Smart School Symposium Heating Ventilation and Air Conditioning ...
Transcript of Smart School Symposium Heating Ventilation and Air Conditioning ...
Smart School Symposium
Heating Ventilation and Air Conditioning Session
HVAC Products
Richard Lord
Overview and Agenda
• My goal today is to give you quick an overview of the current status of HVAC
products and near term improvements that should you can considered when
evaluating School Upgrade programs
• The presentation will cover the following topic;
Typical school Building Load Profiles
Typically HVAC Equipment used in Schools
Efficiency Metrics for HVAC Equipment
Historical Perspective on Efficiency Requirements
Recent and Future Efficiency Improvement Initiatives
Future Industry Initiatives
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School Building Load • One of the key things we have learned in ASHRAE 90.1 is to model the typical
buildings so that we can understand the load profiles as well as all the operating
characteristics
• For this, ASHRAE 90.1, with support from PNNL, have developed 15
benchmark buildings of which two are schools (primary and secondary)
• Schools have a unique building load profile
• They are different than other buildings like office buildings;
High internal people load with average 42.6 ft2/person vs. an office at 200
ft2/person (4.7 times higher occupancy density)
Average plug load of 4.8 W/ft2 vs. offices at .45 W/ft2 (10.6 times higher)
Weekday occupancy from 8:00 am to 8:00 pm, often with limited summer
operation vs. offices with annual operation and similar operating hours
High percentage of ventilation air with an average of 64% outside air during
occupancy vs. offices at 27% (2.4 times higher)
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Climate Zones
• Weather data is not the same, and has a big impact on building loads as well as
the performance of HVAC equipment.
• ASHRAE 90.1 has divided the US and the World into 17 climate zones as
shown in the following map.
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California Climate Zones
• Title 24 does not use the ASHRAE climate zones and has further divided the
California requirements into 16 California Specific climate zones as shown, but
these can be mapped to ASHRAE zones so that we can look at building
modeling work that ASHRAE 90.1 has done
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School Load Data Metrics
• Using the ASHRAE 90.1 benchmark buildings models I have developed the
following metrics for typical primary and secondary school.
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Drybulb Wetbulb Drybulb Wetbulb
F F F RH
Primary Secondary Primary Secondary Primary Secondary Primary Secondary
1A Miami − − 91.8 77.6 47.7 50% 549.4 325.7 101.8 74.4 0.450 0.365 67% 73%
1B Riyadh − − 111.6 65.6 42.7 50% 531.5 403.6 110.6 87.8 0.401 0.383 49% 64%
2A Houston − − 96.8 76.6 29.1 50% 561.0 331.8 51.9 30.7 0.901 0.900 71% 74%
2B Phoenix − − 110.8 70.7 35.3 50% 527.2 417.8 75.7 43.8 0.580 0.795 53% 65%
3A Memphis − − 96 77.3 17 50% 606.9 331.1 54.8 30.5 0.923 0.906 75% 74%
6 Los Angeles 100.6 70.9 36.0 50%
7 San Diego 90.3 67.6 38.9 50%
8 El Toro 92.1 68.1 40.3 50%
9 Burbank 98.3 68.8 39.0 50%
10 Riverside 99.8 70.3 36.0 50%
11 Red Bulff 105.1 69.6 30.0 50%
12 Sacramento 100.4 70.7 31.5 50%
13 Fresno 103.6 71.2 31.5 50%
14 China Lake 103.1 71.1 32.2 50%
15 El Centro 111.1 73.6 35.6 50%
3C San Francisco 3 Oakland 81.8 65 37.2 50% 1084.4 657.0 79.7 41.8 1.133 1.309 76% 76%
4A Baltimore − − 93.9 74.9 12.9 50% 572.1 355.8 66.0 25.5 0.722 1.161 76% 74%
4B Albuquerque − − 95.2 60.3 17.7 50% 739.3 602.1 62.8 35.9 0.981 1.398 59% 66%
4C Salem 4 Sunnyvale 92.3 66.9 35.7 50% 674.9 504.6 59.7 34.4 0.942 1.223 64% 77%
