Breaking the Limits of

HVAC Efficiency

Unitary Rooftop Packaged Equipment

(RTU)

Efficiency Vermont is a Registered Provider with The American Institute of Architects Continuing Education Systems (AIA/CES). Credit(s)

earned on completion of this program will be reported to AIA/CES for

AIA members. Certificates of Completion for both AIA members and

non-AIA members are available upon request.

This program is registered with AIA/CES for continuing professional

education. As such, it does not include content that may be deemed

or construed to be an approval or endorsement by the AIA of any

material of construction or any method or manner of handling, using,

distributing, or dealing in any material or product.

Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation.

Learning Objectives

By the end of this program, participants will be able to:

Learn about best practices in RTU optimization and how attendees can take

advantage of energy saving opportunities through equipment repairs,

retrofits and replacements.

Discuss the latest results of the NBI’s research on a DOE RTU Challenge

technology and better understand how to determine the energy performance

of the new generation RTUs compared with basic RTUs.

Hear about the efficacy of the DOE RTU Challenge units while

demonstrating a method for analyzing RTU data that will save time when

assessing RTU performance efficiency.

Provide attendees with insight into other developments in HVAC research.

Course Evaluations

In order to maintain high-quality learning experiences, please access the evaluation for this course by logging into CES Discovery and clicking on

the Course Evaluation link on the left side of the page.

This Session

• NBI Background

• High Performance Design and Retrofits

• Rooftop Units in the Field

• Best Practices and Emerging Tech for RTU Control and Efficiency Strategies

• NBI Lab/Field Work – DOE High Performance RTU Challenge Units

– Savings Protocol

What is the New Buildings Institute?

www.newbuildings.org

NBI is a non-profit think tank devoted to being a driving force and providing tools & guidance for deeply efficient & ZNE buildings

Focus on small & mid-sized commercial buildings incl. multifamily

Our interest areas include:

Building & Urban Resiliency

Advancing lighting, controls & HVAC

Advancing effective building codes

Design guidance & tools for deep

efficiency in new & existing buildings

Offices: Vancouver, WA/Seattle/Boston

NBI works throughout the US & Canada

NBI and Measured Performance

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Design EUI (Adj2)

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Certified

Silver

Gold

Platinum

LEEDlevel

Source: NBI 2008

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Next Practice in Design and EE

Programs “The future is not what it used to be…” Mickey Newbury

Energy efficiency will be different in the future. We won’t

be able to succeed with the technologies, programs, and

approaches that we have used in the past.

Some future trends include:

• Vast Opportunities in Rooftop HVAC

• A Push for Better Building Designs

• Deeper Savings in Existing Buildings

• More Focus on Multifamily Properties

• Significant Advances in Lighting

www.firstviewtool.com

www.ezsim.com

Deep Retrofits: What is Possible?

Examples of best practices from Deep Retrofits

http://newbuildings.org/sites/default/files/NEEA_Meta_Report_Deep_Savings_NBI_Final8152011.pdf

NBI Net Zero Capable Buildings

• Buildings of EUI of 35 of less

• Built in all climate zones

• Limited to relatively small buildings

• A lot of ‘Interpretive Centers’ = Low plug and latent occupant loads

http://newbuildings.org /sites/default/files/GettingtoZeroReport_0.pdf

Net Zero Buildings – HVAC Choices

Source: NBI 2012

Net Zero Buildings: At What Cost?

ASHRAE 50% Small to Medium Office Guide 2011

RTUs in Commercial Buildings

• Packaged air conditioners and heat pumps (RTUs) are used in approximately 46% of commercial buildings, serving about 60% of the commercial floor space. (EIA 2003)

Source: Little Bird

RTUs in Commercial Buildings

0.00%

5.00%

10.00%

15.00%

20.00%

25.00%

30.00%

35.00%

40.00%

45.00%

Primary HVAC System Type - n= 1.3 billion SF (nearly half the stock) -

#1

#2

Source: NWPPC 6th Regional Power Plan

Average Tons Per Unit

0%

2%

4%

6%

8%

10%

12%

14%

16%

18%

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Pe

rce

nt

of

Bu

ild

ing

s

Building Average Tons per Unit

CBSA Data: Building Average Cooling Tons per Pack HVAC Unit (Systems <50 Tons Cooling per HVAC unit) n=1041

64% of buildings <6 tons 79% of buildings <10 tons

Source: NWPPC 6th Regional Power Plan

RTUs- an aging fleet…

Age category Under 5 tons 5 to 10 tons Over 10 tons

44% 36% 20%

0 to 4 17% 30,000 24,000 14,000

5 to10 32% 56,000 46,000 26,000

10 to 19 35% 62,000 50,000 28,000

20+ years 16% 28,000 23,000 13,000

51% of the units have been on the roof for over a decade!

