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Network connectivity has become nearly ubiquitous, and the energy use of the equipment required for this connectivity is growing. Network equipment consists of devices that primarily switch and route Internet Protocol (IP) packets from a source to a destination, and this category specifically excludes edge devices like PCs, servers and other sources and sinks of IP traffic. This paper presents the results of a study of network equipment energy use and includes case studies of networks in a campus, a medium commercial building, and a typical home. The total energy use of network equipment is the product of the stock of equipment in use, the power of each device, and their usage patterns. This information was gathered from market research reports, broadband market penetration studies, field metering, and interviews with network administrators and service providers. We estimate that network equipment in the USA used 18 TWh, or about 1% of building electricity, in 2008 and that consumption is expected to grow at roughly 6% per year to 23 TWh in 2012; world usage in 2008 was 51 TWh. This study shows that office building network switches and residential equipment are the two largest categories of energy use consuming 40% and 30% of the total respectively. We estimate potential energy savings for different scenarios using forecasts of equipment stock and energy use, and savings estimates range from 20% to 50% based on full market penetration of efficient technologies.

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Abstract-Low power wireless networking standards either do not address variable rate communication or leave the selection of rate outside of the standard. The use of variable data rate can reduce network latency and average power consumption, and automatic rate selection is critical for improving scalability and minimizing network overhead. In the IEEE 802.15.4 standard the SNR can be inferred through the radio reported link quality or received signal strength, and an extension to the standard leads to highly dynamic and accurate rate selection. Using data from an experimental study of 44 IEEE 802.15.4 nodes in an industrial mesh network, SNR is extracted to show sufficient margin exists for higher data rate communication. A variable rate signaling scheme with automatic rate selection is proposed to provide links at the standard 250kb/s as well as 500kb/s, 1000kb/s and 2000kb/s with a minimum of hardware changes. Using the experimental data to generate a model of the real world system, total network energy is compared using legacy and variable rate signaling showing over 40% savings.

(PNNL) to identify monitoring and control needs for small-and medium-sized commercial buildings, and to recommend possible solutions. The scope of this study is to characterize the monitoring and controls needs for the various end uses (for both efficiency and demand response), determine requirements to develop control packages, and calculate the target cost of doing so. Section 1.0 introduces the study scope and analysis approaches used. Discussions regarding the number of buildings in the U.S that comprise "small-size" and "medium-size" buildings, their lack of building automation systems (BAS) and potential energy improvements, as well as challenges, are detailed in this section. Section 2.0 covers the characterization of both small-and medium-sized buildings. Drawing upon Energy Information Administration's Commercial Building Energy Consumption Survey data from various surveys, detailed discussions of energy end-use and electrical end-use consumption values are provided. This section spring boards into further discussions for the various end-use loads and the present penetration of "intelligent" controls in the existing market. Discussions of existing and possible future control methods, strategies and concepts that are applicable (including heating, ventilation and air conditioning (HVAC); lighting and miscellaneous end-use loads) complete this section. Section 3.0 discusses the different communication architectures that might be found in a small-or medium-sized building BAS, as it relates to the communication networks needed to support them. This discussion covers the different technologies that have been in place (older) or are becoming more prevalent (newer), and how they work. This includes wired solutions, wireless solutions or a combination of both (hybrid wired-wireless) networks and industry standards, open and proprietary protocols. For each solution, the limitations of each technology are detailed (speed, bandwidth, reliability, etc.). Cost factors are also discussed because this relates to how these systems are being pushed to the market, and their acceptance (or lack of). Section 4.0 describes the BAS, as has historically been seen and known in large building applications and the small-or medium-sized building applications. This section describes the history of BASs and how they have evolved and improved over time, and summarizes their core functions. This description proceeds to discuss the major architectural requirements needed by new BASs to allow for greater penetration in the existing building stock in the U.S. This section concludes by providing three different options of what a future BAS configuration might look like for either a small-sized building (two different options) or for a medium-sized building (one option). Section 5.0 presents the requirements and capabilities of various devices used to monitor and control different end-use loads found in small-and medium-sized buildings. This includes a robust presentation of the different requirements for the gateway, master controller, co...