1. Commercial Building Re-tuning: Overview and Key Operational Faults and Corrections
Srinivas Katipamula, Ph.D.
Staff Scientist, Pacific Northwest National Laboratory
Better Building by Design – 2011
February 10th, Sheraton Conference Center Burlington, Vermont

2. Presentation Outline Learning Objectives
Definition of Retro-Commissioning and Re-tuning
Why Retro-Commission a Building?
Washington State Project Approach to Re-tuning
U.S. Department of Energy Project on Re-tuning
Overview of Re-tuning Training
Identifying Low-cost/No-cost Operational Faults Using the Re-tuning Approach
Common Operation Faults
Example Operational Faults
Results from Re-Tuning Buildings
Conclusions

3. Efficiency Vermont 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 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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4. At the end of this program, participants will be able to:
Learning Objectives
At the end of this program, participants will be able to:
Understand an overview of Commercial Building Re-Tuning
Understand Key Building Operation Faults and Their Corrections (These presentations will provide an overview of the re-tuning process including the difference between re-tuning and other similar approaches)
Describe the various steps in the re-tuning process
Identify targets that commonly yield significant improvements in operation and decreases in energy use and discuss how re-tuning can yield a “gold mine” in savings
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6. Definitions HVAC Retro-commissioning HVAC Re-tuning
HVAC Re-commissioning
HVAC Continuous CommissioningSM
Monitoring-Based Commissioning
All processes above in part relate to setting up control systems to some known design configurations, verifying set points and adding control algorithms

7. Why Retro-Commission a Buildings?

8. Retro-Commissioning Literature
A number of studies have shown that retro-commissioning buildings can lead to significant energy savings – 5 to 30%
Cost of retro-commissioning varies between 0.1$/sf to 0.6$/sf
Cost savings can range between 0.1$/sf to 0.75$/sf
Simple payback ranging from 3 months to 3 years
A number of the measures addressed by retro-commissioning relate to our inability to control the building operations

9. Why is Retro-Commissioning not Widely Used?
4/1/2017
Why is Retro-Commissioning not Widely Used?
There is a perception that retro-commissioning can be expensive
It can be expensive, but typically has less than 3 year paybacks
There is a perception that measures addressed during retro-commissioning do not persist for a long time (>6 months)

10. Re-tuning can Fill the Gap
Re-tuning can address both the cost and the persistence question
Because re-tuning is implemented by leveraging information from building automation system and primarily targets operational problems, cost of implementation is significantly lower than retro-commissioning
Because re-tuning costs a fraction of retro-commissioning, it can be periodically done to ensure persistence

11. Origins for Re-Tuning
In 1990s several researcher organizations were developing automated fault detection and diagnostics (FDD) tools – the researchers found that the FDD tools can indeed be used for commissioning building systems
Also, at the same time Texas A&M University was using a process called continuous commissioning to retro-commission existing buildings
In 2000s monitoring-based commissioning was being applied at many California campuses

12. What is Re-Tuning?
A systematic process to identify and correct building operational problems that lead to energy waste
Implemented primarily through the building control system at no cost other than the labor required to perform the re-tuning process
Includes small, low-cost repairs, such as replacing faulty sensors
Includes identifying other opportunities for improving energy efficiency that require investment
Might be thought of as a scaled-down retro-commissioning focused on identifying and correcting operational problems

13. Major Focus Areas in Re-Tuning
Occupancy scheduling
Discharge-air temperature control
Discharge-air static pressure control
Air-handling unit (AHU) heating & cooling
AHU outside/fresh air makeup
AHU economizer operation
Zone conditioning
Meter profiles
Central plant

14. Purpose of Re-Tuning
Improve the building’s energy efficiency through low-cost and no-cost operational improvements (mostly control changes)
Identify opportunities to further increase the building’s energy efficiency
Identify problems requiring physical repair
Catch the big energy saving opportunities

15. Life Cycle of Retro-Commissioning/Re-Tuning
Typical commercial building behavior over time
Energy Consumption
Periodic Re-tuning Ensures Persistence
Continuous Re-tuning Maximizes Persistence
Time

