California Energy Commission

STAFF PAPER
Pumped Refrigerant
Economizers for Use in
Computer Rooms
Mark Alatorre, P.E.
Building Standards Office
Efficiency Division
California Energy Commission
California Energy Commission
Edmund G. Brown Jr., Governor
August 2015 | CEC-400-2015-029
i
DISCLAIMER
Staff members of the California Energy Commission prepared this report. As such, it
does not necessarily represent the views of the Energy Commission, its employees,
or the State of California. The Energy Commission, the State of California, its
employees, contractors and subcontractors make no warrant, express or implied,
and assume no legal liability for the information in this report; nor does any party
represent that the uses of this information will not infringe upon privately owned
rights. This report has not been approved or disapproved by the Energy
Commission nor has the Commission passed upon the accuracy or adequacy of the
information in this report.
ii
ABSTRACT
California’s Building Energy Efficiency Standards require the mechanical cooling
equipment serving a computer room to be equipped with either an integrated air-side
economizer or an integrated water-side economizer. A mechanical cooling system
integrated with one of these features can provide cool air to the space without operating
the mechanical cooling system when the outside conditions are cool enough to provide
sufficient cooling to the space. This results in energy savings due to not having to
operate a compressor to cool the air or water mechanically.
Pumped refrigerant economizing uses the same concept for energy savings, in that it
bypasses the compressor for mechanical cooling by using a pump to move the
refrigerant through the evaporator and condenser. The energy savings is achieved by the
difference in energy consumption between the pump and compressor.
California Energy Commission staff proposes that the Commission approve a
compliance option for pumped refrigerant-based economizers to be used as an
alternative to water-side economizing for computer rooms. The proposed alternative is
based on building simulations using CBECC-Com 3b (Build 717).
The proposed alternative of a pumped refrigerant economizer will allow this emerging
technology to be used for standards compliance, where feasible. The benefit of this
technology is not only energy savings, but water savings.
Keywords: California Energy Commission, refrigerant economizer, economizing, Liebert
DSE, Emerson Network Power, AlaJor Engineering, Building Energy Efficiency Standards,
CBECC-Com
Alatorre, Mark, 2015. Pumped Refrigerant Economizers for Use in Computer Rooms.
California Energy Commission. Publication Number: CEC-400-2015-029.
iii
TABLE OF CONTENTS
Page
Abstract ................................................................................................................................................iii
Table of Contents ............................................................................................................................... iv
List of Figures ..................................................................................................................................... iv
List of Tables ....................................................................................................................................... iv
Executive Summary............................................................................................................................. v
Introduction ......................................................................................................................................... 1
Compliance Options ....................................................................................................................... 1
Compliance Option for Refrigerant Economizers .................................................................... 1
Staff Evaluation ................................................................................................................................... 4
Computer Rooms and the Standards.......................................................................................... 4
Review of Computer Room Economizing .................................................................................. 4
Results of Refrigerant Economizer Analysis ............................................................................. 5
Public Review of Refrigerant Economizer Analysis ................................................................. 9
Proposed Alternative for Computer Room Economizing ....................................................... 9
Conclusion ........................................................................................................................................ 9
References ......................................................................................................................................... 10
LIST OF FIGURES
Page
Figure 1: Water-Side Economizer Schematic ................................................................................. 2
Figure 2: Emerson Component Layout ........................................................................................... 3
Figure 3: Pumped Refrigerant Economizer Schematic ................................................................ 3
LIST OF TABLES
Page
Table 1: End Use Summary Comparison − All Climate Zones ................................................... 5
iv
EXECUTIVE SUMMARY
Public Resources Code, Section 25402.1 (b) requires that the California Energy
Commission establish a formal process for certification of compliance options relating
to new products, materials, or calculation methods that are usable for showing
compliance with the Building Energy Efficiency Standards. In response to this
requirement, Section 10-109 of the Building Energy Efficiency Standards establishes the
process for introducing designs, materials, or devices that cannot be adequately
modeled in any currently approved alternative calculation methods or that are not
appropriately accounted for in currently approved compliance approaches.
