Presentation on theme: "Srinivas Katipamula, Ph.D."— Presentation transcript:
1 Commercial Building Re-tuning: Overview and Key Operational Faults and Corrections Srinivas Katipamula, Ph.D.Staff Scientist, Pacific Northwest National LaboratoryBetter Building by Design – 2011February 10th, Sheraton Conference Center Burlington, Vermont
2 Presentation Outline Learning Objectives Definition of Retro-Commissioning and Re-tuningWhy Retro-Commission a Building?Washington State Project Approach to Re-tuningU.S. Department of Energy Project on Re-tuningOverview of Re-tuning TrainingIdentifying Low-cost/No-cost Operational Faults Using the Re-tuning ApproachCommon Operation FaultsExample Operational FaultsResults from Re-Tuning BuildingsConclusions
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.AIA Providers can use their own powerpoint template as long as it doesn’t have your company logos. To personalize this slide, please insert your company name in the purple area. You may change the color used in the text. All other wording on this slide is mandatory and cannot be changed.
4 At the end of this program, participants will be able to: Learning ObjectivesAt the end of this program, participants will be able to:Understand an overview of Commercial Building Re-TuningUnderstand 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 processIdentify targets that commonly yield significant improvements in operation and decreases in energy use and discuss how re-tuning can yield a “gold mine” in savingsTo personalize this slide, please insert your four learning objectives in the purple area on this slide. You may change the color used in the text. Be sure that these four learning objectives are identical to the ones that were submitted on the course registration. Please remove the “sample slide” lingo from the upper right hand corner of the page.
5 Course EvaluationsIn order to maintain high-quality learning experiences, please access the evaluation for this course by logging into CES Discovery and clicking on the Course Evaluation link on the left side of the page.As a new requirement, Providers are required to encourage members to complete the online CES Discovery Evaluation. You may still use your own paper evaluation form to collect feedback for your personal records, however our online evaluation must still be encouraged.
6 Definitions HVAC Retro-commissioning HVAC Re-tuning HVAC Re-commissioningHVAC Continuous CommissioningSMMonitoring-Based CommissioningAll processes above in part relate to setting up control systems to some known design configurations, verifying set points and adding control algorithms
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$/sf to 0.6$/sfCost savings can range between 0.1$/sf to 0.75$/sfSimple payback ranging from 3 months to 3 yearsA 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? 4/1/2017Why is Retro-Commissioning not Widely Used?There is a perception that retro-commissioning can be expensiveIt can be expensive, but typically has less than 3 year paybacksThere 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 questionBecause re-tuning is implemented by leveraging information from building automation system and primarily targets operational problems, cost of implementation is significantly lower than retro-commissioningBecause re-tuning costs a fraction of retro-commissioning, it can be periodically done to ensure persistence
11 Origins for Re-TuningIn 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 systemsAlso, at the same time Texas A&M University was using a process called continuous commissioning to retro-commission existing buildingsIn 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 wasteImplemented primarily through the building control system at no cost other than the labor required to perform the re-tuning processIncludes small, low-cost repairs, such as replacing faulty sensorsIncludes identifying other opportunities for improving energy efficiency that require investmentMight be thought of as a scaled-down retro-commissioning focused on identifying and correcting operational problems
13 Major Focus Areas in Re-Tuning Occupancy schedulingDischarge-air temperature controlDischarge-air static pressure controlAir-handling unit (AHU) heating & coolingAHU outside/fresh air makeupAHU economizer operationZone conditioningMeter profilesCentral plant
14 Purpose of Re-TuningImprove 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 efficiencyIdentify problems requiring physical repairCatch the big energy saving opportunities
15 Life Cycle of Retro-Commissioning/Re-Tuning Typical commercial building behavior over timeEnergy ConsumptionPeriodic Re-tuning Ensures PersistenceContinuous Re-tuning Maximizes PersistenceTime
17 Large Commercial Buildings Project GoalEducate companies that large buildings can be re-tuned economically to save electricityTeach the proper techniques and skills to perform re-tuning, andShow that service providers can provide re-tuning as a service for a feeApproachRecruit 5 to 10 companies that provide HVAC services to commercial buildings to deliver re-tuning services and to help recruit customersEach of the selected service providers are required to recruit at least 6 buildings for re-tuningUse 10 to 20 of the buildings as training grounds for hands-on training of the HVAC service providers on how to perform re-tuning
