Researching plug and process loads to help generate energy cost-savings
Until recently in the conversation of a healthcare facility’s energy consumption, plug and process loads were not commonly included. Prior to 2013, the industry lacked sufficient data to justify potentially smaller power systems, thus, less energy consumption.
Mazzetti partnered with Panoramic Power as part of a collaboration supported by the Israel-US Bi-national Industrial Research and Development (BIRD) Foundation. This partnership focused on developing and testing a low-cost, nonintrusive, real-time circuit level monitoring (CLM) platform for the Healthcare sector.
When we were tasked by one of the nation’s largest not-for-profit healthcare system’s to inform one of its Medical Office Buildings’ (MOB) energy usage attributed to plug loads, we were able to apply the CLM technology. (This was the first pilot installation of 100-sensors.) The study focused on the system’s facilities in the San Francisco Bay Area, chosen to represent a range of size, age, and function within the MOB class of buildings.
Not only were we able to identify energy consumed by each facility, we were able to more granularly identify usage per department and per circuit, not merely the annual aggregate. Even further, we identified usage per specific rooms and equipment within.
With this information, we were able to make recommendations for the appropriate size power system per facility, department, room, and equipment. And we sought opportunities for reducing plug and process loads, as much possible, without compromising patient care.
Results from this study indicate that power systems for plug and process loads in MOBs are typically over-designed. These results were expected as design guidelines have lacked significant quantitative research until this study. At a building level, IEEE peak design W/SF values were 175% higher than measured values, and IEEE average design values were 260% higher. At a room level, typical industry design values were found to be an average of 160% higher than measured peak loads.
Several low to no cost changes in building operations could reduce the plug and process base load. All computers monitored in the study did not enter a sleep mode or power down during weeknights or weekends, and the computers operated at a constant standby power around 40 watts. Simply modifying computer power management settings to power off during unoccupied hours (assuming 60-hour work weeks), annual electricity savings would be about 225 kWh or $30 per computer. The savings would be significant as computers are found in a majority of exam rooms, offices, nurse stations, and reception areas.
While continued research may be needed to change IEEE standards, the results from this study can be used in energy models and design rules of thumb.
The analyzed benefits included:
- Three-year discounted payback on the proposed measures from energy savings, even when including the cost of the monitoring system.
- Ability to identify actual energy usage as opposed to those simulated via an energy model.
- Ability to see huge opportunity in plug load management, reducing otherwise, wasted energy usage.
- Ability to monitor equipment such as motors for fans/pumps/and compressors and scheduling preventative maintenance. This demonstrated that the monitoring system could potentially pay for itself in one year by identifying potential equipment failures before they occur.
- Technology can be used to offer continuous or monitoring-based commissioning (MBCx).
- Technology can be used to better inform facility and performance statistics & improve overall operational efficiency.
Mazzetti presented the results of this study at ASHRAE in 2014. They were also captured and published into: *ASHRAE Article, “AT-15-005 — PLUG AND PROCESS LOADS IN MEDICAL OFFICE BUILDINGS”And since, we have been actively working with ASHRAE towards changing the standards for load factors for our peers to use in their assumptions.
* © 2015, ASHRAE (www.ashrae.org). Published in ASHRAE Transactions 2015, Volume 121, Part 2. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAE’s prior written permission. Contact ASHRAE at www.ashrae.org. To request permission to use this article, visit www.ashrae.org. The content of the paper must match the content as published in ASHRAE Transactions.