Source: NWPPC 6th Regional Power Plan

VERMONT: Average Age – 17 to 25 years

RTUs – Savings on the Table

Source: NBI Analysis 2012

Other Design Considerations Still

Very Important

• Envelope – Roof, walls, glazing, shading

• Internal Loads – Occupancy

– Plug Loads

– Lighting

– Other Process and Server

• Orientation

• RTU Sizing

• Distribution Design – Duct layout and sealing

• Commissioning

• Maintenance

Range of Energy

Performance

Outcome

• SCHEDULE AND USE

• ACTUAL SYSTEM OPERATION (Cx)

• OCCUPANT BEHAVIOR

• MODELED SYSTEM OPERATION

Ener

gy U

se

Src: NBI 2012

Design Operations Tenants

But can’t I just specify a higher EER?

20%

Even

-20%

EER

Ventilation

Thermostat Settings

EUI IMPACT

Source: NBI Sensitivity analysis 2012

What are the Problems with RTUs?

• Most RTUs operate inefficiently

– Lack of equipment maintenance – Lack of advanced control strategies. – Current design limited to constant speed supply fan and continuous

ventilation – Split Incentives

• Many RTUs operate unnecessarily – Thermostat settings and schedule causing unnecessary operation – Distributed standalone T-stats

What are the Problems with RTUs?

• NBI Meta Research

• 500 RTUs, 4 studies

– Lots of problems • 91% had one problem

• 64% had two or more

– Significant impact on delivered efficiency

– Majority or problems are in controls

Source: Several Studies

To

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2 Solutions:

A Story of Inside and Outside… High Refrigeration COP Exact Ventilation Air Economizing and Free Cooling Well Maintained - Long Life

Adhere to Schedule/Set Points Detect Occupancy Exact Ventilation Air Low Loss Ducts and Zoning

To

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…and the Three R’s

Repair Retrofit Replace ReDisplace

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Outside - Displace

VRF and DOAS Minimum Ventilation/Economizing Improved Zoning DCV Fault Detection and Diagnostics

Ideaz2: Net Zero

It is Critical to Upgrade Our Existing Building Stock

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Outside - Retrofit

“SideCar” Evaporative Add-on Non-Energy Benefits

$2000 – unit only

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3

Outside - Repair

RTU Diagnostic Tune Up > RTU DTU

1. CONTROLLER OFF LINE

2. SENSOR FAILURE

3. SENSOR STUCK

4. SENSOR OUT OF CALIBRATION

5. IMPROPER SENSOR LOCATION

6. COOLING/HEATING STAGE FAILURE

7. COOLING/HEATING/ FAN CYCLING

8. DAMPER HUNTING

9. STUCK DAMPER

10. DAMPER LEAKAGE

11. OVERSIZING

12. IMPROPER TEST, ADJUST, BALANCE

13. EXCESS OUTDOOR AIR INTAKE

14. OVER CIRCULATION

15. EXTREMELY UNEVEN RUNTIME RATIO

17. EXCESS AIR FLOW RATE

18. SETPOINTS NOT MET

19. FAULTY ECONOMIZER CONTROL

20. LOW COOLING CAPACITY •Low air flow rate •Low charge •Low compressor efficiency

16. LOW AIR FLOW RATE • Faulty fan • Slipping belt • Fouling • Improper or no TAB

21. OVERCHARGE

22. CONDENSER FOULING

23. LIQUID-LINE RESTRICTION

24. NON-CONDENSIBLE GAS

25. MALFUNCTIONING EXPANSION DEVICE

2013 CA T24 RTU FDD

• Mandatory Measure Jan 2014 for all air cooled unitary (package, split, heat pump, VRF/VCHP) with economizers ≥4.5 tons/54,000 Btu/hr

• Detect the following fault conditions:

Air temperature sensor failure/fault

Not economizing when it should

Economizing when it should not

Damper not modulating

Excess outdoor air

Mark Cherniack, NBI

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Recent Work

Packaged Rooftop Unit

Market Assessment

September 20, 2012

State-of-the-state in Repair,

Retrofit, and Replace.

