california statewide utility codes and standards program energy for change™ 04/15/2010 1...

California Statewide Utility Codes and Standards Program

Energy for Change™

04/15/2010

1

Refrigerated Warehouses Stakeholder Meeting #1

Portland Energy Conservation, Inc.VaCom Technologies

Heschong Mahone Group, Inc

April 15, 2010

CALIFORNIA STATEWIDE UTILITIES CODES AND STANDARDS PROGRAM

04/15/20102011 Refrigerated Warehouse Stakeholder Meeting

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Refrigerated Warehouse 2011 Title 24 Stakeholder Meeting

Welcome and Introductions

Michele Friedrich, PECI



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Agenda

● 10:00–10:20 Introduction

● 10:20–10:35 Overview/History

● 10:35–11:15 Model & Data Analysis

● 11:15-12:00 2011 Measures

● 12:00-12:45 lunch

● 12:45-2:30 2011 Measures (cont)

● 2:30-2:45 Acceptance Tests

● 2:45-3:00 Wrap up



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Ground Rules

● For those attending by telephone/web● Please DO NOT place your phone on HOLD. We do not want to hear

your hold music.● Please mute your microphone, unless you want to speak.● Ask questions/comment by “chat” or by voice.

● We want to hear your concerns. ● Opposing viewpoints are encouraged.● We are seeking information, not resolution.

● Time is limited● Hold questions/comments until the comment periods.● Raise your hand and be acknowledged by presenter.● Clearly state your name and affiliation prior to speaking.● Speak loudly for the people on the phone.

● Minutes and presentation material will be distributed.● If you are attending by phone, DO NOT place your phone on

HOLD.



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Schedule of Refrigerated Warehouses Stakeholder Meetings● There will be at least four refrigerated warehouse

stakeholder meetings:● March 17 and April 15, 2010: present scope,

including:● Code change direction and possible options● Methodology of analysis

● August 2010: present findings, including:● Results of data collection and analysis ● Cost effectiveness● “Strawman” proposed code language

● September 2010: seek final feedback on proposed code language

● All meetings can be attended remotely.● Please sign-in for all future meeting

announcement mailings.



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Stakeholder Process

Cathy Chappell, HMG



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IOU Support for 2011 Title 24

● The California Investor Owned Utilities (IOUs) are actively supporting the California Energy Commission (CEC) in developing the state’s building energy efficiency standard (Title 24).

● Their joint intent is to achieve significant energy savings through the development of reasonable, responsible, and cost-effective code change proposals for the 2011 code update, and beyond.

● As part of the IOU effort, at the request of the CEC, we are hosting stakeholder meetings to get industry input and feedback on our code change proposals.



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Code Change Activity

● 2011 T-24 base code

● 2011 reach standard● Voluntary standards for local govts.● Green Building Standard

● Toward Zero Net Energy goal● 2014 T-24● Future reach codes



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Requirements for a Successful Code Change

To be included in code, a measure must:● Be cost-effective according to the Time

Dependent Valuation (TDV) life-cycle costing methodology set out by the California Energy Commission (CEC)

● Be possible to implement using equipment that is readily available from multiple providers (or that is reasonably expected to be available following the code change).



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Schedule: CEC Key Dates

● Mar 2010 - Dec 2010● CEC develop foundation ● IOUs:

● Conduct research, and cost effectiveness analysis● Present results at stakeholder meetings

● Dec 2010● IOUs finalize code change proposals for submittal to CEC

● Feb 2011● CEC opens Rulemaking for Title 24, develop 45-day

language

● June 15, 2011● Title 24 Adoption date

● Jan. 1, 2013● Title 24 Implementation date



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Stakeholder Meetings Purpose

● Publicize code change proposal● Present to and solicit feedback from stakeholders

on:● Methodology● Technology options● Market status ● Draft code language

● Gather additional information from stakeholders on:

● Best practices● Product/technology availability● Market penetration data● Cost data



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Refrigerated WarehousesSpecific Stakeholders Identified● ASHRAE- American Society of Heating, Refrigerating and Air

Conditioning Engineers● AHRI- American Heating And Refrigeration Institute● IIAR- International Institute Of Ammonia Refrigeration● GCCA – Global Cold Chain Alliance (IARW, IACSC)● Equipment manufacturers● Consultants, energy modelers, etc● Refrigerated warehouse building owners● City and County code officials● Equipment distributers and suppliers● Refrigerated warehouse designers● Investor Owned Utilities● California Energy Commission● California Air Resources Board● Non Governmental Organizations



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2011 CASE Process Overview

Comments?

