{"items": [{"author": "Jess", "source_link": "https://www.facebook.com/jefftk/posts/10100108686123972?comment_id=10100108692885422", "anchor": "fb-10100108692885422", "service": "fb", "text": "What fraction of stations in NYC/Boston/SF are actively cooled in the summer? I just assumed it was near zero, since the large foot traffic and open access means you'd be constantly loosing any air you managed to cool below outside temps. (Another reason for night ventilation.)", "timestamp": "1567042055"}, {"author": "Jeff Kaufman", "source_link": "https://www.facebook.com/jefftk/posts/10100108686123972?comment_id=10100108692885422&reply_comment_id=10100108700135892", "anchor": "fb-10100108692885422_10100108700135892", "service": "fb", "text": "→ I think it's near zero as well, though London has some active cooling: http://content.tfl.gov.uk/lu-cooling-the-tube-programme...", "timestamp": "1567042785"}, {"author": "Jess", "source_link": "https://www.facebook.com/jefftk/posts/10100108686123972?comment_id=10100108692885422&reply_comment_id=10100108711987142", "anchor": "fb-10100108692885422_10100108711987142", "service": "fb", "text": "→ Yah, I had looked at those slides. I am bummed they counted it as a benefit that big fans signaled to the public with a \"visible demonstration of TfL\u2019s commitment to the issue\". :/", "timestamp": "1567044239"}, {"author": "Beth", "source_link": "https://www.facebook.com/jefftk/posts/10100108686123972?comment_id=10100108692885422&reply_comment_id=10100108891028342", "anchor": "fb-10100108692885422_10100108891028342", "service": "fb", "text": "→ It\u2019s near zero in NYC. Not so much as a floor fan in most stations, with the exception of one station, I think it was times square, with what seems to be a bit of localized air conditioning. Temperatures are very obviously much hotter than outside, day and night, and there are also plenty of spots that anyone can tell a strategically placed fan would make a huge impact, such as under ceiling grates that already vent to the street. I\u2019m really confused why there appears to be exactly zero effort to alleviate the problem when there\u2019s so much low hanging fruit at some stations.", "timestamp": "1567172919"}, {"author": "Ari", "source_link": "https://www.facebook.com/jefftk/posts/10100108686123972?comment_id=10100108698479212", "anchor": "fb-10100108698479212", "service": "fb", "text": "When you say \"the stations have enormous heat capacity\"; is the subway station a distinct thermal reservoir? I would have thought that over a course of hours it'll reach equilibrium with the surrounding rock; the problem during the day is that a great deal of heat is being evolved by the people and machines.", "timestamp": "1567042612"}, {"author": "Jeff Kaufman", "source_link": "https://www.facebook.com/jefftk/posts/10100108686123972?comment_id=10100108698479212&reply_comment_id=10100108701004152", "anchor": "fb-10100108698479212_10100108701004152", "service": "fb", "text": "→ The rock around the stations and tunnels is slowly warming up. When London's subway first went in it was known for being cold, and the trains used to have heaters.", "timestamp": "1567042867"}, {"author": "Eli", "source_link": "https://www.facebook.com/jefftk/posts/10100108686123972?comment_id=10100108700964232", "anchor": "fb-10100108700964232", "service": "fb", "text": "Juliet what do you think? Ever heard of this?", "timestamp": "1567042863"}, {"author": "BDan", "source_link": "https://www.facebook.com/jefftk/posts/10100108686123972?comment_id=10100108710669782", "anchor": "fb-10100108710669782", "service": "fb", "text": "Night cooling only works if the thing you\u2019re cooling is warmer than the air at night to start with. That\u2019s mostly not true for underground rocks in the summer, as underground temperature tends to be in the 50s. There\u2019s maybe a thin surface layer that\u2019s a bit warmer, but if the rock is very thermally conductive it will quickly reach equilibrium with the deeper layers, and if it isn\u2019t there won\u2019t be much mass to cool down.
