Evaporative cooling systems in buildings have been criticized for their water use and acclaimed for their low energy consumption, especially when compared to typical cooling systems. In order to determine the overall effectiveness of cooling systems in buildings, both water and energy need to be considered; however, there must be a metric to compare the amount of energy used at the site to the amount of water used at the power plant.A study of power plants and their respective water consumption was completed to effectively analyze evaporative cooling systems. Eighty-nine percent of electricity in the United States is produced with thermally driven water-cooled energy conversion cycles. Thermoelectric power plants withdraw a tremendous amount of water, but only a small percentage is evaporated. The evaporative or consumptive use1 is approximately 2.5% or 3,310 million gal per day (MGD) (12,530 x 10 6 L/d). Moreover, hydroelectric plants produce approximately 9% of the nation's electricity. Evaporative water loss from the reservoir surfaces also results in water being evaporated for electrical production.In thermoelectric plants, 0.47 gal (1.8 L) of fresh water is evaporated per kWh of electricity consumed at the point of end use. Hydroelectric plants evaporate an average of 18 gal (68 L) of fresh water per kWh used by the consumer. The national weighted average for thermoelectric and hydroelectric water use is 2.0 gal (7.6 L) of evaporated water per kWh of electricity consumed at the point of end use. From this information, different types of building cooling systems can be compared for relative water consumption. This paper will aid in High Performance Building research by providing a metric in determining water efficiency in building cooling systems. Further analysis is planned to determine the overall water efficiency of evaporative cooling systems compared to conventional direct expansion systems and chiller systems with cooling towers.

This report uses EnergyPlus simulations of each building in the 2003 Commercial Buildings Energy Consumption Survey (CBECS) to document and demonstrate bottom-up methods of modeling the entire U.S. commercial buildings sector (EIA 2006). The ability to use a whole-building simulation tool to model the entire sector is of interest because the energy models enable us to answer subsequent "what-if" questions that involve technologies and practices related to energy. This report documents how the whole-building models were generated from the building characteristics in 2003 CBECS and compares the simulation results to the survey data for energy use.

Commercial buildings have a significant impact on energy use and the environment. They account for approximately 18% (17.9 quads) of the total primary energy consumption in the United States (DOE 2005). The energy used by the building sector continues to increase, primarily because new buildings are added to the national building stock faster than old buildings are retired. Energy consumption by commercial buildings will continue to increase until buildings can be designed to produce more energy than they consume. As a result, the U.S. Department of Energy's (DOE) Building Technologies Program has established a goal to create the technology and knowledgebase for marketable zero-energy commercial buildings (ZEBs) by 2025. To help DOE reach its ZEB goal, the Buildings and Thermal Systems Center at the National Renewable Energy Laboratory (NREL) studied six buildings in detail over the past four years to understand the issues related to the design, construction, operation, and evaluation of the current generation of lowenergy commercial buildings. These buildings and the lessons learned from them help inform a set of best practices-beneficial design elements, technologies, and techniques that should be encouraged in future buildings, as well as pitfalls to be avoided. The lessons learned from these six buildings are also used to guide future research on commercial buildings to meet DOE's goal for facilitating marketable ZEBs by 2025. The six buildings are:

No abstract

We conducted simulation-based research to study the energy impacts of outside air on U.S. commercial buildings stock. We derived detailed building models from 4,820 buildings in the 2003 Commercial Buildings Energy Consumption Survey (CBECS). Combined with the appropriate weighting factors these 4,820 models form the basis of this national scale study. The energy effects of outside air on commercial buildings were analyzed according to three types of construction. • The commercial sector was analyzed based on a set of models called the Existing Stock Construction Group, which is designed to represent the current CBECS buildings.

The preliminary design for the Open Prototype for Educational NanoSats (OPEN) demonstration spacecraft, OpenOrbiter, is presented. OPEN is designed to facilitate the formation of CubeSat development programs nationally and worldwide via providing a publically-available set of spacecraft design documents, implementation and testing plans. These documents should allow the creation of a 1-U CubeSat with a parts budget of approximately $ 5,000. This allows spacecraft development to be incorporated in regular curriculum and supported from teaching (as opposed to research) funds. The OPEN design, implemented by OpenOrbiter, has an innovative internal structure, separates payload and operations processing and includes features to ease and highlight errors in integration

No abstract

A number of colleagues made this work possible. The authors greatly appreciate the assistance of Brent Griffith and the NREL EnergyPlus analysis and modeling team. Their simulation development and support allowed us to evaluate a variety of energy efficiency technologies. We would also like to thank NREL's High Performance Computing Center's Wesley Jones and Jim Albin for their support in providing dedicated Linux cluster nodes for the simulations needed for the analysis. Finally, we extend our thanks to those who helped edit and review the document: Stefanie Woodward, Michael Deru, and Ian Doebber (all of NREL). iv Executive SummaryThis report documents technical analysis aimed at providing design guidance that achieves wholebuilding energy savings of at least 50% over ASHRAE Standard 90.1-2004 in medium-sized retail buildings. It represents an initial step towards determining how to provide design guidance for energy savings targets larger than 30%, and was developed by the Commercial Buildings Section at the National Renewable Energy Laboratory (NREL), under the direction of the DOE Building Technologies Program.This report:• Documents the modeling and integrated analysis methods used to identify cost-effective sets of recommendations for different locations and business activities.• Demonstrates sets of recommendations that meet, or exceed, the 50% goal. There are forty eight sets of recommendations, one for each combination of sixteen climate zones and three levels of unregulated plug loads.This technical support document (TSD), along with a sister document for grocery stores (Hale et al. 2008), also evaluates the possibility of compiling a 50% Advanced Energy Design Guide (AEDG) in the tradition of the 30% AEDGs available through the American Society of Heating, Refrigerating, and AirConditioning Engineers (ASHRAE) and developed by an inter-organizational committee structure. In particular, we comment on how design guidance should be developed and presented in the next round of 50% TSDs for deployment as AEDGs. MethodologyBecause it is important to account for energy interactions between building subsystems, NREL used EnergyPlus to model the predicted energy performance of baseline buildings and low-energy buildings to verify that the goal of 50% energy savings can be met. EnergyPlus was selected because it computes building energy use based on the interaction of the climate, building form and fabric, internal gains, HVAC systems, and renewable energy systems. Percent energy savings are based on a minimally codecompliant building as described in Appendix G of ASHRAE 90.1-2004, and whole-building, net site energy use intensity (EUI): the amount of energy a building uses for both regulated and unregulated loads, minus any renewable energy generated within its footprint, normalized by building area.The following steps were used to determine 50% savings:• Define architectural-program characteristics (design aspects not addressed by ASHRAE 90.1-2004) for typical retail stores, thereby defining prototype models....