3/4/2014
Advanced RTU Control Strategies
Ryan R. Hoger, LEED AP 708.670.6383 [email protected]
Environmental Impact of Buildings*
• 40% of total U.S. energy consumption
• 39% of total U.S. CO2 emissions • 72% of total U.S. electricity consumption
*Commercial and Residential
1 3/4/2014
Environmental Energy Impact of Buildings
100% USA Energy Consumption (BTU) 38.2% 28%
Transportation
33.4% 32%
Industry
28.3% 40%
Buildings*
Residential & Commercial Buildings 2010 DOE Buildings Energy Data Book 20.26 Quadrillion BTU Site > dropped to 19.99 in 2011 39.29 Quadrillion BTU Primary > means bldgs are about 51-52% efficient in terms of raw energy utilization
Commercial HVAC Energy Consumption
27% of all commercial HVAC energy is used by fans!!!
2 3/4/2014
Efficiency Ratings for RTUs
• Air-Conditioning, Heating, and Refrigeration Institute RTUs < 65,000 Btuh (~5.4 tons) • Use residential test standards • SEER •AFUE • RTUs >= 65,000 Btuh (~5.4 tons) • EER + IEER • Thermal Efficiency
3 3/4/2014
Industry Movement to IEER Ratings
The industry and governing bodies are evolving to Integrated Energy Efficiency Ratio (IEER) values as the leading energy measure:
- IEER models building part load profile – EER measures peak unit performance that is typically experienced 3% of the operating time.
- Codes now specify both a minimum EER and IEER
- Rebate programs generally specify just a part load min IEER
- The Department of Energy (DOE) Rooftop efficiency challenge - ONLY specifies IEER @ 18.0 – NO EER
ASHRAE 90.1-2010 & IECC 2012 Minimums
4 3/4/2014
ASHRAE 90.1-2013 Minimums
Example Manufacture Product Offering High Tier IEER’s
Nearly 70% more efficient than entry level
Includes: up to 3 stage Nearly 50% more cooling, VFD supply fan, and efficient than mid- ECM condenser fan tier SEER / IEER SEER /
High Efficiency Mid-Efficiency Code Tier Tier Minimum RTU
Values are averaged
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Retro-commissioning Most Common* Improvements *DOE / Lawrence Berkley National Lab Study 2009
Retro-commissioning Savings for Key Improvements** **DOE / Lawrence Berkley National Lab Study 2009
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RTU Study Results*
*2004 Study by New Buildings Institute 503 RTUs at 181 Sites
Example RTU Tune-up Checklist
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2013 DOE Study: Advanced Rooftop Control (ARC) Retrofit: Field-Test Results
• Pacific Northwest National Labs • Published July 2013 • Purpose was to study combined energy effects of an economizer, demand controlled ventilation, and multi-speed fan control for RTUs • Field testing done on 66 RTUs on 8 different buildings • Various occupancy types (retail, office, food, and healthcare) • Various climates • Mix of Carrier (32), Trane (21), and Lennox (13) units • Range of RTU sizes, but most (43) were 10 to 15 tons • Data collected on 1 minute intervals for 12 months • Controls were alternated between standard (pre-retrofit mode) and advanced control modes on a daily basis
2013 PNNL Study Key Findings
• An initial study showed gas/electric units saved between 24 and 35% energy and heat pumps saved 20 to 60% • The field data from the 66 RTUs showed a savings range of 22 to 90%, with a 57% savings average for all RTUs • Fan energy savings was the dominant contributor of the savings • Average payback periods were 6, 3, and 2 years for the 3 utility rates ($0.05, 0.10, and 0.15 / kWh) • Cost included both materials and labor • Larger units and longest runtime units had the shortest paybacks, as expected
8 3/4/2014
Products Reviewed
• Available retrofit products: • Transformative Wave’s CATALYST • Enerfit • Bes-Tech’s Digi-RTU Optimizer • All 3 vendors retrofit supply fans with a VFD and generally change speed based on mode (heat, cool, vent, etc.) • All 3 also provide airside integrated economizer controls and CO2-DCV capabilities • Digi-RTU also provides the ability to modulate compressor speed • Based on product maturity and availability, PNNL choose to use the CATALYST product in the field testing
PNNL Field Test Settings
• Vent mode fan speed = 40% • Cool/heat speed = 75 or 90% (depending on # of stages) • CO2 high setpoint = 1,000 PPM
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PNNL Recommendations
PNNL Study Runtime Examples
10 3/4/2014
Programmable Thermostats
Programmable Thermostats
• Stop running heating/cooling 24/7!!! • Relaxes heat/cool setpoints when space not occupied – Only setback about 5º (use 65º for heat and 80º for cooling) – Need to setback minimum of 6 hours to be effective • On average saves 25-30% on heat/cool energy* – If installed in every home would save about 5% of total US energy consumption*
*John Hopkins Univ. AICGS Policy Report
11 3/4/2014
Programmable Thermostat Study Results*
• Residential stats responsible for 11% of total US energy • What kinds of stats do people have? – 14% have no stat at all – 56% non-programmable – 30% programmable • Of those with programmable stats… – 89% have rarely or never programmed a stat – Only 30% of programmable stats are actually programmed – In winter, 60% use for night setback, only 45% setback during day – In summer, 55% use for night, same for day time – 2003 Carrier study also revealed that 53% of prog stats were in “hold”
*2010 - DOE, EPA, and Lawrence Berkley National Labs Study
Programmable Thermostats
• Easy to retro-fit • Adaptive Intelligent Recovery • 2-stage stat for integrated economizer as 1st stage • Shut off ventilation during unoccupied hours • Internet accessible • Payback less than 6 months
*John Hopkins Univ. AICGS Policy Report
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Internet Thermostats
• Low cost alternative to BAS • Ethernet or Wi-Fi • No PC software – uses standard web browser • No access fees • Text/email alerts
Internet Thermostats
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Internet Thermostats
Phone Apps for Thermostats
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Economizers
Outdoor Air Economizers
• Use outside air for “free cooling” instead of compressors • 3 main types of control – Dry-bulb Temperature (enable when OA < 60º) – Enthalpy (enable when OA < 70º and humidity low) – Differential Enthalpy (is OA better than RA?)
