Retrocommissioning of Existing Buildings
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Retrocommissioning of Existing
Buildings
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Presenters
Manus McDevitt, PE, LEED AP
Principal
Sustainable Engineering Group,
Madison, WI
Alex Harris,
Engineer
Sustainable Engineering Group,
Madison, WI
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• Understand the motivation and methods for
accomplishing Retrocommissioning (R-Cx)
• Appreciate the value of Retrocommissioning
by considering several case studies
• Recognize some typical issues uncovered by
Retrocommissioning
Learning Objectives
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What is Retro-Cx?
The process of optimizing the
performance of an existing building
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Retrocommissioning Benefits
• Improve building performance
• Provide appropriate training
to O&M staff
• Improve occupant comfort
• Improve system reliability
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Commercial
Industrial
Transportation
Residential
Buildings
Environmental Impact of Buildings
U.S. Energy Consumption by Sector – 2000
98.5 Quadrillion Btu
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When is Retro-Cx Appropriate?
When there is a good chance of success!
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Approach - Overview
1. Gather Information
2. Identify improvements
3. Monitor implementation
4. Functional testing
5. Update documentation, train operators
6. Final report
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1. Gather Information
From Stakeholders
From DocumentationFrom Observation
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Deliverables
• Operational Intent
– Narratives of facility functional use
– Verifiable performance criteria
– Stakeholder requirements for
• usability, operability, maintainability, functionality
• Basis of Operation
– Documents current building operation
• Installed equipment database
• Control sequences
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10,000SF Office Building Energy Use
Mid-West US (Chicago)
Space Heating,
32%
Space Cooling,
8%
Ventilation , 5%
Water Heating ,
10%
Lighting , 26%
Other, 19%
Building Energy Usage
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Approach - Overview
1. Gather Information
2. Identify improvements
3. Monitor implementation
4. Functional testing
5. Update documentation, train operators
6. Final report
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2. Identify Improvements
• Can the system meet your requirements?
– If so, tune the system to meet your needs
• Examples: Calibrate sensors, adjust control sequences, repair or
replace equipment
– If not, re-design the system as required
• Costs and savings for each improvement
– Prioritize
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Deliverable
• Facility Optimization Study
– Narrative and technical evaluation of each improvement opportunity
– Estimate of project costs
– Analysis of utility savings and other benefits
– Includes:
• Discussion of documentation improvements
• Discussion of training needs
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Audit / Investigation Phase
• Collaborate with facilities
team to identify opportunities
• Review building drawings
and documentation
• Performance testing of
building systems
• Develop list of recommended
improvements
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Potential Measures
• Operational
– Equipment schedules, set points,
• Maintenance
– Valve and damper control issues
• Design
– Identify space function changes, control optimization
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Common Problems Identified
• Time clocks disabled
• Control sequences not optimized
• Energy Management Systems not understood or fully utilized
• Controls/sensors/actuators out of calibration
• Ventilation excessive
• Documentation & training inadequate
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VAV Scheduling
15 kW
Fan Savings
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VAV Scheduling
0
200
400
600
800
1000
1200
8/14/13 8:00:00 PM CDT 8/14/13 10:30:00 PM CDT 8/15/13 1:30:00 AM CDT 8/15/13 5:00:00 AM CDT
Tota
l VA
V B
ox
Reh
eat
(kB
tu/h
r)
AHU-14/15 VAV Box Reheat
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Data Room Setpoints
Data room set-
points are too tight
for temperature and
humidity, leading to
excessive energy
use.
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Adjust CRAC Set Points
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Adjust CRAC Set Points
Annual kW-Hr
Savings
Annual Savings Implementation
Cost
Simple Payback
150,000 $10,391 $50 2 days
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AHU Chilled Water Valve Control Issue
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Cooling Tower Exhaust Dampers & Ductwork
Supports have rusted
out and fell into tower
Dampers linkages are corroded
and not functional
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Disconnected Actuator
Disconnected
actuator is causing
cooling tower to run
at the same time as
boiler. We are heating
the water, only to
reject the heat to the
outdoors
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Cracked Heat Exchanger
There is risk of
carbon
monoxide being
blown into the
occupied
space. Unit
was shutdown
and gas line
shut-off to unit.
