Deemed Savings Methodologies

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Deemed Savings Methodologies

• Reid Hart, PE
• Associate Director, Technical Research
• July 2009 Regional Technical Forum

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Deemed Saving Methodologies

• Need for a New Deemed Method
• Relevant Baseline Parameters
• Approaches
• Decision Framework Matrix
• Expected Value Deemed Savings
• Seeking Approval as Provisional Method

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Need for a New Deemed Method

• Current approaches
• Custom savings require pre-review and approval
• Calculators work well with energy auditor
• Deemed savings desired for contractor delivery
• Limits on deemed savings
• Very few commercial HVAC items
• Savings may be excessively conservative
• Approval of deemed savings not always timely
• Desired Method
• Covers range of conditions
• Arrives at appropriate program-wide savings

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Relevant Baseline Parameters

• Typically Building Type Vintage
• Vintage not account for retrofit changes
• Building types can be generalized
• Meta Parameters (Require Separate Savings)
• Major climate zones
• Heating fuel type
• Analyzed Baseline Parameter Variation
• Internal loads lighting density
• Envelope glazing perimeter/area ratio
• Schedule
• Measure specific parameters

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Measure Specific Baseline Parameters

• Premium Ventilation Package as an exmple
• Economizer found changeover
• Economizer maximum outside airflow
• Minimum outside air setting (Example field data)

Source Ecotope EWEB study 2001
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Parameters for Premium Ventilation
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Individual Baseline Parameter Impact on Savings
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Parameter Sensitivity
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Unit Change Minimizes Some ParameterskWh/square
foot to kWh/ton
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Approaches

• Site specific approaches
• Custom analysis
• Field based monitoring
• Field-data driven model
• Energy bill adjusted parametric tool
• Parametric tool (calculator)
• Simplified analysis (e.g. lighting spreadsheet)
• Deemed approaches
• Matrix method / decision framework
• Deemed savings (vintage, building type, climate)
• Unit rebate
• Expected value deemed method

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Decision Framework Matrix

• Focus on most sensitive parameters group results

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Matrix Results Provide Savings Table
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Expected Value Deemed Savings

• Uses decision analysis methodology

• Typical for supply-side resource risk assessment
• Allows multiple parameters or influences
• Expert judgment can be applied to parameter
  probability distribution

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Decision Tree for Expected Value Analysis

• Each influencing variable assigned states, each
  with
• Probability of occurrence
• Impact on savings

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Parameter Savings Impact and Probabilities
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Simplified Interaction Adjustment

• Simplified correction adjustment factors limit
  adjustment
• Parameter Combination Impacts and Probabilities
• Higher quality as runs limited cf multiple
  regression

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Program-wide Savings Distribution

• Probability of different savings results based
  on range of baseline influences and combinations

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Program-wide Expected Value (EV)

• Range of possible savings shown
• Expected value represents program-wide results

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Compare Matrix Expected Value

• Matrix Framework
• Whole building understanding needed
• Multiple saving values
• Site specific savings
• Gaming inputs possible
• Representation difficult beyond two parameters
• Multiple possible savings or rebates make it
  difficult for contractor delivery
• 1944 runs required for 5 parameters needing 243
  cases (3 states _at_, 2 climates, 2 heat types)

• Expected Value
• No need for information outside discipline
• Single saving value
• Program-wide savings
• Cannot game
• Multiple parameters can be considered
• Single savings and rebate amount makes contractor
  planning and marketing easy
• 96 runs required for 5 parameters needing 12
  cases (3 states _at_, 2 climates, 2 heat types)

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Further Research

• Current analysis is an example without full
  development need
• further develop expected values
• research into extant building characterization
  data
• committee of experts to develop probabilities
  for parameters
• Evaluate the differences in expected value and
  range of results for (kWh/unit) vs. (kWh/sf) vs.
  (kWh/ton) results.
• Use a regression model for high impact parameters
  to determine acceptability of simplified
  interactive method
• Find and test other software tools for expected
  value analysis
• Explore past program impacts on long term results
  as economy of scale takes hold, explore influence
  factor for projection
• Develop a step-by-step Expected Value Deemed
  Savings method for use by others in the region

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Seeking Approval of Deemed Expected Value as
Provisional Savings Method

• Goal Accelerate new measure adoption with
  balance between savings accuracy and information
  needed
• Next step in premium ventilation is to develop
  pilot program approach with evaluation
• For ease of contractor delivery, would prefer
  single rebate approach
• Seeking approval to use the expected value method
  for two-year pilot approach
• After pilot and evaluation, can update and
  continue or seek different approach
• May also consider use of Deemed Expected Value
  for other measures that come before RTF

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Questions?

• Contact Information
• Reid Hart, PE
• Associate Director, Technical Research
• Portland Energy Conservation, Inc.
• 503-961-6142
• rhart_at_peci.org
• www.peci.org

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