16. Washington State Re-Tuning Pilot Project

17. Large Commercial Buildings Project
Goal
Educate companies that large buildings can be re-tuned economically to save electricity
Teach the proper techniques and skills to perform re-tuning, and
Show that service providers can provide re-tuning as a service for a fee
Approach
Recruit 5 to 10 companies that provide HVAC services to commercial buildings to deliver re-tuning services and to help recruit customers
Each of the selected service providers are required to recruit at least 6 buildings for re-tuning
Use 10 to 20 of the buildings as training grounds for hands-on training of the HVAC service providers on how to perform re-tuning

18. U.S. Department of Energy Re-Tuning Project

19. U.S. Department of Energy Re-Tuning Training Outreach
Re-tuning Training was Originally Developed as part of a Project Funded by Washington State (
Extending Training Outreach Beyond WA State (
Organization with large building stock interested in getting trained in the re-tuning process
Train-the-trainer – secondary goal
Working with a number of organizations to recruit for both the above approaches

20. Online Interactive Re-Tuning Training
PNNL is also converting the training into an online interactive training
Role based training with help of learning management system
Modular
Interactive with ability to create abnormal conditions
Questions and answers at the end each module and at the end of the course
PNNL is also looking to automate identification of the no-cost/low-cost operational problems
To improve persistence and cost of retro-commissioning

21. Project Objective
Improve operational efficiency of the commercial building sector by transferring the skills to “re-tune” large commercial buildings
Training building operators and service providers in the general principles and practices of good energy management
Publicizing the results of the project to other building operators and HVAC service providers, who are not part of the training, and to customers to encourage widespread adoption of these energy-saving methods
Preparing case studies to quantify comfort impact and energy savings resulting from re-tuning

22. Overview of Re-tuning Training

23. Re-tuning Training Training consists of two parts Classroom training
6 to 8 hours, limited to 20 to 25 people
Field training
1 day to 3 days, depending on the size of the building
Limited to 4 to 8 people

24. Intent of Re-tuning Training
Provide an in-depth training of the re-tuning approach
Prepare the participating technicians for hands-on field training
Provide an opportunity to ask questions and get clarification on any aspect of the re-tuning process
“Tell me and I'll forget;
show me and I may remember; involve me and I'll understand”
Chinese Proverb

25. Six Primary Steps of Re-Tuning
Collecting Initial Building Information: Basic building information
Pre-Re-Tuning Phase: Trend-data collection and analysis
Building Walk Down: Getting to know the building
Re-Tuning: Identifying and correcting operations problems
Post Re-Tuning: Reporting re-tuning findings
Savings Analysis: Determining and reporting the impacts

26. Six Primary Steps of Re-Tuning
Collecting Initial Building Information: Basic building information
Pre-Re-Tuning Phase: Trend-data collection and analysis
Building Walk Down: Getting to know the building
Re-Tuning: Identifying and correcting operations problems
Post Re-Tuning: Reporting re-tuning findings
Savings Analysis: Determining and reporting the impacts

27. Information to Collect
Overall building geometry
Approximate gross square feet
Number of floors
General building shape
Type of HVAC system(s)
Approximate number of zones
Approximate number of each major type of equipment
Boilers
Chillers
Air handlers
Type of building automation system (manufacturer, model, version)

28. Collecting basic building information
If you manage the building, you probably have all or most of this information at your fingertips
Gather information to guide selection of trend logs to set up in the next phase
Determine the overall design of the building and its mechanical systems

29. Six Primary Steps of Re-Tuning
Collecting Initial Building Information: Basic building information
Pre-Re-Tuning Phase: Trend-data collection and analysis
Building Walk Down: Getting to know the building
Re-Tuning: Identifying and correcting operations problems
Post Re-Tuning: Reporting re-tuning findings
Savings Analysis: Determining and reporting the impacts

30. Trend-Data Collection & Analysis: Purpose
Detect potential operational problems even before visiting the building
Identify problems that require time histories to detect – incorrect schedules, no use of setback during unoccupied modes, poor economizer operation

31. Steps for Trend Data Collection
Develop a monitoring plan – develop forms to guide service providers through this. Plan includes the points to trend and for each point:
Planned trend start time
Planned trend end time
Length of measurement period (2 weeks recommended)
Time interval between logged measurements (30 minutes or less recommended)
Measurement units (e.g., F for temperature)
Implement trend logs in control system

32. Analyze Trend Log Data – Major Steps
Download trend log data files from BAS
Format data files for compatibility with the spreadsheet analysis tool
Open data files in spreadsheet analysis tool and automatically generate graphs
Review graphs to identify operational issues
Record operational issues for reference during re-tuning

