Hospital Case Study

Energy Management Information System (EMIS) – Case study

The Energy Management Information System (EMIS) demonstration and study when conducted will likely focus on an analysis of the existing electrical system circuits in a facility. Thus, the purpose of the study would be to examine specific loads, utilizing digital meters, in order to demonstrate the economic and technical value of an EMIS for this particular application.

Such analysis can be performed in various ways. An example would be to install electrical measuring devices specifically designed for that purpose on existing circuits.

Kilowatt-Hour Usage

Kilowatt-hour usage reflects electrical energy consumption on an hour-by-hour basis. It also acts as a proxy for electrical demand which is billed monthly on an instantaneous basis, and is measured at the peak load in kilowatts in any given fifteen minute interval within the month.

Data is taken all through a month of May, which show consistent patterns, and can, therefore, provide some reliable indicators of the behavior of the electrical loads under examination.

The kitchen utilizes couple of circuits, and the facility may have a laundry that could utilizes one. All three meters were connected to the feeders to the panels, and reflect the consumption of the entire panel, but do not directly measure any branch circuit that supplies individual loads.

For few days were obtained some power consumption which appeared to be quite predictable. For the kitchen, each circuit shows a base load of approximately five kilowatts (kW) for the late night/early morning hours from 11 p.m. to 5 a.m. Between 5 a.m. and 11 p.m., the load climbs to a base of approximately 15 kW with a very pronounced, but consistent, set of demand peaks of approximately 30 kW, 25 kW and 20 kW that occur around 10:00 a.m., 2 p.m. and 7 p.m.

As the data is relatively consistent on all three days, we can reasonably conclude that the three peaks are a regular phenomena, and are most likely attributable to the presence of an electrical booster that provides sanitary cycle rinse water to the dishwasher at a temperature of 185 degrees Fahrenheit. The domestic water supply is normally maintained at temperatures of 120° to 140° Fahrenheit for the balance of the facility, and must, therefore, be separately boosted in order to achieve the legally mandated higher temperature for dishwashing. As this is done through electrical means, the cost of the power for this individual device can be reasonably determined as follows:

The booster appears to be in use for approximately 9 hours per day with an added demand of some 15 kW. At 11 cents per kWh for energy plus approximately 3 cents for distribution with $4.55 for demand, the cost per hour is 14 cents per kW per hour plus the monthly incremental demand.

 

This calculates to $1.26 per hour or $11.34 per day. On a monthly basis, this adds approximately $351 to consumption with an extra $68.25 for demand. The total effect of this load is approximately $421 per month. If this load were supplied by stored water from a co-generator supplied reserve tank, the monthly expense could possibly be eliminated.

The total expense associated with the kitchen alone is approximately $1400 for consumption (kWh) with and additional $135 attributable to demand for a total monthly cost to be approximately $1535.

The laundry was measured as a single circuit and its pattern is quite consistent. The laundry shows a 24 hour base load of approximately 1 kilowatt, increasing to 5 kW for the period from 7 a.m. to 5 p.m. after which the load tapers off gradually to 1 kW somewhere around 10 p.m. This load does not exhibit any unusual peaks and indicates that the machines are used fairly continuously for the bulk of the day.

Calculating the cost of electricity for the laundry, we estimate 1 kW of 24-hour baseload with an additional 4 kW of peak load running for 12 hours per day. Using the same kWh, distribution and demand costs, the electrical expense attributable to the laundry is $10.08 per day plus demand contribution of $22.75 each month. This amounts to a monthly expense of approximately $325 based upon the laundry alone. There may be ways to cut this expense, but this would require an examination of both laundry operations as well as machine efficiency.

Summary and conclusion

The written analysis provides a sample of the types and quality of information available to a user through an EMIS. For even a limited study such as the one conducted for that site on the kitchen and laundry loads, appropriate use of this information could yield some degree of savings through the ability of the EMIS to pinpoint high consumption patterns or other abnormalities of the electrical load.

This demonstrates that on even a limited basis, the EMIS can act as tool to identify excess energy costs. identify problem trends as they develop, and act as a cost-center accounting tool to determine the ongoing expense of particular areas of a given facility.