Questions?



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Overview of 2008 Title 24 for Refrigerated Warehouses (§ 126)




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Refrigerated WarehousesOverview of 2008 T24 (§ 126)

Applicability● Refrigerated Warehouse with Cold or

Frozen Storage > 3,000 ft2

Exceptions● Appliance efficiency (Title 20) applies to

refrigerated space < 3,000 ft2

● Areas designed solely for quick chilling or freezing



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SPACE SURFACE Min R-VALUE(°Fhrft2/BTU)

FrozenStorage

Roof/Ceiling R-36

Wall R-36

Floor R-36

Cold Storage

Roof/Ceiling R-28

Wall R-28

Insulation



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Underslab Heating● Electric resistance heat shall not be used

for the purposes of underslab heating.

● Exception: Thermostatically controlled and disabled during summer on-peak period defined by local utility.



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Fan-powered Evaporators● Single-phase fan motors < 1 HP and < 460

V shall be electronically commutated motors (ECM).

● Fans shall be variable speed, speed controlled in response to space conditions.● Exception: evaporators served by a

single compressor without unloading capability.



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Fan-powered Condensers● Condensers for ammonia systems

shall be evaporatively cooled.● Design condensing temp for

evaporative condenser < design Twetbulb plus: ● 20F when design Twetbulb ≤ 76F, ● 19F when 76F< design Twetbulb < 78F● 18F when 78F ≤ design Twetbulb



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Fan-powered Condensers

● Design condensing temperatures for Air-cooled condensers:● ≤ the design drybulb temperature plus

10F for frozen storage. ● ≤ the design drybulb temperature plus

15F for cold storage.

● Exception: Unitary condensing units



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Refrigerated WarehousesOverview of 2008 T24 (§ 126)Fan-powered Condensers● Condenser fans shall be continuously

variable speed and the speed of all condenser fans serving a common high side are controlled in unison.

● Min condensing temperature set point 70F or less using ambient reset control ● air-cooled reset based on drybulb temp ● evap-cooled reset based on wetbulb temp

● All single phase motors < 1 hp and < 460 V, either permanent split capacitor or ECM.



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Refrigerated WarehousesOverview of 2008 T24 (§ 126)Compressors● Compressors designed to operate at a

minimum condensing temperature ≤ 70F ● Screw compressor > 50 HP

● Speed control in response to load OR ● Input power ≤ 60% of full load power at

50% of full refrigeration capacity. ● Exception: refrigeration plants with

more than one dedicated compressor per suction group



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Information on 2008 Refrigerated Warehouse Standard

● Classes on 2008 StandardSCE: August 2, CTAC- Irwindale

● Energy Efficiency Hotline● E-mail: [email protected]● Phone: 916-654-5106 or● Phone: 1-800-772-3300 (toll free in Calif.)

● Title 24 website www.energy.ca.gov/title24/



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Building Models and Assumptions

Brian Dobbs, VaCom Technologies



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Refrigerated WarehousesData Analysis Overview

● Savings calculated with DOE2.2R ● Whole-building/system hourly simulation tool

● Mass-flow based

● Designed for component/control strategy level modeling● Explicit simulation of most refrigeration control

strategies● Hourly weather file

● Hourly DBT, WBT, wind velocity, solar● Hourly schedules

● Loads, operations, set-points



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● DOE2.2R allows detailed simulation of building envelope● Building constructions

● Define materials and thermal properties

● Calculates roof and wall load● Accounts for building configuration

● Orientation, adjacent spaces



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● Details of space definitions● Simulates infiltration load using:

● ASHRAE methodology for interzonal air exchange (density difference)

● Wind velocity adjusted external infiltration● Hourly activity schedules

● Lighting and lighting controls can be defined● Miscellaneous equipment loads can be added

● Process loads

● Evaporator fan ● Power usage● Controls (VFD, fan cycling)



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● Example of Hourly Schedule Inputs

0%

20%

40%

60%

80%

100%

120%

12:00

AM

2:00

AM

4:00

AM

6:00

AM

8:00

AM

10:00

AM

12:00

PM

2:00

PM

4:00

PM

6:00

PM

8:00

PM

10:00

PM

People Lighting Equipment Infiltration



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● Detail equipment operation



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● Energy usage summary and break-outs



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● Utility usage summary and break-outs



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● Initial Analysis: Sacramento weather

● Baseline simulation models:● Large warehouse (92,000 ft2)

● Screw compressors● R-717 refrigerant● Evaporative-cooled condenser

● Small warehouse (26,000 ft2)● Semi-hermetic compressors● R-404A refrigerant● Air-cooled condensers



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Refrigerated Warehouses Baseline Warehouse Description● Freezer Space

● 40,000 S.F. (Large Warehouse)● 10,000 S.F. (Small Warehouse)● -10°F space temperature● R-36 insulation

● Cooler Space● 40,000 S.F. (Large Warehouse)● 10,000 S.F. (Small Warehouse)● 35°F space temperature● R-28 Insulation

● Loading Dock● 12,000 S.F. (Large Warehouse)● 6,000 S.F. (Small Warehouse)● 40°F space temperature● R-28 insulation



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Refrigerated WarehousesWarehouse Diagrams

Large Warehouse

Small Warehouse



35Refrigerated WarehousesLarge Warehouse System Description● LT Suction Group

● Serves Freezer space● -23°F design SST● (2) screw compressors, 62.5 TR capacity, 165 HP each at design● Evaporator fan power calculated using 34 Btuh/W spec efficiency

● MT Suction Group● Serves Cooler and Dock spaces● 22°F design SST● (2) screw compressors, 110.2 TR capacity, 134 HP each at design● Evaporator fan power calculated using 34 Btuh/W spec efficiency

● Evaporative-cooled Condenser● 6,400 MBH capacity at design TD = 23°F (96°F design SCT, 73°F

design WBT)● 330 Btuh/Watt specific efficiency at 100°F SCT, 70°F WBT● 70°F minimum SCT, wetbulb-following SCT control, variable

speed fans working in unison



36Refrigerated WarehousesSmall Warehouse System Description● Low-Temperature (Freezer) System

● -23°F design SST, 114°F design SCT● (8) Semi-hermetic compressors● Air-cooled condensers, 10°F design TD, 53 Btuh/Watt● 70°F minimum SCT, drybulb-following control strategy,

variable-speed fans● Evaporator fan power calculated using 34 Btuh/Watt

● Medium-Temperature (Cooler and Dock) System● 22°F design SST, 119°F design SCT● (4) Semi-hermetic compressors● Air-cooled condenser, 15°F design TD, 53°F Btuh/Watt● 70°F minimum SCT, drybulb-following control strategy,

variable-speed fans● Evaporator fan power calculated using 34 Btuh/Watt



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Refrigerated Warehouses Screw Compressor Performance

● Model in large warehouse only● Convert two-compressor suction group to

single-compressor● LT and MT system evaluated

● Slide valve part-load performance from manufacturer’s software

● Speed reduction part-load performance from manufacturer’s software● Speed reduction down to minimum speed, then

slide valve unloading● Analysis includes 3% fixed drive losses


Refrigerated Warehouses Screw Compressor Performance

● Sample Part-load Relation


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Percent ofFull Load (%)

Capacity(TR)

Power(BHP)

PerformanceFactor (TR/BHP)

100% 378.2 894.1 0.42390% 340.4 841 0.40580% 302.5 788.4 0.38470% 264.7 736.8 0.35960% 226.9 687 0.33050% 189.1 639.7 0.29640% 151.3 595.4 0.25430% 113.5 555 0.20520% 75.6 519 0.14610% 46 494.3 0.093