5A Chicago − − 91.9 74.6 -4 50% 572.8 362.3 55.5 22.9 0.860 1.317 76% 76%
5B Boise − − 98.1 64.2 2.7 50% 702.5 586.0 46.6 28.4 1.257 1.717 58% 70%
5C Vancouver 5 Santa Maria 84.2 62.8 32.2 50% 917.1 662.6 65.6 37.1 1.165 1.490 69% 81%
6A Burlington − − 88.3 71.0 -8.3 50% 616.4 405.0 33.5 21.5 1.533 1.574 78% 78%
6B Helena 2 Sata Rosa 95.3 67.1 29.7 50% 830.6 652.7 30.3 20.3 2.286 2.680 72% 72%
7 Duluth 1.0 Arcata 70.8 59.3 30.9 50% 635.9 424.3 26.0 18.1 2.039 1.951 80% 71%
8 Fairbanks − − 71.4 58.7 -8.9 50% 973.1 744.2 20.3 15.3 4.003 4.046 84% 74%
US Average 689.7 484.7 58.9 35.7 1.2 1.4 69% 73%
California Avg 795.4 562.4 53.7 31.8 1.4 1.6 70% 74%
0.862 1.012 62% 68%473.6 60.9 39.03B El Paso 629.7
Design
% OA
%
US
Zone
US City California
Zone
California
City
Heating
Intensity
ft-hr/KBtu
Heat/Coil
Ratio
Cooling Design
Intensity
ft/ton
Summer Design Heating Design
School Load Profiles
• Over the years most design decisions and regulations have focused on the
design conditions and full load operation.
• Full load and full ambient design conditions are only 0.4% of the operating
hours and do not always represent the annualized energy
• It is also common for equipment to be oversized and in fact ASHRAE 90.1
Appendix G which defines requirements for building simulation, requires that
cooling equipment be oversized by 15% and heating by 25%
• Building HVAC loads are typically calculated with maximum possible occupancy
and worst case plugs loads
• Bottom line is equipment never runs at the design conditions and is always
running at part load as well as reduced ambients
• This has resulted in new thinking about performance metrics as well as design
features and options that I will talk more about
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Climate Zone 3B Primary School Load Profile
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Equivalent to California climate zone 6-Los Angeles, 7-San Diego, 8-El Toro, 9-Burbank, 10-
Riverside, 11-Red Bluff, 12, Sacramento, 13, Fresno, 14-China Lake, 15-El Centro
Climate Zone 3C Primary School Load Profile
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Equivalent to California climate zone 3-Oakland
Climate Zone 4C Primary School Load Profile
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Equivalent to California climate zone 4-Sunnyvale
Climate Zone 5C Primary School Load Profile
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Equivalent to California climate zone 5-Santa Maria
Climate Zone 6B Primary School Load Profile
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Equivalent to California climate zone 2-Santa Rosa
Climate Zone 7 Primary School Load Profile
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Equivalent to California climate zone 1-Arcata
Typical School HVAC Equipment
The following are typical HVAC Systems that are used in schools
• Packaged Air cooled rooftops
• Air Cooled Central Chiller systems with fan coils or air handlers
• Water Cooled Central Chiller systems with fan coils or air handlers
• Geothermal Water Source Heat Pumps (WSHP) with DOAS for ventilation
• Single Packaged Vertical Air Conditioners (SPVAC) Packaged Air Cooled
(Portable Class Rooms)
• Variable Refrigerant Systems with DOAS for ventilation
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Typical Full Load Efficiency Metrics
• Minimum efficiency standards started back in the 1970’s
• Until recently the primary metrics used were full load efficiency metrics
determined at defined common rating conditions
EER – Ratio of the Net Cooling Capacity in Btu/hr divided by the total unit
power. This metric is typical used on most packed equipment, air cooled
chillers, and VRF systems
KW/ton – Ratio of the total power input divided by the capacity in tons.