Currently, the Building Energy Efficiency Standards prescriptively require that the
mechanical cooling equipment serving a computer room be equipped with either an
integrated air-side economizer or an integrated water-side economizer. A mechanical
cooling system integrated with one of these features can provide cool air to the space
without operating the mechanical cooling system provided the outside conditions are
sufficiently cool. This results in energy savings due to not having to operate a
compressor to mechanically cool the air or water.
Emerson Network Power (Emerson) used the established compliance option process of
Section 10-109 to submit an application for approval of their Liebert DSE data center
cooling system to be accounted for in the currently approved prescriptive compliance
approach. This system features a pumped refrigerant economizer that follows the same
principle of “economizing,” in that it provides cool air to the space when the
compressor is off or assisted and is still able to provide sufficient cooling. The Liebert
DSE system uses pumps to move the refrigerant from the condenser to the evaporator,
absorbing heat from the computer room and rejecting that heat to the outdoors. The
energy savings is the difference in energy consumption between the pump and
compressor. The proper outside conditions must be present for this process to work,
just like air or water-side economizing, but unlike a water-side economizer the Liebert
DSE system does not consume any water.
As part of their application Emerson included building simulation files comparing their
system to a water-side economizer using the approved public domain software CBECCCom. The results showed energy savings in 14 of the 16 climate zones. The climate
zones where their system does not perform as well as a water-side economizer are
climate zones 10 and 15.
Staff therefore recommends approval of this compliance option for pumped refrigerant
based economizers as a prescriptive alternative to water-side economizing for computer
rooms for climate zones 1-9, 11-14 and 16. This proposed alternative will provide
energy savings in 14 out of the 16 climate zones, and will offset the use of water that
would otherwise be consumed by the installation of a water-side economizer.
v
Introduction
This report presents California Energy Commission staff’s recommendation for approval
of a compliance option for the Liebert DSE data center cooling system for computer
rooms. The compliance option is based on energy simulations using approved public
domain software CBECC-Com 3b (Build 717) that shows energy savings in 14 of the 16
climate zones for computer rooms that use a pumped refrigerant economizer opposed
to a water-side economizer.
Compliance Options
Public Resources Code, Section 25402.1 (b) requires the California Energy
Commission to establish a formal certification process for compliance options
relating to new products, materials, or calculation methods that are usable for
showing compliance with the Building Energy Efficiency Standards (Standards). In
response to this requirement of the Public Resources Code, Section 10-109 of the
Standards establishes the process for introducing designs, materials, or devices that
cannot be adequately modeled in any currently approved alternative calculation
methods or that are not appropriately accounted for in the current approved
compliance approaches.
The compliance option process enables the use of new or additional products,
materials, designs, or procedures for demonstrating compliance with applicable
building standards. In doing so, the process encourages market innovation and
allows the Energy Commission to respond to changes in building design,
construction, installation, and enforcement.
Compliance Option for Refrigerant Economizers
To comply with the Standards, mechanical cooling equipment serving computer
rooms must be equipped with an integrated air-side or water-side economizer. The
choice of air-side or water-side economization depends on the mechanical cooling
system type.
Chilled water systems are a type of mechanical cooling that has an integrated waterside economizer and takes advantage of cooler outside conditions to provide cooling
to the space. Generally, during favorable conditions, the chiller can be turned off,
and the cooling tower provides the means of cooling the chilled water used to cool
the space. The water-side economizer loop can also precool the supply air to help
lower the load to the chiller and reduce energy use when the cooling load cannot be
satisfied with the economizer alone.
When the water-side economizer is enabled, pumps are used to move the water
between the cooling tower and the heat exchanger. The “economizing” happens in
1
the form of energy savings due to the chiller being off or assisted and still being
able to provide sufficient cooling to the space. Given the constant cooling load of a
computer room due to always-on heat-generating electronic equipment, these
economizing conditions appear on most days and can be very favorable in certain
climate zones.