Outside and Inside Retrofits

Current Research with RTU Controls

Eliminate: • Simplistic 35-year old solid-

state economizer controllers – Detailed damper control – Supply Fan speed controls – Compressor Speed Controls – FDD

Eliminate • Standalone (non-networked)

thermostats – Web-based interface – Remote monitoring – DCV, Occupancy Sensing – Advanced Scheduling Strategies

OUTDOOR CONTROLS

INDOOR CONTROLS

Premium Ventilation • Ideal World: Integrated Controller Sequence Improvements

– Occupancy Sensor based set-point and ventilation based on ASHRAE 62.1 – Integrated and Differential Economizer Controls – Demand Reduction and Standby – Night Flush Cooling – Optimum Start and Resistance Heat Lockout – Improved Outside Air Damper Seals – Morning warmup lockout

http://e3tnw.org/Webinars.aspx

Source: Reid Hart PECI, PNNL 2011

10-ton RTU with Gas Heat

Source: PNNL 2011 http://www.pnnl.gov/main/publications/external/technical_reports/PNNL-20955.pdf

62.1 & DCV Cycling Fan Control

ASHRAE Standard 62.1 allows fan cycling – Section 6.2.6.2 of Standard 62.1-2010 allows:

• Short-term interruptions of ventilation if,

• Average ventilation levels are maintained

This opens the door for Continuous Ventilation to be modified through the use of DCV and cycling fan control to ensure adequate ventilation while saving energy.

Recent studies show 40% of units are on “Auto”

Current Research with RTU Controls

OUTDOOR CONTROLS

INDOOR CONTROLS

FDD Vendor/

Maintenance

“The Roof”

Outdoor Solutions Name Vendor Description Link

Catalyst Transformative Wave

Premium Ventilation Package Integrate with existing BMS/T-stats., VFD, eIQ software tool,

www.catalysteec.com

Digi-RTU Bes-tech VFD Supply Fan, VFD Compressor, Optimization, Some FDD

www.bes-tech.net

Enerfit V1 Enerfit VFD Supply Fan, DCV, Some FDD. Standalone or BACNet interface.

www.enerfit.com

REGEN Regen Demand response, networked rooftop units – Swarm Logic

terrpinbrightgreen.com

DrivePak NextRev VFD Supply Fan, Integrate with existing BMS/T-stat.

www.drivepak.com

Minimax Innotech A flexible DC module. A version is preprogrammed for outdoor RTU controls.

innotechamerica.com

Economizer Upgrade – Economizer and DCV

Jade Honeywell Enhanced economizer function. RA DCV, basic FDD

Honeywell.com

Zip Belimo Enhanced economizer functionality – 10-15% more than Jade

Zipeconomizer.com

W7220 JADE Economizer

$250 + Sensors

JADE Economizer / DCV Screen

• Sensors not detected or out of range

• Economizer damper stuck

• Compressor contactor failure

• Exhaust fan relay failure

• Mis-wired thermostat

• Supply air temperature drop is

insufficient

Catalyst Example

Source: PECI 2012

~$3000

Digi-RTU Example

Com-Ed Pilot

Source: Bes-Tech 2012

$2,000 to $9,000 for units from 3 to 20 tons

Digi-RTU Example

Source: Bes-Tech 2012

Units in Field Testing

Source: E Source 2012

Combined Indoor & Outdoor Solutions

Name Vendor Description Link

Unity Kite and Lightening Complete integrated package of t-stats, outdoor controls, and software with FDD.

www.kiteandlightening.com

Flex-Stat KMC

DDC Thermostat converted from BAS. Needs compliant outdoor controls. Preprogrammed Premium Ventilation.

www.kmccontrols.com

Visual Logic Alerton

DDC Thermostat converted from BAS. Needs compliant outdoor controls. Preprogrammed Premium ventilation.

www.alerton.com

KMC Flex-Stat

Indoor Solutions

Name Vendor Description Link

DreamWatts Makad Smart T-stat, web-based scheduling, wireless mesh communications, DR, DCV

www.makadenergy.com

Eco-Factor KMC Smart T-stat, web-based scheduling, DR, DCV, Learning algorithm

www.ecofactor.com

EcoBee Alerton Smart T-stat, web-based scheduling, DCV www.ecobee.com

Emme Emme Smart T-stat, web-based scheduling, wireless mesh communications, DR, DCV

www.getemme.com

ezeSystem ezeSystem Smart T-stat, web-based scheduling, kWh/kW monitoring, DR, DCV, Prepayment

www.ezesystem.com

Telkonet EcoSmart Smart T-stat, web-based scheduling, smart-recovery algorithm, DR, DCV

www.telkonet.com

Nest Nest Smart T-stat, web-based scheduling, wi-fi communications, Learning algorithm, DR, DCV