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Outdoor Air Economizers
• Integrated economizer – Economizer assists compressors on certain days • Building pressure relief needed • Occupancy control – Open to ventilation position only when building occupied (interlock to time clock of stat) instead of whenever fan on • Payback less than 6 months
Barometric Relief
Outdoor Air Intake
Barometric Relief
Section 11 – Options and Accessories
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Powered Exhaust Remote Duct Mounted Powered Exhaust
Outdoor Air Intake
Unit Mounted Powered Exhaust
Section 11 – Options and Accessories
IECC 2012: Commercial Economizers
IECC 2012 already required by 8 states
Also additional requirements for relief/exhaust, integrated economizer, types of economizer control, water-side economizers, etc.
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Existing Economizer Optimization • Many systems have never been commissioned at all – Perform functional performance tests • Economizer dampers and controls inoperative or in poor condition – Test bi-annually - repair or replace • Sensors not recalibrated on regular basis (especially enthalpy and CO2 sensors) – Recalibrate sensors bi-annually • Other issues: – Systems have been locked out by operator – Scheduling is not optimized (sometime running 24/7) – Economizer control not optimal (too high of OA setpoint)
Insuring Proper Economizer Operation
• Eliminate outside air for ventilation during unoccupied periods by closing OA dampers • OA damper operation should be monitored and recorded to verify actual operation of economizer • Percent OA can be used to verify that the economizer is properly operating • Percent of OA is calculated using a formula or graph
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OA% Calculation
OA% = (MAT – RAT) (OAT – RAT)
Example: OAT = 10° RAT = 70° MAT = 50°
OA% = (50 – 70) = 33% (10 – 70)
“Typical” Honeywell
W7459 M7415 Economizer Economizer Logic Module Actuator
Depending on sensors used, it is capable of dry-bulb changeover, enthalpy changeover, or differential enthalpy. Not capable of demand controlled ventilation (DCV).
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Honeywell W7212
Also capable of Demand Controlled Ventilation (DCV)
Honeywell W7212
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Honeywell Logic Modules
Honeywell Economizer Simulator
customer.honeywell.com/economizertools
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Outdoor Air Dry-Bulb Economizer
60° F Outdoor AAir Temp
75° F db / 50% rh
Compressor OFF Compressor ON Economizer ON Economizer OFF Modulate OA / RA / Exh. Outdoor Air Damper Section 11 – Options and Accessories at Ventilation Position
Outdoor Air Enthalpy Economizer
65° F Outdoor AAir Temp
75° F db / 50% rh
h = 25
Compressor OFF Compressor ON Economizer OFF Economizer ON Outdoor Air Damper Modulate OA / RA / Exh. Section 11 – Options and Accessories at Ventilation Position
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Integrated Economizer
Compressor OFF Compressor ON Compressor ON Economizer ON Economizer OFF Economizer ON Outdoor Air Damper Outdoor Air Damper SectionModulate 11 – Options OA /and RA Accessories / Exh. Fully OPEN at Ventilation Position
A, B, C, and D Enthalpy Curves
Above Curves: Compressor ON Economizer OFF Outdoor Air Damper at Ventilation Position
75° F db / 50% rh
Below Curves: Compressor OFF Economizer ON Modulate OA / RA / Exh. Section 11 – Options and Accessories
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CO2-based Demand Controlled Ventilation (DCV)
Ventilation Control
How is ventilation provided in buildings today? The same way it was in 1930.
With Fixed Ventilation!
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Minimum Ventilation Rates
Fixed Ventilation
Building codes require ventilation rates based on cfm/person: (typically 20 cfm/person) MaxActual Occupancy: Occupancy: 25 51 people peopleperson = == 500cfm 500cfm500cfm
Inefficient!