Figure 1: Example of Water-Side Economizer on a Chilled Water Plant
Source: 2013 Nonresidential Compliance Manual
2
Pumped refrigerant economizing follows the same principle of “economizing” in
that it provides cooling when the compressor is off or assisted and still being able to
provide sufficient cooling. The Liebert DSE data center cooling system features a
pumped refrigerant economizer that uses pumps to move the refrigerant from the
condenser to the evaporator, absorbing heat from the computer room and rejecting
that heat to the outdoors. The proper outside conditions must be present for this
process to work; just like water-side economizing but unlike a water-side
economizer, this system does not consume any water.
Figure 2: Emerson Pumped Refrigerant Component Layout
Source: Emerson Proposal to Include Refrigerant Economizers in Title 24
Figure 3: Emerson Pumped Refrigerant Schematic
Source: Emerson Response to Energy Commission Questions
3
Staff Evaluation
Computer Rooms and the Standards
Prior to the 2008 Standards, process loads were generally considered exempt from the
standards. The Standards define a process load as a load due to an “activity or treatment
that is not related to the space conditioning, lighting, service water heating or
ventilation of a building as it relates to human occupancy”1. The Standards began to
regulate process loads in 2008 with requirements for refrigerated warehouses. The 2013
Standards added requirements for computer rooms and other process load types.
Review of Computer Room Economizing
The Standards define a computer room as ”a room whose primary function is to house
electronic equipment and that has a design equipment power density exceeding 20
watts per square foot of conditioned space.”1
Computer rooms have a unique set of design requirements necessary for controlling key
indoor air quality features such as dew point, temperature, and relative humidity. The
electronic equipment (computers, servers, networking equipment) housed in these areas
are sensitive to these variables in that they may fail due to high heat or electrostatic
charge. Along with controlling the air quality, personnel must exercise caution, for
example, by implementing personal grounding practices to avoid damaging the
equipment or components.
Direct air economizing is a cost-effective option for computer rooms; however some
care must be exercised depending on the air source. Certain contaminants, such as dust,
may be introduced through poor outdoor air quality. Air-to-air heat exchangers can be
used to control outdoor air contaminants and prevent them from entering the computer
room, but at an added cost and consequently lower efficiency due to the heat exchange.
It was been shown to still be cost-effective, however.
Water-side economizing is more desirable than air-side economizing for large data
centers. An advantage to this type of economizing versus air-side is improved control of
the indoor environment, such as humidity and dust particles, by avoiding the
introduction of large quantities of outside air.
Pumped refrigerant economizing has similar advantages to water-side systems. Indoor
environments can be better controlled by not introducing outdoor air. These systems
1 2013 Building Energy Efficiency Standards, Title 24, Part 6, Section 100.1.
4
also reduce the amount of equipment (such as pumps, fans, cooling towers) needed to
operate in full or partial economizer modes.
Results of Refrigerant Economizer Analysis
As part of the Emerson submittal package, Christian Hurd of AlaJor Engineering, Inc.
performed a simulation analysis comparing the Liebert DSE system to a chilled water
system with an integrated water-side economizer. The results showed that the Liebert
DSE system outperformed the chilled water system with an integrated water-side
economizer in 14 of the 16 California climate zones.
The method used by AlaJor Engineering, Inc. was to create a baseline energy budget by
using the Energy Commission’s public domain software CBECC-Com (Build 717). Once a
baseline energy budget was established, the proposed Liebert DSE model was created
using the CBECC-Com software, by extracting the IDF model (IDF is a format used by
EnergyPlus) and then adding custom curves for the Liebert DSE equipment. The custom
curves were developed from a regression analysis of Liebert pumped refrigerant system
data, following the AHRI 1360 standard used for determining the efficiency rating. The
researchers then simulated the proposed model.
