Hot air - COLD feet

Tom_133

Hey Wallies,

I was called in on a potential commercial project that currently consists of ceiling ducted heat. It keeps the massive space happy at 70 degrees, but any of the desks that are up against outside walls are "freezing under the desk in the winter" where the employees feet get very cold. The loud chorus of complaining has landed on listening ears and so the building supervisor has brought me into to take a look.

Its an old brick building in Burlington Vt, its a large open office space, it has 2' outside walls, 12" of brick and another 12" of sheetrock and framing, but not a whole lot of insulation, hence the complaints. The reason the building supervisor wants to take care of this is the multitude of electric heaters the employees have brought in to take care of the cold under the desk, some bringing up to 3 heaters and they stay on full-time even at times over the weekend due to forgetfulness.

He wants to know how to fix this problem, my only suggestion thus far is commercial style baseboard at low temps, as a tempering device and not adding too much heat in the space. I would install directly behind desks at foot level. This will be a big project due to having some dropped ceiling in the basement but not really having good access and each floor full of people working in offices.

I am open to better and smarter suggestions??

Tom

STEVEusaPA

I am open to better and smarter suggestions??

Insulate

Larry Weingarten

Hi, I'd start with a blower door and see if the leaks can be found and fixed first. and/or walk around with an IR camera on a cold day an see what's what.

Yours, Larry

Jamie Hall

Which building is this? I probably know it from years gone by.

As @STEVEusaPA and @Larry Weingarten said, start by finding any leaks and fixing them, and then if possible add insulation in the 12 inch cavity.

That, however, given Burlington's lamentable winter climate, may not be enough -- and I really like your idea of relatively low temp baseboard heat. With some thought and care, I suspect you might be able to run much of the needed piping in the baseboards themselves, rather than battling with the basement ceiling. I'm thinking of the baseboards in sections, piped parallel reverse return... You are not, after all, trying to heat the space as a whole -- just the area under the desks.

kcopp

The wind off Lake Champlain is wicked.... Cast iron baseboard.

Tom_133

Thanks all,

I agree that insulation is mandatory, but I just dont see it happening, I dont see them cutting open walls that are finished. Now walking around with an IR camera is a good idea to find big trouble areas to do spot repairs or the like. Sadly they put the cart before the horse on this one, and now want try to fix it. I have personally had this same issue in other buildings with adequate insulation that when your feet are under the desk your feet are cold, hot air has limitations. To make it even more interesting, each person is a little different, one thinks its freezing where another would like a little more heat. I was hoping to do bigger baseboard and pipe it just as Jamie suggested and possible put thermostatic valves on. Its a bit of work but ultimately it would be for the best.

Jamie Hall

You know, @Tom , if you piped the baseboard as I suggested, or some variation on that, and gave each cube dweller their own section and their very own TRV, you might have some very happy campers... and come out looking like a hero, which is always nice.

Tom_133

My thought exactly! I love looking like a hero

nicholas bonham-carter

Doesn’t there exist an electrical floor mat?—NBC

GBart

Oh my god, had this exact same problem, it was women dressed in skirts and open toed shoes in the dead of winter, you and I wear pants, socks and good shoes, then they start bringing in heaters, popping the circuits and 200 people lose any work not saved on their computers.

It became a hot bed issue, the way they solved it was they made a rule that NO ONE was allowed to bring in any heaters and you could be fired for doing so, then they bought these foot warmers, they look like a angled foot rest and they just get warm, it was cheaper than losing productivity.

They were something like this.
https://www.homedepot.com/p/Cozy-Products-Toasty-Toes-Heated-Foot-Rest-TT/202933432?cm_mmc=Shopping|G|Base|D27E|27-23_PORTABLE_HEATING|NA|PLA|71700000034238966|58700003946879293|92700031953708174&gclid=EAIaIQobChMIhZbak_GW2wIVleNkCh0sQgscEAQYBCABEgLvb_D_BwE&dclid=CKGm67fxltsCFZEONwodHJgHWg

GBart

Bear in mind if you do a ton of work and this is caused by women wearing open shoes in the winter you will not solve the problem.

Tom_133

GBart, I fear you are probably correct. That is exactly why I am asking the question. Yeah I feel the mats and foot heaters are ok, but the cost of electricity is much higher than natural gas in Burlington. Thats why the super is pushing for baseboard, or something gas fired.

GroundUp

We put a lot of pedestal type baseboard under desks in these settings with favorable results. Most are fairly tight buildings, but in terms of comfort from open-toed shoe wearing cube dwellers, campers have been happy. Ours are all electronically controlled, but I think a TRV would do very well in your case

EBEBRATT-Ed

@Tom

Baseboard is the only fix. Anything else will not work. The cold brick is acting like an ice cube. Heat goes from "where it is to where it aint". from hot to cold. The cold brick is soaking up the heat in the room and no amount of scorched air will fix it. I have fixed many "hot air" job by doing this. Insulation will not work by itself but would only help

Tom_133

Thanks Guys

I will try to remember to let you know how it goes.

