Best HVAC Maintenance and Control Practices
Best HVAC Maintenance and Control Practices October 30, 2009 Ryan Stroupe
Training Objectives •
9:00 Best HVAC Maintenance and Control Practices, – – – – –
• •
10:30 Break 10:45 Best HVAC Maintenance and Control Practices, continued – – – – –
•
Best practice goals for HVAC Retrofits for energy efficiency Optimal control strategies Understanding sequences of operation Questions
Maintenance opportunities Diagnostics and monitoring devices Mystery graphs Role of building commissioning Questions
12:00 Lunch
1
Where Does the Energy Go? • 2005 Building Energy Outlook-USDOE • Annual Energy Outlook 2003-USDOE • BOMA Data
2003 U.S. Commercial Buildings
http://www.boma.org/
• PG&E Commercial Building Surveys
http://www.pge.com/biz/energy_tools_resources/ building_survey/index.html
CA-Electric Usage by End Use
2
CA-Natural Gas Usage by End Use
Load Profiles, Peak Demand and Rates P a r t i a l
60000
P e a k
P e a k
P a r t i a l
P e a k
Megawatts
50000
40000
30000
20000
10000
0
12:00 AM
6:00 AM
12:00 PM
6:00 PM
12:00 AM
Consider that utility rates vary by time of day and year
3
End Use Loads on 2003 Peak Day Exterior Lighting 1%
Domestic Hot Water 1% Office Equipment 2% Refrigeration 5% Ventilation 10%
Cooking 1%
Air Conditioning 32%
Other 18%
Interior Lighting 30%
3 Hour Peak
End Use Loads for California Commercial Sector on 2003 Peak Day
Gigawatts/Hour
Energy Intensity by Building Type Grocery stores and food service have higher end use intensities (kWh/sf) than any other common commercial building type.
Source: 1999 Commercial Building Energy Consumption Survey (CBECS), U.S. DOE, www.eia.doe.gov.
4
Small Office Miscellaneous
Air Compressors 1%
Motors 1%
0.1%
Heating 2%
Miscellaneous 7%
0.1%
Process 0.4%
Water Heating 6.9%
Cooling 18%
Exterior Lighting 5%
Cooking
Office Equipment 21%
Ventilation 11%
Water Heating 1%
Heating
Cooking 0%
92.5%
Refrigeration 4% Interior Lighting 29%
Electric
Natural Gas
Grocery Store Miscellaneous 3% Exterior Lighting 2% Office Equipment
Motors 0%
1%
Cooling 5%
Ventilation 6% Water Heating 0% Cooking
Interior Lighting
5%
20%
Cooking 28% Heating 42%
Water Heating 30%
Refrigeration
Electric
58%
Natural Gas
5
School Air Compressors Miscellaneous 3.8%
0.1% Motors 1.5%
Heating 1.6%
Cooking
Cooling
6%
12.2%
Exterior Lighting
Miscellaneous 0%
10.7%
Office Equipment 5.3%
Ventilation
Water Heating
13.5%
24%
Water Heating 0.9%
Heating
Cooking
Cooling
3.2%
1%
69%
Refrigeration 7.0% Interior Lighting 40.1%
Electric
Natural Gas
Approach to Efficient HVAC • First step is energy conservation through reduced building loads (envelope and interior) • Second step is through selection of efficient equipment to meet loads • Third step is operating equipment and systems only as required to meet intents • Fourth step is maintenance to maintain efficiency
6
Building Loads • Heat Losses – Conduction at envelope – Infiltration at envelope
• Heat Gains – – – – – –
Conduction at envelope Infiltration at envelope Solar gain through glass Lighting Equipment People
• Units: BTU/hr
Load Control
7
Cool Roofing Desired attributes – High solar reflectance – High far IR emissivity
Donald watson - editor. Time-saver standards for Architectural Design Data. McGraw Hill, 1997. Pg. B-254.
Images courtesy of NREL Craig Miller Productions and DOE
Cooling Efficiency • Capacity = Tons 1 Ton of Cooling = 12,000 BTU/hr Note: this is a rate – not a quantity • COP – Coefficient of Performance = (What you get) / (What you pay for) Higher COP is better • kW/ton kW input / (Tons of refrigeration out) Lower kW/ton is better • Energy Efficiency Ratio (EER) (BTU/hr Cooling Out) / (Watts In) Higher EER is better • Seasonal Energy Efficiency Ratio (SEER) (BTU/hr Cooling Out) / (Watts In)
8
Heating Efficiency • Capacity = BTU/hr • Annual Fuel Utilization Efficiency (AFUE) Used for boilers and furnaces BTU-out/BTU-in Higher AFUE is better • Heating Season Performance Factor (HSPF) Seasonal heat output of heat pump in BTU / total electric energy input Higher HSPF is better • Energy Factor (EF) Used for water heaters Hot water produced per unit of fuel consumed Higher EF is better
Motor, Fan and Pump Efficiency • Output/Input • Measured as a percentage • Motor – Input electrical power – Output is mechanical power
• Fan – Input is mechanical power – Output is airflow (CFM) and pressure (in H2O)
• Pump
– Input is mechanical power – Output is liquid flow (GPM) and pressure (ft H2O)
9
CA Title 20 Standards for Single Phase Air-Cooled Air Conditioners with Cooling Capacity Less than 65,000 Btu per Hour and Single Phase AirSource Heat Pumps with Cooling Capacity Less than 65,000 Btu per Hour, Not Subject to EPAct
What to specify: Rooftop / Split
© 2008 Consortium for Energy Efficiency, Inc. All rights reserved. www.cee1.org
Energy Audits
10
Mechanical System Efficiency 25
Energy Efficiency Ratio
20
15
10
5
0 C e n tri fu gal & S cre w C h i l l e rs
Pack age d AC
Ai r C ool e d He at Pu m p
Re ci procati n g C h i l l e rs
Grou n dsou rce h e at pu m ps
Data from Global Green USA 2001
Randall Thomas. Environmental Design, An Introduction for Architects and Engineers. E&FN Spon, 1996. Pg. 112.
Chiller Options for Efficiency • Look at chilled water system as a whole, not as individual parts • High Efficiency = low kW/ton • Ability to run with low condenser water temperatures • VFDs to modulate at part loads • “Free cooling” economizer operation (turns off compressor & uses only condenser water to cool chilled water) www.commercial.carrier.com
2007
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11
Chilled Water System EEMs • Pump Scheduling & Proper Interlocking • Variable Flow Chilled Water Distribution • Variable Speed Cooling Tower Fans • Optimized Condenser Water Setpoint • Variable Flow Condenser Water Distribution • Chilled Water Temperature Resets • Drive-line retrofit • Replacement • Lots, lots, more!!!