Once both models were created and simulated, the results were extracted to the
Exceptional Design Compliance - End-Use Summary Comparison spreadsheet. An
excerpt of the spreadsheet is shown below where the results for each climate zone can
be seen:
Table 1: End-Use Summary Comparison – All Climate Zones
Climate Zone 1
End Use
Space Cooling
Fans
Lighting
Pumps
Heat Rejection
Compliance Total
Interior Equipment
Total
Climate Zone 2
End Use
Space Cooling
Fans
Lighting
Pumps
Heat Rejection
Compliance Total
Interior Equipment
Total
Baseline Waterside Economizer
MWh
TDV kBtuh/ft^2
1,073.5 1,333.2
949.5 1,186.3
42.7 56.8
197.5 242.8
29.4 43.4
2,292.5 2,862.4
DSE Proposed Design ‐ Custom Curves
MWh
TDV kBtuh/ft^2
TDV Margin
1,278.1 1,643.2 (310.1)
285.0 358.6 827.7
42.7 56.8 ‐
‐
‐
242.8
‐
‐
43.4
1,605.8 2,058.6 803.8
7,925.0 9,802.2 7,925.0 9,802.2 ‐
10,217.6 12,664.6 9,530.8 11,860.8 803.8
PASS
Baseline Waterside Economizer
MWh
TDV kBtuh/ft^2
1,105.9 1,415.3
891.2 1,114.1
42.7 56.2
189.5 230.0
48.1 72.3
2,277.4 2,887.9
DSE Proposed Design ‐ Custom Curves
MWh
TDV kBtuh/ft^2
TDV Margin
1,468.8 2,006.5 (591.2)
427.9 539.3 574.8
42.7 56.2 ‐
‐
‐
230.0
‐
‐
72.3
1,939.4 2,602.0 285.9
7,925.0 9,737.3 7,925.0 9,737.3 ‐
10,202.4 12,625.2 9,864.4 12,339.3 285.9
PASS
5
Climate Zone 3
End Use
Space Cooling
Fans
Lighting
Pumps
Heat Rejection
Compliance Total
Interior Equipment
Total
Climate Zone 4
End Use
Space Cooling
Fans
Lighting
Pumps
Heat Rejection
Compliance Total
Interior Equipment
Total
Climate Zone 5
End Use
Space Cooling
Fans
Lighting
Pumps
Heat Rejection
Compliance Total
Interior Equipment
Total
Climate Zone 6
End Use
Space Cooling
Fans
Lighting
Pumps
Heat Rejection
Compliance Total
Interior Equipment
Total
Climate Zone 7
End Use
Space Cooling
Fans
Lighting
Pumps
Heat Rejection
Compliance Total
Interior Equipment
Total
Baseline Waterside Economizer
MWh
TDV kBtuh/ft^2
1,064.0 1,313.5
888.1 1,110.8
42.8 63.5
197.1 239.3
41.3 58.6
2,233.3 2,785.7
DSE Proposed Design ‐ Custom Curves
MWh
TDV kBtuh/ft^2
TDV Margin
1,654.1 2,119.3 (805.8)
171.9 214.9 895.9
42.8 63.5 ‐
‐
‐
239.3
‐
‐
58.6
1,868.9 2,397.7 388.1
7,925.0 9,611.6 7,925.0 9,611.6 ‐
10,158.4 12,397.4 9,793.9 12,009.3 388.1
PASS
Baseline Waterside Economizer
MWh
TDV kBtuh/ft^2
1,116.2 1,390.5
929.1 1,155.2
42.7 55.6
190.8 229.0
53.1 75.8
2,332.0 2,906.1
DSE Proposed Design ‐ Custom Curves
MWh
TDV kBtuh/ft^2
TDV Margin
1,524.0 2,014.3 (623.7)
428.8 542.2 613.0
42.7 55.6 ‐
‐
‐
229.0
‐
‐
75.8
1,995.5 2,612.1 294.0
7,925.0 9,592.8 7,925.0 9,592.8 ‐
10,257.0 12,498.9 9,920.5 12,204.9 294.0
PASS
Baseline Waterside Economizer
MWh
TDV kBtuh/ft^2
1,090.4 1,345.3
955.4 1,196.8
42.7 56.2
190.2 229.6
38.0 55.0
2,316.7 2,882.8
DSE Proposed Design ‐ Custom Curves
MWh
TDV kBtuh/ft^2
TDV Margin
1,417.1 1,827.2 (481.9)
