C A L I F O R N I A E N E R G Y C O M M I S S I O N

2013 Building Energy Efficiency Standards

Residential Zoned AC Discussion

August 18, 2011

C A L I F O R N I A E N E R G Y C O M M I S S I O N

Zoning Proposal Status• CEC Staff Proposal

• Originally sponsored by the California Statewide Utilities Codes and Standards Program as a Codes and Standards Enhancement (CASE) study

• CASE study authors – Bruce Wilcox, P.E.– John Proctor, P.E. Proctor Engineering Group, Ltd.– Rick Chitwood, Chitwood Energy Management, Inc

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Agenda• Importance of AC in California• California cooling climate• Other AC improvements• Why zoning improvements• Magnitude of problem and savings• Laboratory testing of bypass • Review of field studies • Zoning Proposal Recap

August 18, 2011

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Why Air Conditioning is Important

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California Cooling Climate• Features

– high daytime dry bulb temperatures– big solar gains every day– low relative humidity– low nighttime temperatures

• Results– sensible capacity and EER at high outdoor

temperature are important– dehumidification is not useful

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Staff Proposed AC Improvements• Higher solar reflectance roofing• Lower SHGC windows (from 0.4 to 0.25)• Increased wall insulation in all zones• Insulation quality inspections• Whole house fans• Roof deck insulation• Increased attic duct insulation• Mandatory AC minimum air flow • Improved zonal control systems

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Why Zoning Improvements• There are a lot of unimproved zoning

systems in new California homes• Unimproved multi-zone ducted systems

have significantly lower energy efficiency– Laboratory tests by Carrier– Field tests in new California homes

• Many alternative zoning approaches can deliver equivalent efficiency

• Zoning system improvements are cost effective.

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Zoning Code Change Philosophy• Multi-zone systems are fine

• But

• Multi-zoned systems should deliver the same (or better) energy efficiency as single zone systems)

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12% of the Ducted Systems are Dampered Multi-Zoned

Dampered Zoned Split 10 (1Heat Pump)

Single Split 28 (not Zoned)

Multiple Split 17

Ducted Hydronic w AC 11

Heat Pump 5 (not Zoned)

Package 6

Furnace Only 3

Total 80

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Dampered Multi-Zone Systems have Low CFM per Ton andHigh Cooling Fan Power per CFM

Single Zone

Multi Zone All

Multi Zone One

0

100

200

300

400

500

600

AverageMaximum

CF

M p

er

To

n

Single Zone

Multi Zone All

Multi Zone One

0

0.2

0.4

0.6

0.8

1

1.2

1.4

AverageMaximum

Wa

tts p

er

CF

M

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Average Energy Impact

• In typical homes with dampered multi-zone systems:

–Air Conditioning SEER and EER are degraded by 17%

–Furnace AFUE is degraded by 4.4%

August 18, 2011

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Effect of Bypass and Zoning Flow in SEER Terms

Zoned with 50% Bypass

1992 Minimum Standard

Zoned All Dampers Open

2006 Minimum Standard

0

2

4

6

8

10

12

14

9 1011.8

13

SEER

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Eliminate Bypass and Obtain a Minimum Airflow

Series10%

5%

10%

15%

20%

25%

30%

35%

25%

Efficiency Increase

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Carrier Laboratory Testing of Bypass

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Carrier ASHRAE Paper Literature Review

• Papers cited by AHRI to support the zoning performance credit– “All but one study employed variable or two speed

equipment.” – “… the homes were unoccupied and zone

separation (closed doors) was maintained throughout testing caused energy losses to be minimized. Thus, the documented field studies could be considered a ‘best case scenario’ in terms of energy savings.”

August 18, 2011

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Code Change Proposals• Eliminate bypass ducts

• Mandatory airflow and fan Watt verification in all zonal cooling modes(the airflow and Watt draw mandate also apply to single zoned systems)

• Delete the current zonal AC performance compliance credit.

August 18, 2011

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Chitwood’s Redding, California Showcase Home

With 4 zone ducted AC system that meets the proposed requirements.

August 18, 2011