33. Review Graphs & Identify Operation Issues
Issues to investigate with trend log data
PNNL spreadsheets automatically generate graphs needed
We’ll look at some examples of what to look for
Online reference document provides additional information and examples, which you can refer to any time you need to (see
Seven issues
Occupancy Scheduling
DAT Control
DAP Control
AHU heating and cooling at the same time.
AHU OSA problems
AHU Econo problems
Zone conditions
Meter profiles
Central Plant

34. ECAM ≡ Energy Charting And Metrics
ECAM Software
ECAM ≡ Energy Charting And Metrics
Five Easy, Simple Steps
Select data from existing spreadsheet
Map points (optional; required for Re-tuning)
Create schedules (optional)
Input energy project dates (optional)
Create metrics and charts
Will go thru at lunch time and show how it works.

35. Re-tuning Menu

36. ECAM: Example AHU Time Series Charts
Outdoor, return, mixed, and discharge air temperatures vs. time
Discharge air temperature and discharge air temperature set point vs. time
Outdoor air fraction and damper position signal vs. time
Outdoor and return air temperatures, damper position signal vs. time
Damper, chilled water valve, and hot water valve position signals vs. time
Damper position signal vs. time
Discharge static pressure vs. time
Supply fan speed, status, and static pressure vs. time
Return fan speed and status vs. time

37. ECAM: Example AHU Scatter Charts
Discharge air temperature vs. discharge air temperature set point
Chilled water signal vs. hot water signal
Damper signal vs. outdoor air temperature
Mixed air temperature vs. outside air temperature

38. ECAM: Example Zone Charts
Zone damper position signal, reheat valve position signal, occupancy mode, and
Zone temperature vs. time.

39. ECAM: Example Central Plant Charts
CHW supply, return, ΔT, and outdoor air temperature vs. time
HW supply, return, ΔT, and outdoor air temperature vs. time
CHW flow and outdoor air temperature vs. time

40. Six Primary Steps of Re-Tuning
Collecting Initial Building Information: Basic building information
Pre-Re-Tuning Phase: Trend-data collection and analysis
Building Walk Down: Getting to know the building
Re-Tuning: Identifying and correcting operations problems
Post Re-Tuning: Reporting re-tuning findings
Savings Analysis: Determining and reporting the impacts

41. Building Walk Down: Purpose
Get to know the building better
Develop a general impression of:
Overall building condition
Overall building design
HVAC system design
Collect some basic data on the building systems at a level of detail greater than the initial data collection

42. Building Walk Down: Major Steps
Review electrical and mechanical prints
Walk the outside of the building
Walk the inside of the building
Walk down the roof
Walk down the air handlers
Walk down the plant area
Review the DDC system (BAS) front end

43. Six Primary Steps of Re-Tuning
Collecting Initial Building Information: Basic building information
Pre-Re-Tuning Phase: Trend-data collection and analysis
Building Walk Down: Getting to know the building
Re-Tuning: Identifying and correcting operations problems
Post Re-Tuning: Reporting re-tuning findings
Savings Analysis: Determining and reporting the impacts

44. Occupancy Scheduling Shut off systems whenever possible
Night unoccupied schedules
Weekend unoccupied schedules
Daytime no or low use unoccupied schedules
Auditorium, class rooms, conference rooms
Includes lighting
Includes specialized exhaust
Do not restart too early
Use a startup schedule based on building needs
Do not use fresh air during warm-up except last 30 minutes for flushing building 44

45. Occupancy Scheduling (continued)
Shut off systems whenever possible
Refrain from starting up system for the occasional nighttime user or weekend user
Use bypass buttons
Unoccupied mode is a major cost saver
Simple to implement
Simple to track
Simple to administer
Sometimes the least paid employee is the most costly
Janitors working at night with all HVAC running, all fresh air open & lights on
Is this required?