2007
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Chillers - Replacement • Longish payback • Eliminates refrigerant phase-out issues • If replacement is needed, very costeffective to spec VSD • Match chiller to actual load not design load (especially in multiple chiller plant) 2007
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12
Cooling Towers • Run fans in parallel (VFDs) • Reduce condenser water setpoint (but perhaps not all the way) • Install water-side economizer (if oversized) • Regular Maintenance
2007
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Water Side Economizer • Utilize “free” cooling during cold weather • Heat exchanger transfers heat directly from chilled water to condenser water • Eliminates chiller power • Can extend use by – Lower condenser water setpoint (i.e. running tower harder) – Running with higher chilled water temperature
13
Rooftop Equipment Identification • Packaged Unit – All components contained in on location – Ventilation is introduced through the unit – Heating is supplied by a gas furnace, heat pump, electric resistance or a hot water coil
• Split-System – Compressor Component Only – No ventilation provided by unit – Only heating is heat pump http://www.carrier.com
2007
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Energy Efficiency Measures (EEMs) • Retrofits
– Evaporative Cooling – High Efficiency Units – VFD’s
• Controls – – – –
Scheduling / reduce operating hours Programmable thermostats Economizer operation Demand control ventilation
www.carrier.com
• Demand Response • Operations
– Reduce cooling loads – Keep units maintained
2007
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14
High Efficiency Replacements • Package unit replacement isn’t generally cost effective on energy savings alone • So where are the opportunities? – Older units – Early retirement – New additions
• How do we promote it? – Comfort – Reliability – Reduced O&M Costs
2007
www.trane.com
Energy Audits
29
What to specify: Heat pumps • For larger units, use Consortium for Energy Efficiency (CEE) guidelines (www.cee1.org) • Specify Tier 2 or 3 Efficiency level
www.trane.com
2007
30
15
Ground-source Heat Pumps
Geothermal Heat Pump Consortium, Inc. http://geoexchange.us/illustrations/graphics.htm
• AKA
• • • • •
– Geothermal – Ground-water source – Geo-exchange
Uses earth/groundwater for heat sink Cooling mode: rejects heat to ground Heating mode: absorbs heat from ground Efficiency depends ground temperatures Size ranges from residential to large commercial systems • Best applicability: Climates where ground temperatures offer significantly better efficiency over air source • Title 20 Sets minimum standards by size 2007
31
Ground Source Heat Pumps
16
Evaporative Cooling
Evaporative Cooling/Pre-Cooling • Cools air via evaporation of water • Direct evaporative cooling increases humidity • Indirect evaporative cooling is less effective, but does not increase humidity • Evaporative pre-cooling reduces the temperature of air entering the condenser
http://www.muntersamerica.com/
17
Evaporative Cooling
• Direct evaporative coolers draw air through evaporative media lowering the temperature and increasing humidity • Indirect evaporative coolers use a heat exchanger to reduce the air temperature without increasing humidity
Direct Evaporative Cooler www.muntersamerica.com
2007
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Direct Evaporative Cooling
18
Indirect/Direct Evaporative Cooling
http://www.wescorhvac.com/
Evaporative Pre-cooler Details
19
Evaporative Pre-Cooling D inin g U nit 1 E va porative C ond en s er P e rform a nc e
85
Temperature exiting media (F)
80
75
70
65
60
55 55
60
65
70
75
80
85
90
95
10 0
T e m p e ra tu re e n te rin g m e d ia (F )
Evaporative Pre-Cooling D aily E n erg y U sag e fo r D in in g U n it 1 80.0
HD1-E vap Cooler
70.0
HD1
y = 1.9524x - 106.37 R 2 = 0.9762
Linear (HD1-E vap Cooler) Linear (HD1)
Daily Energy Consumption (kWh)
60.0
50.0 y = 1.4888x - 75.758 R 2 = 0.9542 40.0
30.0
20.0
10.0
0.0 65.0
70.0
75.0
80.0
85.0
90.0
95.0
Ave ra ge Am bie nt Dry Bulb Te m pe ra ture be tw e e n 6 a .m . a nd m idnight
2007
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20
Furnaces
JMK
• Furnaces heat air through heat exchange with combustion gases • Rating is Annual Fuel Utilization Efficiency or AFUE • Typical ratings from 80% to 96% AFUE • Condensing Furnaces achieve higher end of efficiencies en.wikipedia.org/wiki/Furnace
Boilers • Types – Hot water (Will have circulation pump) – Steam: Low, Medium & High Pressure (May have condensate return pump) – Atmospheric and forced draft – Fire-tube and water-tube
• Nameplate – Input/Output (MMBtu) – Combustion fan information – Pump size (for boilers with integrated pump) – National Board number
http://www.raypak.com/
21
Slide 41 JMK1
This work is in the public domain in the United States because it is a work of the United States Federal Government under the terms of Title 17, Chapter 1, Section 105 of the US Code. Jim Kelsey, 1/30/2007
Automatic Stack Damper
Instantaneous DHW Implementation • Pitfalls – Spendy! – Requires greater capacity (Btuh) to meet same load
• Savings – Range of 5% to 20% (depends on volume, age of existing) – Find by comparing energy factor
• Non-energy Benefits – Never run out of hot water – Less space/weight required – May help reduce time to get hot water
www.noritz.com
22
Motor Efficiencies (Premium Efficiency) • Compile Inventory of
motors • “High Efficiency” and Premium Efficiency are not equal • Stock premium efficient motors if possible • Take advantage of Incentives and Rebates
Standard (EPAct 1992) and Premium Efficiency Motor Ratings 1200 RPM HP
1 1.5 2 3 5 7.5 10 15 20 25 30 40 50 60 75 100 125 150 200
EPACT (Standard)
80.0% 84.0% 85.5% 86.5% 87.5% 88.5% 90.2% 90.2% 91.0% 91.7% 92.4% 93.0% 93.0% 93.6% 93.6% 94.1% 94.1% 94.5% 94.5%
NEMA Premium Efficiency
82.5% 86.5% 87.5% 88.5% 89.5% 90.2% 91.7% 91.7% 92.4% 93.0% 93.6% 94.1% 94.1% 94.5% 94.5% 95.0% 95.0% 95.4% 95.4%
Open Drip Proof (ODP) 1800 RPM NEMA Premium Efficiency
EPACT (Standard)
82.5% 84.0% 84.0% 86.5% 87.5% 88.5% 89.5% 91.0% 91.0% 91.7% 92.4% 93.0% 93.0% 93.6% 94.1% 94.1% 94.5% 95.0% 95.0%
3600 RPM
EPACT (Standard)
NEMA Premium Efficiency
85.5% n/a 86.5% 82.5% 86.5% 84.0% 89.5% 84.0% 89.5% 85.5% 91.0% 87.5% 91.7% 88.5% 93.0% 89.5% 93.0% 90.2% 93.6% 91.0% 94.1% 91.0% 94.1% 91.7% 94.5% 92.4% 95.0% 93.0% 95.0% 93.0% 95.4% 93.0% 95.4% 93.6% 95.8% 93.6% 95.8% 94.5%
77.0% 84.0% 85.5% 85.5% 86.5% 88.5% 89.5% 90.2% 91.0% 91.7% 91.7% 92.4% 93.0% 93.6% 93.6% 93.6% 94.1% 94.1% 95.0%
Relative Motor Efficiencies By Size ODP Motor Efficiencies 100.0%
Efficiency
95.0% 90.0% 85.0% 80.0% 75.0% 0
50
100
150
200
250
HP Existing
EPACT
NEMA Premium Efficiency
TEFC Motor Efficiencies 100.0% 95.0% Efficiency
• Motor Efficiencies tend to increase with motor size • EPACT is the Energy Policy Act of 1992 which established what we now consider “Standard” efficiency motors • National Electrical Manufacturers Association (NEMA) premium efficiency motors tend to be 1 to 2 percent higher than EPACT motor efficiencies
90.0% 85.0% 80.0% 75.0% 0
50
100
150
200
250
HP Existing
EPACT
NEMA Premium Efficiency
23
Benefits of Efficient Motors • Save energy, save $ – Benefit improves with higher utility rates
• Save demand, save $ – Benefit improves with higher demand costs
• Higher power factors, save $ – Benefit improves with PF charge at facilities with PF < 0.85
• Runs cooler, save energy, save $ – Benefit improves at facilities that are cooled
• Withstand voltage fluctuations and harmonics – Benefit important at facilities with old infrastructure – Benefit important at facilities with non-sinusoidal load types
• Operate quietly – Benefit important at most facilities Efficient Motors: Selection and Application Considerations, Consortium for Energy Efficiency, 1999
Efficient Evaporator Fan Motors
GE Industrial Systems
• New motors are “electrically commutated” a.k.a. “ECM” • Old types are shaded pole or permanent split capacitor (PSC) types • Applications: refrigerated cases, walk-in coolers and freezers
www.GEindustrial.com/ecm
24
Efficient Evaporator Fan Motors
VFD’s for Fans • Many systems use variable flow air distribution • Fan power laws dictate that power is roughly proportional to the flow rate cubed • VFD quality/reliability have improved greatly over time • VFD costs have dropped significantly with wider adoption • Now required by code for many applications in new construction
www.abb.com
2007
50
25
Why fans with VFD’s Save Energy
This relationships between fan energy and fan flow are taken from the California Energy Commission Guide to Preparing Feasibility Studies and the 1998 Nonresidential ACM Approval Manual. Note that a typical system curve, DOE2 default, is assumed and these relationships are not applicable to all systems.
2007
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Control Measures • On/off • Setbacks • Demand Control Ventilation • Lock-outs • Resets • Economizers
2007
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HVAC Controls • Basic control is the thermostat • For complex systems, monitor many control points: air temperature, pressure, fan speeds, etc. • Central computer control is called Building Management System • HVAC without controls is like lighting without switches
The Opportunity: Controls General Concepts • Controls are generally the most cost effective of EEMs • Whatever doesn’t have controls probably needs it • Controls reduce opportunity for human “enhancements” • Limit hours of operation • Use to maximize system efficiencies 2007
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Scheduling
• Mechanical Time Clocks • Consider Twist Timers to reduce usage during off-hours
www.tork.com
www.tork.com
• Some have seasonal / astronomical timers and/or multiple channels 2007
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Setbacks and Programmable Thermostats • Install Programmable Thermostats on all units
www.white-rodgers.com
2007
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Setback Thermostats / Scheduling • Pitfalls – Need to be set correctly, not in “hold” mode – Persistence: document with a system manual how things are intended to work
• Savings – Range widely depending on occupancy and use. Typical is 5% to 50%. – Demand savings are minimal
• Non-Energy Benefits – Reduced wear on equipment
www.white-rodgers.com
Energy Audits
57
Web-enabled Thermostats • Web-based now available • About $250 to $400 each • Include ability to monitor remotely
www.proliphixstore.com
2007
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Space Temperature Setbacks Room tem perature
85
80
75
70
65
60
55
50 8/29
8/30
8/31
9/1
9/2
9/3
9/4
9/5
9/6
9/7
9/8
9/9
9/10
Controls: Lockouts • A lockout is turning a piece of equipment off when a control condition is met • Example lockouts: – Chiller lockout based on outside air temp (and associated CHW pumps, CW pumps) – Boiler lockout based on outside air temp (and associated HHW pumps)
• Lockouts are simple, cheap, effective
30
Controls: Resets A reset is creating a variable setpoint control based on a monitored condition HHW OAT Reset 200
OAT
HHW
65
140
50
180
HHW Setpoint [°F]
190 180 170
OAT = Outside Air Temperature
160
HHW = Heating Hot Water Temperature
150 140 130 120 20
40
60
80
OAT [°F]
Economizers • The economizer cycle refers to using controls and dampers to make use of outside air for “free” cooling when it makes sense • Controls used to bring in outside air instead of return air • An “economizer” is generally not a single piece of equipment, although people may refer to it as such Return Air Exhaust Air
Outside Air
COLD
HOT
62
31
Air-Side Economizer • Damper Control • 100% Free Cooling (ex: OA
P
NO
SR
C NO
P
RA
C
SR
AF=0, NC=C
3-13 Psi
UNOCC, NC=C
SP O O R
28 OA
NO NC
O
OH CALC O I y=mx+b
OA
0%
OA>RAT or OAE>28, NO=C P
I IF >
TC
NC
SP O
EA
RA RESET
20
CO2
5
800
1000
45
Develop a Sequence of Operation for Fan Coil Unit
Operations & Maintenance Assuring equipment is operating properly
46
www.energy.ca.gov/pier PIER Buildings Program Design Guide: Big Savings on Small HVAC Systems
Small HVAC: Frequent Issues
93
Operations and Maintenance • • • • • •
Commissioning: Check Set points, Schedules and Resets Check for controls overrides (e.g. bypassed VFDs) Filter Changes for IAQ Check Fixed Damper and Minimum Damper Positions Adjust/tighten/replace belts Lubricate rotary equipment
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Operations and Maintenance (cont.) • • • • • • •
Clean condenser coils Clean evaporator coils Insulate suction lines Check refrigerant charge Check thermostat/sensor calibration Insulate/seal ductwork Eliminate flex duct
2007
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O&M Issues
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What are Dataloggers? • What they do – Measure – Record
• What they include – – – – – – – – – –
Receive signal from sensor or transducer Analog-to-digital converter Data sampling rate Data storage rate Memory (stores readings) Internal clock Programming and data retrieval software Computer interface Microprocessor Power supply
Honeywell Service Assistant Faults detected: 1. 2. 3. 4. 5.