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Indoor Air Quality
FIRST ALARM SECOND ALARM SENSOR RADIUS OF (TWA) (STEL) LOCATION DETECTION Temperature & Humidity N/A N/A N/A N/A
Carbon Dioxide (CO2) 800-1200 ppm 5000 ppm 19.5% 22% 5 ft. above floor 20 ft. Oxygen (O2) (O2 depletion) (O2 saturation)
CO2 Basics
• CO2 is NOT a contaminant, it is a colorless, odorless gas found naturally in the atmosphere – Outdoor levels are fairly constant at 400 +/- 25 ppm – Typical indoor levels 400 to 2,500 ppm – Not harmful unless concentrations reach 30,000 ppm • Carbon Monoxide (CO) and Carbon Dioxide are NOT the Same
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CO2 Basics
People exhale CO2 at concentrations of 4% (40,000 ppm)
Normal room concentrations are in the range of 400 - 1200 ppm
As a gas, CO2 diffuses and equalizes rapidly throughout a room (like humidity)
CO2 and Ventilation Rates
• CO2 production by people is very predictable based on activity level
• Doubling the people in a
room will double CO2 production
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CO2 and Ventilation Rates
CO2 levels will build until an 3,000 equilibrium level is 2,500 reached with 5 cfm/person outside air 2,000 entering the space 1,500 10 cfm/person
1,000 15 cfm/person CO2 Concentrations (ppm) CO2 Concentrations 20 cfm/person 30 cfm/person 500
- 0:00 1:00 2:00 3:00 4:00 5:00 30 cfm/person 20 cfm/person Time15 cfm/person (hours) 10 cfm/person 5 cfm per person
Ventilation Control
Actual Occupancy 2551 peopleperson people == = 100cfm20cfm 500cfm
Ventilation based on actual occupancy!
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Research & Studies
Numerous Studies Confirm that Correct Ventilation:
• Increases Productivity • Improves Occupant/Customer Satisfaction • Helps Prevent Sick Building Syndrome Health Affects DOE/Lawrence Berkeley Labs Indoor Environment In Schools
Pupils’ Health & Performance In Regard To CO2 Concentrations A significant correlation was found between decreased
performance and high CO2 levels (lower ventilation rates).
Research & Studies
Numerous Studies Confirm that Correct Ventilation:
• Increases Productivity • Improves Occupant/Customer Satisfaction • Helps Prevent Sick Building Syndrome Health Affects
“Air Quality and Ventilation” ranked very high (#2 of 25) on the list of tenant retention issues in a recent survey conducted by Real Estate Information Systems.
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Research & Studies
Numerous Studies Confirm that Correct Ventilation:
• Increases Productivity • Improves Occupant/Customer Satisfaction • Helps Prevent Sick Building Syndrome Health Affects DOE/Lawrence Berkeley Labs Evaluation of Sick Leave Statistics vs. Ventilation Rates (3720 employees / 40 buildings): Optimal ventilation reduces sick time costs. For every $1 spent on ventilation cost, $2 are saved in sick time.
DCV Savings
nChart compares ventilation usage throughout typical Federal Energy Management Program day using purple to represent “demand controlled” Study and green to represent “constant” nDifference between equates to significant savings
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Research Findings Demand Control Ventilation
Energy wasted - no DCV Energy required, DCV control applied
100%
90%
80% 70% HUGE 60% Savings 50%
40%
30%
20%
10%
0% Office Retail Restaurant School
Examples of Potential Energy Savings and ROI
THEATRE SCHOOL OFFICES THEATRE $11,530 $20,051 $3,448 $17,603 Annual Savings Annual Savings Annual Savings Annual Savings RETAIL 8 mo. ROI 18 mo. ROI 15 mo. ROI 7 mo. ROI $18,729 Annual Savings 5 mo. ROI
SCHOOL OFFICES $6,910 $7,112 Annual Savings Annual Savings 15 mo. ROI 12 mo. ROI
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FEMP Study
• 4 CO2 sensors per floor – Energy Model z $81,293 annually z $3,000 per floor z $0.22/ft2 – Actual saving for 6 months was $133,805
Determine if CO2 Control is Appropriate
Rating Legend: A Recommended B Possible (Note 1) C Not Recommended
Application Application Application Rati ng Rati ng Rati ng Correctional facilities Specialty shops Hospitals and medical Cells A Barber and beauty B Patient rooms B Dining halls (Note 2) B Reducing salons B Medical procedure C Guard stations C Florists B Operating rooms C Dry cleaners and laundries Clothiers B Recovery and ICU B Commercial laundry B Furniture B Autopsy rooms C Commercial dry-cleaner C Hardw are B Physical therapy A Storage and pickup B Supermarkets B Lobbies and w aiting areas A Coin-operated laundries A Pet shops C Hotels, resorts and Coin-operated dry C Sports and amusement Bedrooms B Education and schools Spectator areas A Lobbies A Classrooms A Industrial facilities Conference rooms A Laboratories (Note 4) B Heavy manufacturing C Meeting rooms A Training shops B Light manufacturing B Ballrooms and assembly A Music rooms A Materials storage C Gambling casino B Libraries A Training facilities C Game rooms A Locker rooms C Painting and finishing C Ice arenas A Auditoriums A Food and meat processing C Sw imming pools C Smoking lounges (Note 3) B Office buildings A Gy mnas iums A Food and beverage service Retail stores Ballrooms and discos A Dining rooms (Note 2) B Sales floors A Bow ling alleys A Cafeterias (Note 2) B Dressing rooms ATheaters A Bars, cocktail lounges B Malls and arcades A Transportation Kitchens C Shipping and receiving C Waiting rooms A Garages, repair and service C Warehouses C Platf or ms A
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Control Setpoints Condition Of Indoor Air 2,600
Unacceptable 5 cfm/person CO2 Control Point Depends on: 2,400
• Outdoor CO2 Level (typically 2,200 450 ppm) Need To Very Poor 6 cfm/person Increase 2,000 • Required cfm/person Outside Air 1,800 ventilation rate Ventilation Poor 8 cfm/person 1,600 Under Ventilated .