46. Occupancy Scheduling (continued)
When running at night for warm up, cool down, or maintaining temperatures, do not ventilate (no outside air)
Run static pressure at ½ of normal set points, if it does not affect reheat controls
Check to make sure heated areas get full air in unoccupied modes
Push unoccupied mode air to where it is needed
Set VAV boxes in interior zones to unoccupied with 0 air flow
Set VAV boxes with reheat to a high air flow in unoccupied mode, so box will be 100% open during night cycling
Air gets to zones needing heat

47. Occupancy Scheduling (continued)
Building electric consumption should show significant energy drop for nights/weekends
Signifying setbacks are active on all HVAC systems
Base load versus peak loads should be at least 30% difference and as much as 50% with aggressive setbacks
Trended data for zone temps should show 5-10oF deviations from set points when setbacks are active during non-shoulder months
Winter zone temps should drop down to 60-65oF and summer zone temps should rise to 80-85oF

48. Occupancy Schedule (continued)
Trended data for discharge static pressures should show readings of 0” or at least 50% (half) of normal (occupied) static pressure readings
Trended data for main supply/return fan status should indicate “OFF” during unoccupied periods
Trended data for VAV boxes occupied status should indicate “Unoccupied” during unoccupied periods
Trended data for support systems (reheat pumps, reheat converters, reheat hot water boilers, chillers, towers, pumps, etc) should indicate they are turning off at night, if all areas of the building are also shut down

49. Occupancy Schedule (continued)
Unoccupied periods should include weekends, holidays and night hours during work week periods
If facility has sporadic use periods, this may require additional efforts to succeed at implementing setbacks
Make sure the “tail” is not “wagging the dog” – janitors, special events, extreme weather events, overrides, etc
How does your organization respond to trouble calls (occupant complaints)? How do you respond? Is the response a “band-aid” or a long-term solution? Overrides on schedules are not long-term solutions

50. Air Handler Data Analysis
4/1/2017
Air Handler Data Analysis
Key conditions to look for while analyzing the charts:
Unoccupied or 24/7 operation
Unoccupied hour setback
Lower/higher than expected supply air temperature
Excessive outdoor air intake
During occupied periods
During pre-/pre-cooling periods
Significant reheat during summer/cooling season
Is the supply fan modulating (if VAV)
Higher than normal static pressure
Set point and static pressure resets
Economizer is not utilized or not working properly

51. Fan Operation During Occupied and Unoccupied Periods

52. Air Handler Data Analysis: Static Pressure
Purpose: Determine whether the static pressure set point is too high or too low
Approach:
For each air handler, review a plot of the damper positions of all VAV units vs. time
Look for situations where:
Most dampers are nearly closed during cooling – static pressure too high
Several VAV boxes on an air handler have dampers fully open – static pressure is too low and VAV boxes are not able to meet zone loads – starved boxes
Dampers are not modulating as conditions change – VAV boxes that are not being controlled or not responding to control signals

53. Zone Heating and Cooling Demands (continued): Example Use of Graphs
Plot of VAV unit dampers vs. time for all VAV units served by an air handler – Very Good Distribution – Most 50% to 75% open

54. Zone Heating and Cooling Demands (continued): Example Use of Graphs
Plot of VAV unit dampers vs. time for all VAV units served by an air handler – Distribution Marginally OK

55. Zone Heating and Cooling Demands (continued): Example Use of Graphs
Plot of VAV unit dampers vs. time for all VAV units served by an air handler – Bad Distribution – Too many near fully open

56. Zone Heating and Cooling Demands (continued): Example Use of Graphs
Plot of VAV unit dampers vs. time for all VAV units served by an air handler – Bad Distribution – Too many near fully closed

57. Zone Damper Position
50% or less
50~99%
100%
Some building automation systems provide information about the status of zone dampers
Plotting the information as a function of time, will tell you whether or not the fan static pressure is appropriate
162 -
(82%) 27
(14%) 8
(4%)

58. Air Handler Data Analysis: Discharge Set point
Purpose
Review discharge air temperatures for the air handlers
Determine whether discharge air temperatures are maintained relatively stable
Determine whether the discharge-air temperatures are too cool or too warm
Approach
For each air handler monitored, review plots of discharge-air temperature and discharge-air set point vs. time and supply-air temperature vs. supply-air set point
Look for deviations between discharge-air temperatures and set points
Look for unusually high (> 70F) or low (< 55F) discharge-air temperatures

59. Air Handling Unit: Minimum Outdoor-Air Operations
Purpose
Review minimum outdoor-air operations
Determine whether sufficient outdoor air is being supplied for ventilation
Determine whether more outdoor air than needed is being brought in at times (e.g., when the outdoor-air temperature < 40F or > 60F or when the zones served are unoccupied)
Determine whether outdoor-air dampers close during night and weekend setback and during startup mode in the morning.

