Speaking of Metro air conditioning, is the air conditioning in Dupont Circle working? The station is extremely hot. Gallery Place seems to be slightly cooler, but Dupont is almost like a steam room. Ugh.

by Aaron on Jun 1, 2011 8:31 am • link • report

That Unsuck report on AC is pretty damning.

I found it funny that the original Swedish article on commuting uses a train as an illustration.

http://www.thelocal.se/33966/20110524/#

The article on VMT and TOD is something I'd like to agree with. Clearly, not having to drive 10 miles roundtrip to go CVS or the grocery store makes a big difference. However, anytime you talk about VMT you're dealing with a bunch of false indicators. And their data shows a big drop when you factor in transit, but a smaller drop for transit+TOD.

by charlie on Jun 1, 2011 8:51 am • link • report

re: NSF move, I think it's interesting you said "Arlington's congressional delegation". The signers of the letter to GSA were our two US senators and Moran, who also represents Alexandria. All three of those people are also, by the same token, "Alexandria's congressional delegation".

by Lou on Jun 1, 2011 8:55 am • link • report

@Lou, I agree with you on the questionable terminology re: "Arlington delegation", but it comes directly from the linked article.

by Jacques on Jun 1, 2011 9:21 am • link • report

Metro stations are not air conditioned. There is a cooling system that lowers their temperature by 5-10 degrees relative outside (and prevents the system from turning into a NYC-style oven), but that's it.

by andrew on Jun 1, 2011 9:35 am • link • report

@Andrew - could you elaborate on the technology used to cool stations and how it differs from standard AC?

by HID (Hot In DC) on Jun 1, 2011 9:43 am • link • report

Do you think that when Sulaimon Brown walks into the Wilson Building, this will be playing?: http://www.youtube.com/watch?v=TAGI5d4iUCs

by Shipsa01 on Jun 1, 2011 9:47 am • link • report

"Underground stations have chilled water air handling units, or chillers, not air conditioners, to cool the air. The Metrorail cooling system was developed in the 1970s to reflect energy conservation standards of the time. Temperatures in stations were designed to be up to 20 degrees cooler than outside temperatures"

This is a little confusing since they defined an AC system, but people usually think of an AC system that uses Freon or Freon like coolant instead of chilled water.

by RJ on Jun 1, 2011 10:02 am • link • report

RJ: What chills the water? Usually a refrigeration unit with an evaporator heat exchanger.

This typically works by chilling water using a refrigeration unit (works just like an air conditioner), and then circulating the chilled water (at about 40-50F) to cooling coils distributed in air ducts, where it cools and dehumidifies the air that is distributed to the space.

I think there is little technical difference between saying what you're saying and that the stations are "air conditioned". The spec on maximum ambient temperature may be higher than expected, but the air is still cooled and somewhat dehumidified.

by Michael Perkins on Jun 1, 2011 10:10 am • link • report

One of the differences in a chilled water loop system is it can be switched over the heating water in the cold months to provide heat. If you want to provide heating in a DX type AC system (freon expansion condenser units), you have a downstream duct heating system (usually electrical resistance) that are very inefficient. That's why most large facilities rely on central plant type design for HVAC.

Having said that, with most of Metro underground or exposed to weather I don't even know if they provide heat in the stations, or need to. Similar to most 7-11's that do not have heating systems, they just recycle the rejected heat from the food coolers, and most people have their coats on in the winter anyway so they don't notice.

by Lou on Jun 1, 2011 10:21 am • link • report

Also just to add on the differences, dehumidification in a chilled water system is not nearly as effective as a "normal" AC system like at home. That's why the stations get so oppressively humid. I think that's probably the most relevant point in this instance.

by Lou on Jun 1, 2011 10:35 am • link • report

Lou,

Another problem is the stations are not sealed environments. Trains entering and leaving couple with the open entrances, draws the outside air further decreasing their efficiencies.

by RJ on Jun 1, 2011 10:45 am • link • report

Fairfax/Loudoun County delegate Jim LeMunyon has requested money from the Commonwealth Transportation Board for "congestion reduction" projects such as widening highways and building new expressway bridges.

Did you read the press release? The guy asks for a study that's already in the works (I-66 and VA-28), and better access to metro stations for the residents of his suburban district where there barely is any transit. So, GGW here is making fun of a republican that is trying to get his residents faster to existing metro stations. Well done GGW. That'll teach him!

by Jasper on Jun 1, 2011 10:46 am • link • report

The stations are indeed air conditioned. Whether this is accomplished by a chilled water system (think your office) or a DX refrigeration system (think your home) doesn't matter.

To properly cool a space like a metro station to what most people would want at home or in their office is just unrealistic and a total waste of energy. Instead the system is set up to only cool or heat a small portion of air in the space (lets ballpark it at 8-10' above the platform) and to only reduce the temperature 10-15 degrees below ambient. That means that even on a day in the 90's the station will only be in the 80's. Not super comfortable but a HUGE improvement over baking in the sun.

