• Hui Zhang Ph.D. • Edward Arens Ph.D. • Tiefeng Yu Ph.D. • Charlie Huizenga UC Berkeley ASHRAE June 2008
Significance • More than 160 cities have rapid transit systems. Twentyfive cities have new systems under construction. More cities are planning subway systems. --- World Metro List • 100 Millions of people are using subway daily • Subway environments affect comfort and well-being of passengers and operating personnel
Challenges • Highly transient and nonuniform environments • Passengers with different activity levels and various clothing insulations • Transitional space • Energy efficient and cost effective system • CFD cannot tell you thermal comfort… • Design tool to quantify and model thermal comfort
How Do Low Energy Strategies Affect Comfort? Spot cooling Directly conditioning occupied zone
Platform Screen Door (PSD) Separate the tunnel and the station
Disney Line Station, HK
Mong Kok Station, HK
How to Improve Comfort by New Architectural Designs?
Building-station Integration Large open space Large skylights “Green” Designs Opportunities: • Radiant cooling • Displacement ventilation • Innovative control strategies…
IFC Station, HK
St Pancras Station, UK
Thermal Index for Subway Application • Predicted Mean Vote (PMV) • Predicted Percent Dissatisfied (PPD) model • Warm Environment: Relative Warmth Index (RWI) • Cool Environment: Relative Strain Index (RSI) “Thermal comfort”, Fanger, 1972 “Subway Environmental Design Handbook”, DOT, 1976
ASHRAE Std 55: Acceptable comfort ranges of operative temperature (1.1 met, 0.1 m/s)
UCB Transient Thermal Comfort Model
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Physiology modeling
Psychological thermal perception modeling
Physiology Model
Upper Arm
Lower Arm
Solar load on the body
core muscle fat skin
Radiation model
core muscle fat skin
core muscle fat skin core muscle fat skin
core muscle fat skin
core muscle fat skin
16 body segments, 4 layers
Hand
Counter-current blood flow
Body-builder model
Psychological Model My leg is uncomfortable My leg is cold
Human subject testing
Overall, I’m warm Overall, I’m uncomfortable
Model prediction
Comfort Scale very comfortable
4
comfortable
2
just comfortable just uncomfortable
0 -0
uncomfortable
very uncomfortable
-2
-4
Threshold for thermal environment acceptability
Model Applications – Vehicle Comfort Solar radiation (W/m2)
Very comfortable
Very hot
Just comfortable Just uncomfortable
Very cold
Solar radiation coming through driver’s window reaches left arm, part of the right arm, hands, and left side of head
Very uncomfortable
These parts feel warmer…
…and experience local discomfort
Model Applications for Typical Building Non-uniform Environments
Cold window
Cooled ceiling
Displacement ventilation/UFAD
Heated floor
Solar radiation and façade comfort
UCB Comfort Model Validation – Vehicle Wind Tunnel Test • Wide range of realistic transient automobile thermal conditions • Measured skin and core temperatures, subjective votes and environmental conditions
Subway Thermal Comfort Graphic User Interface
Outdoor walking
Platform
Stalled train
A series of “phases” define •environmental conditions •passengers’ metabolic level and clothing •corresponding geometry surroundings
Scenario for a Typical Subway Riding 10 min outdoor
1 min mezzanine
5 min platform
1 min stairs
10 min in train
24s train coming, step into it
Comfort Simulation for Spot Cooling
just comfortable just uncomfortable Threshold for acceptability uncomfortable
very uncomfortable
Testing Radiant Cooled Panels
Cooled floor (20ºC/68ºF)
Cooled vertical panels (20ºC/ 68ºF)
Cooled ceiling panel (20ºC/ 68ºF)
Comfort Simulation for Radiant Panels
just comfortable just uncomfortable Threshold for acceptability uncomfortable
very uncomfortable
Comfort Simulation for PSD comfortable
just comfortable just uncomfortable Threshold for acceptability uncomfortable
very uncomfortable
Mitigation Measures of a Congested Train
Air temperature and humidity will increase
Ttunnel (ºC/ºF) Train ventilation
36(97), 31(88) 554 cfm
Activity Level and Core Temperature Increase
Suggestions in a Congested Train
• Ventilation of the train
• Quietly seated
• Taking off clothing
Thermal comfort and energy consumption 4
2 comfortable
0 -0 just comfortable Air Tempering
-2 uncomfortable No AC
-4 very uncomfortable
Thermal comfort
Relative energy consumption %
very comfortable 100 90 80 70 60 50 40 30 20 10 0
PSD
Spot cooling (85F)+ mezz vent
Spot cooling (82F)
Entire space 82F
Energy consumption
Radiant panel
No AC
New generation tools for future station design… • Complex thermal environments • Transient comfort model for design optimization Beijing South Station, China (Terry Farrell)
