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.

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Learning Objectives

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1. Identify the tools required for successful monitoring based commissioning

2. Differentiate between existing BAS capabilities and MBCx

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

Retro-Commissioning Measure Examples

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• 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

Space Scheduling

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VAV Scheduling Impact on AHU

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$5,600 savings just in fan power

Changing from CV to VAV Fan Impact

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50%fanpowersavings=75kW

Occupancy Sensors – Conference Room

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OccupiedAirFlow

ConferenceRoomVAVBox $7,925savingsperyear!

UnoccupiedAirFlow

Unoccupied Zones

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OvercooledasCVcooling-onlybox

Minimalairflowmaintains72Fspacetemp

Drift Following ReCx

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11

0

200,000

400,000

600,000

800,000

1,000,000

1,200,000

1,400,000

1,600,000

1,800,000

2,000,000

ElectricUse,kilo

Watth

ours

GatewayMC- MonthlyElectricUse

2011Energy(kWh)

2012Energy(kWh)

2013Energy(kWh)

2014Energy(kWh)

2015Energy(kWh)

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ReCxBegins

DriftBegins MBCxBeginsCompleteDeeperDive

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CompleteReCx DriftBegins

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CompleteReCx

DriftBegins

ReCx vs MBCx

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• Operator overrides to address facility issues• Balancers overriding AHU dampers during testing• Valve and damper failures

Causes of Drift

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Chilled Water Plant Override

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dP raised to 60 psi increases pump power by 100 kW

Dual Duct Air Handler

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Hot duct manual damper closed preventing pressure measurement (damage cold ductwork)

• 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

Monitoring-based Commissioning (MBCx)

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Hospital Example – Return on Investment

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AnnualSavings$449,000

4,770,000kwh

13,600dtherms

ROI:225%

Trend Viewer

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Hot Water Valve Leak

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Chiller Cycling

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Fault Detection / Predictive Maintenance

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CHW Valve Leak

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Faultreported

Chilledwatervalvehasfailedopen,overcoolingSA

MBCx Economizer Fix

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When to Change Air Filters

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Lookingfortheinflectionpoint

Balancingfilterchangecosts,energycosts,andoccupantairquality

Filter Loading

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Airflowvsspeedrelationshipdropsindicatingfiltersloading

Filtersreplaced

• Allow priority of maintenance• Comfort• Ventilation requirements• Energy use

Terminal Unit Reports

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VAV Boxes not Flowing Properly

Notification of Faults - Email

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Notification of Faults - Email

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Notification of Faults (Software Interface)

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Measurement of Performance

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Model Baseline Energy Use Using Regression

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Temperature Humidity kW

Collecthistoricalweatherandpowerconsumptiondataforaperiodofmonthsoryears;bestifhourly

Useregressiontorelateweather-relatedvariablestopowerconsumption;forexample,torelatetemperatureandhumiditytokW

AgoodregressionmodelwillhaveanR-squaredvaluecloseto1;thiswouldmeanthatforeverytemperatureandhumidityyoucanusetheregressionequationtoreliablypredictpowerconsumption

Model Baseline Using Weather Data

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Power(k

W)

Date

ChillerPlantModeledPowerUse

kW=f(temp,humidity)

March Nov

Actual Performance Relative to Baseline

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Power(k

W)

Date

StartedWork

ChillerPlantModeled(Yellow)vs.Actual(Blue)PowerUse

StartedWork

March Nov

SavedPower

Visualize Monthly kWh Savings

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Compareactualtobaselinepoweruseforeachmonth

ShowkWhsavedeachmonth

ShowcumulativekWhsavedover

time

Workflow Management

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Workflow Overview

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Workflow Discussions

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Reporting Results

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KPI Analysis

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Thunderbird Results

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Chillerplantproject FaultDetectionDeployed EnergyProjects

MBCx

$800,000/yeardelivered(>20%savings)

• 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

What Next?

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Identifying Opportunities and Testing Solutions

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Controlling VAV Parameters

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VAVt-stats:Setting±2Fdeadbandsontempsetpointsandlimitingsetpointrangeto70to78F

Reduce Outdoor Air When Hot

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Withoutsidetemp=110F,bringingin35%to67%outsideair

Effective Airside Economizers

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OAintakedrawsinreliefair,preventingeffectiveeconomizing

ReliefairdirectedawayfromOAintake.MATtracksOAT–reducingcoolingload

Testedwithcardboard– willcompletepermanentsolutionon15AHUs

Questions?

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Glen Anderson, PEganderson@etcgrp.com