Structural design in sub-zero temperatures

[Daria]

I have to design a small 15,000 sq. ft. single storey freezer building. (25 ft. height steel building with metal roof deck and insulated wall panels).

The operating temperature inside will be -50 deg F (-45 Celcius). Assuming summer construction, the differential temperature will be in order of 120 deg F (65 deg C). The building is completely insulated (walls, floors and roof).

Are there any design guidelines I need to follow? Any words of wisdom? Any good details I should consider from your past experiences?

I appreciate your help.
Daria

 

[Geof]

I'm a mechanical, but in an industrial refrigeration course that I took, the subject came up.

"Industrial Refrigeration Handbook" by William F. Stoeker (the book was used in the course, and the writer taught it) has a chapter entitled "Refrigerated Structures". It notes a few critical items but isn't really meant as a design guide.

These include vapor barriers, underfloor heating, & column considerations.

The wall and ceiling vapor barriers prevent frost from forming inside insulation and blowing out the walls. We saw a presentation that showed results of construction with inadequate vapor barriers - it was pretty bad. We also saw photos of the results of floor heaving without underfloor heating - jagged concrete, multiple spots up about a foot and a big lawsuit.

Columns are usually installed with a 6" block of oak wood between the column base and the footing, installed with the grain up for some reason. This acts to slow heat loss from the refrigerated space through the steel.

Good luck - I hope this helps.

 

[Daria]

Thanks for the helpful comments Geof

 

[Watermelon]

If you're going to do structural design in sub-zero temperatures I would recommend you wear your mittens and keep a thermos of hot chocolate nearby.
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I'm sorry, I just couldn't help myself.

 

[Daria]

I like your sense of humour Watermelon. That's the kind of response that would always get me in trouble with the teaching staff in high school ... I miss those days.

 

[Watermelon]

Daria:

Unfortunately, structural engineers do not get much training in the area of thermo-dynamics. Equally true is to say mechanical engineers don't get much training in structures.

Geof, the grain needs to be parallel to the load because it is stronger that way and also because shrinkage is less of a concern. And I agree, wood is a good insulator.

Back to Daria:

The reality is that structurals often have to insulate foundations and often have to be aware that certain portions of buildings may not be heated.

I'm not a wizard with your type of problem, but I can tell you about a few things I have seen. Take from it what you will.

In an ice-arena I saw large portions of the structural steel frame extended outside the building. Architecturally it looked great. Except these huge fins acted as giant heat exchangers. In the winter, warm moist air in the bleachers would condense on the ice-cold steel and drip on the people. In the summer, heat from the steel would make it tough to make ice. It was obvious to me they did not consult a mechanical engineer for heat loss etc.

Concerning a cold-storage building, I saw a report written by an engineer recommending an apron of insulation to protect the foundation from freezing and heaving. But there was no heat in the building, so insulation would only delay the inevitable.

I'd suggest you employ a mechanical for thermo considerations.

I'm not sure about Geof's comment concerning in-floor heating. You want this building to be cold, you don't want heat.

Don't know where you're building this; tropics or nothern climes. Do have to worry about ground freezing from normal outside temperatures?

You will want the vapor barrier on the outside face of the wall.

Pay attention to your foundation materials. You want excellent drainage and granular materials which are not frost-susceptible.