This used for water cooled chillers
COP – Ratio of the output heating capacity in watts divided by the power
input in watts. This is used for heat pump when operating in heating.
EC, ET – Combustion Efficiency. Used for gas and oil fired heating products
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Typical Annualized Efficiency Metrics
• Recently the industry has started to used annualized metrics that also consider
part load operation
SEER – Seasonal Energy Efficiency ratio which is the total cooling output of
an air conditioner during its normal annual usage period for cooling (in
Btu/h) divided by the total electric power input during the same period (in
W). Used on residential and light commercial
IPLV – Integrated part load Value which is a weighted average of the EER,
or kw/ton at 100%, 75%, 50% and 25% loads for a typical US commercial
building and climate zone. Used for chillers.
IEER – Integrated energy efficiency ratio which is the weighted average of
the EER, at 100%, 75%, 50% and 25% loads for a typical US commercial
building and climate zone.
HSPF - Heating seasonal performance factor which is the total heating
output of a heat pump during its normal annual usage period for heating (in
Btu/h) divided by the total electric energy input (in W) during the same
period
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Typical Efficiency Metrics Trends
• With the new annualized metrics the industry and efficiency standards are
gradually switching from a focus on full load metrics to the annualized metrics
• These better represent the potential efficiency improvements that will be
obtained when purchasing new more efficient equipment, but they do not
represent the direct savings that will be obtained in a given building and climate
zone
• They typically represent the performance of a HVAC units, but do not include all
the power and efficiency impacts of the complete HVAC System.
• The current best approach to determine the energy savings in a specific
building and climate zone is to run an energy model of a building using tools like
EQuest, DOE2, EnergyPlus, HAP, Trace, etc
• But currently only about 20% of the buildings are being modeled as the
modeling is expensive to run and time consuming
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Current Industry Efficiency Standards
• The current approach to industry efficiency standards like ASHRAE 90.1, Title
24 and DOE federal requirements are to define prescriptive requirements for
components like unit efficiencies
• They also then define prescriptive requirements for components like
economizers, energy recovery, cooling towers, piping, controls, etc
• But not all the components are currently regulated
• This approach also does not factor in the system aspects of things like multiple
chillers, ductwork pressure drop, pumping power, and more
• When looking at new systems or replacement systems you should consider the
full system impact.
• We are working on new approaches for HVAC systems which I will talk more
about.
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Chiller Water “System” Efficiency Example
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Cooling
Tower
Condenser
Evaporator
Condenser Water
Pump
Compressor
Air
Handler
Chilled Water
Pump
Conditioned Space
Current 550/590 Chiller
Standard and
Certification focus
ASHRAE 90.1 Full and
part load efficiency
ASHRAE 90.1 fan
power requirement,
no approach
requirement and
ignore water use
No focus on condenser
water pumping power
other than a pipe sizing
requirement
No focus on chilled
water pumping power
other than pipe sizing
No focus on duct pressure
drop and very little on
applied fan power
Very little focus on
the effective air
distribution
Do not address multiple chillers
and towers although most are
applied that way
No integration of
economizers, exhaust fans,
ERV and IAQ
Outside
Air
