On subway systems in Tokyo (such as Tokyo Metro and the Toei Subway), train car cooling is operated using a two-tier temperature setting system consisting of "regular cars" and "weakly air-conditioned cars" (Mildly Air-Conditioned Cars) to ensure passenger comfort and accommodate diverse preferences regarding body temperature.
Here is a specific breakdown of this system and service:
1. Specific Temperature Settings
While temperatures are dynamically adjusted based on the season, outside temperature, and train crowding levels, the standard summer baseline settings are generally as follows:
Regular Cars: Approx. 25°C – 26°C (77°F – 79°F)
Toei Subway lines (such as the Asakusa, Mita, and Shinjuku lines) primarily target 25°C, while Tokyo Metro lines generally set their standard at 26°C.
(Note: Certain lines like the Toei Oedo Line use lower settings, such as 22°C, due to unique car structures and heat accumulation.)
Weakly Air-Conditioned Cars: Approx. 28°C (82°F)
Set 2°C to 3°C higher than regular cars (typically around 28°C).
As a rule, a specific car within a train formation (usually located around the middle of the train) is designated as the weakly air-conditioned car.
2. Why is a "Two-Tier" System Necessary?
A person's thermal sensation varies greatly depending on age, gender, physical condition, clothing, and whether they have just walked a long distance in the intense summer heat. Furthermore, excessive temperature gaps between chilled indoor environments and scorching outdoor weather ("thermal gap fatigue") have become a growing health concern.
The two-tier zoning system addresses these contrasting needs:
For those who get hot easily: Commuters and students arriving from packed, sweltering streets need the cooler temperatures (25°C–26°C) of regular cars to cool down their overheated bodies.
For those sensitive to cold:
Women, the elderly, individuals sensitive to strong air conditioning, or those prone to chilling benefit from weakly air-conditioned cars set around 28°C as a comfortable refuge.
3. Operational Challenges and Efforts
Operating underground presents unique environmental hurdles, requiring railway companies to fine-tune the climate control constantly:
Combination of Sensors and Automated Control:
Sensors monitor car temperature and crowding levels, automatically regulating cooling, dehumidification, and ventilation to maintain target temperatures.
The Dilemma of Rush Hours and Ventilation:
Unlike surface trains, subway doors open frequently at stations, letting in hot air from outside. During morning and evening rush hours, dense crowds cause internal temperatures to spike quickly. Consequently, staff must carefully balance dynamic management so that standard cars still feel adequately cool despite heavy congestion.
Consistency Across Through-Services:
Toei and Tokyo Metro connect directly with various private railway lines (such as Keisei, Keikyu, Odakyu, Tobu, and Seibu). Although base temperature designs can vary slightly by operator, collaborative adjustments are made to ensure a seamless experience for passengers.
Ultimately, the summer two-tier temperature system on Tokyo's subways reflects a meticulous, passenger-centric service tailored to individual health and comfort differences in a high-density public transit network.
