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

2

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)

3

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.

4

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

5

School Load Data Metrics

• Using the ASHRAE 90.1 benchmark buildings models I have developed the

following metrics for typical primary and secondary school.

6

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

7

Climate Zone 3B Primary School Load Profile

8

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

9

Equivalent to California climate zone 3-Oakland


10

Equivalent to California climate zone 4-Sunnyvale


11

Equivalent to California climate zone 5-Santa Maria

Climate Zone 6B Primary School Load Profile

12

Equivalent to California climate zone 2-Santa Rosa

Climate Zone 7 Primary School Load Profile

13

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

14

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

15

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

16

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

17

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.

18

Chiller Water “System” Efficiency Example

19

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

20

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


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

22

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

23

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

24

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





≥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






≥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

25

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



• Compressor Staging

ASHRAE 90.1 and Title 24 are also adding requirements for compressor staging

CV Units shall have a minimum of 2 stages


>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

26

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

28

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

30

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

32

Typical Commercial Building Load Profile

33

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

36

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

37


38

New Configurations Blade Seals

Gear Drive Economizers

Leakage Testing

Life Testing


39

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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


Chilled Water System Example (Proposed)

49

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


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

51

Documents

Smart School Symposium Heating Ventilation and Air Conditioning