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Standard Protocol Development for Advanced RTU Control Retrofit

Standard Protocol Development for Advanced RTU Control Retrofit. August 15, 2013 Presentation to: Regional Technical Forum RTUG Subcommittee Sponsored by: Bonneville Power Administration Presented by: Michael Baker, SBW Consulting, Inc. Bill Koran, NorthWrite , Inc. Agenda.

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Standard Protocol Development for Advanced RTU Control Retrofit

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  1. Standard Protocol Development for Advanced RTU Control Retrofit August 15, 2013 Presentation to: Regional Technical Forum RTUG Subcommittee Sponsored by: Bonneville Power Administration Presented by: Michael Baker, SBW Consulting, Inc. Bill Koran, NorthWrite, Inc.

  2. Agenda • Introductions • Review Specification for Advanced RTU Control Retrofit Measure • Developing an RTF Standard Protocol • Subcommittee Guidance on How to Proceed

  3. Key Terms Premise – a collection of utility meters that generally serve an entire building but can be a portion of a building as in the common areas of a mall. Premise interval metering – measurement of power at the utility meters for intervals of time. Used to derive daily premise energy use. Unit Power – in this context is the power draw of a retrofit RTU. Signal to Noise – the change in use due to the measure is the signal. Other unrelated use on the premise or unit meter is the noise. Cycling – refers to switching between standard and efficient mode for the advanced controls. Standard more tries to emulate baseline conditions, but has its limitations. Daily cycling has been used at PNNL sites. Other trends – refers to changes in premise energy use unrelated to the measure, such as modification to set points

  4. RTF Standard Protocols – Development and Application • Develop • Measure specification • Define best practice savings estimate • Identify candidate simplified methods • Data to prove simplest reliable method is … • Not available or sufficient - approve a Provisional protocol and use in collecting needed data • Available – approve protocol as Proven • Apply • Two options • Use in estimating savings for all projects • Use in estimating savings for a sample in support of impact evaluation • Can be applied by a program operator, subject to “faithful application” review by an impact evaluator

  5. Protocol Measure Specification • Eligible systems • Rooftop package and split systems providing heating, cooling and ventilation with constant or multi speed supply fans and constant or multi speed compressors. Either gas or electric (resistance or heat pump) heating. • RTF Baseline • Pre-conditions • Eligible controls retrofit • Supply fan control using variable speed drive, multi-speed or cycling; demand-controlled ventilation; and differential, integrated economizer control; control of heating and cooling coordination with fan speed optimization. • Can operate in standard (baseline simulation) and efficient modes and cycle between modes on a daily basis

  6. Test sites and their characteristics Federal Way Commons Heat pump Mall common Area 11 out of 11 RTU retrofit • Everett Service Center • Heat pump • Office and warehouse • 6 of 6 RTU retrofit • Staples • Gas pack • Retail • 5 of 6 RTU retrofit

  7. Best practice savings estimates • Definition • Long-term cycling – approximately 1 year • Interval measurements of true power for each unit used to derive total daily kWh for all retrofit RTUs • Savings derived from comparison ECAM change point models of daily temperature vs. total unit kWh • Models for standard and for efficient mode days • Limitation • Cannot model other improvements such as RCx • Standard mode may not equal baseline • Broken economizer • Fans set to Auto

  8. Can we simplify best practice method? • Simplification • Use utility interval meters to derive total daily premise-level electric use • Avoids costly unit-level power measurements • Challenge • Signal to noise ratio • How much of the premise-level use is associated with the RTUs • Test • Model same period of cycling • Compare savings and uncertainty

  9. Premise vs. Unit Cycling modelsSame time periods for each model at a site

  10. Everett Service Center Models

  11. Everett Service Center Interval Models

  12. Staples Models

  13. Banner Bank Models

  14. Federal Way Commons Models

  15. Simplified method #1 – Premise level pre/post • Method • Derive daily premise kWh from utility interval metering • ECAM change point models comparing pre and post years • Advantages • Avoids need to cycle • Captures true baseline • Captures other efficiency improvements made at the same time • Limitations • Requires interval metering (what is the status of AMR?) • Reliability depends on signal to noise • Cannot handle unrelated trends • Protocol would have rules about acceptable model residuals

  16. Comparison of unit-cycling to premise pre/post modelsDifferent time periods for each model at a site. Placed on common time using TMY3. What happened?

  17. What Happened #1Everett Service Center Changes over Time

  18. What Happened #1Everett Service Center Changes over Time RTU Power Model

  19. What happened #2Staples Ventilation Changes Pre-install interval meter baseline Post-install baseline emulation

  20. More Challenges: Federal Way Commons Baseline RTU Power Scatter With Model

  21. What happened? HeatingSetpoint Change

  22. Omit Data After Setpoint Change Including Setpoint Change ExcludingSetpointChange

  23. When can this method be used? • Signal to Noise • Screen using low-cost metrics • Name plate RTU kW vs. peak daily premise kW • Other trends • Screen using time-series trends in model residuals • Does this bias standard protocol • Signal to Noise and other trends are independent of savings • Savings per ton derived from sample of measures that passed screen should be reliable and applicable to program savings estimate

  24. A second simplified method? • What if there is no premise interval meter? • Use best practice measurements and models • Unit power metering • Cycling • Can we cycle for less than one year? • Proposed to test • 60 days starting with each of 12 months • 2 30 day periods, 6 months apart, starting with each of 12 months • What periods are feasible in terms of project development • When can this method be used • Working economizer • Fans not on auto

  25. Is there a third Method? • Premise interval data with cycling • Same limitations as Method 2 • Economizer working • Fans not on Auto • Additional limitation • Signal to Noise Ratio • Requires • Premise interval meter • Cycling like method 2 • Advantage • Avoids unit power measurement

  26. Can fan power be used instead of unit power Would models be biased by excluding measurements of heating and cooling? Can a relationship be derived to estimate unit power from fan power based on the PNNL data?

  27. Comparison of fan and unit savings

  28. Guidance on how to proceed • Possible protocol strategies • Further analysis of PNNL data • Investigate short-term cycling periods • Estimating savings from fan power • What is a practical plan for provisional data collection • Can we create more test sites from existing projects • Sites with premise interval metering before and after install • Where we could install temporary power metering and turn on cycling • Posting PNNL data on RTUG website • Would another year of PNNL post (non-cycling data)

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