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Duct to Nowhere
Supply duct is
blowing into
plenum space.
This area was
remodeled and
drop ceiling
added, but the
duct was never
capped, as
shown on
remodel plans.
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Poor Sensor Location
Heat pump
serving this
space is always
in cooling, even
though the
room
temperature is
65°F.
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Approach - Overview
1. Gather Information
2. Identify improvements
3. Monitor implementation
4. Functional testing
5. Update documentation, train operators
6. Final report
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3. Monitor Implementation
RCx provider’s role varies depending on
1. Needs of the client
2. Number and complexity of improvements
3. Type of improvements
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Approach - Overview
1. Gather Information
2. Identify improvements
3. Monitor implementation
4. Functional testing
5. Update documentation, train operators
6. Final report
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4. Functional Testing
• RCx provider’s role varies
• Verify the performance of building systems
• May use statistical sampling
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Approach - Overview
1. Gather Information
2. Identify improvements
3. Monitor implementation
4. Functional testing
5. Update documentation, train operators
6. Final report
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5. Documentation & Training
• Update documentation
– Drawings
– O & M manuals
– Operating sequences
– Equipment database
– Maintenance schedules
• Schedule training
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Approach - Overview
1. Gather Information
2. Identify improvements
3. Monitor implementation
4. Functional testing
5. Update documentation, train operators
6. Final report
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6. Final Report
• Based on the Facility Optimization Study
– Includes discussion of implemented projects and testing
– Reference document for future projects and operations
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Persistence
Phase:
Verify
Persistence
of Savings
(Optional)
Implementation Phase:
Implement Selected
Measures & Verify Actual
Savings
Audit Phase:
Complete Audit &
Quantify Measures
Qualify
Customer
& Submit
Application
Focus on Energy RCx Process
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Medical Clinic
• Established in 1996
• 22 Clinics
• 2 million+ outpatient visits
• 1 South Park Street
• 174,000 ft2
• 6 OR’s
• 2 MRI’s
• 392 kBtu/ft2-yr (source)
Medical Clinic, Madison, WI
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Medical Clinic
Proposed Phase Workbook
Description
Electric
Energy
Savings
(kW-hr)
Electric
Demand
Savings
(kW)
Natural
Gas
Savings
(Therms)
Measure
Installatio
n
Incentive
($)
Energy
Cost
Savings
($)
Measure
Cost ($)
Simple
Payback
(Years)
M1On all air handlers, increase economizer
switchover from 51.5°F to 68°F 101,130 - - N/A $7,079 $100 0.0
M2Modify air handler schedules 123,599 - 5,727 N/A $10,617 $100 0.0
M3 Replace RTU-2 Control Board 44,800 - 5,880 N/A $6,570 $500 0.1
M4Replace 52W Incadescent Bulbs with
CFL's 6,841 1.8 -134 N/A $231 $200 0.9
M5Install lighting occupancy sensors on
Floors 5, 6, 7 and lower level 19,314 - -358 N/A $1,098 $9,100 8.3
Proposed Phase Savings
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Medical Clinic
Project Summary
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Medical Clinic
Persistence CheckGreat Persistence:
• Controls programming changes
• VFD Installs
• Equipment Upgrades
Poor Persistence:
• Schedule modifications
• Set point modifications
• Fixing valves / equipment
(Grease Fan BRGS Yearly!!)