Regulations No regulations
Chart prepared by Richard Lord
Packaged Ducted Rooftop “System” Example
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Packaged Rooftop
Conditioned Space
Rating of the rooftop EER and
IEER with part of the fan power is
covered by AHRI 340/360 but we
do not certify the full operating map
Only part of the duct work
pressure drop included in
the ratings
No annualized
performance for heating
Demand ventilation not
reflected in ratings
ERV/Rooftop CEF
can be used for full
load, but not part
load and annualized
Power Exhaust not
included in ratings
Very little focus on
the effective air
distribution
On VAV units reheat
not reflected in ratings
Economizer and
outside air not
reflected in ratings
Chart prepared by Richard Lord
HVAC Efficiency Improvement Background Great progress has been made in building efficiency and HVAC unit efficiencies and this can
be important when considering replacement units
21 Chart based on ASHRAE 90.1 determination study conducted by PNNL
HVAC Efficiency Improvements
• As you can see considerable progress has been made in efficiency
improvements with considerable progress made in 2010 with an overall
improvement of 32% for regulated building loads
• More improvements also have been approved for the 2013 release of ASHRAE
90.1 standards which typically are aligned with the title 24 requirements
• In the following pages I will summarize some of the improvements that you
should be aware of when consider school upgrades
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Rooftop Efficiency Improvements
• For packaged equipment including rooftops the IEER will increase by an
average of 13% effective in 2016
• Similar improvements also being made for heat pumps and split systems
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11
.20
11
.00
10
.00
9.7
0
11
.0 11
.2
11
.0
10
.0
9.7
13
.0
11
.4
11
.2
10
.1
9.8
14
.0
12
.9
12
.4
11
.6
11
.2
9
10
11
12
13
14
15
<65K 65K to 135K 135K to 240K 240K to 760K >760K
Effi
cie
ncy
(Btu
/hr)
Capacity Category (KBtu/hr)
2010 EER 2016 EER Series5 2010 IEER 2016 IEER
Chart based ASHRAE 90.1 Packaged Rooftop Efficiency Requirements
2015 Chiller Efficiency Change Details
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Full IPLV Full IPLV Full IPLV Full IPLV
< 150 Tons EER 9.560 12.500 9.560 12.500 10.100 13.700 9.70 15.80
≥ 150 Tons EER 9.560 12.750 9.560 12.750 10.100 14.000 9.70 16.10
< 75 Tons kw/ton 0.780 0.630 0.800 0.600 0.750 0.600 0.780 0.500
≥75 Tons and <150 Tons kw/ton 0.775 0.615 0.790 0.586 0.720 0.560 0.750 0.490
≥150 Tons and <300 Tons kw/ton 0.680 0.580 0.718 0.540 0.660 0.540 0.680 0.440
≥300 Tons and <400 Tons kw/ton 0.620 0.540 0.639 0.490 0.610 0.520 0.625 0.410
≥400 Tons and <500 Tons kw/ton 0.620 0.540 0.639 0.490 0.610 0.520 0.625 0.410
≥500 Tons and <600 Tons kw/ton 0.620 0.540 0.639 0.490 0.610 0.520 0.625 0.410
≥600 Tons kw/ton 0.620 0.540 0.639 0.490 0.560 0.500 0.585 0.380
< 75 Tons kw/ton 0.634 0.596 0.639 0.450 0.610 0.550 0.695 0.440
≥75 Tons and <150 Tons kw/ton 0.634 0.596 0.639 0.450 0.610 0.550 0.695 0.440
≥150 Tons and <300 Tons kw/ton 0.634 0.596 0.639 0.450 0.610 0.550 0.635 0.400
≥300 Tons and <400 Tons kw/ton 0.576 0.549 0.600 0.400 0.560 0.520 0.595 0.390
≥400 Tons and <500 Tons kw/ton 0.576 0.549 0.600 0.400 0.560 0.500 0.585 0.380
≥500 Tons and <600 Tons kw/ton 0.576 0.549 0.600 0.400 0.560 0.500 0.585 0.380
≥600 Tons kw/ton 0.570 0.539 0.590 0.400 0.560 0.500 0.585 0.380
ASHRAE 90.1-2015 Final Proposal
Path A Path BPath A Path B
ASHRAE 90.1-2010
Water Cooled
Centrifugal
Equipment
TypeSize Category Units
Air Cooled
Chiller
Water Cooled
Positive
Displacement
Full IPLV Full IPLV
5.6% 9.6% 1.5% 26.4%
5.6% 9.8% 1.5% 26.3%
3.8% 4.8% 2.5% 16.7%
7.1% 8.9% 5.1% 16.4%
2.9% 6.9% 5.3% 18.5%
1.6% 3.7% 2.2% 16.3%
1.6% 3.7% 2.2% 16.3%
1.6% 3.7% 2.2% 16.3%
9.7% 7.4% 8.5% 22.4%
3.8% 7.7% -8.8% 2.2%
3.8% 7.7% -8.8% 2.2%
