Non-Intrusive Electric Load Monitoring in Commercial Buildings

Increased interest in optimal control, energy scorekeeping and fault detection for HVAC equipment in commercial buildings has focused attention on instrumentation required to obtain the desired data. In this paper we investigate what can be learned from measurements of electrical power at a single point, that of the electrical service for the entire HVAC system. This low-cost measurement has proved in field tests to be capable of detecting the power change when a piece of equipment turns on or off; detecting oscillating equipment power caused by poorly tuned controllers; and detecting suboptimal staging of multiple chillers. Detection of equipment start and stop transitions was strengthened by application of a nonlinear filter that determines the point of median power from a filtering window of user-selected width. A review of electric motor literature indicated that samples of electrical current taken at slightly faster than twice the 60 Hz fundamental can be used to detect several indicators of incipient motor failure. Tests were initiated to determine whether this technique can be applied to a number of motors on the same circuit

Influence of Air Conditioner Operation on Electricity Use and Peak Demand

Electricity demand due to occupant controlled room air conditioners in a large mater-metered apartment building is analyzed. Hourly data on the electric demand of the building and of individual air conditioners are used in analyses of annual and time-of-day peaks. Effects of occupant schedules and behavior are examined. We conclude that room air conditioners cause a sharp annual peak demand because occupants have strongly varying thresholds with respect to toleration of high indoor temperatures. However, time-or-day peaking is smoothed by air conditioning in this building due to significant off-peak operation of air conditioners by some occupants. If occupants were billed directly for electricity, off-peak use would probably diminish making the peaks more pronounced and exacerbating the utility company's load management problems. Future studies of this type in individually metered apartment buildings are recommended

Empirical Modeling of a Rolling- Piston Compressor Heat Pump for Predictive Control in Low Lift Cooling

ABSTRACT Measured performance and empirical modeling of an inverter-drive

Cannabinoid Regulation of Nitric Oxide Synthase I (nNOS) in Neuronal Cells

In our previous studies, CB1 cannabinoid receptor agonists stimulated production of cyclic GMP and translocation of nitric oxide (NO)-sensitive guanylyl cyclase in neuronal cells (Jones et al., Neuropharmacology 54:23–30, 2008). The purpose of these studies was to elucidate the signal transduction of cannabinoid-mediated neuronal nitric oxide synthase (nNOS) activation in neuronal cells. Cannabinoid agonists CP55940 (2-[(1S,2R,5S)-5-hydroxy-2-(3-hydroxypropyl) cyclohexyl]-5-(2-methyloctan-2-yl)phenol), WIN55212-2 (R(+)-[2,3-dihydro-5-methyl-3-[(morpholinyl)methyl]pyrrolo[1,2,3-de]-1,4-benzoxazinyl]-(1-naphthalenyl)methanone mesylate), and the metabolically stable analog of anandamide, (R)-(+)-methanandamide stimulated NO production in N18TG2 cells over a 20-min period. Rimonabant (N-(piperidin-lyl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-H-pyrazole-3-carboxamide), a CB1 receptor antagonist, partially or completely curtailed cannabinoid-mediated NO production. Inhibition of NOS activity (NG-nitro-l-arginine) or signaling via Gi/o protein (pertussis toxin) significantly limited NO production by cannabinoid agonists. Ca2+ mobilization was not detected in N18TG2 cells after cannabinoid treatment using Fluo-4 AM fluorescence. Cannabinoid-mediated NO production was attributed to nNOS activation since endothelial NOS and inducible NOS protein and mRNA were not detected in N18TG2 cells. Bands of 160 and 155 kDa were detected on Western blot analysis of cytosolic and membrane fractions of N18TG2 cells, using a nNOS antibody. Chronic treatment of N18TG2 cells with cannabinoid agonists downregulated nNOS protein and mRNA as detected using Western blot analysis and real-time polymerase chain reaction, respectively. Cannabinoid agonists stimulated NO production via signaling through CB1 receptors, leading to activation of Gi/o protein and enhanced nNOS activity. The findings of these studies provide information related to cannabinoid-mediated NO signal transduction in neuronal cells, which has important implications in the ongoing elucidation of the endocannabinoid system in the nervous system

Park Load Reduction by Preconditioning of Buildings at Night

Cooling loads during the peak period can be reduced if a building is subcooled a few degrees below its normal thermostat setpoint during the preceding night. During the day, the thermostat must control the warmup in such a way that the stored energy is released when it brings maximum, benefit. This strategy exploits the heat capacity of the building itself; it can be implemented at low cost and without sacrifice in comfort. To evaluate the strategy for a given building and control the thermostat one needs to know the thermal behavior of the building. Building temperature, internal load and solar data are used to determine values of a small number of thermal parameters which characterize the building. Several thermostat control strategies. distinguished by their knowledge of the building dynamics, are described and simulated, both with a data-based dynamic model. Universal graphs for effective storage capacity and storage efficiency are developed. A simple economic analysis shows that subcooling is likely to be cost-effective for many commercial buildings with current electric rate schedules

Park Load Reduction by Preconditioning of Buildings at Night

Cooling loads during the peak period can be reduced if a building is subcooled a few degrees below its normal thermostat setpoint during the preceding night. During the day, the thermostat must control the warmup in such a way that the stored energy is released when it brings maximum, benefit. This strategy exploits the heat capacity of the building itself; it can be implemented at low cost and without sacrifice in comfort. To evaluate the strategy for a given building and control the thermostat one needs to know the thermal behavior of the building. Building temperature, internal load and solar data are used to determine values of a small number of thermal parameters which characterize the building. Several thermostat control strategies. distinguished by their knowledge of the building dynamics, are described and simulated, both with a data-based dynamic model. Universal graphs for effective storage capacity and storage efficiency are developed. A simple economic analysis shows that subcooling is likely to be cost-effective for many commercial buildings with current electric rate schedules

Monitoring energy use of copiers to determine program design and potential savings for the energy star copier program

In the past five years, considerable attention has been focused on the electricity use of office equipment in commercial office buildings. Several groups have monitored energy use of PCs, monitors, printers and fax machines. However, little attention has been paid to monitoring energy use of copiers. Procedures for testing energy usage and usage profiles of copiers are needed to make valid comparisons between machines and to determine overall energy use and potential energy savings. In this paper, the authors present a method to analyze the energy use and usage profiles of copiers. This method is determined through long-term measurements from a Watt-hour meter connected to the copier and by measuring light flashes from the copier. Energy use from the copier can also be estimated by using a test procedure developed by Dandridge. Results from using the long term monitoring methods will be presented for several different sized copiers, and compared to the estimated energy use derived from the American Society for Testing and Materials (ASTM) method. After summarizing these results, the authors determine criteria for a program to recognize energy-efficient copiers. These criteria were submitted as an Energy Star Copier program to the Environmental Protection Agency (EPA). The new Energy Star Copier Program was announced in July 1995, with criteria based on these suggestions. Using the final Energy Star Copier program criteria and this data, the authors determine potential future savings for the program. The ability to automatically turn the copier off at night is the greatest energy-saving feature most copiers can have. The best way to reduce overall office costs is to have the copier set automatically to make double-sided copies