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Medical Clinic
Performance Since Implementation
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Medical Clinic, Madison, WI
100
200
300
400
500
600
700
1 2 3 4 5 6 7 8 9 10 11 12
Ele
ctr
ic C
on
su
mp
tio
n (
MW
-hr)
Month of year (January = 1, December =12)
Monthly Electric Consumption
2009 2010 2011 2012 2013-Pre RCx 2013 2014
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Medical Clinic, Madison, WI
Portfolio Manager Tracking
Before After
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Medical Clinic
Review of Incentives Paid Out
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Medical Clinic
Evaluate Economics
• Savings
$66,000/yr utility cost avoidance
• Expenses
$50,000 study cost
$30,000 implementation cost
• Incentive
+$63,000 incentive
• Simple Payback = 0.3 years (after incentive)
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505 Passenger Vehicles / Year
62,000 trees grown for 10 years
121 Homes / Year
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Solar Equivalent of Electric Savings
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Retro-Cx Effort at Area School
• Built in 1960’s
• Several additions in 1980’s and 1990’s
• Total area of 250,000 ft2
• 30 Air Handling Units
• Mix of Constant Volume
and VAV
• 7 Boilers and 2 Chillers
Main concern is
energy consumption
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Retro-Cx Effort at Area School
• A heating system controller was installed to allow for proper sequencing of all boiler units.
• The hot water system has been modified to allow for variable flow operation.
• Schedules have been modified to reflect space occupancy patterns for each air-handling unit zone.
• Economizer modes have been modified to improve comfort and energy efficiency
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Retro-Cx Effort at Area School
• Existing chillers are being replaced with more efficient, variable flow and smaller capacity models.
• Computer labs and the IT room have been removed from main chilled water system and are now cooled by independent cooling units, which results in a shorter seasonal operating window for the chillers and improves comfort in winter.
New
Old
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Airflow checking and rebalancing results in enhanced
occupant comfort and potentially lower operating costs
Retro-Cx Effort at Area School
• Staff have reported problems with “stuffiness” in several spaces
• Perimeter areas of Office and Guidance spaces too cold in winter
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Savings of about $30-50,000 / year in gas
Retro-Cx Effort at Area School
Normalized Gas Use Comparison
0
5000
10000
15000
20000
25000
30000
35000
October November December January February March
Ga
s U
se
(T
he
rms)
)
2005
2006
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Savings of about $10-20,000 / yr in electricity
Retro-Cx Effort at Area School
Electric Use Comparison
0
50000
100000
150000
200000
250000
October November December January February March
Ele
ctr
ic U
se
(kW
h)
)
2005
2006
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Retro-Cx Effort at Area School
OLD NEW
Electric Use (kWh) 11,000 1,900
Electric Demand (kW) 18 3
• Existing roof-mounted chilled water pipe insulation is badly deteriorated
• It is being replaced with thicker aluminum shielded, weather-resistant insulation
Savings of about $500 / yr
Savings due to improved insulation
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Retro-Cx Effort at Area School
Annual estimated savings:
$40,000 to $70,000
Estimated cost to realize savings:
~$35,000
Payback period: 6-10 months
Bonus: Improved comfort and operation!
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Life After Retrocommissioning
• RCx Process
• RCx Results
• Life After RCx
• Next Steps
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Portfolio Manager Tracking
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Continuous Commissioning Tools
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Continuous Commissioning Tools
• BAS Integrated Continuous Commissioning Tools
– “Building Analytics”
– “Building Management Performance Analytic Tools”
• Provide following capabilities
– Equipment and system fault detection and diagnostics
– Ongoing commissioning including optimization of building control
– Demand response
– Performance benchmarking
• Typically Cloud Based
– Monthly subscription fee
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LEED EB RCx
• Credits for:
– Documenting building operations and benchmarking performance
– Retrocommissioning audit phase
– Implementing identified retrocommissioning measures
– Ongoing commissioning
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What Can YOU Do?
• Benchmark your facilities
• Set goals
• Put an energy plan together
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Complete the RCx Process!
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Developing an Energy Plan
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