If OA CO is 400 ppm: Concentration (ppm) 10 cfm/person 2 2 1,400
20 cfm/person = 930 ppm CO Ventilation Rate 2 1,200 Marginal
15 cfm/person = 1,100 ppm CO2 15 cfm/person 10 cfm/person = 1,450 ppm CO CO Inside 1,000 Ideal 2 20 cfm/person 800 25 cfm/person Opportunity Over Ventilated 30 cfm/person To Save Energy 600 By Reducing Ventilation 400 Typical Outside Levels
Now Allowed by Most Mechanical Codes
Benefits of Ventilation Control • Proof of Compliance ASHRAE Standard 62.1
International Mechanical Code (IMC)
Local Codes
Using CO2-based ventilation control ensures compliance to codes and standards
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Now Allowed by Most Mechanical Codes
ASHRAE 62.1-2010
Written into the actual standard since ASHRAE 62-2004
Now Allowed by Most Mechanical Codes
Commentary To The International Mechanical Code (IMC) Section 403.3.1 “The intent of this section is to allow the rate of ventilation to modulate in proportion to the number of occupants. This can result in significant energy savings. Current technology can permit the design of ventilation systems that are capable of detecting the occupant load of the space and automatically adjusting the ventilation rate accordingly.
For example, carbon dioxide (CO2)detectorscanbeusedtosense the level of CO2 concentrations which are indicative of the number of occupants. People emit predictable quantities of CO2 for any given activity, and this knowledge can be used to estimate the occupant load in a space.”
Was written into the actual code for IMC 2006
34 3/4/2014
Now Required by Most Energy Codes
Benefits of Ventilation Control • Proof of Compliance ASHRAE Standard 90.1
International Energy Conservation Code (IECC)
Local Codes
Also required in green codes such as ASHRAE 189.1, IgCC, and LEED
DCV Now Required by Most Codes
IECC 2012 requires DCV at population densities of 25 people per 1000 ft2
IECC 2009 requires DCV at 40 people per 1000 ft2
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Why Now?
• Digital Control Systems – Integration of ventilation control • Increased Ventilation Rates (ASHRAE/IMC) • Increasing Energy Costs • Required by Energy Codes • Decreasing Sensor Costs (First & Life Cycle) & Increased Sensor Reliability
Sensor Cost
• Control system $1500 integration • Sensor technology $500 Installed Cost and integration Per Point (CO2 + Temp) • Volume increases 1992 1997 2003
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Sensor Reliability
• 15 Year design life • Non- interactive, selective to
CO2 only • Stable - lifetime calibration
Self Calibration of a CO2 Detector 1000
• Automatic Baseline 900 Calibration (ABC Logic) 800 • Self calibrating 700 algorithm Concentration 2 • Considers lowest CO2 600 level every 24 hrs 500 • Looks at long term CO Indoor changes in baseline 400 • Applies a correction factor for calibration 300 Days
Slight Long Term Sensor Drift Calculated Over Number Of Days TEMA Corrected Baseline
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Self Calibration of a CO2 Detector
800
700
Sensor 1 Sensor 2 600 Sensor 3
500
400 PPM
300
200
100
0 2000/12/29 2000/12/30 2000/12/31 2000/12/31 2001/01/01 2001/01/02 2001/01/02 2001/01/03 2001/01/04 14:58'08 07:38'08 00:18'08 16:58'08 09:38'08 02:18'08 18:58'08 11:38'08 04:18'08
Sensor Reliability
1400 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1300 1200 1100 1000 900 800 700 600 500 CO2 Concentration (ppm) 400 300 200 12/27 12/28 12/29 12/30 12/31 1/1 1/2 1/3 1/4 1/5 1/6 1/7 1/8 1/9 1/10 1/11 Day
Self Calibration Over 14 Days
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Long Term Sensor Stability
2000 Test Gas: 980 ppm CO2 in Nitrogen 1750 1500 1250 1000 750 PPM (CO2) 500 250 0 1 365 729 1093 TIME (DAYS)
Stat, Econ, and DCV Energy Savings
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Example Rebates for CO2-based DCV
• Focus on Energy in Wisconsin • Single Zone RTU = $400 • Multi-zone RTU = $0.20 per OA CFM • Nicor, North Shore, and Peoples Gas in Illinois • $0.50 per ft2 • ComEd Electric in Illinois • $0.04 per ft2 • NIPSCO Gas in Indiana • $0.15 per ft2 • Efficiency United in Michigan • $0.08 per ft2 (gas side) • $0.035 per ft2 (electric side) Please read all rules and qualifications for each incentive.