3.8% 7.7% 0.6% 11.1%
2.8% 5.3% 0.8% 2.5%
2.8% 8.9% 2.5% 5.0%
2.8% 8.9% 2.5% 5.0%
1.8% 7.2% 0.8% 5.0%
ASHRAE 90.1-2015 Final Proposal
Path A Path B
Chiller efficiencies are also being improved with increased full and part load requirements as well
as expanded path B part load intensive requirements. Categories have also be revised and aligned
Other Prescriptive Requirements
• In addition to the HVAC unit efficiency improvements there also have been
changes made to other prescriptive requirements in 2010 and in the 2013
ASHRAE 90.1 standard and the new 2014 Title 24 requirements
• Addition of 2 speed indoor fan requirements
• New staging requirements for packaged units
• New economizer requirements including in Title 24 diagnostics and
commissioning
• Economizer damper leakage requirements
• Lower threshold on demand ventilation
• Expanded requirements for energy recovery
• Controls requirements for VAV systems
• We do not have time to go through all of these, but I will cover some of the
significant changes that will impact school energy efficiency
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2 Speed Fan and Staging • Indoor Fan Speed Control
Because the power of the indoor fan decreases to the cube of the speed and the fan
runs continuously during occupancy for ventilation, the savings are significant
New requirements are being added to ASHRAE 90.1 and Title 24 for 2 speed fans
on constant volume and inverters on VAV
>110K Btu/hr – effective 1/1/2010
>75K Btu/hr – effective 1/1/2014
>65K Btu/hr – effective 1/1/2016
• Compressor Staging
ASHRAE 90.1 and Title 24 are also adding requirements for compressor staging
CV Units shall have a minimum of 2 stages
>75K Btu/hr – effective 1/1/2014
>65K Bu/hr – effective 1/1/2016
VAV units shall have the following staging effective 1/1/2014
65K to 240K – minimum 3 stages
>340K – minimum 4 stages
Additional staging and modulation
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2 Speed Fan Savings
27
• When the speed of a fan decreases the airflow decreases directly with the speed, but the fan
power decreases to the cube of the speed resulting in significant energy savings
• Compared to single speed indoor fan motor systems, Carrier’s staged air volume (SAV) system
utilizing variable frequency drive (VFD) and 2-speed indoor fan motor can save substantial energy.
Up to 65%*
0%
20%
40%
60%
Miami Los Angeles Phoenix New York St. Louis Atlanta
Staged Air Volume% Energy Savings ($) *
* Annual estimated electric energy savings utilizing Carrier’s Hourly Analysis (HAP) Program v4.6. Based on cooling and ventilation fan runtime hours using
ASHRAE 90.1 office application, default schedule, weather and building data. Carrier model 48/50TC 12 at .10 ($/kWh) energy rate.
Fan Energy Savings • Additional energy savings are possible with further fan speed control and the new high
efficiency Carrier 48/50LC is using a triple speed fan control
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The fan speed options
also require multiple
minimum position
economizers to control
minimum ventilation
Economizer Changes • In addition to efficiency changes
there also has been significant
changes to the requirements for
economizers
• Economizers are now required on
all systems with a fan and a capacity
greater than 54K all Title 24 zones and
ASHRAE 90.1 zones 1a and 2a
• In addition new requirements have been
defined for integrated economizers as to how they should operate during integration as
a result of field problems.
• Testing on high limit sensors has also shown that there are issues with sensor accuracy
and quality and new requirements have been added to Title 24 and the same are being
added to ASHRAE 90.1
• Tighter damper leakage requirements have been added for outside air as well as return
air dampers
• There are also changes for the high limit set points as well as the high limit changeover
methods.