Low pumping efficiency High side heat transfer problem Low side heat transfer problem Fan speed too high Restricted refrigerant flow through the small orifice 6. Too little charge 7. Too much charge 8. Charge contaminated with non-condensables
49
Drywell Bath • Used for in-situ sensor calibration • Temperature maintained for calibration): 14° to 251° F (± 0.9° F) • Kit includes 1/16", 1/4", 3/16" and 1/2" removable inserts
Measuring Airflow • • • • • •
Anemometers DP sensors Pitot tubes Velgrid Flow hoods Duct blasters
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Gas Efficiencies • Thermal: Steady State measure of the units ability to transfer heat to the water. • Combustion: Efficiency of the fuel burning process. Depends on fuel mix as measured with a combustion analyzer. • AFUE: Annual Fuel Utilization Efficiency. Similar to a SEER, rated for average seasonal conditions. • Standby Loss: A measure of the relative amount of heat that the unit will lose to the environment
Efficiency as Make-up Air Varies
http://www.engineeringtoolbox.com/boiler-combustion-efficiency-d_271.html
51
Mystery Graph #1 75
F degrees
70
65
60
55 6/17/00 0:00
6/17/00 12:00
6/18/00 0:00
The graph above is showing temperature. It represents: 1. interior temperature in an enclosed office building 2. outside air temperature over a year 3. outside air temperature over a day 4. the temperature at a light fixture 5. chilled water supply temperature
Mystery Graph #2 Mystery Graph 2 100
Three inter-related parameters
90
80
70
60
50
40 08/12/04 12:00 AM
08/12/04 03:00 AM
08/12/04 06:00 AM
08/12/04 09:00 AM
08/12/04 12:00 PM
08/12/04 03:00 PM
08/12/04 06:00 PM
08/12/04 09:00 PM
08/13/04 12:00 AM
Date
The graph at right shows three inter-related parameters. They are… 1. outside air, mixed air and supply air temperatures at an air handler 2. annual electricity, natural gas and water use 3. space temperature, air flow and damper position for a working VAV box 4. temperature, relative humidity and dew point of air 5. chilled water flow, chilled water supply temperature and condenser water supply temperature for an optimized chiller
52
Mystery Graph #3 The three variables illustrated in the graph depicted here are?
a. outside air, mixed air and return air temperatures at an air handler with an economizer b. daily electricity, natural gas and water use. c. space temperature, air flow and damper position for a working VAV box.
d. temperature, relative humidity and dew point of an air volume. e. chilled water flow, chilled water supply temperature and condenser water supply temperature for an optimized chiller.
Mystery Graph #4 Mystery Graph
120
Temperature, °F
110
100
90
80
70
60 5/20/05 12:00 PM
5/21/05 12:00 AM
5/21/05 12:00 PM
5/22/05 12:00 AM
5/22/05 12:00 PM
5/23/05 12:00 AM
5/23/05 12:00 PM
5/24/05 12:00 AM
Date and time
What does the temperature data above indicate? 1. temperature in a space with evening setbacks 2. the temperature at a chair indicating occupancy 3. condenser water temperature at a chip fabrication facility (with night shutdown shown) 4. the temperature in a refrigerated warehouse with a regular evening stocking crew 5. the scheduled operation of a motor
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140
Mystery Graph #5
120
100
80
60
40
20
0
12:00 AM
6:00 AM
12:00 PM
6:00 PM
12:00 AM
What does the data above represent? 1. percent speed for a VFD-controlled fan in a retail space 2. the power draw of a chiller connected to thermal storage 3. solar radiation in San Francisco on a foggy day 4. an erratic control valve for chilled water flow in an office building 5. the lighting energy use at a quickie-mart
Mystery Graph 6 1200 1000
ppm
800
The data shown to the right is an indication of which condition?
600 400 200 0 6/28/02 12:00 AM
a. Total dissolved solids in condenser water for a cooling tower. b. Volatile organic compounds (VOC) levels during construction of an office building.
6/28/02 12:00 PM
6/29/02 12:00 AM
6/29/02 12:00 PM
6/30/02 12:00 AM
6/30/02 12:00 PM
7/1/02 12:00 AM
c. CO levels in a parking garage. d. CO2 levels in the open office area of a law office. e. CO2 levels in a movie theater.
54
Mystery Issue #7
What obvious visible indicator is shown in the image? 1. a throttled valve on the discharge of the pump 2. a strainer in need of cleaning 3. a section of pipe with inadequate insulation 4. a valve missing an actuator 5. a missing pressure gauge
What Is Building Commissioning? Commissioning is a quality assurance strategy. Commissioning is a systematic process of ensuring that all building systems perform interactively according to the contract documents, the design intent and the building owner’s operational needs.
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Why Commission? • • • • • • • • • • •
Owners do not typically receive fully functional building systems Owners face increasing numbers of performance problems Buildings have more complex life safety, security, communication, and comfort control systems Building systems are becoming increasingly specialized and integrated Many problems are masked by energy-wasting process Multiple trades and contracts are involved (fragmentation) Conflicting loyalties and objectives Increasing costs (change orders, call backs) Emphasis on fast track Design fees do not reflect reality Requirements – LEED, CHPS, Title 24
Commissioning is Quality Assurance • A coordination process to optimize building performance (comfort, reliability, safety, energy) • Articulating/verifying energy-related design intent • Construction observation; warranty enforcement • Controlling first cost • Training operators • Enhancing safety and risk management • Creating more cohesion among team members
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A Common Industry Perspective; Commissioning; A Bandage for a Broken Process
An Emergency Response • Treating the wound • Add-on process • Last-ditch effort – Resurrect quality – Identify deficiencies – Force accountability
Images courtesy www.talkingproud.us
Building problems (a.k.a. “deficiencies”) are pervasive – These include Design flaws; Construction defects;
Malfunctioning equipment; Deferred maintenance
EXISTING BUILDINGS
NEW CONSTRUCTION
Simultaneous heating+cooling
Oversized equipment
Mis-sized valves/dampers, chillers
Unnecessary components (valves)
Low-quality or clogged filters
Construction debris blocking ventilation
VFD or economizer overridden/stuck
Specified equipment not installed
Dumb alarms (false; ignored)
Wrong set points or control sequences
Circuitous duct or piping runs
Wrong sensors (inappropriate sensitivity)
Bad or inaccurate sensors
Improper startup (e.g. daylighting sensors)
Supply fans running; return not (or visa-versa)
57
First-cost savings alone can pay for cost of Cx!