Energy Recovery Ventilation (ERV)
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Potential HVAC Energy Conservation
Analyzed 40 technologies Summary report shows top 15 technologies Power station provides about 1.1 quad per year 1 quad = 1015 BTU/H
U.S. Department of Energy July 2002
Energy Recovery Ventilators (ERV)
• Uses exhaust air to pre-heat or pre-cool ventilation air • Can be adapted to existing systems • HRV or ERV? Wheel or fixed plate? • Improvements to IAQ • Required by code in some cases • Paybacks less than 24 months
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Identifying Potential Applications
“Clean” Candidates Exhaust Air for Recovery RTU • Retail • Schools High Levels of Ventilation Air • Offices • Theaters • Fitness Centers • Gymnasiums • Hospitals • Restaurants • Nursing Homes
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50 to 80 % Plate Exchanger Crossflow sensible effectiveness – latent possible
Tight Seal Construction
Module Sidewall
Return Air Supply Air
Outdoor Air Exhaust Air
Drain Pan
Energy Wheel Operation 55 to 90% total (sensible + latent) effectiveness
10 and 60 rev/min
Exhaust Air Return Air
Ventilation Air Supply Air
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RTU Integrated ERV
• Cost effective method of providing a RTU with an ERV • Retro-fit or factory install • Optional economizer and power exhaust function
RTU Combination Curb
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Technology Comparison
5000 CFM and equal face velocities
Reduced Operating Range
• Range of ventilation air “Weather Compressor” conditions introduced to the HVAC unit is significantly reduced • HVAC unit cooling system can be downsized and will operate at a higher sensible heat ratio (less dehumidification required), which is typical of most packaged DX rooftop units • HVAC unit heating system can be downsized or possibly even eliminated
Airxchange catalog, January 2006
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IECC 2012: Requirement for Energy Recovery
Required in many high population areas (gyms, theaters, etc.)
Check map for climate zone
Look up supply fan CFM and OA fraction
Note: IECC 2009 only required ERVs above 70% OA on a 5,000 supply CFM system (regardless of climate)
Helena MT Duluth, MN
Burlington, VT Boise, ID Chicago, IL
Salem, OR
Baltimore MD
San Francisco CA Phoenix, AZ El Paso, TX Miami FL Memphis TN
Albuquerque, NM Houston, TX
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Staged Air Volume (SAV) …or Single Zone VAV …or Multi-stage Air Volume (MSAV) …or Adaptive Fan Control
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SAVTM System
Industry Overview Definition Application Need Acronym Variable Air Typically multi-zone, VAV Standard and High Efficiency units Volume large applied systems Staged Air Single zone VAV, SAV Electro-mechanical or Digital Controls Volume simple, saves energy! Constant Air VFD: pre-configured and adjustable CAV Traditional System Volume Adaptive Integrated Economizer Control: Prevents over/under ventilation
(VFD) Fan Automatically Adjusts To Unit Indoor Fan Motor Speed Controller Operation Per New Standard Belt Drive 2 Speed
1st Stage Cooling = Fan at 67%
1st and 2nd Stage Cooling = Fan at 100%
Any Heating = Fan at 100%
Ventilation Only = Fan at 67%
Why Two Speed Fan Control?
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SAVTM SYSTEM DESIGN Why a VFD?
• A two speed (two winding) indoor fan motor would require the next size motor frame in order to achieve the same CFM. The VFD system can use the smaller standard motor frame.
• VFDs can also provide advanced options for special application including soft start capabilities, higher power factors, and lower full load KVA values
• VFDs also allow programming to meet very specific applications, and to adjust the speed of the powered motor.
Variable Frequency Drives (VFDs)
• Retro-fit to fans • Varies the power input to motor • On average building fan systems in the US are oversized by 60%* • If a motor running at 100% speed costs $1,000/month, what about: – Running at 75% speed = $420 – Running at 50% speed = $125 – Due to the Affinity Laws • Soft start means less wear & tear on couplings, belts, and motors •Payback less than 18 months *John Hopkins Univ. AICGS Policy Report
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FAN LAW BASICS
Energy saved... Third Fan Law 9 Let’s quickly re-visit the third fan law: 8 Brake horsepower (BHP) varies as 7 the cube of the fan speed: 6 5
4 CFM BHP
Flow and Power 3 For simplicity, if we assume 2
RPM1 = 1000, BHP1 = 2.0, 1 and then decrease fan speed 0 to 677 RPM (or 67%) 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 Relative Wheel Velocity
Staged Air Volume (SAV)
• Improves humidity control and saves energy • Saves about 25-30% electrical energy in Midwest climate • Minimum OA needs means of automatic adjustment when fan slows • Similar logic could potentially be applied to heating mode if RTU has multiple stage heat, but pay attention to heat exchanger airflow needs
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ASHRAE 90.1-2010 Fan Power Limitation
• All manufacturers offer (or will) SAV on 10 ton RTUs and up…several offer on smaller sizes also • Note: this is a requirement of ASHRAE 90.1-2010 and 2013, but is not currently included in IECC 2012 (probable for IECC 2015 when published)
Example Manufacture Product Offering w/ SAV Option SEER / IEER SEER / Models only available SAV available with only Models
High Efficiency Mid-Efficiency Code Tier Tier Minimum RTU
Values are averaged
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Operating Cooling Cost Comparison
Savings between 27% to 56% - WOW!