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 (www.retuning.org)Extending Training Outreach Beyond WA State (www.pnl.gov/buildingretuning)Organization with large building stock interested in getting trained in the re-tuning processTrain-the-trainer – secondary goalWorking 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 trainingRole based training with help of learning management systemModularInteractive with ability to create abnormal conditionsQuestions and answers at the end each module and at the end of the coursePNNL is also looking to automate identification of the no-cost/low-cost operational problemsTo improve persistence and cost of retro-commissioning
21 Project ObjectiveImprove operational efficiency of the commercial building sector by transferring the skills to “re-tune” large commercial buildingsTraining building operators and service providers in the general principles and practices of good energy managementPublicizing 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 methodsPreparing case studies to quantify comfort impact and energy savings resulting from re-tuning
23 Re-tuning Training Training consists of two parts Classroom training 6 to 8 hours, limited to 20 to 25 peopleField training1 day to 3 days, depending on the size of the buildingLimited to 4 to 8 people
24 Intent of Re-tuning Training Provide an in-depth training of the re-tuning approachPrepare the participating technicians for hands-on field trainingProvide 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 informationPre-Re-Tuning Phase: Trend-data collection and analysisBuilding Walk Down: Getting to know the buildingRe-Tuning: Identifying and correcting operations problemsPost Re-Tuning: Reporting re-tuning findingsSavings Analysis: Determining and reporting the impacts
26 Six Primary Steps of Re-Tuning Collecting Initial Building Information: Basic building informationPre-Re-Tuning Phase: Trend-data collection and analysisBuilding Walk Down: Getting to know the buildingRe-Tuning: Identifying and correcting operations problemsPost Re-Tuning: Reporting re-tuning findingsSavings Analysis: Determining and reporting the impacts
27 Information to Collect Overall building geometryApproximate gross square feetNumber of floorsGeneral building shapeType of HVAC system(s)Approximate number of zonesApproximate number of each major type of equipmentBoilersChillersAir handlersType 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 fingertipsGather information to guide selection of trend logs to set up in the next phaseDetermine the overall design of the building and its mechanical systems
29 Six Primary Steps of Re-Tuning Collecting Initial Building Information: Basic building informationPre-Re-Tuning Phase: Trend-data collection and analysisBuilding Walk Down: Getting to know the buildingRe-Tuning: Identifying and correcting operations problemsPost Re-Tuning: Reporting re-tuning findingsSavings Analysis: Determining and reporting the impacts
30 Trend-Data Collection & Analysis: Purpose Detect potential operational problems even before visiting the buildingIdentify 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 timePlanned trend end timeLength 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 BASFormat data files for compatibility with the spreadsheet analysis toolOpen data files in spreadsheet analysis tool and automatically generate graphsReview graphs to identify operational issuesRecord operational issues for reference during re-tuning
33 Review Graphs & Identify Operation Issues Issues to investigate with trend log dataPNNL spreadsheets automatically generate graphs neededWe’ll look at some examples of what to look forOnline reference document provides additional information and examples, which you can refer to any time you need to (seeSeven issuesOccupancy SchedulingDAT ControlDAP ControlAHU heating and cooling at the same time.AHU OSA problemsAHU Econo problemsZone conditionsMeter profilesCentral Plant
34 ECAM ≡ Energy Charting And Metrics ECAM SoftwareECAM ≡ Energy Charting And MetricsFive Easy, Simple StepsSelect data from existing spreadsheetMap points (optional; required for Re-tuning)Create schedules (optional)Input energy project dates (optional)Create metrics and chartsWill go thru at lunch time and show how it works.
36 ECAM: Example AHU Time Series Charts Outdoor, return, mixed, and discharge air temperatures vs. timeDischarge air temperature and discharge air temperature set point vs. timeOutdoor air fraction and damper position signal vs. timeOutdoor and return air temperatures, damper position signal vs. timeDamper, chilled water valve, and hot water valve position signals vs. timeDamper position signal vs. timeDischarge static pressure vs. timeSupply fan speed, status, and static pressure vs. timeReturn fan speed and status vs. time
37 ECAM: Example AHU Scatter Charts Discharge air temperature vs. discharge air temperature set pointChilled water signal vs. hot water signalDamper signal vs. outdoor air temperatureMixed air temperature vs. outside air temperature
38 ECAM: Example Zone Charts Zone damper position signal, reheat valve position signal, occupancy mode, andZone temperature vs. time.