Evan Mills: The Cost-Effectiveness of Commercial Buildings Commissioning, 2004
Payback Times: New Construction
Median Payback Time = 4.8 years
Payback times not always attractive (if NEBs excluded)
58
RCX Payback Times for Existing Buildings Excluding NEI’s
Median Payback Time = 0.7 years
Attractive payback times across a range of Cx costs
Cx Cost Outliers
Smaller bldgs tend to have higher Cx costs
Larger bldgs tend to achieve economies of scale
59
PEC: Pre and Post Commissioning Data Average Daily Electrical Consumption PG&E Pacific Energy Center 1,200
Average Daily kWh
1,000
A pril 2000 - March 2001
800
A pril 2002 - March 2003
600
A pril 2003 - March 2004 400
200
M ar ch
Fe br ua ry
Ja nu ar y
D ec em be r
O ct ob er N ov em be r
Au gu st Se pt em be r
Ju ly
Ju ne
M ay
Ap ril
0
Existing Building Cx in California (SMUD)
Avg of 8 buildings Avg of 7 buildings
Avg of 4 buildings
60
Commissioning report on site
Lab and Office 1 (1996)
N Y
Office Building 1 (1996)
N Y
Office Building 2 (1996)
N N
Office Building 3 (1996)
Y Y N
Office Buidling 4 (1994)
N
-
-
Office Building 5 (1997)
N
-
Y
Medical Facility 1 (1998)
Y
Y
Y
Medical Facility 2 (1997)
Y
Y
Y
Lab and Office 2 (1997)
N
-
Y
Lab and Office 3 (2000)
N
-
N
Occupancy sensor
Skylight louver operation
PREFUNCTIONAL TESTS
Scheduling
Sensor error or failure
Sensor placement or addition
Wiring and instrumentation
Valve modification
AIR HANDLING AND DISTRIBUTION
Piping and fitting problems
Terminal units
Space temperature control
Duct static pressure
Dessicant cooling
VFD modulation
Simultaneous heating and cooling
CENTRAL PLANT
Discharge air temperature reset
Economizer control algorithm
Hydronic control
Boiler control
DOCUMENTS
Cooling tower control
BUILDING (year commissioned)
Chiller control
Control sequences available
California
Commissioning report used
Pacific Northwest
Emergence & Persistence of Energy Savings
New Construction Persistence Research Results
Red = did not persist Blue = persisted
OTHER
61
Commissioning Benefits • • • • • • • •
Energy savings Smoother turnover from construction to occupancy Improved occupant comfort/satisfaction Reduced construction and warranty issues More complete documentation Avoided O&M costs / increased reliability Team building with all role players Brings an integration perspective to design – – – –
Minimizes design related commissioning issues Buildings are integrated, interactive assemblies An Integrated Design leads to an Integrated Project Can reduce first cost of construction
Examples from Cx Projects
62
Types of Deficiencies Discovered New (N=3300)
Existing (N=3500) Envelope 0.2% Plug loads 0.2% Lighting 5%
Facility-wide (e.g. EMCS or utility related) 10%
Facility-wide (e.g. EMCS or utility related) 4% HVAC (combined heating and cooling) 6%
Plug loads 8%
HVAC (combined heating and cooling) 15%
Cooling plant 16% Cooling plant 9%
Terminal units 6%
Lighting 16%
Heating plant 6%
Heating plant 9%
Terminal units 11%
Air handling & distribution 54%
Air handling & distribution 25%
Fixed Economizer Actuator Motor
63
Looking at Multiple Trends Why doesn’t the AHU ever shut off ?
Looks like there are not any equipment lockouts
Why is the TES system melting ice at night?
Hot Water System Evaluation & Trending HWST & Pump status with time
Pump status
HWS Temp (deg F)
Low HWS Temp on Mondays
It takes all of Monday to heat up the HW Loop
64
Commissioning Resources
Resources •
PECI
•
CA Commissioning Collaborative online library
•
LBNL cost-benefit study
•
Commissioning Functional Test Guide
•
Design Intent Tool http://ateam.lbl.gov/DesignIntent/home.html
•
Energy Design Resources
•
Pacific Energy Center Cx workshops!
http://www.peci.org http://resources.cacx.org/library/
(and spreadsheet download) http://eetd.lbl.gov/emills/PUBS/Cx-Costs-Benefits.html http://buildings.lbl.gov/hpcbs/FTG
http://energydesignresources.com
65
Energy Design Resources • Building Commissioning Guidelines • Design Briefs –Building Commissioning –Field Review –Design Review –Smart Buildings
• Commissioning Assistant Tool • www.energydesignresources.com
Public Interest Energy Research • • • • • • •
Functional Test Guide Is Commissioning Once Enough? Persistence of Benefits from New Building Commissioning Persistence of Savings Obtained from Continuous Commissioning Optimization Measures that Persist in Existing Buildings Strategies for Improving the Persistence of Commissioning Benefits www.energy.ca.gov/pier
66
California Commissioning Collaborative • Download documents from California Cx Collaborative’s Online Library • www.cacx.org/library
ASHRAE and Green This nearly 200-page book offers essential reference and guidance to HVAC&R system designers involved in green or sustainable building design. The GreenGuide is a step-by-step manual for the entire building lifecycle, from the very earliest stages of a green building design project and through to the resulting structure’s construction, operation, maintenance, and eventual demolition. [Source: ASHRAE]
67
TLL homepage: www.pge.com/pec/tll
On-line Tool Request Form • Method for all loans • Information requested – About borrower – About project
• Sends automatic email to TLL staff • Typical response is within 24 hours • Tools can be shipped across California
68
Sign-out Sheet • To borrow tools – Business card – Signature
• Agree
– To return tools – That borrower is liable for damages to equipment and/or customer facility – Use licensed electrician for installing meters on equipment over 12v – Software cannot be copied for use after loan
On-line Catalog
69
Application Notes
Universal Translator (utonline.org) • Data Management Tool – – – – – –
Trend and logger data Re-sampling Time corrections Slope and offset corrections Calculated channels Schedule and data filters
– – – – – –
Economizer Run time of equipment Lighting controls Plug load controllers Psychrometrics Set-point analysis
• Data Analysis Tool
70
Universal Translator Interface
TLL Measurement Equipment • • • • • • • • • • • •
Temperature Humidity Electrical power (kW) Run time (EMF) Gas use (therms) CO2 CO Liquid flow Pressure (high) Air flow Pressure (low) Refrigerant charge
71
Tool Lending Library • Tool loaned for FREE • Intended for EE projects • Can be used for building diagnostics, sensor calibration or commissioning • Over 5000 tools in library • Support information at: www.pge.com/pec
Thank You, Ryan [email protected]
72
Mystery 1 The three variables illustrated in the graph depicted here are?
a. outside air, mixed air and return air temperatures at an air handler with an economizer b. daily electricity, natural gas and water use. c. space temperature, air flow and damper position for a working VAV box.
c. temperature, relative humidity and dew point of an air volume. d. chilled water flow, chilled water supply temperature and condenser water supply temperature for an optimized chiller.
73
Mixed is warmer than return, but much cooler than outside when outside temp is above return.
Mystery 1
The three variables illustrated in the graph depicted here are?
Mixed and return track when air handler is off.
Mixed tracks outside when the outside temp is below return.
a. outside air, mixed air and return c. temperature, relative air temperatures at an air humidity and dew point of an handler with an economizer air volume. b. daily electricity, natural gas and d. chilled water flow, chilled water use. water supply temperature and condenser water supply c. space temperature, air flow and temperature for an optimized damper position for a working chiller. VAV box.
1200
Mystery 2
1000
ppm
800
The data shown to the right is an indication of which condition?
600 400 200 0 6/28/02 12:00 AM
6/28/02 12:00 PM
a. Total dissolved solids in condenser water for a cooling tower. b. Volatile organic compounds (VOC) levels during construction of an office building.
6/29/02 12:00 AM
6/29/02 12:00 PM
6/30/02 12:00 AM
6/30/02 12:00 PM
7/1/02 12:00 AM
c. CO levels in a parking garage. d. CO2 levels in the open office area of a law office. e. CO2 levels in a movie theater. .
74
1200
The movie schedule is apparent in CO2 spikes.
Mystery 2
1000
The data shown to the right is an indication of which condition?
ppm
800 600 400
The night shut-down of the air handler causes the CO2 levels to dissipate slowly.
200 0 6/28/02 12:00 AM
6/28/02 12:00 PM
a. Total dissolved solids in condenser water for a cooling tower. b. Volatile organic compounds (VOC) levels during construction of an office building.
6/29/02 12:00 AM
6/29/02 12:00 PM
6/30/02 12:00 AM
6/30/02 12:00 PM
7/1/02 12:00 AM
c. CO levels in a parking garage. d. CO2 levels in the open office area of a law office. e. CO2 levels in a movie theater. .
Underfloor Air Distribution
75
Radiant Heating
Radiant Heating
76
Radiant Heating
Demand Response: HVAC Measures • Setback temperatures
• Fan speed limiting • Pre-cooling • Production scheduling
12:00 AM
10:00 PM
8:00 PM
6:00 PM
4:00 PM
2:00 PM
12:00 PM
8:00 AM
10:00 AM
6:00 AM
4:00 AM
2:00 AM
12:00 AM
kW
– Zone temps – CHW temps – Supply air temps
77
Thermal Storage Partial Peak
140
Peak
Partial Peak
120
kW
100 80 kW w/ thermal storage
60 kW w/o thermal storage
40 20 0
12:00 AM
6:00 AM
12:00 PM
6:00 PM
12:00 AM
Full Storage vs. Demand Limiting
78
Thermal Storage Issues • Peak demand reduction (saves $) • More efficient operation at night • Smaller electrical service required • Requires space • Requires knowledgeable facility engineers • Efficiency losses as cooling is stored and retrieved
Alternative Approach: NightBreeze System • Summer: If house is warm and it’s cool outside, system brings outside air • Winter: Heats the house using heat from the water heater or from a conventional gas furnace and also introduces outside air to provide adequate ventilation. • Primarily Residential, but some small commercial application
2007
http://www.davisenergy.com/technologies/nightbreeze.php
158
79
Night Ventilation Cooling
Night Ventilation Cooling Actual Performance Conventional A/C vs NightVent Cooled House Performace
100
12 Outdoor Temperature NightVent Indoor Temp A/C Indoor Temp NightVent Power A/C Power
10
80
8
70
6
60
4
50
2
40
0 0:00
6:00
12:00
Power (kW)
Temperature (deg F)
90
18:00
Hour
80
Training Objectives •
9:00 Best HVAC Maintenance and Control Practices, – – – – –
• •
10:30 Break 10:45 Best HVAC Maintenance and Control Practices, continued – – – – –
•
Best practice goals for HVAC Retrofits for energy efficiency Optimal control strategies Understanding sequences of operation Questions
Maintenance opportunities Diagnostics and monitoring devices Mystery graphs Role of building commissioning Questions
12:00 Lunch
1
Where Does the Energy Go? • 2005 Building Energy Outlook-USDOE • Annual Energy Outlook 2003-USDOE • BOMA Data
2003 U.S. Commercial Buildings
http://www.boma.org/
• PG&E Commercial Building Surveys
http://www.pge.com/biz/energy_tools_resources/ building_survey/index.html
CA-Electric Usage by End Use
2
CA-Natural Gas Usage by End Use
Load Profiles, Peak Demand and Rates P a r t i a l
60000
P e a k
P e a k
P a r t i a l
P e a k
Megawatts
50000
40000
30000
20000
10000
0
12:00 AM
6:00 AM
12:00 PM
6:00 PM
12:00 AM
Consider that utility rates vary by time of day and year
3
End Use Loads on 2003 Peak Day Exterior Lighting 1%
Domestic Hot Water 1% Office Equipment 2% Refrigeration 5% Ventilation 10%
Cooking 1%
Air Conditioning 32%
Other 18%
Interior Lighting 30%
3 Hour Peak
End Use Loads for California Commercial Sector on 2003 Peak Day
Gigawatts/Hour
Energy Intensity by Building Type Grocery stores and food service have higher end use intensities (kWh/sf) than any other common commercial building type.