As for Lou's comment that a chilled water system is not as efficient at dehumidifying as a DX system...well that just isn't true. To properly dehumidify you need to bring the temperature down far enough to remove the moisture and then "reheat" the air back up to a comfortable temperature.

Lets be realistic though...the real reason that metro stations are uncomfortable is that for years the infrastructure hasn't been maintained. Anyone remember just last year or the year before when the chiller serving Metro Center and Farragut North was out? We had months of horribly high temps in those stations and the temporary fans didn't help much.

The article below covers some of Metro's targets and touches on the equipment they use:

http://www.washingtonpost.com/wp-dyn/content/article/2009/08/15/AR2009081502627.html

by Craig on Jun 1, 2011 11:48 am • link • report

Craig, that's exactly what a DX system does though. Your basic commercial grade fan coil unit will overcool the air and condense the majority of moisture out. You have plenty of buildings, even hospitals that utilize this type of DX cooling with reheat (electric or even sometimes steam) in some spaces to achieve some humidity control.

With a chilled water system, your humidification is more like taking a Gatorade bottle out of the fridge and setting it outside on a day like today, watching the water form on the surface.

by Lou on Jun 1, 2011 12:25 pm • link • report

Lou-

I don't disagree that a DX unit can achieve the same thing. Regardless of which method provides cooling, the coil is going to be where the moisture condenses out of the air and will be designed for a certain leaving air temperature (typically 55 degrees or so). While the coils are designed differently for chilled water or DX they do the exact same thing.

It really comes down to which application is more appropriate for your use. In a system like metro (or any large facility or office) chilled water is going to win out purely from a distribution standpoint. It's non-toxic (no need for large refrigerant exhaust fans or expensive monitors), easy to distribute over large distances and doesn't require individual condensing units for every air handling unit. For a small equipment room however a DX unit is going to win out. Again it all depends on the application.

To really wring out all the humidity in an environment such as this is going to be very difficult or impossible. You've got the humidity from the surrounding environment plus the latent load produced by all of the passengers. Throw in the stations being open and trains frequently coming and going and the best your going to be able to do is try and make it more bearable.

by Craig on Jun 1, 2011 1:08 pm • link • report

aren't the trains designed to provide some air movement in stations when entering or leaving? Just anecdotally, they don't seem to do that anymore...at least you don't have marilyn monroe moments on the street level grates.

If you believe in global warming, you're going to have to find ways to AC (and dehudify!) those stations.

by charlie on Jun 1, 2011 1:33 pm • link • report

Charlie-

Only way I can think of to do that efficiently is to build platform screens and add entry vestibules to the station instead of having them wide open. I can think of several added benefits to this too...such as limiting the ability of people to jump in front of trains. Of course this would require trains to stop in the same spot every time. I have my doubts as to whether that is possible

by Craig on Jun 1, 2011 1:50 pm • link • report

@Craig

Why do you doubt it is possible? Plenty of other Metro systems around the world do it without fail every day.

Hell, why not look into full automation, as Paris has done with their new Line 14 and is retrofitting into Line 1.

by Alex B. on Jun 1, 2011 2:01 pm • link • report

Alex B.-

Let me rephrase...I believe it's entirely possible...just not with Metro. Unfortunately my confidence in their ability to do something like stop in the same place every time, or run on a schedule, or be completely automated has been shot. Maybe they could've done it at one point but I just don't see them being able to accomplish that now and I find that sad.

by Craig on Jun 1, 2011 2:09 pm • link • report

Is there a timeframe for returning to ATC?

While I see the need for AC and sealing the tunnels, aren't the regular station entries OK? I mean, doesn't cool air sink?

by charlie on Jun 1, 2011 2:28 pm • link • report

@ Craig: Unfortunately my confidence in their ability to do something like stop in the same place every time, or run on a schedule, or be completely automated has been shot.

You must not be using metro a lot. Since the trains stop at the end of the platform, I can totally predict where my favorite doors stop, within a foot. I am surprised not more people have figured this out, but am happy because it gives me a larger chance of getting in at a crowded platform.

Trains in Franconia-Springfield often stop and then pull up the last 4 feet for some reason. It's very funny to see people run to a door, not move myself, and then have the train pull straight in front of me, with a lot of frustrated people next to me "loosing" spot at the door. /snickers.

by Jasper on Jun 1, 2011 4:24 pm • link • report

I remember when the NSF move to Ballston was a real coup. Office space in NoVA had been overbuilt during the 1989/90 real estate boomelt and it was a bargain. The Metro-centric location would be difficult to beat and I'll bet GSA would end up with a hefty bill for parking elsewhere.

by Rich on Jun 1, 2011 9:36 pm • link • report