Varying Temperatures.
—Commercial demands require a variety of temperatures, some at zero, some at fifteen degrees and some at thirty-two or over, in the one building. The maintaining of these varying temperatures in one building requires most careful designing, since the concrete everlastingly conveys cold and attempts to cut off a floor from that above can only be done by comprehensive and extravagant insulating.
There have been storage houses where with a freezer situated over or under an egg room a stove was maintained in the egg room to offset the cold temperature from above or below. A dangerous, costly expedient as well as the risk of freezing eggs. To encase and isolate a room to maintain zero to fifteen degrees in it and, say, thirty-two above, it is necessary to perform the following insulating: Line the ceiling and beams; cover the floor; cover the columns, so as to really envelop the cold. When insulation is placed on the floor, naturally the question of a wearing surface over the insulation is apparent and to maintain it fire-proof this must be cement or perhaps mastic. This causes an expenditure for wearing surface over the floor insulation, increased column quantity and strength, increased deadload of floors, insulation of floor and ceiling, of columns, and this, conservatively speaking, amounts to a total of eighty-five to ninety cents per square foot of area. This over one foot is but a small amount, but on a building one hundred feet square it becomes eighty-five hundred dollars per story.
How to Sub-divide.
—To meet the variety of temperatures required, subdividing the premises into sections, but doing it vertically rather than attempt to divide it horizontally, with a portion set aside for each division of temperature. If the business is of such volume as to permit this, make no attempt to insulate one floor from that above, as there is no practical way to do it and obviate an investment in insulation from which there is no return. A thorough external wall and roof insulation is strongly recommended, and the cold radiating into a room above that may be only partially filled or empty may be considered as no great loss, provided the outer contacts are eliminated or minimized.
In fire-proof construction the loss of cold through the ground is an unsolvable problem. To effectually do so it would be required to insulate every floor slab, top and bottom, all wall beam and column surfaces. From the foregoing deduction the cost would be prohibitive.
Basement Freezers.
—It is obvious from this argument that freezers should not be located in basements. It is far better to locate them on the upper floors of the buildings and make the cellar a moderately cold room, permitting the cold that will to radiate from the columns to chill it, but supplying such additional piping as may be required to maintain a regular temperature. If a freezer is placed on a first floor, it requires insulating the basement ceiling, which can be readily done. The basement columns are not insulated.
Piping Systems.
—With reference to piping for freezing boxed goods or beef cuts, the shelving system made from coils of pipe upon which to store the product while freezing is preferable. They are equally efficacious, whether used in brine circulation or direct expansion of ammonia. The coils in the freezing rooms are located on ceilings, making one layer over ceiling for fifteen-degree rooms where conditions permit, for handiness in removing frost. If the rooms be carried at thirty-two degrees or over, group the coils in alleys to enable easy location of pans for collecting drip, when coils are out of service. Whether one uses direct refrigerating by expansion of ammonia or brine circulation through pipes hung in rooms or indirect refrigerating by circulation of chilled air is a matter governed by local conditions and requirements.