39 ECAM: Example Central Plant Charts CHW supply, return, ΔT, and outdoor air temperature vs. timeHW supply, return, ΔT, and outdoor air temperature vs. timeCHW flow and outdoor air temperature vs. time
40 Six Primary Steps of Re-Tuning Collecting Initial Building Information: Basic building informationPre-Re-Tuning Phase: Trend-data collection and analysisBuilding Walk Down: Getting to know the buildingRe-Tuning: Identifying and correcting operations problemsPost Re-Tuning: Reporting re-tuning findingsSavings Analysis: Determining and reporting the impacts
41 Building Walk Down: Purpose Get to know the building betterDevelop a general impression of:Overall building conditionOverall building designHVAC system designCollect 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 printsWalk the outside of the buildingWalk the inside of the buildingWalk down the roofWalk down the air handlersWalk down the plant areaReview the DDC system (BAS) front end
43 Six Primary Steps of Re-Tuning Collecting Initial Building Information: Basic building informationPre-Re-Tuning Phase: Trend-data collection and analysisBuilding Walk Down: Getting to know the buildingRe-Tuning: Identifying and correcting operations problemsPost Re-Tuning: Reporting re-tuning findingsSavings Analysis: Determining and reporting the impacts
44 Occupancy Scheduling Shut off systems whenever possible Night unoccupied schedulesWeekend unoccupied schedulesDaytime no or low use unoccupied schedulesAuditorium, class rooms, conference roomsIncludes lightingIncludes specialized exhaustDo not restart too earlyUse a startup schedule based on building needsDo not use fresh air during warm-up except last 30 minutes for flushing building44
45 Occupancy Scheduling (continued) Shut off systems whenever possibleRefrain from starting up system for the occasional nighttime user or weekend userUse bypass buttonsUnoccupied mode is a major cost saverSimple to implementSimple to trackSimple to administerSometimes the least paid employee is the most costlyJanitors working at night with all HVAC running, all fresh air open & lights onIs 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 controlsCheck to make sure heated areas get full air in unoccupied modesPush unoccupied mode air to where it is neededSet VAV boxes in interior zones to unoccupied with 0 air flowSet VAV boxes with reheat to a high air flow in unoccupied mode, so box will be 100% open during night cyclingAir gets to zones needing heat
47 Occupancy Scheduling (continued) Building electric consumption should show significant energy drop for nights/weekendsSignifying setbacks are active on all HVAC systemsBase load versus peak loads should be at least 30% difference and as much as 50% with aggressive setbacksTrended data for zone temps should show 5-10oF deviations from set points when setbacks are active during non-shoulder monthsWinter 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 readingsTrended data for main supply/return fan status should indicate “OFF” during unoccupied periodsTrended data for VAV boxes occupied status should indicate “Unoccupied” during unoccupied periodsTrended 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 periodsIf facility has sporadic use periods, this may require additional efforts to succeed at implementing setbacksMake sure the “tail” is not “wagging the dog” – janitors, special events, extreme weather events, overrides, etcHow 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 4/1/2017Air Handler Data AnalysisKey conditions to look for while analyzing the charts:Unoccupied or 24/7 operationUnoccupied hour setbackLower/higher than expected supply air temperatureExcessive outdoor air intakeDuring occupied periodsDuring pre-/pre-cooling periodsSignificant reheat during summer/cooling seasonIs the supply fan modulating (if VAV)Higher than normal static pressureSet point and static pressure resetsEconomizer 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 lowApproach:For each air handler, review a plot of the damper positions of all VAV units vs. timeLook for situations where:Most dampers are nearly closed during cooling – static pressure too highSeveral 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 boxesDampers 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 Position50% or less50~99%100%Some building automation systems provide information about the status of zone dampersPlotting the information as a function of time, will tell you whether or not the fan static pressure is appropriate162-(82%)27(14%)8(4%)
58 Air Handler Data Analysis: Discharge Set point PurposeReview discharge air temperatures for the air handlersDetermine whether discharge air temperatures are maintained relatively stableDetermine whether the discharge-air temperatures are too cool or too warmApproachFor 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 pointLook for deviations between discharge-air temperatures and set pointsLook for unusually high (> 70F) or low (< 55F) discharge-air temperatures