60. Air Handling Unit: Minimum Outdoor-Air Operations (continued)
Approach
For each air-side economizer, review plots of:
Outdoor-air fraction (OAF) vs. time
Outdoor-air damper and occupancy mode vs. time
Outdoor-air fraction vs. fan speed (if available)
Determine if OAF > minimum OAF for ventilation when the system is not economizing
Determine whether outdoor-air ventilation is being provided when the building is unoccupied and ventilation is not required for some other reason
If OAF and fan speed are tracking each other, it is an indication of return-air problems
20% damper position is never 20% outdoor air
Need to add oaf formula

61. Air Handling Unit: Minimum Outdoor-Air Operations (continued)
Potential issues to identify
Insufficient outdoor-air ventilation provided – minimum outdoor-air fraction (OAF) is too low
Too much outdoor-air ventilation provided when the air handler is not economizing
Too much outdoor-air ventilation provided during unoccupied times (nights and weekends), during setback
Use air fraction to find % of outside air
Works if air is mixed relatively evenly
OAF = ((Return-Mixed)/(Return-Outside))*100
Add into code for all air handlers and track history
Especially schools and other public spaces

62. Economizer Fundamentals The Basics of Airside Economizers
Airside Economizer: “A duct-and-damper arrangement and automatic control system that, together, allow a cooling system to supply outdoor air to reduce or eliminate the need for mechanical cooling during mild or cold weather.”
Return Air
Relief Air
Supply Air
Outdoor Air
Airside economizers simply utilize air source energy from outside the building to cool the building or to supplement the mechanical cooling system. Typically a air source system will use duct work on a central air handling unit (AHU) or on a packaged rooftop unit (RTU).
Typically automatic controls will operate the economizer cycle automatically.
_______________________________________________________________
Source: ASHRAE Standard

63. Potential Economizer Savings from Enthalpy Control
Approximately
15% Savings
_______________________________________________________________
Source: Honeywell Controls

64. Economizer Operation Purpose
To determine whether air-side economizers are operating properly
Do economizers open, close, and/or modulate under appropriate conditions?
At what temperature compared to the discharge temperature?
At what apparent control signal values do the economizers open?
Does the cooling coil operate (chilled water flow) during economizing?

65. Economizer Operation (continued)
Approach
For each air-side economizer, review plots of:
Outdoor-air temperature, mixed-air temperature, return-air temperature and discharge-air temperature vs. time
Outdoor-air damper position (% open), outdoor-air temperature, and return-air temperature vs. time
Outdoor-air damper position and chilled-water valve position (% open) vs. time
Look for outdoor-air dampers (economizer) open at unusual times of day or under unusual outdoor temperature conditions
Look for outdoor-air dampers not open to economizer under favorable conditions (outdoor-air temperature between 40F and 60F)
Look for outdoor-air damper not closing to minimum position for freeze prevention when outdoor temperature is less than about 40F

66. Economizer Operation (continued)
Potential issues to identify
Incorrect economizer operation – numerous causes (identified later during on-site work)
Incorrect control strategy
Stuck dampers
Disconnected or damaged linkages
Failed actuator
Disconnected wires
Failed, uncalibrated or miscalibrated sensors
2 X 4 in damper
Others?

67. Economizer Operation (continued): Example use of Graphs – 1 Day
Return
Discharge
Outdoor
Mixed

68. Economizer Operation (continued): Example use of Graphs – 3 Days

69. Economizer Operation (continued): Example use of Graphs – 1 Day - Faulty
Outdoor-Air Damper Stuck Fully Closed
Return
Mixed
Discharge
Outdoor

70. Economizer Operation (continued): Example use of Graphs – 1 Day - Faulty
Outdoor-Air Damper Stuck Fully Open
Return
Discharge
Outdoor
Mixed

71. ECAM: AHU Scatter Plot Sample

72. Why Economizers Fail and Increase Energy Use
Jammed or frozen outside-air damper
Broken and/or disconnected linkage
Nonfunctioning actuator or disconnected wire
Malfunctioning outside air/return air temperature sensor
Malfunctioning controller
Faulty control settings
Installed wrong or wired incorrectly
Disconnected Damper
_______________________________________________________________
Source:
Financial Times Energy
Wired poorly
Jammed/Frozen Damper