London has the opposite problem, though: very poorly thermally conductive soil which is now at temperatures in the 70s thanks to over a century of running trains. It might work a little better there, but the lack of thermal conductivity would have the same problem.", "timestamp": "1567043990"}, {"author": "Jeff Kaufman", "source_link": "https://www.facebook.com/jefftk/posts/10100108686123972?comment_id=10100108710669782&reply_comment_id=10100108713554002", "anchor": "fb-10100108710669782_10100108713554002", "service": "fb", "text": "→ BDan I guess I hadn't thought the layer of heated rock was that thin? The subway stations have been warming it for a century!", "timestamp": "1567044512"}, {"author": "Jeff Kaufman", "source_link": "https://www.facebook.com/jefftk/posts/10100108686123972?comment_id=10100108710669782&reply_comment_id=10100108868478532", "anchor": "fb-10100108710669782_10100108868478532", "service": "fb", "text": "→ I realized another thing that makes me think the station is holding a lot of heat at a different temperature from there surrounding rock. On cool mornings in the summer, like this one, when I walk into Davis it's substantially warmer than outside or than the ground temperature. This comes from a couple months exposure to warm summer air. By shifting that exposure towards the cooler end of things we should be able to have much cooler stations.", "timestamp": "1567167422"}, {"author": "Ruthan", "source_link": "https://www.facebook.com/jefftk/posts/10100108686123972?comment_id=10100108710669782&reply_comment_id=10100109240223552", "anchor": "fb-10100108710669782_10100109240223552", "service": "fb", "text": "→ Recognizing that it's cheaper to heat things than to forcibly chill them, does there come a point in fall or winter when having cooled the station in summer is regrettable?", "timestamp": "1567384329"}, {"author": "Jeff Kaufman", "source_link": "https://www.facebook.com/jefftk/posts/10100108686123972?comment_id=10100108710669782&reply_comment_id=10100109255952032", "anchor": "fb-10100108710669782_10100109255952032", "service": "fb", "text": "→ Ruthan I believe the stations are unheated
In general people are traveling in their outdoor clothes, so I think this is fine. I don't like how buses/trains are often warm enough that I have to take off my coat and carry it.", "timestamp": "1567394390"}, {"author": "Mac", "source_link": "https://www.facebook.com/jefftk/posts/10100108686123972?comment_id=10100108710949222", "anchor": "fb-10100108710949222", "service": "fb", "text": "Night cooler -- no brainer. With super low cost fan movement of air, rather than heat pumping for AC.
That's how we cooled our house in SC -- lonng ago. That's how I cool my house today in MA.
And it pays to cool the warmer wall treatments. Because obviously, the rock is not adequate.", "timestamp": "1567044045"}, {"author": "Michael", "source_link": "https://www.facebook.com/jefftk/posts/10100108686123972?comment_id=10100108736368282", "anchor": "fb-10100108736368282", "service": "fb", "text": "Much of the time in NYC, the air in the stations is much warmer the air outside. Ventilation is very poor. I had this demonstrated to me as I struggled down a bit platform and walked through a blast of cool air and realized I had just walked under a side walk grate. The effect was limited to immediately under the grate.", "timestamp": "1567065494"}, {"author": "Gavin", "source_link": "https://www.facebook.com/jefftk/posts/10100108686123972?comment_id=10100108827326002", "anchor": "fb-10100108827326002", "service": "fb", "text": "In Boston, one thing I often see, and I think it's very advanced*, is air conditioning condensers placed in public areas in a subway station, with the conditioned area being private to employees of the MBTA.
You can see this in many stations, but not the least among them is South Station, Central Square and Harvard Square.
Jeff Kaufman, I haven't run the dynamics on your idea. But I hope you can also appreciate my point about the amount of respect the MBTA shows its customers; every one of these condensers is just a big middle finger, isn't it?", "timestamp": "1567124618"}, {"author": "Avi", "source_link": "https://www.facebook.com/jefftk/posts/10100108686123972?comment_id=10100108836208202", "anchor": "fb-10100108836208202", "service": "fb", "text": "I think the NYC subways need high capacity ventilation 24/7 during the summer, not just at night. I think the trains generate a ton of heat so I don't think ventilation at night is enough.", "timestamp": "1567129922"}, {"author": "Bill", "source_link": "https://www.facebook.com/jefftk/posts/10100108686123972?comment_id=10100109179445352", "anchor": "fb-10100109179445352", "service": "fb", "text": "These problems can be solved, with an engineering budget and political will to assign it. The subways in Montreal were quitr comfortable both times I visited (hopefully more). So NYC and Boston should learn from them. My recollection is that they were DRY, which makes both cold and hot air more comfortable for humans.", "timestamp": "1567350691"}, {"author": "Jeff Kaufman", "source_link": "https://www.facebook.com/jefftk/posts/10100108686123972?comment_id=10100109179445352&reply_comment_id=10100109182374482", "anchor": "fb-10100109179445352_10100109182374482", "service": "fb", "text": "→ Bill Montreal is a lot colder than NYC and Boston though, which probably means this easier?", "timestamp": "1567352793"}]}