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Time Dependent Valuation (TDV) for Energy Standards. Statewide Codes & Standards Program Prepared for CEC Workshop April 2, 2002 Presentation by PG&E/HMG/E3/Eley/BSG. TDV Project History. 1998-99 CEC/PG&E Study: “Dollar-Based Performance Standards”

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time dependent valuation tdv for energy standards

Time Dependent Valuation (TDV)for Energy Standards

Statewide Codes & Standards ProgramPrepared for CEC Workshop April 2, 2002Presentation by PG&E/HMG/E3/Eley/BSG

tdv project history
TDV Project History
  • 1998-99 CEC/PG&E Study: “Dollar-Based Performance Standards”
  • 1999-2001 PG&E/SCE/SoCalGas further development of Time Dependent Valuation
    • TDV Cookbook - economics methodology
    • Engineering model enhancement
    • Demonstrations of compliance outcomes
    • Complete & present proposal to CEC
tdv project team
TDV Project Team
  • CEC staff - advise and comment
  • PG&E - development lead
  • SCE & SoCalGas - support, review, advise
  • Consultant team - lead by HMG
    • Economics: E3
    • Engineering: Eley, BSG
  • Other stakeholders consulted: CBIA, NRDC, public workshop
tdv goals statewide
TDV Goals - Statewide
  • Bldg population with lower peak demands
  • Lower peak costs for electricity system
  • Insurance against future blackouts
  • Long-term demand reduction
  • Cheapest to do with new construction (rather than retrofit)
tdv goals compliance
TDV Goals - Compliance
  • Replace “flat rate” energy basis
  • Transparent to compliance end-user
  • Credit for measures that perform on-peak, less for off-peak measures
  • Better signals to designers
  • Method tied to CEC weather tapes and ACM performance calcs
tdv policy choices
TDV Policy Choices
  • Change savings valuation in Title 24
    • Abandon source energy flat valuation
    • Replace with time dependent valuation
  • Change source energy
    • Abandon electricity source energy (mult = 3)
    • Replace with TDV energy (hourly factors) based on CEC forecasts of costs
    • Distinguish between natural gas & propane
tdv policy choices continued
TDV Policy Choices (continued)
  • Adopt economic valuation methodology
    • Publicly available (mostly CEC) data sources
    • Repeatable over time
    • Easily adjusted as forecasts change…but not expected to update frequently
  • Adopt engineering analysis upgrades
    • Hourly HVAC equipment models
    • Hourly analysis of measures
    • Others...
tdv policy choices continued9
TDV Policy Choices (continued)
  • Uses of TDV
    • For optional performance trade-offs
    • For new compliance options
    • For demonstrating cost-effectiveness of new standards requirements
tdv policy choices continued10
TDV Policy Choices (continued)
  • Methodology Choices (our recommendations)
    • Use 1992 Standards valuations? (no)
    • Use current CEC forecast? (yes)
    • Use temp-dependent allocation of T&D? (yes)
    • True up to overall revenue requirements? (yes)
    • Use environmental externalities? (yes)
why not use rates
Why Not Use Rates?
  • There are many different rates (which?)
  • Rates average the high cost periods and dilute the price signal
  • Rates change with policy/political choices
  • TDV reflects long-term system costs
    • CEC 30 year generation forecast
    • Utility T&D cost experience
    • Overall revenues to run utility system
how tdv works electricity
How TDV Works (electricity)

Time Dependent Energy Value

With TDV value a kW saved during a high-cost peak hour is valued more highly than a kW saved during an off-peak hour