73. Poorly Designed Packaged Rooftop Units with Economizer Installed Next to Heat Source from Condenser
This economizer in this picture will never work correctly because of the rejected heat from the condenser at the intake of the outside air dampers.
_______________________________________________________________

74. Inefficient Designs on RTU Contribute to Poor Air Circulation at Intake Air
Notice, this picture shows brand new RTU equipment on a building in Notice the outside air intake is either right on top of the exhaust or next to the exhaust on the unit. The bottom right picture shows a exhaust damper against a wall. Adjacent to the wall, next to the exhaust is the outside air intake for bring fresh air into the building. This is not a good design and will never work properly unless duct work is added to the unit to exhaust the air properly.
_______________________________________________________________ 74

75. Air Handling Unit: Outdoor-Air Lockouts for Heating & Cooling (continued)
Potential issues to identify
Air-handler heating and cooling coils operating simultaneously
Heating and cooling lockouts possibly overlapping (need to be confirmed in control-code settings during on-site re-tuning)
Unreasonable values are set for the heating and cooling lockouts

76. Outdoor-Air Lockouts for Heating & Cooling (continued): Example use of Graphs
Air handler heating vs. cooling valve positions
Worse
Bad

77. Zone Heating and Cooling Demands
Purpose
Get a feel for how many zones on each monitored air handler are heating and how many are cooling at the same time
Get a sense of which areas are heating and which are cooling at any given time
Determine if any individual zones are heating and cooling at the same time
Others?

78. Zone Heating and Cooling Demands (continued)
Approach
For each air handler, count the number of zones served that are in heating mode and those in cooling mode under various conditions (e.g., time of day and approximate outdoor air temperature). Use a plot of number of zones in each mode and the outdoor temperature vs. time
Note which areas of the building (e.g., interior core vs. perimeter zones or zones facing certain directions) are in heating and cooling
Look for any monitored zones that are using both heating and cooling over relatively short time periods or cycling between heating and cooling

79. Zone Heating and Cooling Demands (continued)
Potential issues to identify
Supply-air temperature too cool or too warm
No use of supply-air reset
Certain zones (e.g., corner offices) driving air handler operation
Some zones out of control, oscillating between heating and cooling
Others

80. Importance of Terminal Units Re-tuning
4/1/2017
Importance of Terminal Units Re-tuning
Terminal boxes are major building HVAC components and directly impact comfort and energy costs
Terminal boxes control may cause occupant discomfort and waste energy, if they have inappropriate operation and control
Improper minimum air flow setting and control may result in significant simultaneous heating and cooling, extra fan power consumption and higher energy consumption in the summer

81. Sign of Problem with Zone Control!

82. Sign of Problem with Zone Control!

83. What’s Wrong with this?
Thermostat

84. Central Plant and Whole Building Meter Profiles
Training also covers
Chiller and boiler plants
Meter profiles

85. Re-tuning Examples

86. Re-tuning Example
VFD speed is greater than 80% before re-tuning; note the speed after re-tuning

87. Re-tuning Example (cont)
Lockout chilled water consumption in winter

88. Re-tuning Example (cont)
Eliminated alternating cooling/heating

89. Six Primary Steps of Re-Tuning
Collecting initial building information: Basic building information
Pre-Re-Tuning Phase: Trend-data collection and analysis
Building Walk Down: Getting to know the building
Re-Tuning: Identifying and correcting operations problems
Post-Re-Tuning: Reporting re-tuning findings
Savings Analysis: Determining and reporting the impacts

90. Post-Re-Tuning: Calculating Energy Savings – Overview of Approach
Calculated as the difference between the actual energy use in the post-re-tuning 12 months and the energy use that would have occurred during the same 12 months if the building had not been re-tuned.
= energy savings for a specific building (j)
= actual measured energy use of the building during the 12 months after re-tuning
= energy consumption of the building during the 12 months after re-tuning if it had not been re-tuned

91. Highlights of Re-Tuning
Every set point adjustment made will have an impact of some sort on the utility meter
Can save energy and keep occupants comfortable
It takes time to tune a building
There are no magic set points that work all the time
Always monitor the utility meters (gas & electric) to see what affect you have had
Look at the big picture when making adjustments
Watch the meter profiles weekly
Learn and know the building’s personality

92. Questions?