Annual Energy Savings ($, %) In Using High Efficiency RTUs*
10 Ton 15 Ton 20 Ton
Mid Tier $ 359 $ 320 $ 523 w/ SAV 39% 27% 35%
$ 596 $ 655 $ 842 Mid Tier 51% 43% 46%
Entry $ 454 $ 558 $ 834 Level w/ 45% 39% 46% SAV
Entry $ 709 $ 916 $ 1,217 Level 56% 51% 55% * These models use three stages of cooling capacity control and matching fan speed controls $
**Building Profile: Memphis, TN (Single Story Office Building Simulated 10, 15 and 20 ton Models Using DOE Energy Plus software .10 kWh
Operating Cooling Cost Comparison
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Operating Cooling Cost Comparison
Operating Cooling Cost Comparison
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High Efficiency RTU w/ SAV Product Design Strategy
Benefits - Saves Energy
- Greater Comfort
- Better Match, Typical Building Profiles
- Greater IEER’s
- Simple Design
Typical office – Memphis TN Sizes 07-09 use two speed indoor fan motor, all other use three speed
SAVTM SYSTEM DESIGN Key components (DDC Controls) Unit Internal Components Belimo Economizer Actuator (if installed) Space Sensor (Field Central Terminal Provided) Board (CTB)
RTU Open Controller
Fan Relay Inverter Variable Frequency Board Duty Rated Drive (VFD) Motor
Designed factory logic automatically adjusts fan speed
VFD is factory programmed for 67% and 100%
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SAVTM SYSTEM DESIGN Key components (electro-mechanical unit) Unit Internal Components Central Terminal Honeywell W7220 Honeywell MS3103 Board (CTB) Economizer Controller Economizer Actuator (if installed) (if installed)
Thermostat (Field Provided)
Inverter Fan Relay Variable Frequency Duty Rated Board Drive (VFD) Motor
Designed factory logic automatically adjusts fan speed
VFD is factory programmed for 67% and 100%
Compatible Economizer for SAV
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ECONOMIZER IMPACT Why TWO minimum economizer positions? FullLow SpeedSpeed (100%)(67%) Blower:Blower Blower: withoutwith adaptive adaptive economizer economizer operation: operation: 40002680 CFM SA (now(67%),(100%) 67%) economizerwith 800 CFM atopens originalOA ventilationmore, position, Æ now (20% now ventilation SA) ventilating back 520 to CFM 800 CFM
Blower 100%67% Evaporator 67% 100% Notice the change in ventilation airflow
100% without an adaptive 67% economizer Entering Assumptions: 10 ton 2-speed fan unit with 400 CFM/ton (4000 CFM SA) 800 CFM ventilation requirement (20% SA)
Choices for SAV
New RTUs Retro-fit Kits • Carrier/Bryant • CATALYST • Daikin/McQuay • Enerfit • Lennox • Digi-RTU • Trane
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Carrier WeatherExpert vs McQuay Rebel™ - Efficiency
Gas Heat / Electric Cooling Models SEER or IEER (depending on SEER size)
Ton Size
Carrier from product catalogs (April 2012 and March 2013) McQuay from catalog 256-6 (March 2013) and website (Jan 2014) Lennox data not published with SAV included in IEER Trane data not available
Items to Consider When Choosing
• Is the RTU or Retrofit kit available with adaptive integrated economizer control (aka dual minimum setpoints) to ensure minimum ventilation rate is not impacted?
• Is knowledge of a specific brand of DDC controls required?
• Is the SAV option available on their high-end and entry level units or must you get all the bells and whistles just to get SAV?
• Are other advanced options, such as ERV or dehumidification systems available on the same RTU?
• Is VFD field programming required or is it factory set?
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The CATALYST is a complete retrofit solution for existing RTUs
¾Adds 4‐5 new sensors and a variable frequency drive. ¾Provides CO2‐based demand control ventilation ¾Advanced economization control sequence. ¾Variable speed supply fan control ¾Remote web‐based communications via smart phone, tablet, or browser.
The CATALYST is a complete retrofit solution for existing RTUs
¾Proven track record of reducing overall energy use by 25%‐50% ¾Maintains comfort & IAQ ¾Automatic air flow adjustments to protect equipment. ¾Solves Power Exhaust problem ¾Upgrade option replaces thermostats with Tridium BMS control via the web. ¾Demand‐Response capable
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Constant Volume RTUs
The Most Potential:
¾ Units 5‐tons and up ¾ 1 hp fan motors and up ¾ All brands and ages ¾ Fan‐only = OK
The CATALYST is delivered as a complete retrofit “kit”
Other 46% Packaged Units 54%
Pre‐engineered, pre‐programmed, and can be installed in only a few hours. Produces a repeatable and scalable process with predictable results.