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Refrigerated WarehousesWarehouse Load Description

Large Warehouse Small WarehouseLights 0.70 Watts/S.F., all spaces 0.70 Watts/S.F., all spaces

People 1,500 S.F., 1,450 Btuh per person 1,500 S.F., 1,450 Btuh per person

Forklifts 30 forklifts (20 MBH ea), 10 pallet lifts (10 MBH ea), distr. by SF

10 forklifts (20 MBH ea), 3 pallet lifts (10 MBH ea), distr. by SF

Product Load Freezer: 400,000 lb/day, 5°F pulldown, 0.50 Btuh/(lb °F) specific heat

Cooler: 400,000 lb/day, 10°F pulldown, 0.65 Btuh/(lb °F) specific heat PLUS 750 tons respiring product, 5,500 Btuh/ton heat of respiration

Freezer: 100,000 lb/day, 5°F pulldown, 0.50 Btuh/(lb °F) specific heat

Cooler: 100,000 lb/day, 10°F pulldown, 0.65 Btuh/(lb °F) specific heat PLUS 188 tons respiring product, 5,500 Btuh/ton heat of respiration



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Refrigerated WarehousesWarehouse Load Description

Large Warehouse Small WarehouseInfiltration 4,000 CFM (200 CFM/dock door,

subject to hourly schedule and wind effects).

Assume inter-zonal doors between Dock and Cooler/Freezer open 15 times per hour each (once every four minutes)

Assume inter-zonal door between Cooler and Freezer opens 4 times per hour (once every 15 minutes.

Assumed inter-zonal door opening time: 5 seconds to open/close, 15 second stand-open time, 20 seconds total open time per opening

1,200 CFM (200 CFM/dock door, subject to hourly schedule and wind effects).

Assume inter-zonal doors between Dock and Cooler/Freezer open 15 times per hour each (once every four minutes)

Assume inter-zonal door between Cooler and Freezer opens 4 times per hour (once every 15 minutes.

Assumed inter-zonal door opening time: 5 seconds to open/close, 15 second stand-open time, 20 seconds total open time per opening



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2011 Refrigerated WarehousesBuilding Model and Assumptions

Comments?

Questions?



42Refrigerated Warehouse 2011 Title 24 Stakeholder Meeting2011 Enhancements of Title 24 for

Refrigerated Warehouses

Doug Scott, VaCom Technologies



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Refrigerated Warehouse 2011 Cycle Title 24 Measures

Base Code (2011)● Freezer Floor and Roof Insulation R-values● Evaporator Specific Efficiency (BTUh/W)● Condenser Specific Efficiency (BTUh/W)● Ammonia System Air-cooled Condensers● Screw Compressor Part-load Performance● Acceptance Tests

Reach Code● Condensing Unit EER (BTUh/W)



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2008 Refrigerated WarehouseInsulation Analysis Summary

However, 2008 Standard R-values selected to matched Title 20 Standard for walk-ins

2008 freezer roof and floor: R-36

2008 CASE Study FindingsBenefit/Cost Ratio

Coastal (CZ 3)

Central Valley (CZ

13)

Ceiling R-35 to 50 R-46 R-49 3.7 4.3Wall R-35 to 40 R-32 R-40 1.9 2.2Floor R-27 to 32 R-30 R-30 4.8 5.0Ceiling R-24 to 40 R-24 to R-40 R-35 1.1 2.0Wall R-24 to 32 R-25 R-25 0.6 1.1

Shell Component

Freezer

Cooler

ASHRAE 2002

Handbook

Common Practice

2008 CASE Recommendation



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2011 Freezer Roof and Floor Insulation Measures

● Investigate cost-effectiveness of additional freezer roof insulation● Greater choices for refrigerated warehouses R-

values than for foamed-in-place walk-in panels

● Investigate cost-effectiveness of R-36 floor insulation vs. a lower level, consistent with standard increment of extruded polystyrene under slab insulation

● Make analysis and requirements consistent in terms of rating temperature (applied temperatures or ~75 F) and new vs. aged


2011 Freezer Roof and FloorInsulation Analysis

● Increase freezer roof insulation incrementally from R-36 to ~R-50

● Decrease freezer floor insulation incrementally from R-36 to ~R-24


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2011 Freezer Roof and FloorInsulation Data Summary

● Obtain details on common insulation size increments and incremental costs for:● Underfloor extruded polystyrene● Common over-deck insulation compositions● EPS and ISO sandwich roof/ceiling panels.

