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Estimating Efficiency and Establishing Baselines for Verifying the Energy Saving Benefits Associated with Servicing Air Conditioners. Todd M. Rossi, Ph.D. Field Diagnostic Services, Inc. Presentation. Estimating efficiency economically on a large scale Benchmark for comparison

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Estimating Efficiency and Establishing Baselines for Verifying the Energy Saving Benefits Associated with Servicing Air Conditioners

Todd M. Rossi, Ph.D.

Field Diagnostic Services, Inc.


Presentation
Presentation Verifying the Energy Saving Benefits Associated with Servicing Air Conditioners

  • Estimating efficiency economically on a large scale

  • Benchmark for comparison

  • Selling service based on energy savings payback


Important technology
Important Technology Verifying the Energy Saving Benefits Associated with Servicing Air Conditioners

  • A/C consumes much energy

  • Efficiency sensitive to service

  • First technology relating service effectiveness to energy savings deployed on large scale

“You can’t fix what you can’t measure”


Define efficiency
Define Efficiency Verifying the Energy Saving Benefits Associated with Servicing Air Conditioners


Electric heated evaporator
Electric Heated Evaporator Verifying the Energy Saving Benefits Associated with Servicing Air Conditioners


Dx evaporator air side
DX Evaporator - Air side Verifying the Energy Saving Benefits Associated with Servicing Air Conditioners


Refrigerant side measurement
Refrigerant Side Measurement Verifying the Energy Saving Benefits Associated with Servicing Air Conditioners


Compressor performance data
Compressor Performance Data Verifying the Energy Saving Benefits Associated with Servicing Air Conditioners


Estimating efficiency
Estimating Efficiency Verifying the Energy Saving Benefits Associated with Servicing Air Conditioners


Required measurements
Required Measurements Verifying the Energy Saving Benefits Associated with Servicing Air Conditioners


Instrument
Instrument Verifying the Energy Saving Benefits Associated with Servicing Air Conditioners

palm

comp

AMB

RWB

LT

ST

LP/DP

CT

SP

ET


Practical measurements
Practical Measurements Verifying the Energy Saving Benefits Associated with Servicing Air Conditioners

  • Commonly used in the field for diagnostics

  • Field personnel comfortable with concepts and required instruments

  • Special apparatus speeds up measurement process


Data collection tool
Data Collection Tool Verifying the Energy Saving Benefits Associated with Servicing Air Conditioners


Efficiency benchmark for service
Efficiency Benchmark for Service Verifying the Energy Saving Benefits Associated with Servicing Air Conditioners

  • Same unit serviced to achieve:

    • “benchmark”

    • “ideal”

    • “as new”

  • No design changes


A c units respond to their environment
A/C Units Respond to their Environment Verifying the Energy Saving Benefits Associated with Servicing Air Conditioners

  • Characterized by:

    • AMB - Outdoor Drybulb Temperature

    • RWB - Evaporator Entering Air Wetbulb

  • Assumptions

    • Air cooled, DX Equipment

    • Water condensing on Evaporator


Characterizing performance
Characterizing Performance Verifying the Energy Saving Benefits Associated with Servicing Air Conditioners

  • Evaporating Temperature

    • ET(AMB,RWB)

  • Suction Line Superheat

    • SH(AMB,RWB)

    • Standard Charging Chart - Fixed Orifice

  • Condensing Temperature Over Ambient

    • COA(AMB,RWB)

  • Liquid Line Subcooling

    • SC(AMB,RWB)


Getting the benchmark
Getting the Benchmark Verifying the Energy Saving Benefits Associated with Servicing Air Conditioners

  • Measure the driving conditions (AMB, RWB)

  • Evaluate expected ET, SH, COA, SC for current AMB and RWB

  • “Ideally” these are the values measured when the unit was new and installed properly under the current conditions.


Estimating benchmark efficiency
Estimating Benchmark Efficiency Verifying the Energy Saving Benefits Associated with Servicing Air Conditioners

  • Feed expected values (no faults, current conditions) of ET, COA, SH, SC into the same COP calculation as the measured values.


Efficiency index
Efficiency Index Verifying the Energy Saving Benefits Associated with Servicing Air Conditioners

  • “Efficiency of the unit as it is currently operating relative to how it could be performing if serviced to “like new” under the same operating conditions”


Example dirty condenser
Example - Dirty Condenser Verifying the Energy Saving Benefits Associated with Servicing Air Conditioners


Advantages of ei
Advantages of EI Verifying the Energy Saving Benefits Associated with Servicing Air Conditioners

  • Same compressor model used to calculate actual and expected performance - reduces sensitivity to model errors

  • Intrinsic value - does not scale with size of unit


Field measurement ei
Field Measurement - EI Verifying the Energy Saving Benefits Associated with Servicing Air Conditioners

* based on a sampling of 506 units


Creating customer value
Creating Customer Value Verifying the Energy Saving Benefits Associated with Servicing Air Conditioners

  • Get from EI to $ by considering:

    • Nominal capacity (tons)

    • SEER/EER rating

    • Utility rates (e.g $/kwh)

    • Annual runtime hours

  • Estimate $/year wasted because of degraded equipment performance


Service decisions
Service Decisions Verifying the Energy Saving Benefits Associated with Servicing Air Conditioners

  • $/year in wasted energy

  • Compare to cost of service to enhance performance

  • Making service decisions (e.g. when to clean coils) based on energy savings payback.

  • Other criteria also exist in making service decisions


Service strategically
Service Strategically Verifying the Energy Saving Benefits Associated with Servicing Air Conditioners

  • Assess all units in portfolio

  • Prioritize units with most compelling service needs (e.g. energy payback)

  • Target service for maximum effect

  • Verify expected performance


Prioritize sites
Prioritize Sites Verifying the Energy Saving Benefits Associated with Servicing Air Conditioners


Energy savings example
Energy Savings Example Verifying the Energy Saving Benefits Associated with Servicing Air Conditioners

Case study:

  • Big box retail store

  • 14 RTU’s, 11 with two stages (25 cycles)


Results all stages all units
Results: All stages all units Verifying the Energy Saving Benefits Associated with Servicing Air Conditioners

Before Tune-up: 318 kW 46,917 hours of cooling

  • After Tune-up: 268 kW 37,738 hours of cooling

  • Savings: 50 kW (15.8%) 9,179 hours (19.6%)


Payback
Payback Verifying the Energy Saving Benefits Associated with Servicing Air Conditioners

  • Total costs of service: US$ 4,300

  • Estimated energy savings in one year: US$ 21,000


How the add up
How the $ add up Verifying the Energy Saving Benefits Associated with Servicing Air Conditioners

  • Give a tech a tool

  • He applies it to 1000 tons

    • 100x10 ton units, 200x5 ton units

  • Units run between 300 and 2500 hours/year

  • 1 kW/ton - 12 EER

  • 10 cents/kwh


How the add up1
How the $ add up Verifying the Energy Saving Benefits Associated with Servicing Air Conditioners

  • That tech is responsible for roughly $100,000 in energy spent annually.

  • 10% improvement because of strategic application of the same resource based on better information

  • $10,000 saved each year

  • How much would you pay for this information?


Benefits
Benefits Verifying the Energy Saving Benefits Associated with Servicing Air Conditioners

  • Quick measurements

    • It doesn’t have to cost much more or require high skill

  • Measure and Document Efficiency

  • Target Service Strategically

  • Verify Effectiveness


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