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Energy Savings Strategies
Integrated Economizer with Differential Changeover Control
Variable Speed Fan Control to Match the Needs of the Space Served
Elimination of Over‐Ventilation via Demand Control Ventilation (DCV)
Remediation of Service and Operational Issues
ECONOMIZER PERFORMANCE VERIFICATION
Fault detection monitors for numerous conditions including economizer damper failure and sensor failures.
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CATALYST Service Switch
• A multi‐position selectable switch for service personnel use. This will enable techs to operate the system in any mode of operation for maintenance purposes. Other 46% • The use of the service switchPackaged will suppress data collection byUnits the eIQ 54% Platform to avoid negative impact on fault detection and analytics.
Empowers contractors to easily perform preventative maintenance and verify economizer functions without undermining the CATALYST installation.
Department of Energy
New study by PNNL shows CATALYST saved an average energy savings of 57% on 66 RTUs across 4 US climate zones.
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Department of Energy
The DOE chose to work with Transformative Wave’s CATALYST based on “its features & product maturity”
RTU EFFICIENCY STRATEGY
1 2 3 optimize upgrade perpetuate
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Performance Monitoring Visual Fault Reporting Perpetual Trending Fault Prioritization Icon‐based Status Indications Demand Management Remote Troubleshooting Unit sub‐metering Outlier Identification Predictive Maintenance Life Cycle Extension Advanced Fault Detection and Diagnostic Routines Portfolio Energy & Performance Management HVAC Asset Management Tools
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This screenshot from the eIQ summary view of the store shows the various aspects of the eIQ web interface that can be customized for each client. Humidity is controlled based on dew point. Lower fan speed allows for more effective dehumidification by the HVAC system.
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Fault Detection has identified fan belts slipping on Units 1‐3. Humidity has historically been an issue at this store during the “monsoon” season. The CATALYST supermarket control sequence has enabled us to get the store humidity issues under control.
The CATALYST has a four‐year track record of proven results.
The product is mature and fully commercialized with almost 1,000 installations.
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Department of Energy
The CATALYST is the basis for the inclusion of RTU retrofit in the recently announced ADVANCED RTU CAMPAIGN
www.advancedrtu.org
The Retrofit That Makes Your HVAC Unit Energy Fit
Retrofit, Don’t ® Replace
Patented 2011
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WHAT IS ENERFIT?
Enerfit is a patented retrofit system for single zone HVAC units.
Using a customized set of hardware, controls and logic, it dynamically scales the electrical and mechanical capacity of generally oversized HVAC units to yield massive energy savings and increase user comfort.
ENERFIT what’s in the box?
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ENERFIT COMPONENTS
Enerfit Controller VFD Enerfit Face Damper (Variable Frequency Drive) (Used with face split DX Coils)
ENERFIT COMES IN 3 DIFFERENT VERSIONS:
VERSION 1 (V1) operates in conjunction with your V existing HVAC unit controls or thermostat. It monitors heating and cooling calls from the unit 1 controller or thermostat and integrates them into the Enerfit control logic.
VERSION 2 (V2) is a complete direct digital control V system. It can operate as a standalone controller for your unit or as open-protocol BACnet HVAC unit 2 controller.
Version 2 can operate in conjunction with the factory RTU controls or replace them entirely (V2 BACdrop).
VERSION 3 (V3) works with chilled water systems V3 and allows installers to use the same board, plugs and service tools that work with the DX rooftop & split systems.
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ENERFIT COMES IN 3 DIFFERENT VERSIONS:
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ENERFIT COMES IN 3 DIFFERENT VERSIONS:
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ENERFIT FACE DAMPER Enerfit addresses the differences in the two primary evaporator coil circuiting schemes:
INTERLACED & FACE-SPLIT
EVAPORATOR COILS: INTERLACED
CIRCUIT 2 NO DIVIDER COMPRESSOR 2
COMPRESSOR 1
FRONT/BACK VIEW SIDE VIEW
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EVAPORATOR COILS: FACE-SPLIT
TOP COIL
CIRCUIT 2 DIVIDER COMPRESSOR 2
CIRCUIT 1 COMPRESSOR 1
BOTTOM COIL
FRONT/BACK VIEW SIDE VIEW
ENERFIT: what does it do?
IMPROVES COMFORT
• Passive dehumidification
• Reduces drafts
• Reduces air noise 2 • Controls CO levels
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ENERFIT: what does it do? CASE STUDY: SPACE RELATIVE HUMIDITY
ENERFIT: what does it do?
REDUCES MAINTENANCE COSTS
• Reduces belt wear & tightening frequency
• Extends lubrication intervals
• Lowers filter change frequency
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ENERFIT: what does it do?
EXTENDS UNIT LIFE
• Eliminates starting torque on fan and motor bearings
• Improves compressor motor cooling
• VFD adds safety protection for entire unit
ENERFIT how do you service it?
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ENERFIT EMT (ENERFIT MONITORING TOOL)
Every job site comes standard with an EMT. It was designed to be a quick and simple way to find out what’s going on not only with Enerfit - but also the unit - in real time.