● Determine assumptions for insulation rating temperature and aged vs. new R-value

● Verify FIP panels can meet requirement● Identify other constructability issues


2011 Freezer Roof and FloorInsulation Data Collection Tasks


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● Contact:● Cold storage construction contractors

● Insulation and panel manufacturers

● GCCA/IACSC (Intl Assn for Cold Storage Const.)

● Extract information from past new construction projects

● Review requirements in Fed WI Test Standard for testing consistency



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2011 Freezer Roof and FloorInsulation

Comments?

Questions?

CALIFORNIA STATEWIDE UTILITIES CODES AND STANDARDS PROGRAM2011 Evaporator Specific Efficiency Code Change Options● Specific Efficiency = Cooling capacity at a

standard rating value divided by power.● Rating point: 10°F TD between entering air

temperature and saturated suction; doesn’t mean this is the applied TD

● Very large range of specific efficiencies.

● High potential savings simply by eliminating the least efficient (high fan power) models, which are not normally used in well engineered systems.


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512011 Evaporator Specific Efficiency Code Change Options● Savings is the improvement from below

minimum up to minimum efficiency● Easy to justify excluding worst performing

models. BUT:● This cannot be done properly without test

standards and certified ratings for BOTH cooling capacity and power.

● No evaporators currently state testing to standards and none indicate certification.

● Requires changes to existing standards.● Changes caused by evaporator testing and

certification are potentially far-reaching.



522011 Evaporator Specific Efficiency Issues with Ratings● Evaporator ratings, especially in smaller

sizes, generally thought to be significantly commercialized.

● Fan power often not listed, available upon request but may be nominal motor power, not applied power.

● AHRI Standard 420 tests at reasonable conditions but some issues (e.g. freezer coil rated with no frost).



532011 Evaporator Specific Efficiency Air Circulation Volume, RH, Defrosts● Air circulation volume and cooling capacity are

not generally independent design parameters; airflow usually an unmanaged consequence of coil selection for cooling capacity and price.

● Evaporator are selected to maintain temperature and frequently also humidity; industry has experience-driven practice to achieve proper humidity – typically via coil TD but essentially airflow vs. capacity.

● Industry has experience with TD and FPI (fins per inch) for satisfactory defrosts: which indirectly affects airflow and specific efficiency.



542011 Evaporator Specific Efficiency Analysis and Rating Issues● Refrigerants and fluids: NH3, halocarbon, volatile indirect

(e.g. CO2), single phase indirect (e.g. glycol)● Application temperature: two temperatures not enough for

rating standards for all application conditions● External static pressure: accommodate penthouse coils but

not oversized motors or excessive throw● Motor loading: define at application conditions● Feed type: DX vs. recirculated or flooded● Assumptions for wet or dry; frosted or non-frosted coil ● Assumptions for defrost method and efficiency● Fin density: could improve specific efficiency with more FPI

but cause excessive defrosts● Liquid-suction heat exchanger: may be most cost effective

means to increase DX coil performance● Refrigerants with glide



552011 Evaporator Specific Efficiency Summary of Available data● Savings By Design program history used to

establish beginning values: ● Provisional minimum efficiency = 34 BTUh/W● Average of units purchased in California that

were below minimum efficiency = 26 BTUh/W

● Cataloged models put in database

● Evaluate European standards and test methods for evaporators

● Obtain costs from published price lists and sample vendor quotes



562011 Evaporator Specific Efficiency Data Collection Tasks

● Contacts:● Evaporator coil manufacturers

● Obtain European standards

● Identify and obtain any available test data to relate catalog data to applied conditions, frosted operation, etc.