• Due to problems with economizers, California as also expanded the requirements for
economizer design and commissioning and this is also being considered by ASHRAE
90.1 and the IECC standard
29
Economizer Problems • Several field studies have been conducted and the following problems have been
found with economizers
Damper Linkage Failure
Economizer damper motor not functioning
Economizer disconnected
Minimum ventilation position not properly set
Changeover sensor inaccuracy and failure
Solar impact on changeover temperature sensor failure
Supply temperature sensor failure and inaccuracy
Integrated Economizer controls and operational issues
Building pressurization (improper exhaust/relief)
Exhaust air recirculation
Damper blade leakage (outside and return)
Lack of Maintenance
Lack of and improper commissioning
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These are being addressed by the industry thru new economizer design, new
economizer controllers, and new standards requirements like the Title 24 2014
diagnostics and commissioning requirements
Economizer Problems
31
Damper Linkage Problems Damper Leakage Problems
Economizer Hoods and Maintenance Problems
Sensor and Actuator Problems
High Limit Controls and
Sensor Accuracy Integrated Economizer and Controls Problems
Airside Economizer Technology
• Shown is a typical packaged rooftop with an airside economizer
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Typical Commercial Building Load Profile
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Economizer only Operation
1322 hrs
Integrated Economizer
Comp + Economizer
1316 hrs
Mechanical Cooling
No Economizer
73 hrs
Economizer Annual Energy Savings • The following chart shows the energy savings for an integrated economizer vs. a small
rooftop unit without an economizer for a small office building. Note that these savings are
not factored into the IEER metric
34
4.95%
11.37%
15.77%
17.19%
13.28%
26.93%
39.71%
30.70%
35.69%
37.24%
29.41%
37.13%
41.05%
31.99%
37.96%
44.73%
41.97%
0.00% 5.00% 10.00% 15.00% 20.00% 25.00% 30.00% 35.00% 40.00% 45.00% 50.00%
1A - Miami
1B - Riyadh
2A - Houston
2B - Phoenix
3A - Memphis
3B - El Paso
3C - San Francisco
4A - Baltimore
4B - Albuquerque
4C - Salem
5A - Chicago
5B - Boise
5C - Vancouver
6A - Burlington
6B - Helena
7 - Duluth
8 - Fairbanks
California climate zones
Economizer Integration Requirements
• Building standards require that economizers be integrated where the
economizer can be used and supplemented by mechanical cooling
• Some controls today do not do this properly, especially for VAV and the
economizer and compression fight each other due to poor control integration as
shown in the following plot
35
New requirements have been
added to ASHRAE 90.1-2013
to address this
Economizer Operating Hrs • The following chart shows the operating hr profiles for a small office building in each of
the ASHRAE climate zones and benchmark cities and the benefits of integrated
economizers
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219
593
630
782
1004
981
1322
904
1106
979
765
980
808
913
1029
801
728
113
446
144
430
130
679
1316
290
837
673
236
642
1003
360
654
659
662
2894
2395
2060
1922
1520
1371
73
1084
938
371
979
613
70
561
325
277
54
0 500 1000 1500 2000 2500 3000 3500 4000
1A - Miami
1B - Riyadh
2A - Houston
2B - Phoenix
3A - Memphis
3B - El Paso
3C - San Francisco
4A - Baltimore
4B - Albuquerque
4C - Salem
5A - Chicago
5B - Boise
5C - Vancouver
6A - Burlington
6B - Helena
7 - Duluth
8 - Fairbanks
Annual hrs
Economizer Only Integrated Mechanial Only
3236
3434
2834
31342654
3031
2711
2278
2881
2023
1980
2235
1881
1834
2008
1734
1444
California climate zones
Economizer Improvements
• The benefits of the use of economizers are significant but prior studies have shown actual
savings in the field were not being obtained due to problems previously mentioned.