59 Air Handling Unit: Minimum Outdoor-Air Operations PurposeReview minimum outdoor-air operationsDetermine whether sufficient outdoor air is being supplied for ventilationDetermine whether more outdoor air than needed is being brought in at times (e.g., when the outdoor-air temperature < 40F or > 60F 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) ApproachFor each air-side economizer, review plots of:Outdoor-air fraction (OAF) vs. timeOutdoor-air damper and occupancy mode vs. timeOutdoor-air fraction vs. fan speed (if available)Determine if OAF > minimum OAF for ventilation when the system is not economizingDetermine whether outdoor-air ventilation is being provided when the building is unoccupied and ventilation is not required for some other reasonIf OAF and fan speed are tracking each other, it is an indication of return-air problems20% damper position is never 20% outdoor airNeed to add oaf formula
61 Air Handling Unit: Minimum Outdoor-Air Operations (continued) Potential issues to identifyInsufficient outdoor-air ventilation provided – minimum outdoor-air fraction (OAF) is too lowToo much outdoor-air ventilation provided when the air handler is not economizingToo much outdoor-air ventilation provided during unoccupied times (nights and weekends), during setbackUse air fraction to find % of outside airWorks if air is mixed relatively evenlyOAF = ((Return-Mixed)/(Return-Outside))*100Add into code for all air handlers and track historyEspecially 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 AirRelief AirSupply AirOutdoor AirAirside 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 Approximately15% Savings_______________________________________________________________Source: Honeywell Controls
64 Economizer Operation Purpose To determine whether air-side economizers are operating properlyDo 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) ApproachFor each air-side economizer, review plots of:Outdoor-air temperature, mixed-air temperature, return-air temperature and discharge-air temperature vs. timeOutdoor-air damper position (% open), outdoor-air temperature, and return-air temperature vs. timeOutdoor-air damper position and chilled-water valve position (% open) vs. timeLook for outdoor-air dampers (economizer) open at unusual times of day or under unusual outdoor temperature conditionsLook for outdoor-air dampers not open to economizer under favorable conditions (outdoor-air temperature between 40F and 60F)Look for outdoor-air damper not closing to minimum position for freeze prevention when outdoor temperature is less than about 40F
66 Economizer Operation (continued) Potential issues to identifyIncorrect economizer operation – numerous causes (identified later during on-site work)Incorrect control strategyStuck dampersDisconnected or damaged linkagesFailed actuatorDisconnected wiresFailed, uncalibrated or miscalibrated sensors2 X 4 in damperOthers?
67 Economizer Operation (continued): Example use of Graphs – 1 Day ReturnDischargeOutdoorMixed
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 ClosedReturnMixedDischargeOutdoor
70 Economizer Operation (continued): Example use of Graphs – 1 Day - Faulty Outdoor-Air Damper Stuck Fully OpenReturnDischargeOutdoorMixed
72 Why Economizers Fail and Increase Energy Use Jammed or frozen outside-air damperBroken and/or disconnected linkageNonfunctioning actuator or disconnected wireMalfunctioning outside air/return air temperature sensorMalfunctioning controllerFaulty control settingsInstalled wrong or wired incorrectlyDisconnected Damper_______________________________________________________________Source:Financial Times EnergyWired poorlyJammed/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 identifyAir-handler heating and cooling coils operating simultaneouslyHeating 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 positionsWorseBad
77 Zone Heating and Cooling Demands PurposeGet a feel for how many zones on each monitored air handler are heating and how many are cooling at the same timeGet a sense of which areas are heating and which are cooling at any given timeDetermine if any individual zones are heating and cooling at the same timeOthers?
78 Zone Heating and Cooling Demands (continued) ApproachFor 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. timeNote which areas of the building (e.g., interior core vs. perimeter zones or zones facing certain directions) are in heating and coolingLook 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 identifySupply-air temperature too cool or too warmNo use of supply-air resetCertain zones (e.g., corner offices) driving air handler operationSome zones out of control, oscillating between heating and coolingOthers
80 Importance of Terminal Units Re-tuning 4/1/2017Importance of Terminal Units Re-tuningTerminal boxes are major building HVAC components and directly impact comfort and energy costsTerminal boxes control may cause occupant discomfort and waste energy, if they have inappropriate operation and controlImproper 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
86 Re-tuning ExampleVFD 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 informationPre-Re-Tuning Phase: Trend-data collection and analysisBuilding Walk Down: Getting to know the buildingRe-Tuning: Identifying and correcting operations problemsPost-Re-Tuning: Reporting re-tuning findingsSavings 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 meterCan save energy and keep occupants comfortableIt takes time to tune a buildingThere are no magic set points that work all the timeAlways monitor the utility meters (gas & electric) to see what affect you have hadLook at the big picture when making adjustmentsWatch the meter profiles weeklyLearn and know the building’s personality