Breaking the Limits of HVAC Efficiency · 2020. 1. 31. · 2013 CA T24 RTU FDD ... –Web-based...
Transcript of Breaking the Limits of HVAC Efficiency · 2020. 1. 31. · 2013 CA T24 RTU FDD ... –Web-based...
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Breaking the Limits of
HVAC Efficiency
Unitary Rooftop Packaged Equipment
(RTU)
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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.
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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.
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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.
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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
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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
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NBI and Measured Performance
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Design EUI (Adj2)
Actu
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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
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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
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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
http://newbuildings.org/http://newbuildings.org/
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Net Zero Buildings – HVAC Choices
Source: NBI 2012
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Net Zero Buildings: At What Cost?
ASHRAE 50% Small to Medium Office Guide 2011
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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
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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
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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
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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
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RTUs – Savings on the Table
Source: NBI Analysis 2012
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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
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Range of Energy
Performance
Outcome
• SCHEDULE AND USE
• ACTUAL SYSTEM OPERATION (Cx)
• OCCUPANT BEHAVIOR
• MODELED SYSTEM OPERATION
Ener
gy U
se
Src: NBI 2012
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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
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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
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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
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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
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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
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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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Outside - Repair
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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
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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.
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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
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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
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10-ton RTU with Gas Heat
Source: PNNL 2011 http://www.pnnl.gov/main/publications/external/technical_reports/PNNL-20955.pdf
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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”
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Current Research with RTU Controls
OUTDOOR CONTROLS
INDOOR CONTROLS
FDD Vendor/
Maintenance
“The Roof”
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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
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W7220 JADE Economizer
$250 + Sensors
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JADE Economizer / DCV Screen
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• 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
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Catalyst Example
Source: PECI 2012
~$3000
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Digi-RTU Example
Com-Ed Pilot
Source: Bes-Tech 2012
$2,000 to $9,000 for units from 3 to 20 tons
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Digi-RTU Example
Source: Bes-Tech 2012
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Units in Field Testing
Source: E Source 2012
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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
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KMC Flex-Stat
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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
http://www.makadenergy.com/http://www.ecofactor.com/http://www.ecobee.com/http://www.getemme.com/http://www.ezesystem.com/http://www.telkonet.com/http://www.nest.com/
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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
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Dreamwatts – RTU1…
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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
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NBI Recent Work
• Variable Speed Components on an RTU
• DOE RTU Challenge Testing
• Screening Tool and Analysis Approach
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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
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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
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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
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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
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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
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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:
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Savings Protocol
RTU Energy Signatures
http://rtf.nwcouncil.org/measures/measure.asp?id=186
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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.
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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
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Apply Typical Climate Data
Baseline
Improved Case
Normalized Annual Consumption (NAC)
TMY3 – Any City
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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
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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
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• 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