Flat Energy Value

With flat energy value a kW saved is valued the same for every hour of the day

Energy value

Friday

Monday

building up the electric tdvs
Building up the Electric TDVs

Hot

afternoon

Environment

T&D

PX

CASE Initiative Project

Copyrighted © 2000 PG&E All Rights Reserved

1. Start with the CEC Forecast Commodity Costs

2. Add the marginal T&D delivery costs as f(temp)

3. Adjust to bring to revenue requirement (rate levels)

4. Add environmental externality of reduced pollution (optional)

5. Convert to equivalent energy units (TDV energy units)

Forecast Costs

TDV Energy Value

Revenue Neutrality Adjustment

Monday Tuesday Wednesday Thursday Friday

building up gas and propane tdvs
Building up Gas and Propane TDVs

Commodity Cost

Environmental

Externality

CASE Initiative Project

Copyrighted © 2000 PG&E All Rights Reserved

1. Start with the CEC Forecast Gas Commodity Costs

2. Adjust to bring to revenue requirements (rate levels)

3. Add environmental externality of reduced pollution (optional)

4. Convert to equivalent energy units (TDV energy units)

Forecast Costs

Energy Value

Revenue Neutrality Adjustment

December

January

how does tdv compliance work
How Does TDV Compliance Work?
  • Used for performance trade-offs(instead of old source energy trade-offs)
  • Compliance runs done per usual
  • Compliance software enhanced to do hourly base/proposed calculations
  • TDV value for each hour multiplied by hourly energy, totaled for annual savings
  • Same compliance report printed out
changes to title 24 for tdv
Changes to Title 24 for TDV
  • Delete definition of SOURCE ENERGY
  • Add definition of TDV ENERGY
  • Adjust ACM rules for engineering enhancements
  • Adjust rules for propane & natural gas
  • Adjust ACM output reports
tdv engineering enhancements
TDV Engineering Enhancements
  • Goal: Credit air conditioning systems that perform better on-peak
    • Hourly equipment model for residential
    • Improved performance curves for nonres
  • Goal: Improved treatment of water heating
    • Hourly hot water usage profiles
    • More complete distribution options
  • Goal: Credit other measures that perform better on-peak (e.g. cool roofs, daylighting)
residential tdv modeling
Residential TDV Modeling
  • Air Conditioners
  • Heat Pumps
  • Duct Systems in Attics

Engineering ACM Enhancement

to better implement TDV

residential air conditioners
Residential Air Conditioners
  • Historical perspective

Sensible loads

SEER as Seasonal Efficiency

  • 2001 Standards changed

Conservative EER/SEER assumption

Temperature and installation adjusted SEER

as seasonal efficiency

tdv air conditioner model
TDV Air Conditioner Model
  • NAECA SEER primary input
  • 2001 EER/SEER assumed at 95 degF
  • Efficiency above 95F based on PG&E tests
  • Optional EER input
  • Constant 62 WB indoors
tdv indoor air handler fan
TDV Indoor Air Handler Fan
  • Adjust SEER and EER to remove fan

Fan is defaulted not tested

365 w/1000 CFM assumed

510 W/1000 CFM actual (Proctor)

  • Model fan power separately

Assume 300 CFM/ton, 510 W/1000 CFM

Allow inputs for field verified CFM and W

tdv heat pump model
TDV Heat Pump Model
  • HSPF is primary input

Default COP at 47F = 0.4 x HSPF

  • Capacity at 47F

Default to Rated Cooling Capacity

  • DOE2 hourly model
tdv hourly duct efficiency
TDV Hourly Duct Efficiency
  • For ducts in attics
  • Adjusts ACM Seasonal Efficiency on an hourly basis for heating and cooling
  • Roof Sol Air Temperature driven
  • Includes effects of all current options
  • Invisible to ACM user
residential water heating

Residential Water Heating

Engineering ACM Enhancement

to better implement TDV

hourly loads
Hourly Loads
  • Make consistent with current method
redefining nonresidential equipment performance curves

Redefining Nonresidential Equipment Performance Curves

Engineering ACM Enhancement

to better implement TDV

nonres performance background
Nonres Performance Background
  • Use ACM software for whole-building trade-offs
  • Requires two energy simulations
    • proposed design
    • budget building.
  • The rules tightly defined by the ACM manual.
  • The default curves were developed in the 1970s; some were updated with the 1993 supplement.
  • Propose changes to the ACM manual:
    • allow users to input data for particular HVAC equipment
    • update of the default curves to reflect performance of modern equipment.
the five doe 2 curves
The Five DOE-2 Curves

wet, dry bulb temperature

COOL-CAP-FT

cooling capacity

wet, dry bulb temperature

cooling energy input ratio

COOL-EIR-FT

COOL-EIR-PLR

part load ratio

energy input ratio

dry bulb temperature

HEAT-CAP-FT

heating capacity

dry bulb temperature

HEAT-EIR-FT

heating EIR

our initial approach
Our Initial Approach
  • Investigated the technologies for 150 different rooftop package units from several manufacturers
    • Tried to draw conclusions between the technologies and performance.
    • No statistically robust methods of predicting an actual performance curve based on the data available.
current approach three sets of curves
Current Approach: Three Sets of Curves
  • The current DOE default curve (from ACM)
  • Best-fit curves
    • The most accurate representation of the data set for each particular equation determined with least-squares regression
    • Found divergences between the current defaults and actual performance
  • P15 curves
    • Lowest performing 15% of the data set..
    • In general, equipment that performed poorly did so at all temperatures.
    • Performed a least-squares regression on the worst performing subset to create the P15 curves.
recommended changes to acm
Recommended Changes to ACM