Source: 1999 Commercial Building Energy Consumption Survey (CBECS), U.S. DOE, www.eia.doe.gov.
4
Small Office Miscellaneous
Air Compressors 1%
Motors 1%
0.1%
Heating 2%
Miscellaneous 7%
0.1%
Process 0.4%
Water Heating 6.9%
Cooling 18%
Exterior Lighting 5%
Cooking
Office Equipment 21%
Ventilation 11%
Water Heating 1%
Heating
Cooking 0%
92.5%
Refrigeration 4% Interior Lighting 29%
Electric
Natural Gas
Grocery Store Miscellaneous 3% Exterior Lighting 2% Office Equipment
Motors 0%
1%
Cooling 5%
Ventilation 6% Water Heating 0% Cooking
Interior Lighting
5%
20%
Cooking 28% Heating 42%
Water Heating 30%
Refrigeration
Electric
58%
Natural Gas
5
School Air Compressors Miscellaneous 3.8%
0.1% Motors 1.5%
Heating 1.6%
Cooking
Cooling
6%
12.2%
Exterior Lighting
Miscellaneous 0%
10.7%
Office Equipment 5.3%
Ventilation
Water Heating
13.5%
24%
Water Heating 0.9%
Heating
Cooking
Cooling
3.2%
1%
69%
Refrigeration 7.0% Interior Lighting 40.1%
Electric
Natural Gas
Approach to Efficient HVAC • First step is energy conservation through reduced building loads (envelope and interior) • Second step is through selection of efficient equipment to meet loads • Third step is operating equipment and systems only as required to meet intents • Fourth step is maintenance to maintain efficiency
6
Building Loads • Heat Losses – Conduction at envelope – Infiltration at envelope
• Heat Gains – – – – – –
Conduction at envelope Infiltration at envelope Solar gain through glass Lighting Equipment People
• Units: BTU/hr
Load Control
7
Cool Roofing Desired attributes – High solar reflectance – High far IR emissivity
Donald watson - editor. Time-saver standards for Architectural Design Data. McGraw Hill, 1997. Pg. B-254.
Images courtesy of NREL Craig Miller Productions and DOE
Cooling Efficiency • Capacity = Tons 1 Ton of Cooling = 12,000 BTU/hr Note: this is a rate – not a quantity • COP – Coefficient of Performance = (What you get) / (What you pay for) Higher COP is better • kW/ton kW input / (Tons of refrigeration out) Lower kW/ton is better • Energy Efficiency Ratio (EER) (BTU/hr Cooling Out) / (Watts In) Higher EER is better • Seasonal Energy Efficiency Ratio (SEER) (BTU/hr Cooling Out) / (Watts In)
8
Heating Efficiency • Capacity = BTU/hr • Annual Fuel Utilization Efficiency (AFUE) Used for boilers and furnaces BTU-out/BTU-in Higher AFUE is better • Heating Season Performance Factor (HSPF) Seasonal heat output of heat pump in BTU / total electric energy input Higher HSPF is better • Energy Factor (EF) Used for water heaters Hot water produced per unit of fuel consumed Higher EF is better
Motor, Fan and Pump Efficiency • Output/Input • Measured as a percentage • Motor – Input electrical power – Output is mechanical power
• Fan – Input is mechanical power – Output is airflow (CFM) and pressure (in H2O)
• Pump
– Input is mechanical power – Output is liquid flow (GPM) and pressure (ft H2O)
9
CA Title 20 Standards for Single Phase Air-Cooled Air Conditioners with Cooling Capacity Less than 65,000 Btu per Hour and Single Phase AirSource Heat Pumps with Cooling Capacity Less than 65,000 Btu per Hour, Not Subject to EPAct
What to specify: Rooftop / Split
© 2008 Consortium for Energy Efficiency, Inc. All rights reserved. www.cee1.org
Energy Audits
10
Mechanical System Efficiency 25
Energy Efficiency Ratio
20
15
10
5
0 C e n tri fu gal & S cre w C h i l l e rs
Pack age d AC
Ai r C ool e d He at Pu m p
Re ci procati n g C h i l l e rs
Grou n dsou rce h e at pu m ps
Data from Global Green USA 2001
Randall Thomas. Environmental Design, An Introduction for Architects and Engineers. E&FN Spon, 1996. Pg. 112.
Chiller Options for Efficiency • Look at chilled water system as a whole, not as individual parts • High Efficiency = low kW/ton • Ability to run with low condenser water temperatures • VFDs to modulate at part loads • “Free cooling” economizer operation (turns off compressor & uses only condenser water to cool chilled water) www.commercial.carrier.com
2007
22
11
Chilled Water System EEMs • Pump Scheduling & Proper Interlocking • Variable Flow Chilled Water Distribution • Variable Speed Cooling Tower Fans • Optimized Condenser Water Setpoint • Variable Flow Condenser Water Distribution • Chilled Water Temperature Resets • Drive-line retrofit • Replacement • Lots, lots, more!!!
