The U.S. Department of Energy (DOE) Building Technologies program has set aggressive goals for energy efficiency improvements in buildings that will require collaboration between the DOE laboratories and the building industry. This report details the development of standard or reference energy models for the most common commercial buildings to serve as starting points for energy efficiency research. These models represent reasonably realistic building characteristics and construction practices. Fifteen commercial building types and one multifamily residential building were determined by consensus between DOE,

No abstract

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.

No abstract

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

Abstract"Net Zero Energy Building" has become a prominent wording to describe the synergy of energy efficient building and renewable energy utilization to reach a balanced energy budget over a yearly cycle. Taking into account the energy exchange with a grid infrastructure overcomes the limitations of seasonal energy storage on-site. Even though the wording "Net Zero Energy Building" focuses on the annual energy balance, large differences may occur between solution sets in the amount of grid interaction needed to reach the goal. The paper reports on the analysis of example buildings concerning the load matching and grid interaction. Indices to describe both issues are proposed and foreseen as part of a harmonized definition framework. The work is part of subtask A of the IEA