• So the industry has been working to improve the economizers and their performance
• Some of the things the industry has implemented are;
New drive configurations using gears
New digital economizer with electronic feedback
Low leak dampers on outdoor and return air
New sensors with digital signals and error detection
New control logic for integrated control
Reliability Cycle Testing
Factory run testing
Outdoor cfm sensors
New microprocessor based controllers
Integrated displays and error detection
2 speed Economizers for reduced energy use
Integration with energy recovery
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Economizer Improvements
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New Configurations Blade Seals
Gear Drive Economizers
Leakage Testing
Life Testing
Economizer Improvements
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ECONOCMD
ECONOPOS
OA_TEMP
SAT_DISP
COMP_A
COMP_B
Y1
Y2
Low Cool SAT Setpoint = 60High Cool SAT Setpoint = 50SAT Min High = 55SAT Min Low = 45
48-644-180: 57 ambient, free cooling, Y1 then Y2, B stayed off due to SAT
Many new smart economizer controllers
Advanced controllers
With integrated diagnostics New digital sensors
New high limit control concepts New integrated control logic to eliminate damper cycling
Title 24 Economizer Commissioning
• California has also added new requirements for inspection and commissioning
of economizers.
• There are two options;
Field commissioning using a defined procedure
Factory certification with some field setup commissioning
40
Title 24 Economizer Diagnostics • In addition Title 24 has also added requirement for economizer diagnostics in 2014
• Economizer Fault Detection and Diagnostics is a mandatory requirement for all newly
installed air-cooled unitary direct-expansion units, with mechanical cooling capacity at
AHRI conditions of greater than or equal to 54,000 Btu/hr, and equipped with an
economizer.
• Where required, the Fault Detection and Diagnostics (FDD) system shall meet the
requirements of 120.2(i)2 through 120.2(i)9, as described below. Air-cooled unitary direct
expansion units include packaged, split-systems, heat pumps, and variable refrigerant
flow (VRF), where the VRF capacity is defined by that of the condensing unit.
• The following temperature sensors shall be permanently installed to monitor system
operation: outside air, supply air, and return air
• Temperature sensors shall have an accuracy of ±2°F over the range of 40°F to 80°F
• The controller shall have the capability of displaying the value of each sensor
• The controller shall provide system status by indicating the following conditions:
Air temperature sensor failure/fault.
Not economizing when it should.
Economizing when it should not.
Damper not modulating.
Excess outdoor air.
• Controller shall have a manual operating mode.
• Fault detection reporting shall be available to service personnel 41
Industry Efficiency Options to Consider • Over the past 10 years the industry has also adopted a tiered efficiency approach with
ASHRAE 90.1 and Title 24 being the minimum, but then there are tier II and III option
standards like EnergyStar, CEE, and FEMP which should be considered in school
upgrades. The following is an example of the Carrier rooftop Tiered Product Line
42
Future Efficiency Improvement Options
43
Historical Approach (Business as usual) - Full Load Improvements
• We are approaching “Max-Tech” on many products and significant
improvements in base product full load efficiencies will be limited and often not
cost effective
• We also face issues with the phase down of the HFC refrigerants that are used
today, and will have to evolve to new lower GWP refrigerants that may not be
as efficient, could be semi-flammable and could be more expensive to apply
Alternate Approaches to Consider
1. Switch to new part load or annualized metrics like IPLV for chillers and IEER
for rooftops, splits, and VRF
2. Hybrid system with rating approaches like AHRI guideline V
3. Subsystems approaches (focus of discussion today)
4. Whole Building System approaches (ASHRAE Building Energy Quotient)
5. Defined commissioning requirements to make sure equipment runs correctly
6. Integrated Fault Detection (FDD)
Hybrid Systems • The concept for a hybrid system approach is to take two or more technologies and
combine them together utilizing some type of combined rating.