2007
23
Chillers - Replacement • Longish payback • Eliminates refrigerant phase-out issues • If replacement is needed, very costeffective to spec VSD • Match chiller to actual load not design load (especially in multiple chiller plant) 2007
24
12
Cooling Towers • Run fans in parallel (VFDs) • Reduce condenser water setpoint (but perhaps not all the way) • Install water-side economizer (if oversized) • Regular Maintenance
2007
25
Water Side Economizer • Utilize “free” cooling during cold weather • Heat exchanger transfers heat directly from chilled water to condenser water • Eliminates chiller power • Can extend use by – Lower condenser water setpoint (i.e. running tower harder) – Running with higher chilled water temperature
13
Rooftop Equipment Identification • Packaged Unit – All components contained in on location – Ventilation is introduced through the unit – Heating is supplied by a gas furnace, heat pump, electric resistance or a hot water coil
• Split-System – Compressor Component Only – No ventilation provided by unit – Only heating is heat pump http://www.carrier.com
2007
27
Energy Efficiency Measures (EEMs) • Retrofits
– Evaporative Cooling – High Efficiency Units – VFD’s
• Controls – – – –
Scheduling / reduce operating hours Programmable thermostats Economizer operation Demand control ventilation
www.carrier.com
• Demand Response • Operations
– Reduce cooling loads – Keep units maintained
2007
28
14
High Efficiency Replacements • Package unit replacement isn’t generally cost effective on energy savings alone • So where are the opportunities? – Older units – Early retirement – New additions
• How do we promote it? – Comfort – Reliability – Reduced O&M Costs
2007
www.trane.com
Energy Audits
29
What to specify: Heat pumps • For larger units, use Consortium for Energy Efficiency (CEE) guidelines (www.cee1.org) • Specify Tier 2 or 3 Efficiency level
www.trane.com
2007
30
15
Ground-source Heat Pumps
Geothermal Heat Pump Consortium, Inc. http://geoexchange.us/illustrations/graphics.htm
• AKA
• • • • •
– Geothermal – Ground-water source – Geo-exchange
Uses earth/groundwater for heat sink Cooling mode: rejects heat to ground Heating mode: absorbs heat from ground Efficiency depends ground temperatures Size ranges from residential to large commercial systems • Best applicability: Climates where ground temperatures offer significantly better efficiency over air source • Title 20 Sets minimum standards by size 2007
31
Ground Source Heat Pumps
16
Evaporative Cooling
Evaporative Cooling/Pre-Cooling • Cools air via evaporation of water • Direct evaporative cooling increases humidity • Indirect evaporative cooling is less effective, but does not increase humidity • Evaporative pre-cooling reduces the temperature of air entering the condenser
http://www.muntersamerica.com/
17
Evaporative Cooling
• Direct evaporative coolers draw air through evaporative media lowering the temperature and increasing humidity • Indirect evaporative coolers use a heat exchanger to reduce the air temperature without increasing humidity
Direct Evaporative Cooler www.muntersamerica.com
2007
35
Direct Evaporative Cooling
18
Indirect/Direct Evaporative Cooling
http://www.wescorhvac.com/
Evaporative Pre-cooler Details
19
Evaporative Pre-Cooling D inin g U nit 1 E va porative C ond en s er P e rform a nc e
85
Temperature exiting media (F)
80
75
70
65
60
55 55
60
65
70
75
80
85
90
95
10 0
T e m p e ra tu re e n te rin g m e d ia (F )
Evaporative Pre-Cooling D aily E n erg y U sag e fo r D in in g U n it 1 80.0
HD1-E vap Cooler
70.0
HD1
y = 1.9524x - 106.37 R 2 = 0.9762
Linear (HD1-E vap Cooler) Linear (HD1)
Daily Energy Consumption (kWh)
60.0
50.0 y = 1.4888x - 75.758 R 2 = 0.9542 40.0
30.0
20.0
10.0
0.0 65.0
70.0
75.0
80.0
85.0
90.0
95.0
Ave ra ge Am bie nt Dry Bulb Te m pe ra ture be tw e e n 6 a .m . a nd m idnight
2007
40
20
Furnaces
JMK
• Furnaces heat air through heat exchange with combustion gases • Rating is Annual Fuel Utilization Efficiency or AFUE • Typical ratings from 80% to 96% AFUE • Condensing Furnaces achieve higher end of efficiencies en.wikipedia.org/wiki/Furnace
Boilers • Types – Hot water (Will have circulation pump) – Steam: Low, Medium & High Pressure (May have condensate return pump) – Atmospheric and forced draft – Fire-tube and water-tube
• Nameplate – Input/Output (MMBtu) – Combustion fan information – Pump size (for boilers with integrated pump) – National Board number
http://www.raypak.com/
21
Slide 41 JMK1
This work is in the public domain in the United States because it is a work of the United States Federal Government under the terms of Title 17, Chapter 1, Section 105 of the US Code. Jim Kelsey, 1/30/2007
Automatic Stack Damper
Instantaneous DHW Implementation • Pitfalls – Spendy! – Requires greater capacity (Btuh) to meet same load
• Savings – Range of 5% to 20% (depends on volume, age of existing) – Find by comparing energy factor
• Non-energy Benefits – Never run out of hot water – Less space/weight required – May help reduce time to get hot water
www.noritz.com
22
Motor Efficiencies (Premium Efficiency) • Compile Inventory of
motors • “High Efficiency” and Premium Efficiency are not equal • Stock premium efficient motors if possible • Take advantage of Incentives and Rebates
Standard (EPAct 1992) and Premium Efficiency Motor Ratings 1200 RPM HP
1 1.5 2 3 5 7.5 10 15 20 25 30 40 50 60 75 100 125 150 200
EPACT (Standard)
80.0% 84.0% 85.5% 86.5% 87.5% 88.5% 90.2% 90.2% 91.0% 91.7% 92.4% 93.0% 93.0% 93.6% 93.6% 94.1% 94.1% 94.5% 94.5%
NEMA Premium Efficiency
82.5% 86.5% 87.5% 88.5% 89.5% 90.2% 91.7% 91.7% 92.4% 93.0% 93.6% 94.1% 94.1% 94.5% 94.5% 95.0% 95.0% 95.4% 95.4%
Open Drip Proof (ODP) 1800 RPM NEMA Premium Efficiency
EPACT (Standard)
82.5% 84.0% 84.0% 86.5% 87.5% 88.5% 89.5% 91.0% 91.0% 91.7% 92.4% 93.0% 93.0% 93.6% 94.1% 94.1% 94.5% 95.0% 95.0%
3600 RPM
EPACT (Standard)
NEMA Premium Efficiency
85.5% n/a 86.5% 82.5% 86.5% 84.0% 89.5% 84.0% 89.5% 85.5% 91.0% 87.5% 91.7% 88.5% 93.0% 89.5% 93.0% 90.2% 93.6% 91.0% 94.1% 91.0% 94.1% 91.7% 94.5% 92.4% 95.0% 93.0% 95.0% 93.0% 95.4% 93.0% 95.4% 93.6% 95.8% 93.6% 95.8% 94.5%
77.0% 84.0% 85.5% 85.5% 86.5% 88.5% 89.5% 90.2% 91.0% 91.7% 91.7% 92.4% 93.0% 93.6% 93.6% 93.6% 94.1% 94.1% 95.0%
Relative Motor Efficiencies By Size ODP Motor Efficiencies 100.0%
Efficiency
95.0% 90.0% 85.0% 80.0% 75.0% 0
50
100
150
200
250
HP Existing
EPACT
NEMA Premium Efficiency
TEFC Motor Efficiencies 100.0% 95.0% Efficiency
• Motor Efficiencies tend to increase with motor size • EPACT is the Energy Policy Act of 1992 which established what we now consider “Standard” efficiency motors • National Electrical Manufacturers Association (NEMA) premium efficiency motors tend to be 1 to 2 percent higher than EPACT motor efficiencies
90.0% 85.0% 80.0% 75.0% 0
50
100
150
200
250
HP Existing
EPACT
NEMA Premium Efficiency
23
Benefits of Efficient Motors • Save energy, save $ – Benefit improves with higher utility rates
• Save demand, save $ – Benefit improves with higher demand costs
• Higher power factors, save $ – Benefit improves with PF charge at facilities with PF < 0.85
• Runs cooler, save energy, save $ – Benefit improves at facilities that are cooled
• Withstand voltage fluctuations and harmonics – Benefit important at facilities with old infrastructure – Benefit important at facilities with non-sinusoidal load types
• Operate quietly – Benefit important at most facilities Efficient Motors: Selection and Application Considerations, Consortium for Energy Efficiency, 1999
Efficient Evaporator Fan Motors
GE Industrial Systems
• New motors are “electrically commutated” a.k.a. “ECM” • Old types are shaded pole or permanent split capacitor (PSC) types • Applications: refrigerated cases, walk-in coolers and freezers
www.GEindustrial.com/ecm
24
Efficient Evaporator Fan Motors
VFD’s for Fans • Many systems use variable flow air distribution • Fan power laws dictate that power is roughly proportional to the flow rate cubed • VFD quality/reliability have improved greatly over time • VFD costs have dropped significantly with wider adoption • Now required by code for many applications in new construction
www.abb.com
2007
50
25
Why fans with VFD’s Save Energy
This relationships between fan energy and fan flow are taken from the California Energy Commission Guide to Preparing Feasibility Studies and the 1998 Nonresidential ACM Approval Manual. Note that a typical system curve, DOE2 default, is assumed and these relationships are not applicable to all systems.
2007
51
Control Measures • On/off • Setbacks • Demand Control Ventilation • Lock-outs • Resets • Economizers
2007
52
26
HVAC Controls • Basic control is the thermostat • For complex systems, monitor many control points: air temperature, pressure, fan speeds, etc. • Central computer control is called Building Management System • HVAC without controls is like lighting without switches
The Opportunity: Controls General Concepts • Controls are generally the most cost effective of EEMs • Whatever doesn’t have controls probably needs it • Controls reduce opportunity for human “enhancements” • Limit hours of operation • Use to maximize system efficiencies 2007
54
27
Scheduling
• Mechanical Time Clocks • Consider Twist Timers to reduce usage during off-hours
www.tork.com
www.tork.com
• Some have seasonal / astronomical timers and/or multiple channels 2007
55
Setbacks and Programmable Thermostats • Install Programmable Thermostats on all units
www.white-rodgers.com
2007
56
28
Setback Thermostats / Scheduling • Pitfalls – Need to be set correctly, not in “hold” mode – Persistence: document with a system manual how things are intended to work
• Savings – Range widely depending on occupancy and use. Typical is 5% to 50%. – Demand savings are minimal
• Non-Energy Benefits – Reduced wear on equipment
www.white-rodgers.com
Energy Audits
57
Web-enabled Thermostats • Web-based now available • About $250 to $400 each • Include ability to monitor remotely
www.proliphixstore.com
2007
58
29
Space Temperature Setbacks Room tem perature
85
80
75
70
65
60
55
50 8/29
8/30
8/31
9/1
9/2
9/3
9/4
9/5
9/6
9/7
9/8
9/9
9/10
Controls: Lockouts • A lockout is turning a piece of equipment off when a control condition is met • Example lockouts: – Chiller lockout based on outside air temp (and associated CHW pumps, CW pumps) – Boiler lockout based on outside air temp (and associated HHW pumps)
• Lockouts are simple, cheap, effective
30
Controls: Resets A reset is creating a variable setpoint control based on a monitored condition HHW OAT Reset 200
OAT
HHW
65
140
50
180
HHW Setpoint [°F]
190 180 170
OAT = Outside Air Temperature
160
HHW = Heating Hot Water Temperature
150 140 130 120 20
40
60
80
OAT [°F]
Economizers • The economizer cycle refers to using controls and dampers to make use of outside air for “free” cooling when it makes sense • Controls used to bring in outside air instead of return air • An “economizer” is generally not a single piece of equipment, although people may refer to it as such Return Air Exhaust Air
Outside Air
COLD
HOT
62
31
Air-Side Economizer • Damper Control • 100% Free Cooling (ex: OA
P
NO
SR
C NO
P
RA
C
SR
AF=0, NC=C
3-13 Psi
UNOCC, NC=C
SP O O R
28 OA
NO NC
O
OH CALC O I y=mx+b
OA
0%
OA>RAT or OAE>28, NO=C P
I IF >
TC
NC
SP O
EA
RA RESET
20
CO2
5
800
1000
45
Develop a Sequence of Operation for Fan Coil Unit
Operations & Maintenance Assuring equipment is operating properly
46
www.energy.ca.gov/pier PIER Buildings Program Design Guide: Big Savings on Small HVAC Systems
Small HVAC: Frequent Issues
93
Operations and Maintenance • • • • • •
Commissioning: Check Set points, Schedules and Resets Check for controls overrides (e.g. bypassed VFDs) Filter Changes for IAQ Check Fixed Damper and Minimum Damper Positions Adjust/tighten/replace belts Lubricate rotary equipment
47
Operations and Maintenance (cont.) • • • • • • •
Clean condenser coils Clean evaporator coils Insulate suction lines Check refrigerant charge Check thermostat/sensor calibration Insulate/seal ductwork Eliminate flex duct
2007
95
O&M Issues
48
What are Dataloggers? • What they do – Measure – Record
• What they include – – – – – – – – – –
Receive signal from sensor or transducer Analog-to-digital converter Data sampling rate Data storage rate Memory (stores readings) Internal clock Programming and data retrieval software Computer interface Microprocessor Power supply
Honeywell Service Assistant Faults detected: 1. 2. 3. 4. 5.