● And/or, perform testing in lab (SCE RTTC) or in field, particularly on DX evaporators, possibly along with condensing unit test.

● Request info. from technical advisors



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2011 Evaporator Specific Efficiency

Comments?

Questions?



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2011 Condenser Specific Efficiency Code Change Options

● Specific Efficiency = Heat rejection capacity at standard rating value divided by power.● Rating point: 10°F TD between entering air

temperature and saturated condensing temperature; doesn’t mean this is the applied TD

● (10°F may be questionable if research determines this is not actually being achieved)

● Midpoint between bubble point and dew point for glide refrigerants

● Very large range of specific efficiencies.● High potential savings simply by eliminating

the least efficient models.



592011 Condenser Specific Efficiency

Code Change Options● Savings is the improvement from below

minimum up to minimum efficiency.● Similar to evaporators, need test standards

and certified ratings for both capacity and power.

● No condenser catalogs currently state testing to standards and none indicate certification.

● Requires changes to existing standards.● Changes caused by condenser testing and

certification are potentially far-reaching.● Air cooled: affects other applications such as

supermarket condensers● Evap cooled: affects many industrial applications



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2011 Condenser Specific Efficiency Issues with Evap-Cooled Ratings

● Wide range of types:● Forced draft, induced draft● Indoor location with external static

● Standards:● ASHRAE Standard updated in 2005 (methods)● AHRI test points: 78°F WBT and 105°F SCT (R-22) and

96°F (NH3) – WBT is far from normal range. Relies on manufacturers application correction factors.

● Cooling Tower Institute not yet investigated.

● High cost of testing and rating

● Variable speed changes low power economics



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2011 Condenser Specific Efficiency Issues with Air-Cooled Ratings

● Air cooled capacity historically shown with a single Q=UATD from 1 to 30°F TD.● AHRI Standard based on 30°F TD standard test

point vs. 10°F and 15°F commercial application● (Not saying AHRI Standard is being used)

● Fan power often not listed, OEM motors, power available upon request but may be nominal motor power, not applied power.

● New product changes: BLDC motors (variable speed; variable specific efficiency by setting max speed); micro channel HX.



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2011 Condenser Specific Efficiency Issues with Air-Cooled Ratings

● Test ratings at high SCT may not fairly compare operation at (more common) reduced head pressure due to internal pressure drop at reduced pressure.

● European standards may give guidance on defining performance for application conditions.

● Variable speed changes economics of low power condensers.● Most of year is not at reduced speed; third

power fan power reduction. Longer payback for larger and/or low power condenser.



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2011 Condenser Specific EfficiencySummary of Available data● Savings By Design program history used to

establish beginning values:● Provisional minimum specific efficiency:

● Evap: 330 BTUh/W at 100°F SCT, 70°F WBT● Air: 53 BTUh/W at 10°F TD

● Average of units purchased in California that were below minimum efficiency:

● Evap: 220 BTUh/W● Air: 44 BTUh/W

● Most cataloged models have been databased● Evaluate European standards and test methods● Obtain costs from published price lists, pricing

software and sample vendor quotes



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2011 Condenser Specific EfficiencyData Collection Tasks

● Contacts:● Condenser manufacturers

● Obtain European standards

● Identify and obtain any available test data:

● Air-cooled, in particular 30°F vs. 10°F TD

● Evap-cooled, in particular information on correction factors related to test/standard basis

● Request info. from technical advisors.



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65

2011 Condenser Specific Efficiency

Comments?

Questions?



662011 Air-Cooled Ammonia CondenserCode Change Options● Allow use of air-cooled condensers on

ammonia systems.● Potential benefits:

● Ammonia air-cooled systems with T24 sizing and control may have comparable annual kWh as evap-cooled in many regions (Air-cooled has higher peak kW.)

● Water savings – important in California● Energy savings with ammonia (if air is going to

be used anyway)



672011 Air-Cooled Ammonia Condenser Analysis Issues● Evaluate a cost-effective minimum specific

efficiency; probably different than halocarbon condensers.

