Reducing Hospital Energy Use and Maintaining Savings Glen Anderson, PE
AIA Quality Assurance The Building Commissioning Association is a Registered Provider with The American Institute of Architects Continuing Education Systems (AIA/CES). Credit(s) earned on completion of this program will be reported to AIA/CES for AIA members. Certificates of the Completion for both AIA members and non-aia members are available upon request. This program is registered with AIA/CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product. Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation. 2
Learning Objectives 1. Identify the tools required for successful monitoring based commissioning 2. Differentiate between existing BAS capabilities and MBCx 3
Retro-Commissioning Measure Examples Major Equipment AHU economizers AHU valves AHU humidifier controls Chiller plant staging Heating plant staging Low flow cooling towers Terminal Equipment Space scheduling Occupancy sensors Repair dampers, valves, airflow stations Temperature settings Minimum airflow requirements 4
Space Scheduling When the space is unoccupied: Decrease the minimum airflow set point to 0 CFM Increase the cooling set point by 1-2F Decrease the heating set point by 1-2F Airflow will increase, if necessary, to maintain space conditioning When space is occupied, not much warm-up or cool-down will be needed If an occupant enters at night, the room will still be conditioned 5
VAV Scheduling Impact on AHU $5,600 savings just in fan power 6
Changing from CV to VAV Fan Impact 50% fan power savings = 75 kw 7
Occupancy Sensors Conference Room Conference Room VAV Box $7,925 savings per year! Occupied Air Flow Unoccupied Air Flow 8
Unoccupied Zones Overcooled as CV cooling-only box Minimal airflow maintains 72F space temp 9
Drift Following ReCx 10
Gateway MC - Monthly Electric Use Electric Use, kilowatt hours 2,000,000 1,800,000 1,600,000 1,400,000 1,200,000 1,000,000 800,000 600,000 400,000 200,000 0 2011 Energy (kwh) 2012 Energy (kwh) 2013 Energy (kwh) 2014 Energy (kwh) 2015 Energy (kwh) 11
ReCx Begins Drift Begins MBCx Begins Complete Deeper Dive 12
Complete ReCx Drift Begins 13
Complete ReCx Drift Begins 14
ReCx vs MBCx 15
Causes of Drift Operator overrides to address facility issues Balancers overriding AHU dampers during testing Valve and damper failures 16
Chilled Water Plant Override dp raised to 60 psi increases pump power by 100 kw 17
Dual Duct Air Handler Hot duct manual damper closed preventing pressure measurement (damage cold ductwork) 18
Monitoring-based Commissioning (MBCx) Platform Trend Viewer Automated Diagnostics, Fault Detection and Diagnostics many names being used Predictive Maintenance Measurement of Performance Workflow management Service Continuous Engagement Advantages Sustained Savings Identify new opportunities 19
Hospital Example Return on Investment Annual Savings $449,000 4,770,000 kwh 13,600 dtherms ROI: 225% 20
Trend Viewer 21
Hot Water Valve Leak 22
Chiller Cycling 23
Fault Detection / Predictive Maintenance 24
CHW Valve Leak Chilled water valve has failed open, over cooling SA Fault reported 25
MBCx Economizer Fix 26
When to Change Air Filters Looking for the inflection point Balancing filter change costs, energy costs, and occupant air quality 27
Filter Loading Airflow vs speed relationship drops indicating filters loading Filters replaced 28
Terminal Unit Reports Allow priority of maintenance Comfort Ventilation requirements Energy use 29
VAV Boxes not Flowing Properly 30
Notification of Faults - Email 31
Notification of Faults - Email 32
Notification of Faults (Software Interface) 33
Measurement of Performance 34
Model Baseline Energy Use Using Regression Collect historical weather and power consumption data for a period of months or years; best if hourly Use regression to relate weather-related variables to power consumption; for example, to relate temperature and humidity to kw A good regression model will have an R-squared value close to 1; this would mean that for every temperature and humidity you can use the regression equation to reliably predict power consumption Temperature Humidity kw 35
Model Baseline Using Weather Data Chiller Plant Modeled Power Use Power (kw) kw = f(temp, humidity) March Date Nov 36
Actual Performance Relative to Baseline Chiller Plant Modeled (Yellow) vs. Actual (Blue) Power Use Started Started Work Work Saved Power Power (kw) March Date Nov 37
Visualize Monthly kwh Savings Compare actual to baseline power use for each month Show kwh saved each month Show cumulative kwh saved over time 38
Workflow Management 39
Workflow Overview 40
Workflow Discussions 41
Reporting Results 42
KPI Analysis 43
Thunderbird Results Chiller plant project Fault Detection Deployed Energy Projects MBCx $800,000/year delivered (> 20% savings) 44
What Next? Chilled Water System differential pressure driven by elevator room cooling Replace fan coil with water source heat pump Modify outdoor air intakes to not draw in relief air Re-calculate minimum airflows for VAV boxes operating as constant volume boxes Reduce minimum outside air requirements for specific AHUs Standardize temperature settings in hospital 45
Identifying Opportunities and Testing Solutions 46
Controlling VAV Parameters VAV t-stats: Setting ±2F deadbands on temp set points and limiting set point range to 70 to 78F 47
Reduce Outdoor Air When Hot With outside temp = 110F, bringing in 35% to 67% outside air 48
Effective Airside Economizers OA intake draws in relief air, preventing effective economizing Relief air directed away from OA intake. MAT tracks OAT reducing cooling load Tested with cardboard will complete permanent solution on 15 AHUs 49
Questions? 50
Glen Anderson, PE ganderson@etcgrp.com