Connecting an EMT should be the first step to troubleshooting any Enerfit installation. It connects to the Enerfit controller and gives read-only access to over 20 different control points and alarm codes.
ENERFIT EMT (ENERFIT MONITORING TOOL) It connects to the Controller Enclosure and does not require the technician to unscrew the controller lid.
Point Details and Units are printed on back of EMT lid flap for easy EXTERNAL reference. RJ45 JACK
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SUMMARY: HOW DOES ENERFIT REDUCE OPERATING COSTS?
Reduces Reduces Extends Improves HVAC maintenance the life of comfort operating cost your unit cost
SUMMARY: HOW DOES ENERFIT REDUCE OPERATING COSTS?
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Compressor Capacity Control
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Capacity Control Options for DX RTUs
• On/Off – single fixed speed compressor • Multiple, staged compressors – Saves energy – Improves humidity control – Cannot be retrofitted
Unloaders
• Reciprocating compressors only • Saves some energy • Improves humidity control • Can be easily retro-fitted • Pressure unloaders vs. electric unloaders
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Hot Gas Bypass (HGB)
• Improves humidity control • Can be retro-fitted
APR Control – Rawal Devices
• Improves humidity control • Can be retro-fitted • Uses about 12% less energy than standard HGBP
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Copeland Digital Scroll
• Modulates compressor capacity output from 10 to 100% • Improves humidity control • Can be retro-fitted, but not easily • Uses about 30% less annual energy than standard HGBP
Variable Speed
• Scroll, rotary, screw, or centrifugal type compressors • Modulates compressor capacity output from 20 to 100% • Improves humidity control • Can be retro-fitted, but not easily • May use less energy than Digital Scroll
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Final Thoughts & Additional Resources
Cumulative Savings…
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Cumulative Savings…
Occupancy Sensors
• Motion & Thermal Detectors – Control lights – Relax HVAC setpoints • Security system interlock – Swipe out of building with key fob and automatically turns off lights in your office and relaxes HVAC setpoints • Light activated thermostats – Control HVAC when lights on – Payback less than 3 months • Operable window and door interlock – Disables zone heat/cool/vent
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Building Automation Systems
• Centralized controls • Change scheduling for multiple HVAC units at same time • Monitor “health” of equipment • Internet accessible • Alarming via text msg or email • Collect/trend data • Integrate to lighting control or security system
“Right Sizing” Equipment
• On average building fan systems in the US are oversized by 60%* • Most chillers are oversized by 50 to 200%** • Spend < 1% of operation at full load – Don’t add “safety factors” when sizing or selecting • Better dehumidification – Smaller equipment will dehum better allowing higher cooling setpoints • Less temperature swings – Equipment runs even cycles instead of rapid on…off…on… • Lower first cost – Smaller is better
*John Hopkins Univ. AICGS Policy Report **US EPA Report “Good Energy Management is Good Business”
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Worker Productivity Costs MORE than Energy
Pie charts: ASHRAE Journal July 2013 Table: U.S. Department of Energy July 2002
Supporting Documents Available
• Advanced Rooftop Control (ARC) Retrofit: Field-Test Results – Pacific Northwest National Labs (July 2013) • Single-Zone VAV Performance Evaluation – Quest Energy Group (Feb. 2010) • Energy Savings and Economics for Advanced Control Strategies for Pakcaged AC Units with Gas Heat – Pacific Northwest National Labs (Dec. 2011) • Staged Air Volume System – 2-Speed Fan Control Strategy for Packaged RTUs – Carrier Corp. (March 2012)
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Supporting Documents Available
• Identifying Energy Savings Potential on Rooftop Commercial Units – Ecotope, Inc. & Eugene Water & Electric Board • How People Actually Use Thermostats – Lawrence Berkley National Labs (2010) • Unique Approach to Part Load Operation and Energy Savings for Unitary Applications – Carrier Corp. (May 2010) • Understanding Single Zone VAV Systems – Trane (April 2013) • Review of Commercial RTU Field Studies in the Pacific NW and CA – New Buildings Institute (Oct. 2004)
Resources
• ASHRAE 90.1 – Updated every 3 years – Specifies minimum energy performance for new buildings – www.ashrae.org • International Energy Conservation Code (IEEC) – www.iccsafe.org • Advanced RTU Campaign – New effort to promote RTU efficiency – Tools, calculators, webinars, etc. – www.advancedrtu.org
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Resources • ASHRAE Advanced Energy Design Guides – Prescriptive approach by climate zone – 30% Guides • Save 30% more energy than ASHRAE 90.1-1999 • 6 versions published: Office, Retail, School, Warehouse, Hotel, Healthcare – 50% Guides • Save 50% more energy than ASHRAE 90.1-2004 • 4 versions published: Office, Retail, School, Hospital – Free download at www.ashrae.org/aedg
Resources
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Ryan R. Hoger, LEED AP 708.670.6383 [email protected]
Special Thanks to those who allowed me to use their slides or graphics today…
Ryan R. Hoger, LEED AP 708.670.6383 [email protected]
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