● Include specific efficiency requirement and existing VFD requirement.

● Utilize existing mandatory sizing requirements of 10°F (low temp) and 15°F (med temp).

● Calculate water savings.



682011 Air-Cooled Ammonia CondenserData Collection Tasks

● Obtain information from ammonia air-cooled condenser manufacturers (there are two or more).

● Obtain price quotes.



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69

2011 Air-Cooled Ammonia Condenser

Comments?

Questions?



702011 Compressor Part Load Efficiency Code Change Options● Change: Simplify 2008 screw compressor

variable speed requirement and/or the exemption via part-load efficiency.

● Issue: Industrial screw compressor ratings are generally not published in accordance with a rating standard and are not certified, at either full load or for part load performance.

● Possible change to mandatory application-based criteria, eliminating compressor part-load efficiency as a basis of compliance.



712011 Compressor Part Load Efficiency Analysis● Simulation analysis to determine:

● Threshold saturated suction temperature below which variable speed is consistently cost effective for single stage compressors.

● Whether variable speed for booster compressors (on two stage systems) is cost effective.



722011 Compressor Part Load Efficiency Summary of Available data● Utilize existing manufacturers performance

software.● Obtain additional lab test information as

available from manufacturers.



732011 Compressor Part Load Efficiency Data Collection Tasks● Obtain costs from compressor manufacturers

price lists, price quotes and from VFD vendors.



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74

2011 Compressor Part-Load Efficiency

Comments?

Questions?



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Reach Code Option Air-Cooled Condensing Unit EER

● 2008 Code exempts most unitary air-cooled condensing units from condenser sizing (TD) requirement.● Large air-cooled units ARE required to meet

TD, but problematic for “catalog” units since the application conditions are not known when designed.

● EER (Energy Efficiency Ratio) is cooling capacity divided by input power of the entire condensing unit (compressor and condenser fan energy).

● EER and (usually) power are not published and capacity is generally thought to be based on compressor ratings not unitary test standards.



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● Condensing unit capacity based on compressor standard ratings inherits a large and long standing error:● Most refrigeration compressor are rated at a

fixed 65°F RGT (return gas temperature) regardless of saturated suction.

● All superheat from evaporator temperature to 65°F is assumed to be productive refrigeration.

● Potential error between catalog capacity and actual productive refrigeration can be 15-35%.

● Test data lacking on:● Actual productive cooling capacity vs. unit rating● Compressor performance at varying RGT



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● EER standards must be done in parallel with evaporator standards, to avoid causing a mismatch.

● Capacity shortfall probably masked by rule-of-thumb load calculations and adjustment for “18 hour” run times. If system capacity ratings decrease, equipment will be larger than before and with less run time. Training needed to select equipment properly under new ratings.

● EER standards would likely cause all catalogs to change, impacting other uses.

● Compressor manufacturers will need to provide rating data or adjustments for lower RGTs.



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Reach Code OptionAir-Cooled Condensing Unit EER

Comments?

Questions?



79Refrigerated Warehouse 2011 Title 24 Stakeholder Meeting

Acceptance Tests




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Refrigerated WarehousesAcceptance Tests

● What are acceptance tests?● Tests performed on the building’s systems in order

to show compliance with the code.

● When are acceptance tests implemented?

● After start-up● Before normal use of the equipment

● Who can do the acceptance tests?● Licensed mechanical engineer, civil engineer,

architect or contractor



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Refrigerated WarehousesAcceptance Tests

How to show Compliance?● Checklist● Certificate of acceptance● Submittal of necessary

documentation



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2011 Acceptance Tests

Development Process

1. Post installation verification site visits

2. Develop preliminary version or tests

3. Pilot test the tests

Solicit input from stakeholders



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83


Acceptance Requirements for 2008 Code

● Electric Resistance Underslab Heating

● Evaporator Fans

● Evaporative-cooled Condenser Fans

● Air-cooled Condenser Fans

● Screw Compressors



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Comments?

Questions?



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Wrap Up


california statewide utility codes and standards program energy for change™ 04/15/2010 1...

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