430.9 542.5 654.3
42.7 56.2 ‐
‐
‐
229.6
‐
‐
55.0
1,890.6 2,425.8 457.0
7,925.0 9,638.4 7,925.0 9,638.4 ‐
10,241.7 12,521.2 9,815.6 12,064.2 457.0
PASS
Baseline Waterside Economizer
MWh
TDV kBtuh/ft^2
1,113.6 1,369.5
870.9 1,076.5
42.7 57.1
197.5 236.6
68.0 89.1
2,292.7 2,828.8
DSE Proposed Design ‐ Custom Curves
MWh
TDV kBtuh/ft^2
TDV Margin
1,584.6 1,996.1 (626.6)
428.4 541.6 534.9
42.7 57.1 ‐
‐
‐
236.6
‐
‐
89.1
2,055.7 2,594.8 234.0
7,925.0 9,565.6 7,925.0 9,565.6 (0.0)
10,217.7 12,394.3 9,980.7 12,160.4 233.9
PASS
Baseline Waterside Economizer
MWh
TDV kBtuh/ft^2
1,113.7 1,409.2
884.7 1,112.8
42.7 57.4
195.7 238.6
65.2 87.6
2,302.0 2,905.6
DSE Proposed Design ‐ Custom Curves
MWh
TDV kBtuh/ft^2
TDV Margin
1,607.3 2,063.8 (654.6)
426.9 549.3 563.5
42.7 57.4 ‐
‐
‐
238.6
‐
‐
87.6
2,076.9 2,670.5 235.0
7,925.0 9,776.8 7,925.0 9,776.7 0.0
10,227.0 12,682.3 10,001.9 12,447.3 235.1
PASS
6
Climate Zone 8
End Use
Space Cooling
Fans
Lighting
Pumps
Heat Rejection
Compliance Total
Interior Equipment
Total
Climate Zone 9
End Use
Space Cooling
Fans
Lighting
Pumps
Heat Rejection
Compliance Total
Interior Equipment
Total
Climate Zone 10
End Use
Space Cooling
Fans
Lighting
Pumps
Heat Rejection
Compliance Total
Interior Equipment
Total
Climate Zone 11
End Use
Space Cooling
Fans
Lighting
Pumps
Heat Rejection
Compliance Total
Interior Equipment
Total
Climate Zone 12
End Use
Space Cooling
Fans
Lighting
Pumps
Heat Rejection
Compliance Total
Interior Equipment
Total
Baseline Waterside Economizer
MWh
TDV kBtuh/ft^2
1,128.2 1,408.8
893.2 1,092.1
42.7 57.1
189.9 228.4
64.1 86.1
2,318.1 2,872.6
DSE Proposed Design ‐ Custom Curves
MWh
TDV kBtuh/ft^2
TDV Margin
1,609.7 2,079.7 (670.9)
426.6 537.5 554.6
42.7 57.1 ‐
‐
‐
228.4
‐
‐
86.1
2,079.0 2,674.3 198.3
7,925.0 9,655.5 7,925.0 9,655.5 ‐
10,243.1 12,528.1 10,004.0 12,329.8 198.3
PASS
Baseline Waterside Economizer
MWh
TDV kBtuh/ft^2
1,139.2 1,411.4
875.1 1,067.7
42.7 56.3
191.1 230.0
70.9 94.9
2,318.9 2,860.2
DSE Proposed Design ‐ Custom Curves
MWh
TDV kBtuh/ft^2
TDV Margin
1,629.2 2,074.7 (663.3)
429.8 542.6 525.1
42.7 56.3 ‐
‐
‐
230.0
‐
‐
94.9
2,101.7 2,673.5 186.7
7,925.0 9,516.6 7,925.0 9,516.6 ‐
10,243.9 12,376.8 10,026.7 12,190.1 186.7
PASS
Baseline Waterside Economizer
MWh
TDV kBtuh/ft^2
1,059.0 1,359.2
938.6 1,158.3
42.7 55.6
165.3 195.8
42.8 63.2
2,248.3 2,832.1
DSE Proposed Design ‐ Custom Curves
MWh
TDV kBtuh/ft^2
TDV Margin
1,669.6 2,231.7 (872.5)
434.1 546.6 611.7
42.7 55.6 ‐
‐
‐
195.8
‐
‐
63.2
2,146.4 2,834.0 (1.8)
7,925.0 9,598.6 7,925.0 9,598.6 ‐
10,173.3 12,430.7 10,071.4 12,432.5 (1.8)
FAIL
Baseline Waterside Economizer
MWh
TDV kBtuh/ft^2
1,181.0 1,526.7
1,076.1 1,308.7
42.7 56.5
180.4 218.7
54.3 79.2
2,534.5 3,189.7
DSE Proposed Design ‐ Custom Curves
MWh
TDV kBtuh/ft^2
TDV Margin
1,666.1 2,332.6 (806.0)
