Glass Box Front Entrance 4

[Norm01]

Hello,
I am working on a new 2 storey front entrance to a hospital with large south facing windows (see attached sketch). The entrance will be used to connect people to the main hospital and a doctor’s clinic. It will be equipped with seating along the south and east walls and include a water feature (not determined yet) in the middle. The existing cooling system in the hospital is maxed out and with a tight budget we looked at providing a new AHU to serve the new entrance. Cooling would be provided by a DX coil, while we could use the existing boiler plant for heating. I would like to get your thoughts on how to treat the south facing and east facing windows. I am not sure if air would be the best approach or if hydronic should be used. Air would be able to address both heating and cooling, where as hydronic would only allow for heating.
Any thoughts or comments would be appreciated.
Thank you.

 

[KiwiMace]

You need to first work with the architect to get the glass transmissivity someways workable. Perimeter underfloor air would be my first approach. You don't have the option of hydronic cooling. Is there a usable ceiling space?

The seating - can this move to the north side (assuming northern hemisphere here)? Sitting in the sun will always feel hot and the seating will need to be set out from the glass for airflow. Blinds will also help.

 

[WindOption]

Hi there, I am a Junior HVAC engineer from Jamaica. I don't know exactly where you are, so I can tell you what I think, judging from my experience in Jamaica, and only with the cooling aspect, as Jamaica never needs to heat. I would either shade or tint the windows (especially the east)and use blinds as KiwiMace said. Depending on your location, the south may not be as bad, but even with the blinds, right at the window, the occupants will be hot.

 

[IRstuff]

I've yet to see windows, shaded to anything short of opaque, not overheat anyone sitting in front of them. Even a solid wall, if thin enough, will absorb sufficient solar load to heat up the interior.

You'll definitely need double-paned, low-e windows, but some sort of shading, particularly for late afternoon needs to be considered. However, there are a variety of architectural artifices that can be applied to minimize the solar load into the area.

TTFN

FAQ731-376

 

[marcoh]

I am currently working on something similar, and are using perimeter floor grilles along the glazing with displacement ventilation. Glazing is an low-e IGU (U=1.7, SC=0.25)with limited shading (ie effective shading was not architecturally acceptable!). If the the people sitting near the windows get uncomfortable, they have the option to move.

If you are in a cold climate I would go for underfloor heating, and if you install an underfloor heating system, using it for slab cooling also becomes an option which is very effective for atriums with extensive glazing and solar loads. The cool slab immediately absorbs any solar radiation that hits the floor, thus effectively reducing the space sensible load that the air needs to cool.

 

[willard3]

What is your location and its climate? It will make a difference.

 

[Ziggypump]

How about hot water/dx air handler for the entrance, with some fintube radiators along the base of the windows? this would help with the heating load in the winter, is relatively inexpensive (a lot cheaper than radiant floor - but I like this idea) and like marcoh said, "people have the option of moving".

Also, what is outside the windows at the entry? are there lots of trees, buildings, something nearby that might cut down on the solar radiation into the space?

 

[Norm01]

The location of this project is Winnipeg, Manitoba, Canada so it very cold in the winter and very hot in the summer. A radiant floor system would probably be ideal choice, but it is outside the budget. There are no trees in front of the entrance. Recently, the architect is looking at using triple pain glazing with a low-e on the exterior.
I was looking at using fintube at the base of the windows for heating in the winter, but I'm not sure of the best way to deal with air distribution in the summer. Top down is not an option (no drop ceiling provided), maybe jet nozzles placed along the west wall at approximately 10-12ft height discharging sideway?
Thank you for all your input please keep the discussion going.

 

[willard3]

I would change whatever you have to change to do a radiant floor for heating. It takes less space, has no visual impact and heats better than fin-tube. It will also keep the ice and snow on the entry floor to a minimum.

 

[Ziggypump]

What about radiant baseboard with a VRF heat pump system with the indoor air conditioning units spaced along the perimeter? This would allow for cooling and supplemental heating, and the architect could go to town with designing a ceiling system.