Low pumping efficiency High side heat transfer problem Low side heat transfer problem Fan speed too high Restricted refrigerant flow through the small orifice 6. Too little charge 7. Too much charge 8. Charge contaminated with non-condensables
49
Drywell Bath • Used for in-situ sensor calibration • Temperature maintained for calibration): 14° to 251° F (± 0.9° F) • Kit includes 1/16", 1/4", 3/16" and 1/2" removable inserts
Measuring Airflow • • • • • •
Anemometers DP sensors Pitot tubes Velgrid Flow hoods Duct blasters
50
Gas Efficiencies • Thermal: Steady State measure of the units ability to transfer heat to the water. • Combustion: Efficiency of the fuel burning process. Depends on fuel mix as measured with a combustion analyzer. • AFUE: Annual Fuel Utilization Efficiency. Similar to a SEER, rated for average seasonal conditions. • Standby Loss: A measure of the relative amount of heat that the unit will lose to the environment
Efficiency as Make-up Air Varies
http://www.engineeringtoolbox.com/boiler-combustion-efficiency-d_271.html
51
Mystery Graph #1 75
F degrees
70
65
60
55 6/17/00 0:00
6/17/00 12:00
6/18/00 0:00
The graph above is showing temperature. It represents: 1. interior temperature in an enclosed office building 2. outside air temperature over a year 3. outside air temperature over a day 4. the temperature at a light fixture 5. chilled water supply temperature
Mystery Graph #2 Mystery Graph 2 100
Three inter-related parameters
90
80
70
60
50
40 08/12/04 12:00 AM
08/12/04 03:00 AM
08/12/04 06:00 AM
08/12/04 09:00 AM
08/12/04 12:00 PM
08/12/04 03:00 PM
08/12/04 06:00 PM
08/12/04 09:00 PM
08/13/04 12:00 AM
Date
The graph at right shows three inter-related parameters. They are… 1. outside air, mixed air and supply air temperatures at an air handler 2. annual electricity, natural gas and water use 3. space temperature, air flow and damper position for a working VAV box 4. temperature, relative humidity and dew point of air 5. chilled water flow, chilled water supply temperature and condenser water supply temperature for an optimized chiller
52
Mystery Graph #3 The three variables illustrated in the graph depicted here are?
a. outside air, mixed air and return air temperatures at an air handler with an economizer b. daily electricity, natural gas and water use. c. space temperature, air flow and damper position for a working VAV box.
d. temperature, relative humidity and dew point of an air volume. e. chilled water flow, chilled water supply temperature and condenser water supply temperature for an optimized chiller.
Mystery Graph #4 Mystery Graph
120
Temperature, °F
110
100
90
80
70
60 5/20/05 12:00 PM
5/21/05 12:00 AM
5/21/05 12:00 PM
5/22/05 12:00 AM
5/22/05 12:00 PM
5/23/05 12:00 AM
5/23/05 12:00 PM
5/24/05 12:00 AM
Date and time
What does the temperature data above indicate? 1. temperature in a space with evening setbacks 2. the temperature at a chair indicating occupancy 3. condenser water temperature at a chip fabrication facility (with night shutdown shown) 4. the temperature in a refrigerated warehouse with a regular evening stocking crew 5. the scheduled operation of a motor
53
140
Mystery Graph #5
120
100
80
60
40
20
0
12:00 AM
6:00 AM
12:00 PM
6:00 PM
12:00 AM
What does the data above represent? 1. percent speed for a VFD-controlled fan in a retail space 2. the power draw of a chiller connected to thermal storage 3. solar radiation in San Francisco on a foggy day 4. an erratic control valve for chilled water flow in an office building 5. the lighting energy use at a quickie-mart
Mystery Graph 6 1200 1000
ppm
800
The data shown to the right is an indication of which condition?
600 400 200 0 6/28/02 12:00 AM
a. Total dissolved solids in condenser water for a cooling tower. b. Volatile organic compounds (VOC) levels during construction of an office building.
6/28/02 12:00 PM
6/29/02 12:00 AM
6/29/02 12:00 PM
6/30/02 12:00 AM
6/30/02 12:00 PM
7/1/02 12:00 AM
c. CO levels in a parking garage. d. CO2 levels in the open office area of a law office. e. CO2 levels in a movie theater.
54
Mystery Issue #7
What obvious visible indicator is shown in the image? 1. a throttled valve on the discharge of the pump 2. a strainer in need of cleaning 3. a section of pipe with inadequate insulation 4. a valve missing an actuator 5. a missing pressure gauge
What Is Building Commissioning? Commissioning is a quality assurance strategy. Commissioning is a systematic process of ensuring that all building systems perform interactively according to the contract documents, the design intent and the building owner’s operational needs.
55
Why Commission? • • • • • • • • • • •
Owners do not typically receive fully functional building systems Owners face increasing numbers of performance problems Buildings have more complex life safety, security, communication, and comfort control systems Building systems are becoming increasingly specialized and integrated Many problems are masked by energy-wasting process Multiple trades and contracts are involved (fragmentation) Conflicting loyalties and objectives Increasing costs (change orders, call backs) Emphasis on fast track Design fees do not reflect reality Requirements – LEED, CHPS, Title 24
Commissioning is Quality Assurance • A coordination process to optimize building performance (comfort, reliability, safety, energy) • Articulating/verifying energy-related design intent • Construction observation; warranty enforcement • Controlling first cost • Training operators • Enhancing safety and risk management • Creating more cohesion among team members
56
A Common Industry Perspective; Commissioning; A Bandage for a Broken Process
An Emergency Response • Treating the wound • Add-on process • Last-ditch effort – Resurrect quality – Identify deficiencies – Force accountability
Images courtesy www.talkingproud.us
Building problems (a.k.a. “deficiencies”) are pervasive – These include Design flaws; Construction defects;
Malfunctioning equipment; Deferred maintenance
EXISTING BUILDINGS
NEW CONSTRUCTION
Simultaneous heating+cooling
Oversized equipment
Mis-sized valves/dampers, chillers
Unnecessary components (valves)
Low-quality or clogged filters
Construction debris blocking ventilation
VFD or economizer overridden/stuck
Specified equipment not installed
Dumb alarms (false; ignored)
Wrong set points or control sequences
Circuitous duct or piping runs
Wrong sensors (inappropriate sensitivity)
Bad or inaccurate sensors
Improper startup (e.g. daylighting sensors)
Supply fans running; return not (or visa-versa)
57
First-cost savings alone can pay for cost of Cx!