429.3 541.3 767.4
42.7 56.5 ‐
‐
‐
218.7
‐
‐
79.2
2,138.1 2,930.4 259.3
7,925.0 9,884.7 7,925.0 9,884.7 ‐
10,459.5 13,074.4 10,063.1 12,815.1 259.3
PASS
Baseline Waterside Economizer
MWh
TDV kBtuh/ft^2
1,126.7 1,454.8
927.8 1,163.7
42.7 56.2
191.1 230.1
53.7 78.7
2,342.0 2,983.5
DSE Proposed Design ‐ Custom Curves
MWh
TDV kBtuh/ft^2
TDV Margin
1,577.1 2,170.3 (715.6)
426.0 537.8 625.9
42.7 56.2 ‐
‐
‐
230.1
‐
‐
78.7
2,045.7 2,764.4 219.2
7,925.0 9,785.6 7,925.0 9,785.6 ‐
10,267.0 12,769.2 9,970.7 12,550.0 219.2
PASS
7
Climate Zone 13
End Use
Space Cooling
Fans
Lighting
Pumps
Heat Rejection
Compliance Total
Interior Equipment
Total
Climate Zone 14
End Use
Space Cooling
Fans
Lighting
Pumps
Heat Rejection
Compliance Total
Interior Equipment
Total
Climate Zone 15
End Use
Space Cooling
Fans
Lighting
Pumps
Heat Rejection
Compliance Total
Interior Equipment
Total
Climate Zone 16
End Use
Space Cooling
Fans
Lighting
Pumps
Heat Rejection
Compliance Total
Interior Equipment
Total
Baseline Waterside Economizer
MWh
TDV kBtuh/ft^2
1,145.7 1,464.9
911.6 1,122.1
42.7 56.3
189.3 229.5
57.5 83.7
2,346.8 2,956.5
DSE Proposed Design ‐ Custom Curves
MWh
TDV kBtuh/ft^2
TDV Margin
1,684.2 2,299.9 (835.0)
429.0 539.8 582.2
42.7 56.3 ‐
‐
‐
229.5
‐
‐
83.7
2,155.9 2,896.0 60.4
7,925.0 9,781.4 7,925.0 9,781.4 ‐
10,271.8 12,737.8 10,080.9 12,677.4 60.4
PASS
Baseline Waterside Economizer
MWh
TDV kBtuh/ft^2
1,143.7 1,457.3
1,021.0 1,269.5
42.7 55.8
182.4 220.7
35.4 57.3
2,425.2 3,060.6
DSE Proposed Design ‐ Custom Curves
MWh
TDV kBtuh/ft^2
TDV Margin
1,727.8 2,404.3 (947.0)
450.2 562.9 706.6
42.7 55.8 ‐
‐
‐
220.7
‐
‐
57.3
2,220.7 3,023.0 37.6
7,925.0 9,774.9 7,925.0 9,774.9 ‐
10,350.2 12,835.5 10,145.7 12,797.9 37.6
PASS
Baseline Waterside Economizer
MWh
TDV kBtuh/ft^2
1,227.9 1,575.5
834.3 1,003.9
42.7 55.8
182.9 219.5
78.9 107.9
2,366.6 2,962.7
DSE Proposed Design ‐ Custom Curves
MWh
TDV kBtuh/ft^2
TDV Margin
1,996.8 2,671.7 (1,096.1)
421.1 527.1 476.8
42.7 55.8 ‐
‐
‐
219.5
‐
‐
107.9
2,460.6 3,254.6 (291.9)
7,925.0 9,702.3 7,925.0 9,802.2 (99.9)
10,291.6 12,665.0 10,385.6 13,056.8 (391.8)
FAIL
Baseline Waterside Economizer
MWh
TDV kBtuh/ft^2
1,118.6 1,438.3
1,067.7 1,311.4
42.7 56.3
185.8 223.4
29.7 52.5
2,444.5 3,081.9
DSE Proposed Design ‐ Custom Curves
MWh
TDV kBtuh/ft^2
TDV Margin
1,297.0 1,824.4 (386.1)
472.7 591.1 720.3
42.7 56.3 ‐
‐
‐
223.4
‐
‐
52.5
1,812.4 2,471.7 610.1
7,925.0 9,749.2 7,925.0 9,749.2 (0.0)
10,369.5 12,831.0 9,737.4 12,221.0 610.1
PASS
Source: Proposal to Include Refrigerant Economizers in the California Energy Commission 2013 Building Energy
Efficiency Standards.
8
Public Review of Refrigerant Economizer Analysis
The entire submittal packaged was posted for a 60-day public review and comment
period, including the simulation run files, end-use summary comparison, and custom