User Options:

1) Input the performance data of their particular equipment directly into the compliance software.

Best captures the details of the unit’s performance

2) Do not input data - revert to the P15 performance curves.

Because these units represent the worst performers in the population, the user is motivated to use equipment with better performance and input it into the model.

The reference building will use the best-fit performance curves for each piece of equipment.

but to aid discussion we reduce it to two dimensions as shown below
… but to aid discussion, we reduce it to two dimensions as shown below.

COOL-CAP-FT Current Defaults

1.1

EWB = 72

1

EWB = 67

0.9

Normalized capacity

EWB = 62

0.8

0.7

0.6

85

95

105

115

125

Dry bulb temperature

as expected p15 curves diverge from the current defaults and best fit at higher temperatures
As expected, P15 Curves diverge from the current defaults and best-fit at higher temperatures.

COOL-CAP-FT Comparison of Curves

EWB = 72

1.1

EWB = 67

1

Current Default

EWB = 62

Best Fit

0.9

P15

Normalized capacity

0.8

0.7

0.6

85

95

105

115

125

Dry bulb temperature

cool eir ft normalized cooling efficiency as a function of dry and wet bulb temperatures
COOL-EIR-FT - normalized cooling efficiency as a function of dry and wet bulb temperatures.

worse

better

actual equipment performance is much worse than the current doe2 defaults at high temperatures
Actual equipment performance is much worse than the current DOE2 defaults at high temperatures.

P15

worse

best fit

current defaults

better

heat cap ft normalized heating capacity as a function of outside dry bulb temperature
HEAT-CAP-FT - normalized heating capacity as a function of outside dry bulb temperature

HEAT-CAP-FT Curve Comparison

1.2

1

0.8

Normalized capacity

0.6

0.4

17

27

37

47

57

Dry bulb temperature

Current Defaults

Best Fit

P15

There is little divergence in the data for this curve.

heat eir ft normalized heating efficiency as a function of dry bulb temperatures
HEAT-EIR-FT - normalized heating efficiency as a function of dry bulb temperatures.

HEAT-EIR-FT Curve Comparison

1.9

1.8

1.7

1.6

1.5

Normalized EIR

1.4

1.3

1.2

1.1

1

0.9

17

27

37

47

57

Dry bulb temperature

Current Defaults

Best Fit

Proposed Defaults

worse

The worst performers significantly higher EIRs below 37°.

better

cool eir fplr normalized cooling efficiency as a function of part load
COOL-EIR-FPLR - normalized cooling efficiency as a function of part load.
  • Not recommending any changes to the current defaults
  • Lack of scientific data
    • Current manufacturer and scientific data was either non-existent or unavailable for study. We attempted a proxy based on Integrated Part Load Values (IPLV), but we did not have the defendable research to justify our modeling assumptions.
  • DOE-2 modeling issues.
    • Losses due to the cycling of compressors is a large factor in the overall part load performance of the equipment.
    • Losses could not be quantified due to a lack of data
    • Losses could not be modeled due to the non-linear discontinuities in the performance curve that are formed when a compressor cycles on or off.
conclusions
Conclusions
  • Changes to the ACM manual and default curves are needed to most accurately model present-day HVAC equipment
  • Recommended approach is the best compromise between usability, accuracy, and consistency
nonresidential schedules

