AIA CAFM - BAF - 2
Transcript of AIA CAFM - BAF - 2
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Using Air Movement to Improve Energy Efficiency
Overview• Benefits of air movement
• Thermal comfort & ASHRAE Standard 55
• Energy savings: cooling & heating
• Product overview
• Application examples
Thermal Comfort
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ASHRAE Standard 55‐2010: Thermal Comfort
“Specify the combination of indoor thermal environmental factors and personal factors that will produce thermal environmental conditions acceptable to a majority of the occupants…”
Said another way…
‐ Quantify comfort for most
What is Thermal Comfort?
It Is All A Matter Of Perspective
Definition:“That condition of mind which expresses satisfaction with the thermal environment and is assessed by subjective evaluation.”
ANSI/ASHRAE Standard 55‐2010, Section 3
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Thermal Comfort – what affects it?
Thermal Comfort Variables:
Environmental Factors
• Air temperature (°F)
• Humidity (% RH)
• Radiant temperature (°F)
• Air speed (fpm)
Personal Factors
• Clothing insulation (clo)
• Metabolic rate (met)
Definitions
• Predicted Percentage of Dissatisfied (PPD)
• Predicted Mean Vote (PMV)
• Operative Temperature
Comfort Zone
PMV: ‐0.5 to +0.5
PPD < 10%
Operative Temperature ‐ Graphical Method
Operative Temperature (what people feel) = Air Temp +/‐ Radiant Effects – Air Speed Cooling Effect
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Comfort Zone ‐ Computer Model Method
Source: CBE Thermal Comfort Tool
Air Movement in Conditioned and Non‐Conditioned Spaces
Temperature vs. Productivity & Accuracy
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Benefits of Large Overhead Fans
Cooling Applications
Designing for Thermal Comfort ‐ Cooling
Typical School Cooling Values
• Air temperature (75 °F)
• Humidity (50% RH)
• Metabolic rate (1 met)
• Radiant temperature (75 °F)
• Clothing insulation (0.5 to 1.0 clo)
• Air speed (40 fpm or less)
Typical
PPD 8%
PMV ‐0.39
Air Speed and Thermostat Offset
ASHRAE Thermal Comfort Tool100 ‐ 350 fpm best cooling per Watt
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Cooling Effect (°F)
Air Speed (Feet Per Minute)
Cooling Effect From Elevated Air Speed
Assumptions:85F Air Dry Bulb & Mean Radiant Temp20 fpm Air Speed (Base Conditions)60% Relative Humidity1.3 Met Metabolic Rate0.5 Clo Clothing Level
Sources:Thermal Comfort Tool ‐ UC BerkeleyANSI/ASHRAE Standard 55
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Graphical Method ‐ Shifting the Comfort Zone
Operative Temperature (what people feel) = Air Temp +/‐ Radiant Effects – Air Speed Cooling Effect
Designing for Thermal Comfort
Alternate Office Cooling Values
• Air temperature (79.5 °F)
• Humidity (50% RH)
• Metabolic rate (1 met)
• Radiant temperature (79.5 °F)
• Clothing insulation (0.5 to 1.0 clo)
• Air speed (125 fpm)
Alternate
PPD 5%
PMV ‐0.05
Savings from Airflow to Offset Temperature Increase
• According to the U.S. EPA and D.O.E. Energy Savings Calculator*, each degree of this 4.5°F thermostat offset saves 3% to 6% of cooling energy.
• This gives a total saving of 13% to 27% of cooling energy.
*U.S. EPA and D.O.E. Energy Savings Calculator
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Airflow in Non‐Sensitive Spaces
Reductions of 10‐20% in cooling energy
Benefits of Large Overhead Fans
Heating Applications
Air Movement for Winter Energy Efficiency
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Stratification in Heating Mode
• Difficult to balance heating and cooling requirements with one distribution system
• Warmer air rises towards the ceiling
• Stratification of 0.5 – 1.0 F°/ft.
• Higher average space temperature, heat loss, equipment runtime, discomfort
Fan Jet Requirement
• Jet that reaches floor• Minimum fan size• Open areas
Forward Operation (No Reverse)
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Fan Energy (%
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Fan Speed (% Max RPM)
Fan Energy Consumption
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No Drafts
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Cooling Effect (°F)
Air Velocity (Feet Per Minute)
Cooling Effect From Elevated Air Speed
Destratification Fan ResultsFan Off
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11/2/2009 0:00 11/3/2009 0:00 11/4/2009 0:00 11/5/2009 0:00 11/6/2009 0:00 11/7/2009 0:00 11/8/2009 0:00 11/9/2009 0:00 11/10/2009 0:00
5’ AFF15’ AFF35’ AFF
Destratification Fan ResultsFan On
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ASHRAE Std 62.1 & Overhead Heating
Office
Zone Floor Area ‐ (ft2) 2000
Zone Population ‐ (people) 16
Breathing Zone Outdoor Airflow (cfm) 200
Typical Zone Air Distribution Effectiveness (Ez) 0.8
Outdoor Air Intake Flow (cfm) 250
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Winter Destratification ‐ Review
1. Uniform distribution
2. Reduce heating energy*
3. Reduce outdoor air intake requirements
*No change in thermostat setpoint
Reclaim the Ceiling
Ductwork Minimization
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• Problem:– Moist air + cold surface = condensation
–Corrosion of metal– Loss of product– Safety
Condensation Mitigation
•Solution:–BAF mitigate condensation by:
–Disturbing stagnant air film–Increasing surface temperature–Increasing air temperature near floor
Improving IAQ
Applications
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Industrial Applications (Factories, DC, & Service Centers)
Auto Dealerships – Showrooms and Service Centers
Aircraft Hangars & Terminals
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Health Clubs & Recreation Centers
Healthcare & Physical Therapy
Schools – K‐12 & Universities
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Large Diameter Fans and Energy Efficiency
LEED & Large Diameter Fans
Where fans can help:
• Energy & Atmosphere
– Reduce Energy Use
• Indoor Environmental Quality
– Increase Thermal Comfort
– Reduce Ventilation Intake
• Innovation & Design Process– Materials Reduction, etc…
LEED Details http://www.bigassfans.com/page/leed_pts
Big Ass Fans Testing Laboratory
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Locust Trace
Summary ‐ Benefits of Large Diameter Fans
• Improve thermal comfort
• Summer and winter energy savings
• Improve air distribution
• Reduce condensation
Questions
Contact information:Greg Phipps