www.nest.com

Based on Operating Schedules

– Average annual savings for 30 RTUs: 3,307 kWh

– Average annual savings 7 tons and greater: 5,198 kWh

– 83% of the units realized savings

– Maximum savings: 15,408 kWh

Thermostat Upgrade Savings

Source: BPA RTU Research Project 2009

Dreamwatts – RTU1…

Indoor Controls Advantageous Characteristics

• Wireless Mesh

– Cheap – Components and Install

– Additional Sensors/Actuators

• Web-Based

– Non-energy benefits for tenants

– Coolness factor

• Remote Monitoring

– Eventual link with Outside Controls

NBI Recent Work

• Variable Speed Components on an RTU

• DOE RTU Challenge Testing

• Screening Tool and Analysis Approach

Variable Speed Component

Testing

RTU

Compress

or

Condenser Fan

Supply

Fan

Single Phase 120/240

Three-Phase

240

ACH550-UH-046A-

2

ACH550-UH-012A-

2 ACH550-

UH-012A-2

NEEA/NBI 2012

Results

City Loading Savings

Average %

Compressor Savings %

Condenser Fan Saving

%

Supply Fan Savings %

Portland Low 13 -6 41 63

Portland Medium 5 -11 35 61

Boise Medium 4.5 -17 32 59

Portland High 3.5 -7 19 33

Boise High 5.2 -5 20 33

NEEA/NBI 2012

Outdoor – Replace

High Performance RTUs

Measure three RTUs in controlled circumstances at NBI

Lab (NBIL): – Federal minimum code (2011)

• Trane Precedent

– Advanced Performance RTUs:

• AAON RQ Series

• Daikin McQuay Rebel – DOE High Performance Challenge RTU

Measure the two advanced RTUs on the roof at two Fred

Meyer (Kroger Corporation) Idaho locations: – AAON RQ (Delays prevented monitoring for this year)

– Daikin McQuay Rebel

NEEA BPA Variable RTU Test (VRTUT) 2012

RTU Specifications Trane Precedent AAON RQ Series Daikin McQuay Rebel

Short name used in report Trane AAON Daikin

Nominal Size, Tons 5 5 5

SEER, AHRI 13.0 14.8 18.0

EER, AHRI 11.0 12.7 12.7

Cooling Capacity kBTU/hour, AHRI

62.27 63.50 61.75

Economizer Control Dry bulb Comparative Enthalpy

Comparative Enthalpy

Supply/Condenser Fans Direct drives ECM/VFD

Direct drives ECM/VFD

Direct drives

Compressor Scroll Digital™ Scroll Inverter scroll

Refrigeration Metering Device TXV TXV EXV

Exhaust Air Barometric Barometric Barometric

Model Year 2011 2012 2012

NEEA BPA Variable RTU Test (VRTUT) 2012

Rebel Field Trial

Model Comparison Top

ic 1

• Schedule 8:30AM –

10:00PM

• Set Points 72/76

• Constant Ventilation 24

hours

• Integrated Economizer

• OA Fraction 40%

Code Level Projection

NEEA BPA Variable RTU Test (VRTUT) 2012

Model Comparison Results

DOE Challenge 1 - Field Trial To

pic 1

Code Baseline

DOE

ID-1 Savings kWh Savings %

No Economizer 6,618 4,176

2,442 37%

With Economizer

6,091 1,915 31%

Model-based Cooling Season May 1 to October 31 Energy Usage (kWh) for Boise, ID:

Savings Protocol

RTU Energy Signatures

http://rtf.nwcouncil.org/measures/measure.asp?id=186

Types of Retrofits and Repairs

• Physical repair measures

– Dampers, airflow changes, drive adjustments

• Operational repair measures

– Set points, schedule, and economizer adjustments

• Maintenance measures

– Coil cleaning, filter changes, refrigerant charge

• Equipment upgrade measures

– Supply fan, controls, compressor change, etc.

Data Needs

• A maximum of 3-minute interval data

– RTU Power

– Outdoor Air Temperature

– Optional: Supply Air Temperature

• 28-days before and after retrofit

• TMY3 file for target city

http://rtf.nwcouncil.org/measures/measure.asp?id=186

Apply Typical Climate Data

Baseline

Improved Case

Normalized Annual Consumption (NAC)

TMY3 – Any City

NBI RTF Savings Protocol

• Simple Consistent Methodology

• Results can be projected to any city

• Potential for measured performance comparison to ‘code level’

• Results are harmonized across pilot projects

NBI Savings and Enhanced

Protocol RTU Cooling End Uses

0

10

20

30

40

50

60

45 50 55 60 65 70 75 80 85

Average 24 Hour Temperature

En

erg

y k

Wh

/day

economizer

Internal loads

shell/thermal loads

vent min OSA

fan

• Ideally we all go Net Zero Capable but in the mean time… – Repair, Retrofit, Replace

• Optimizing RTUs to operate efficiently and consistently can save significant energy.

• New inside and outside controls approaches are breaking to barriers to efficiency and energy outcomes – Reducing ventilation energy

– Maintaining schedules and set points

– Integrating FDD and remote monitoring

– Easy wireless BAS for small buildings

• Move past EER,SEER, and IEER comparisons

Summary