Nonresidential Schedules

Engineering ACM Enhancement

to better implement TDV

current schedules
Current Schedules
  • Daytime Schedule
  • 24-Hour Schedule
recommended schedules
Recommended Schedules
  • Continue to use the daytime and 24-hour schedules for LCC analysis and as a default
  • Permit alternate schedules when the building use is known for: offices, retail, schools and assembly
  • Base the alternate schedules on the NRNC database
tdv measures analysis method
TDV Measures Analysis Method
  • Perform annual energy simulation of building with existing compliance tools
    • Residential - MicroPas
    • Non-residential - EnergyPro
  • Multiply hourly energy consumption for each fuel by its TDV value for that hour
  • Sum hourly results over 8,760 hours
  • Compare base case to proposed case
tdv measures analysis graphs
TDV Measures Analysis Graphs
  • Comparison of source energy method and TDV energy method (two bars)
  • Measures reported as % savings (y-axis)
    • Savings divided by total source energy or TDV energy of standard building
  • Measures can be directly compared
residential analysis
Residential Analysis
  • Four example houses provided by Consol
    • Small house - 1290 sf, 1 story, 16.5% glazing
    • Medium house - 2190 sf, 2 stories, 20.2% glazing
    • Large house - 3278 sf, 2 stories, 25.8% glazing
    • Townhouse - 1697 sf, 2 stories, 18.6% glazing
  • 24 measures vs. to base configuration
  • Climate zones 6, 12, 13, 14
  • Compliance margin comparisons
residential measures
Residential Measures

01 Windows U=0.50, SHGF=0.65

02 Windows U=0.65, SHGF=0.40

03 Windows U=0.35, SHGF=0.35

04 No radiant barrier

05 Radiant barrier

06 R38 ceiling

07 R30 ceiling

08 R19 ceiling

09 Wall R13

10 Wall R13 w/ foam = R17.2

11 Wall R19

12 AC TXV (thermal expan valve)

13 AC SEER 12

14 AC SEER 14.4

15 Furnace AFUE 90

16 Duct R6

17 Duct R8

18 Tight ducts

19 ACCA standard ducts

20 DHW EF=0.60 & 50 gal tank

21 DHW EF=.62 & 40 gal tank

22 DHW pipe insulation

23 Glass area -10%

24 Glass area +10%

nonresidential analysis
Nonresidential Analysis
  • Two sample buildings
    • Office - 117,000 sf, 6 stories, built-up VAV
    • Retail - 50,000 sf, 1 story, packaged VAV
  • Six measures
    • Electric vs gas chillers
    • Increase cooling efficiency
    • Add economizer
    • Add cool roof
    • Lower SHGC on south and west
    • Reduce lighting LPD by 20%
externalities analysis results
Externalities Analysis Results
  • Consistency with CPUC measure valuation
  • Adding externality costs have little effect on trade-offs between measures
  • Slight effect on measures that reduce peak electricity demand
  • Main effect is on evaluating the cost-effectiveness of measures that have a benefit/cost ratio close to 1.0
compliance outcomes
Compliance Outcomes
  • Any electricity saving measure is more valued by TDV than by source valuation
  • Difference between flat and TDV indicates demand impact of measure
  • Gas measures - minimal difference between flat and TDV gas
  • Propane - TDV gives greater value to propane than to natural gas
likely winners losers
Likely Winners/Losers

Winners

Peak air conditioning (SEER/EER issue)

Fenestration (more directional)

Gas cooling

Cool roofs

Other on-peak

Losers

Propane (smaller advantage over elec)

Economizers

Other off-peak

No Change

Insulation

Res. water heating

questions for a tdv regime
Questions for a TDV Regime
  • Does TDV appropriately increase valuation of peak measures? (yes)
  • Does TDV maintain similar stringency as current standards basis? (depends)
  • Does TDV create “pathological” cases? (none found yet)
  • Possible to “game” TDV in ACM? (depends)
  • Are engineering modeling changes ready? (mostly)
why change
Why Change?
  • Helps economy - least cost energy design
  • Saves $$ for everybody
  • Right signals to designers(best way to do this)
  • Right signals on costs(economists developed method)
why change80
Why Change?
  • Flat, source energy is clearly incorrect
  • Electricity demand crisis in CA
  • Compliance process won’t change
  • Evolutionary change to standards
  • Market-wide adjustments to building design and equipment selection
  • Unique time in history to do this
for more information
For More Information
  • Project Web Site: www.h-m-g.com
  • PG&E: Gary Fernstrom
    • 415-973-6054
    • gbf1@pge.com
  • HMG: Douglas Mahone
    • 916-962-7001
    • dmahone@h-m-g.com