstrates how a large-scale office building can cost-effectively achieve net-zero energy. The vision of NZEBs is compelling. In theory, these highly energy-efficient buildings will produce, during a typical year, enough renewable energy to offset the energy they consume from the grid. The NREL NZEB definition framework classifies NZEBs according to the criteria being used to judge net-zero status and the way renewable energy is supplied to achieve that status. We use the new U.S. Department of Energy/NREL 220,000-ft2 Research Support Facilities (RSF) building to illustrate why a clear picture of NZEB definitions is important and how the framework provides a methodology for creating a cost-effective NZEB. The RSF, scheduled to open in June 2010, includes contractual commitments to deliver a Leadership in Energy Efficiency and Design (LEED) Platinum Rating, an energy use intensity of 25 kBtu/ft2 (half that of a typical LEED Platinum office building), and net-zero energy status. We will discuss the analysis method and cost tradeoffs that were performed throughout the design and build phases to meet these commitments and maintain construction costs at $259/ft2. We will discuss ways to achieve large-scale, replicable NZEB performance. Many passive and renewable energy strategies are utilized, including full daylighting, high-performance lighting, natural ventilation through operable windows, thermal mass, transpired solar collectors, radiant heating and cooling, and workstation configurations allow for maximum daylighting. This paper was prepared by the client and design teams, including Paul Torcellini, PhD, PE, Commercial Building Research Group Manager with NREL; Shanti Pless and Chad Lobato, Building Energy Efficiency Research Engineers with NREL; David Okada, PE, LEED AP, Associate with Stantec; and Tom Hootman, AIA, LEED AP, Director of Sustainability with RNL.

Executive Summary BackgroundIn June 2010, the National Renewable Energy Laboratory (NREL) completed construction on the new 220,000-square foot (ft 2 ) Research Support Facility (RSF) which included a 1,900-ft 2 data center (the RSF will expand to 360,000 ft 2 with the opening of an additional wing December, 2011). The project's request for proposals (RFP) set a whole-building demand-side energy use requirement of a nominal 35 kBtu/ft 2 per year. On-site renewable energy generation offsets the annual energy consumption. The original "legacy" data center had annual energy consumption as high as 2,394,000 kilowatt-hours (kWh), which would have exceeded the total building energy goal. As part of meeting the building energy goal, the RSF data center annual energy use had to be approximately 50% less than the legacy data center's annual energy use. This report documents the methodology used to procure, construct, and operate an energy-efficient data center suitable for a net-zeroenergy-use building. Development ProcessThe legacy data center on NREL's campus used a number of individual servers, with a utilization of less than 5%. When the total data center power draw was divided among all users, the continuous power consumption rate per person was 151 watts (W). The uninterruptible power supply (UPS) and room power distribution units were 80% efficient. Chilled water was created using one multi-stage air-cooled chiller unit and a backup single-stage air conditioning (AC) chiller unit, delivering chilled water to seven computer room air handlers (CRAHs). This cool air was delivered through an underfloor plenum, which was also a passageway for most cables, conduits, and chilled water pipes. This increased the fan energy required to move air between the CRAHs and the servers. Open hot and cold aisles added to the inefficiency of the existing data center by allowing the chilled supply air to mix with hot return air. Additionally, two walls of the data center were floor-to-ceiling exterior windows with southwestern exposure that introduced solar heat gain to the space and required additional cooling. Evaluation Approach and ResultsThe RSF data center was designed using blade servers running virtualized servers. When the total data center power draw is divided among all users, the continuous power consumption rate per person is 45 W. The UPS and room power distribution is 95% efficient. Evaporative cooling and air-side economizing is designed to cool the air to 74 o F.Cool air is supplied to the servers through dedicated underfloor and overhead plenums. Cooling efficiency is enhanced by having a contained hot aisle. This also allows waste heat from the hot aisles to be recovered and used elsewhere in the building when needed, which reduces heating loads. The new data center is mostly below grade and has no windows, helping to insulate the room from ambient outdoor conditions. ResultsAt 958,000 kWh, the RSF annual data center energy use is approximately 60% less than the legacy data center annual energy use; this results in ...

NOTICEThis report was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States government or any agency thereof. Executive SummaryBackground Plug and process loads (PPLs) are building electrical loads that are not related to lighting, heating, ventilation, cooling, and water heating, and typically do not provide comfort to the occupants. PPLs in commercial buildings account for almost 33% of U.S. commercial building electricity use (McKenney et al. 2010). At the building level, they account for approximately 25% of the total electrical load in a minimally code-compliant commercial building, and can exceed 50% in an ultra-high efficiency building . Minimizing PPLs is a critical part of the design and operation of an energy-efficient building.A complex array of technologies that meter and control PPLs has emerged in the marketplace. NREL has developed guidance for evaluating and selecting a range of technologies. Control strategies that match PPL energy use to user work schedules can save considerable energy in most commercial buildings. PPL control strategies are also effective in reducing peak demand. ResultsWe evaluated PPLs and related control strategies to ensure that the RSF would meet its energy goals. These results were distilled into a flowchart so others could achieve similar savings based on our experiences (see Section 2.2.2). The flowchart asks a series of questions about a PPL's use and specifies a control strategy. It highlights situations where the PPL could be operated more efficiently, and points out key areas where manufacturers could make their equipment more energy efficient.Uncontrolled workstations in an office building formed a baseline to highlight the savings potential-the importance of encouraging "good" behavior and turning off PPLs when they are not being used. Ideally, all PPL control strategies would counteract "bad users," but not all are "user proof." Educational programs that encourage "good" user behavior should be implemented along with these strategies wherever possible. Figure Determine which loads can be controlled cost effectively. How To Use This Document To Choose a Cost-Effective Control DeviceWhere to find in this paper: Section 2.3, and Appendix A Research Commercially Available Control DevicesOutcome:Arrive at a li...

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