• During the annual operation each hybrid technology is used where it delivers the most
benefit
• Some examples are;
Airside economizer
Hydronic economizer
Free Cooling refrigerant cycles
Integrated Heat Recovery
Integrated Exhaust Air Energy Recovery
Dual fuel heat pumps
Thermal Storage
Energy storage
Desiccant systems
Evaporative pre-cooling condensers
Evaporative outdoor air coolers, direct and indirect
Desuperheaters and integrated hot water heaters
Solar assisted units
44
Example Combined Efficiency
45
ERVby consumed power electrical Total
ERVby recovered ngconditioni NetRER
RTUby powerelectric Total
RTU ofcapacity ngconditioni NetEER
CEF = Combined Efficiency Factor
EER RER
RTU Energy Efficiency Ratio
Example:
Rooftop + ERV = System CEF (30 ton system)
EER & RER = CEF
12.0 & 124.69 = 17.19
17.19 System EER for a 30 ton total system
ERV Recovered Energy Efficiency Ratio
Office Code Document Code 0
Return
Air
Plenum
Balance of Unitary
Air ConditionerExhaust
Blower
AA
HX
ERV Unitary Air Conditioner
Efficiency Comparison (ERV Example) Base Rooftop Unit EnergyX
Model: Rooftop ERV
Location: Tampa, FL Tampa, FL
Altitude (ft) 0.0 ft 0.0 ft
CFM 3500 3500
Ext static press: 0.75" 0.75"
Ventilation Air: 50% or less
(economizer) 50% OA (1750 cfm)
5.0
7.0
9.0
11.0
13.0
15.0
17.0
19.0
21.0
23.0
65 70 75 80 85 90 95 100 105 110 115 120 125
EE
R o
r C
EF
Outdoor Air Temp (deg F)
CEF vs Application EER
Base Unit Application EER
EnergyX System CEF
Full load Rating Point
Combined Rating Improvement
Example shows how over the
operating range a hybrid unit like
an ERV/Rooftop can have further
improvements at non standard
rating conditions. This is also true
for hybrid options like evaporative
cooling
46
Possible Future Roadmap - Systems
47
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
110%
2004 2007 2010 2013 2016 2019 2022 2025 2028 2031 2034 2037
Re
gula
ted
Bu
idlin
g En
erg
y U
se v
s A
SHR
AE
90
.1-2
004
Year
Commercial HVAC Efficiency Requirements
ASHRAE 90.1
Building Target
Possible Path to
nearly Net Zero Buildings
Equipment Level Limit
MaxTech Limit Full Load Efficiency
Systems Approach &
Renewable Energy
Chart is an estimate of possible future regulations to achieve Near Net Zero by 2034 based on studies done by
Carrier on technical limits of HVAC equipment
Aver
age
AS
HR
AE
90.1
2013 R
equir
emen
ts
Chilled Water System Example (Current)
48
Current ASHRAE 90.1 Regulations (Prescriptive Approach)
Full Load & IPLV HP/GPM
Full Load & IPLV HP/GPM
Maximum Fan
Power
CO2
Component Efficiency
Requirements
No Requirements
Prescriptive Requirements
Chart prepared by Richard Lord
Chilled Water System Example (Proposed)
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Proposed Systems Approach
Maximum Fan
Power
CO2
Annualized HVAC System Efficiency (annualized)
Overall Efficiency
Minimum Set by
climate zone and
building type and then
component
efficiencies can be
traded off to meet the
overall targets
System Level Climate
Zone Efficiency
Requirements
Chart prepared by Richard Lord
HVAC Systems Concept
• The HVAC systems concept would involve the following;
User would select from one of the 15 ASHRAE 90.1 Benchmark buildings
closest to the proposed building (may need more building types).
ASHRAE 90.1 committee would define the baseline system using industry
reasonable best practices and this then would be the baseline HVAC
System efficiency. This would include HVAC efficiencies as well as all
components in the system (i.e.. Cooling towers, pumps, economizer, etc.)
User would then run proposed system using the system computer tool
(hourly) using the selected benchmark building, and weather data from
one of ASHRAE 90.1 17 climate zones benchmark cities.
If the proposed HVAC system uses less power then the benchmark system
then the system could be used.
Key to the approach is that all annualized power of the complete system
is considered
User would be allowed to trade off all aspects of the system as long as the
annualized energy use was equal to or less. (i.e.. Chiller efficiency, cooling
tower approach, pumping power, economizers, energy recovery, fan power,
etc)
Goal is to start off with equal performance to the prescriptive approach 50
Questions
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