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Retrocommissioning of Existing Buildings
- 1. 1Retrocommissioning of Existing Buildings
- 2. 2Presenters Manus McDevitt, PE, LEED AP Principal Sustainable Engineering Group, Madison, WI Alex Harris, Engineer Sustainable Engineering Group, Madison, WI
- 3. 3 •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
- 4. 4 What is Retro-Cx? The process of optimizing the performance of an existing building
- 5. 5RetrocommissioningBenefits •Improve building performance •Provide appropriate training to O&M staff •Improve occupant comfort •Improve system reliability
- 6. 6 Commercial Industrial Transportation Residential Buildings Environmental Impact of Buildings U.S. Energy Consumption by Sector – 2000 98.5 Quadrillion Btu
- 7. 7 When is Retro-Cx Appropriate? When there is a good chance of success!
- 8. 8 Approach -Overview 1. Gather Information 2. Identify improvements 3. Monitor implementation 4. Functional testing 5. Update documentation, train operators 6. Final report
- 9. 9 1. Gather Information From Stakeholders From Documentation From Observation
- 10. 10 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
- 11. 11 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
- 12. 12 Approach -Overview 1. Gather Information 2. Identify improvements 3. Monitor implementation 4. Functional testing 5. Update documentation, train operators 6. Final report
- 13. 13 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
- 14. 14 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
- 15. 15Audit / Investigation Phase •Collaborate with facilities team to identify opportunities •Review building drawings and documentation •Performance testing of building systems •Develop list of recommended improvements
- 16. 16Potential Measures •Operational –Equipment schedules, set points, •Maintenance –Valve and damper control issues •Design –Identify space function changes, control optimization
- 17. 17 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
- 18. 18VAV Scheduling 15 kW Fan Savings
- 19. 19VAV 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 Total VAV Box Reheat (kBtu/hr) AHU-14/15 VAV Box Reheat
- 20. 20 Data Room Setpoints Data room set- points are too tight for temperature and humidity, leading to excessive energy use.
- 21. 21Adjust CRAC Set Points
- 22. 22Adjust CRAC Set Points Annual kW-Hr Savings Annual Savings Implementation Cost Simple Payback 150,000 $10,391 $50 2 days
- 23. 23AHU Chilled Water Valve Control Issue
- 24. 24 Cooling Tower Exhaust Dampers & Ductwork Supports have rusted out and fell into tower Dampers linkages are corroded and not functional
- 25. 25 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
- 26. 26 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.
- 27. 27 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.
- 28. 28 Poor Sensor Location Heat pump serving this space is always in cooling, even though the room temperature is 65°F.
- 29. 29 Approach -Overview 1. Gather Information 2. Identify improvements 3. Monitor implementation 4. Functional testing 5. Update documentation, train operators 6. Final report
- 30. 30 3. Monitor Implementation RCxprovider’s role varies depending on 1.Needs of the client 2.Number and complexity of improvements 3.Type of improvements
- 31. 31 Approach -Overview 1. Gather Information 2. Identify improvements 3. Monitor implementation 4. Functional testing 5. Update documentation, train operators 6. Final report
- 32. 32 4. Functional Testing • RCx provider’s role varies • Verify the performance of building systems • May use statistical sampling
- 33. 33 Approach -Overview 1. Gather Information 2. Identify improvements 3. Monitor implementation 4. Functional testing 5. Update documentation, train operators 6. Final report
- 34. 34 5. Documentation & Training • Update documentation – Drawings – O & M manuals – Operating sequences – Equipment database – Maintenance schedules • Schedule training
- 35. 35 Approach -Overview 1. Gather Information 2. Identify improvements 3. Monitor implementation 4. Functional testing 5. Update documentation, train operators 6. Final report
- 36. 36 6. Final Report • Based on the Facility Optimization Study – Includes discussion of implemented projects and testing – Reference document for future projects and operations
- 37. 37 Persistence Phase: Verify Persistence of Savings (Optional) Implementation Phase: ImplementSelected Measures & Verify Actual Savings Audit Phase: Complete Audit & Quantify Measures Qualify Customer & Submit ApplicationFocus on Energy RCx Process
- 38. 38 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
- 39. 39 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) M1 On all air handlers, increase economizer switchover from 51.5°F to 68°F 101,130 - - N/A $7,079 $100 0.0 M2 Modify 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 M4 Replace 52W Incadescent Bulbs with CFL's 6,841 1.8 -134 N/A $231 $200 0.9 M5 Install 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
- 41. 41Medical ClinicPersistence Check Great Persistence: •Controls programming changes •VFD Installs •Equipment Upgrades Poor Persistence: •Schedule modifications •Set point modifications •Fixing valves / equipment (Grease Fan BRGS Yearly!!)
- 42. 42Medical ClinicPerformance Since Implementation
- 43. 43Medical Clinic, Madison, WI 100 200 300 400 500 600 700 1 2 3 4 5 6 7 8 9 10 11 12 Electric Consumption (MW-hr) Month of year (January = 1, December =12) Monthly Electric Consumption 2009 2010 2011 2012 2013-Pre RCx 2013 2014
- 44. 44Medical Clinic, Madison, WIPortfolio Manager Tracking Before After
- 45. 45Medical ClinicReview of Incentives Paid Out
- 46. 46Medical ClinicEvaluate Economics •Savings $66,000/yrutility cost avoidance •Expenses $50,000 study cost $30,000 implementation cost •Incentive +$63,000 incentive •Simple Payback = 0.3 years (after incentive)
- 47. 47 505 Passenger Vehicles / Year 62,000 trees grown for 10 years 121 Homes / Year
- 48. 48Solar Equivalent of Electric Savings
- 49. 49 Retro-CxEffort 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
- 50. 50 Retro-CxEffort 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
- 51. 51 Retro-CxEffort 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
- 52. 52 Airflow checking and rebalancing results in enhanced occupant comfort and potentially lower operating costs Retro-CxEffort at Area School •Staff have reported problems with “stuffiness” in several spaces •Perimeter areas of Office and Guidance spaces too cold in winter
- 53. 53 53 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 Gas Use (Therms) ) 2005 2006
- 54. 54 54 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 Electric Use (kWh) ) 2005 2006
- 55. 55 Retro-CxEffort 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
- 56. 56 Retro-CxEffort 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!
- 57. 57Life After Retrocommissioning •RCxProcess •RCx Results •Life After RCx •Next Steps
- 60. 60Continuous 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
- 61. 61 LEED EB RCx •Credits for: –Documenting building operations and benchmarking performance –Retrocommissioning audit phase –Implementing identified retrocommissioning measures –Ongoing commissioning
- 62. 62What Can YOUDo? •Benchmark your facilities •Set goals •Put an energy plan together
- 63. 63Complete the RCx Process!
- 64. 64 Developing an Energy Plan
- 65. 65