Evan Mills: The Cost-Effectiveness of Commercial Buildings Commissioning, 2004
Payback Times: New Construction
Median Payback Time = 4.8 years
Payback times not always attractive (if NEBs excluded)
58
RCX Payback Times for Existing Buildings Excluding NEI’s
Median Payback Time = 0.7 years
Attractive payback times across a range of Cx costs
Cx Cost Outliers
Smaller bldgs tend to have higher Cx costs
Larger bldgs tend to achieve economies of scale
59
PEC: Pre and Post Commissioning Data Average Daily Electrical Consumption PG&E Pacific Energy Center 1,200
Average Daily kWh
1,000
A pril 2000 - March 2001
800
A pril 2002 - March 2003
600
A pril 2003 - March 2004 400
200
M ar ch
Fe br ua ry
Ja nu ar y
D ec em be r
O ct ob er N ov em be r
Au gu st Se pt em be r
Ju ly
Ju ne
M ay
Ap ril
0
Existing Building Cx in California (SMUD)
Avg of 8 buildings Avg of 7 buildings
Avg of 4 buildings
60
Commissioning report on site
Lab and Office 1 (1996)
N Y
Office Building 1 (1996)
N Y
Office Building 2 (1996)
N N
Office Building 3 (1996)
Y Y N
Office Buidling 4 (1994)
N
-
-
Office Building 5 (1997)
N
-
Y
Medical Facility 1 (1998)
Y
Y
Y
Medical Facility 2 (1997)
Y
Y
Y
Lab and Office 2 (1997)
N
-
Y
Lab and Office 3 (2000)
N
-
N
Occupancy sensor
Skylight louver operation
PREFUNCTIONAL TESTS
Scheduling
Sensor error or failure
Sensor placement or addition
Wiring and instrumentation
Valve modification
AIR HANDLING AND DISTRIBUTION
Piping and fitting problems
Terminal units
Space temperature control
Duct static pressure
Dessicant cooling
VFD modulation
Simultaneous heating and cooling
CENTRAL PLANT
Discharge air temperature reset
Economizer control algorithm
Hydronic control
Boiler control
DOCUMENTS
Cooling tower control
BUILDING (year commissioned)
Chiller control
Control sequences available
California
Commissioning report used
Pacific Northwest
Emergence & Persistence of Energy Savings
New Construction Persistence Research Results
Red = did not persist Blue = persisted
OTHER
61
Commissioning Benefits • • • • • • • •
Energy savings Smoother turnover from construction to occupancy Improved occupant comfort/satisfaction Reduced construction and warranty issues More complete documentation Avoided O&M costs / increased reliability Team building with all role players Brings an integration perspective to design – – – –
Minimizes design related commissioning issues Buildings are integrated, interactive assemblies An Integrated Design leads to an Integrated Project Can reduce first cost of construction
Examples from Cx Projects
62
Types of Deficiencies Discovered New (N=3300)
Existing (N=3500) Envelope 0.2% Plug loads 0.2% Lighting 5%
Facility-wide (e.g. EMCS or utility related) 10%
Facility-wide (e.g. EMCS or utility related) 4% HVAC (combined heating and cooling) 6%
Plug loads 8%
HVAC (combined heating and cooling) 15%
Cooling plant 16% Cooling plant 9%
Terminal units 6%
Lighting 16%
Heating plant 6%
Heating plant 9%
Terminal units 11%
Air handling & distribution 54%
Air handling & distribution 25%
Fixed Economizer Actuator Motor
63
Looking at Multiple Trends Why doesn’t the AHU ever shut off ?
Looks like there are not any equipment lockouts
Why is the TES system melting ice at night?
Hot Water System Evaluation & Trending HWST & Pump status with time
Pump status
HWS Temp (deg F)
Low HWS Temp on Mondays
It takes all of Monday to heat up the HW Loop
64
Commissioning Resources
Resources •
PECI
•
CA Commissioning Collaborative online library
•
LBNL cost-benefit study
•
Commissioning Functional Test Guide
•
Design Intent Tool http://ateam.lbl.gov/DesignIntent/home.html
•
Energy Design Resources
•
Pacific Energy Center Cx workshops!
http://www.peci.org http://resources.cacx.org/library/
(and spreadsheet download) http://eetd.lbl.gov/emills/PUBS/Cx-Costs-Benefits.html http://buildings.lbl.gov/hpcbs/FTG
http://energydesignresources.com
65
Energy Design Resources • Building Commissioning Guidelines • Design Briefs –Building Commissioning –Field Review –Design Review –Smart Buildings
• Commissioning Assistant Tool • www.energydesignresources.com
Public Interest Energy Research • • • • • • •
Functional Test Guide Is Commissioning Once Enough? Persistence of Benefits from New Building Commissioning Persistence of Savings Obtained from Continuous Commissioning Optimization Measures that Persist in Existing Buildings Strategies for Improving the Persistence of Commissioning Benefits www.energy.ca.gov/pier
66
California Commissioning Collaborative • Download documents from California Cx Collaborative’s Online Library • www.cacx.org/library
ASHRAE and Green This nearly 200-page book offers essential reference and guidance to HVAC&R system designers involved in green or sustainable building design. The GreenGuide is a step-by-step manual for the entire building lifecycle, from the very earliest stages of a green building design project and through to the resulting structure’s construction, operation, maintenance, and eventual demolition. [Source: ASHRAE]
67
TLL homepage: www.pge.com/pec/tll
On-line Tool Request Form • Method for all loans • Information requested – About borrower – About project
• Sends automatic email to TLL staff • Typical response is within 24 hours • Tools can be shipped across California
68
Sign-out Sheet • To borrow tools – Business card – Signature
• Agree
– To return tools – That borrower is liable for damages to equipment and/or customer facility – Use licensed electrician for installing meters on equipment over 12v – Software cannot be copied for use after loan
On-line Catalog
69
Application Notes
Universal Translator (utonline.org) • Data Management Tool – – – – – –
Trend and logger data Re-sampling Time corrections Slope and offset corrections Calculated channels Schedule and data filters
– – – – – –
Economizer Run time of equipment Lighting controls Plug load controllers Psychrometrics Set-point analysis
• Data Analysis Tool
70
Universal Translator Interface
TLL Measurement Equipment • • • • • • • • • • • •
Temperature Humidity Electrical power (kW) Run time (EMF) Gas use (therms) CO2 CO Liquid flow Pressure (high) Air flow Pressure (low) Refrigerant charge
71
Tool Lending Library • Tool loaned for FREE • Intended for EE projects • Can be used for building diagnostics, sensor calibration or commissioning • Over 5000 tools in library • Support information at: www.pge.com/pec
Thank You, Ryan [email protected]
72
Mystery 1 The three variables illustrated in the graph depicted here are?
a. outside air, mixed air and return air temperatures at an air handler with an economizer b. daily electricity, natural gas and water use. c. space temperature, air flow and damper position for a working VAV box.
c. temperature, relative humidity and dew point of an air volume. d. chilled water flow, chilled water supply temperature and condenser water supply temperature for an optimized chiller.
73
Mixed is warmer than return, but much cooler than outside when outside temp is above return.
Mystery 1
The three variables illustrated in the graph depicted here are?
Mixed and return track when air handler is off.
Mixed tracks outside when the outside temp is below return.
a. outside air, mixed air and return c. temperature, relative air temperatures at an air humidity and dew point of an handler with an economizer air volume. b. daily electricity, natural gas and d. chilled water flow, chilled water use. water supply temperature and condenser water supply c. space temperature, air flow and temperature for an optimized damper position for a working chiller. VAV box.
1200
Mystery 2
1000
ppm
800
The data shown to the right is an indication of which condition?
600 400 200 0 6/28/02 12:00 AM
6/28/02 12:00 PM
a. Total dissolved solids in condenser water for a cooling tower. b. Volatile organic compounds (VOC) levels during construction of an office building.
6/29/02 12:00 AM
6/29/02 12:00 PM
6/30/02 12:00 AM
6/30/02 12:00 PM
7/1/02 12:00 AM
c. CO levels in a parking garage. d. CO2 levels in the open office area of a law office. e. CO2 levels in a movie theater. .
74
1200
The movie schedule is apparent in CO2 spikes.
Mystery 2
1000
The data shown to the right is an indication of which condition?
ppm
800 600 400
The night shut-down of the air handler causes the CO2 levels to dissipate slowly.
200 0 6/28/02 12:00 AM
6/28/02 12:00 PM
a. Total dissolved solids in condenser water for a cooling tower. b. Volatile organic compounds (VOC) levels during construction of an office building.
6/29/02 12:00 AM
6/29/02 12:00 PM
6/30/02 12:00 AM
6/30/02 12:00 PM
7/1/02 12:00 AM
c. CO levels in a parking garage. d. CO2 levels in the open office area of a law office. e. CO2 levels in a movie theater. .
Underfloor Air Distribution
75
Radiant Heating
Radiant Heating
76
Radiant Heating
Demand Response: HVAC Measures • Setback temperatures
• Fan speed limiting • Pre-cooling • Production scheduling
12:00 AM
10:00 PM
8:00 PM
6:00 PM
4:00 PM
2:00 PM
12:00 PM
8:00 AM
10:00 AM
6:00 AM
4:00 AM
2:00 AM
12:00 AM
kW
– Zone temps – CHW temps – Supply air temps
77
Thermal Storage Partial Peak
140
Peak
Partial Peak
120
kW
100 80 kW w/ thermal storage
60 kW w/o thermal storage
40 20 0
12:00 AM
6:00 AM
12:00 PM
6:00 PM
12:00 AM
Full Storage vs. Demand Limiting
78
Thermal Storage Issues • Peak demand reduction (saves $) • More efficient operation at night • Smaller electrical service required • Requires space • Requires knowledgeable facility engineers • Efficiency losses as cooling is stored and retrieved
Alternative Approach: NightBreeze System • Summer: If house is warm and it’s cool outside, system brings outside air • Winter: Heats the house using heat from the water heater or from a conventional gas furnace and also introduces outside air to provide adequate ventilation. • Primarily Residential, but some small commercial application
2007
http://www.davisenergy.com/technologies/nightbreeze.php
158
79
Night Ventilation Cooling
Night Ventilation Cooling Actual Performance Conventional A/C vs NightVent Cooled House Performace
100
12 Outdoor Temperature NightVent Indoor Temp A/C Indoor Temp NightVent Power A/C Power
10
80
8
70
6
60
4
50
2
40
0 0:00
6:00
12:00
Power (kW)
Temperature (deg F)
90
18:00
Hour
80