I am very limited on depth off the wall (3 1/4" - 3.5") I was thinking high output baseboard. I would like a commercial baseboard something tall to hide piping, any suggestions?

Zman

If you can swing it, a low profile rad like the Runtals would work great. I like the TRV idea, you could also put that loop on occupancy control.
The scenario you describe exists every where. I love going into offices where you know everyone have an electric heater and ask them how the heat in the building is working. They almost always say it works fine, probably fearful that someone will take away their electric.

JUGHNE

I know this would be too little....too late for that building, but for the few ceiling FAF systems I did design/build I make a point to place some RA grills in the low wall/baseboard mode. This helps reduce the cold floor for a normal studded building on slab.
I have never seen this done on a job that had a ME stamp on the plan. SA and RA all above would keep your head warm.

GBart

EBEBRATT-Ed said:

@Tom

Baseboard is the only fix. Anything else will not work. The cold brick is acting like an ice cube. Heat goes from "where it is to where it aint". from hot to cold. The cold brick is soaking up the heat in the room and no amount of scorched air will fix it. I have fixed many "hot air" job by doing this. Insulation will not work by itself but would only help

wrong, FOOT HEATERS are the only fix, baseboard will only warm them WHEN IT'S ON

besides, those heaters are not actual electric heating elements, they cost very little to run, they are warmers not heaters, 90watts and less

Jamie Hall

I beg to differ. Having suffered in a building somewhat similar... only in Waterbury, VT, not Burlington.

A foot warmer helps, but... the cascade of cold air coming down the wall will make your feet, ankles, and lower legs turn a funny greyish blue colour in about 15 minutes. The baseboard counteracts that; that's the whole idea. And if @Tom does it right -- which I daresay he will! -- the baseboard will be nicely modulated so that it is always on and warm in the chilliest cubes.

GBart

Look at where your feet are in comparison to a baseboard heater, they are at the air intake not the outlet, PLUS if you are dealing with a situation involving women wearing summer open shoes and skirts in the winter forget it, no win scenario.

The owner really needs to look at caulking, insulating, etc, that state should have a energy grant system for companies to get an audit and then you see where you infiltration is, it's cheaper by far, this is all speculation, this is not how you solve this problem, you get an energy audit complete with blower door and thermal imaging and find the sources of the problems and you address them.

GBart

I took a course in Sustainability and I'm a SBA, you might want to point these things out to the owner/employer, a good environment at the workplace increases productivity, reduces absenteeism, comfort and HVAC generally increase productivity 11%. Generally having a "green" environment increases productivity 26%.

So employee comfort really matters, but you really have to do a study to find the real problems.

Jamie Hall

Green sells. So does sustainability. Unfortunately, so does practical. So.. what you want is something which is practical, and which increases employee comfort and satisfaction. And which doesn't cost an arm and a leg.

If this is the building I'm thinking of, frankly it would be cheaper to knock it down and build something new (which is neither green nor sustainable -- nor historically sound) than to try to get it all nice and upgraded.

Or you could put in baseboards and everyone goes home happy.

Leonard

Got to add heat to bottom of that tall cold wall. Without it there's a boundary layer of cold air flowing down the wall , onto floor and people's feet.

Allways on baseboard sounds good, but sounds like lot of $ hardware to set it up if water based. No experience but might try to tap a duct off the hvac to distribute warm air in a long plenum along base of wall.

Tom_133

I like the different perspectives I am reading here all. My thinking is Runtals, one or two tier baseboard style would work well, low temp, condensing, modulating based on outdoor temp, always circulating during occupied times as Zman brought out.

By using this style it would help heat lower to the ground and better at their feet.

I am in no way stating that is the "perfect" scenario just want to do what makes the most sense in a practical way. Cant tear it down, and cant fix all thats not right. In fact I am only entertaining this because its what they want to do, and they feel I am the outside of the box enough type of guy.

Jamie Hall

Sounds like a plan, @Tom -- go for it!

Zman

GBart said:

EBEBRATT-Ed said:

@Tom

Baseboard is the only fix. Anything else will not work. The cold brick is acting like an ice cube. Heat goes from "where it is to where it aint". from hot to cold. The cold brick is soaking up the heat in the room and no amount of scorched air will fix it. I have fixed many "hot air" job by doing this. Insulation will not work by itself but would only help

wrong, FOOT HEATERS are the only fix, baseboard will only warm them WHEN IT'S ON

besides, those heaters are not actual electric heating elements, they cost very little to run, they are warmers not heaters, 90watts and less

@GBart , any chance you could turn down the volume a bit?

There is more than one way to approach any problem, this is a conversation about different opinions and options.

Obviously making it mandatory for all employees to wear wool paints and insulated boots would solve the problem. Mandating women's wardrobe choices is likely to prove problematic