curves.
After the 60-day public review and comment period was completed, only one comment
was docketed. The commenter, Mark Hydeman from Taylor Engineering, was the
primary author of the original Codes and Standards Enhancement Initiative (CASE)
report that was the basis of the 2013 Standards computer room requirements, and he
expressed that the “proposed energy savings calculations are reasonable.” Mr. Hydeman,
did have some concerns with a lack of both scope and clarity, however, and included
recommended changes to the submitted materials.
Proposed Alternative for Computer Room Economizing
Staff proposes that an alternative to the prescriptive requirement found in Section
140.9(a)1B be given for pumped refrigerant economizers installed in Climate Zones 1-9,
11-14, and 16. This alternative prescriptive requirement will have little impact in the
implementation compared to the existing requirement. Some changes to the existing
compliance forms will be needed.
When complying under the performance approach, the proposed design should assume
the same default as a standard design chilled water system with an integrated waterside economizer. No further compliance credit should be granted for this system until a
rule set is developed and incorporated into CBECC-Com.
Conclusion
Staff proposes that pumped refrigerant economizers be allowed as an alternative
component package. The proposed alternative will provide energy savings in 14 out of
the 16 climate zones and will offset the use of water that will otherwise be consumed by
the installation of a water-side economizer. Allowing the use of this technology is
consistent with the compliance options process prescribed by Public Resources Code,
Section 25402.1(b) and Section 10-109 of the Building Energy Efficiency Standards, which
allows for the introduction of designs, materials, or devices that cannot be adequately
modeled in the currently approved alternative calculation methods or are not
appropriately accounted for the currently approved approaches.
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References
ASHRAE Handbook – HVAC Applications 2007, Chapter 17, DATA PROCESSING AND
ELECTRONIC OFFICE AREAS.
CALIFORNIA ENERGY COMMISSION. 2013 Building Energy Efficiency Standards, Title 24,
Part 6.
CALIFORNIA ENERGY COMMISSION. 2013 Nonresidential Compliance Manual, Chapter
10.
CALIFORNIA ENERGY COMMISSION. 2013 Codes and Standards Enhancement Initiative,
Data Centers.
EMERSON NETWORK POWER. “Emerson Response to California Energy Commission
Request for Additional Information and Questions.”
EMERSON NETWORK POWER. “Proposal to Include Refrigerant Economizers in the
California Energy Commission 2013 Building Energy Efficiency Standards.”
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