Obviously you wouldn’t want to let it warm up again before you bottled it. Which meant you needed to store it cold. This is all way more complicated than naturally-conditioned bottled beer. Bass Pale Ale just needed to be left in a wooden hogshead in a cellar for a few months. No messing around with cold tanks, artificial carbonation or filtering.
“Storage of Chilled Beer
Once beer has been chilled to a temperature of 33º, or thereabouts, it is essential to keep it at that temperature until bottled. It is usual to store the beer in tanks placed in a specially insulated room. The tanks resemble those used for conditioning, to all intents and purposes, except that in most instances they are not fitted with rousers. This omission has its disadvantages. It is invariably necessary to add the finings at this stage, and without rousers it is more difficult to ensure that they are thoroughly mixed in with the beer.”
"Brewing Theory and Practice" by E. J. Jeffery, 1956, page 339.
I assume the main reasons for the constant cool temperature were to keep the beer stable and to keep the CO2 in solution. If the beer got too warm, all sorts of nastiness could happen if it wasn’t totally sterile. I’m sort of surprised finings were added at this point. Hadn’t they got rid of all the sediment in the conditioning phase?
The solution wasn’t just to have a tank kept cool, but a whole room:
“The cold room is usually insulated by covering the walls, roof, and floor by a double thickness of cork slabs. The thickness amounts in all to about 8 inches. The joints should be staggered so that the two layers do not coincide. The whole surface is faced with cement, which should be of special texture to avoid cracking. The most suitable method of cooling is by cold air, the temperature of which has been reduced by its passage over a series of cooling pipes connected with a refrigerating plant. This plant is usually situated at one end of the insulating room, being partitioned off. The cold air is carried into the room by means of ducts fixed to the roof, and passes into the room through various ports. The apertures of these ports can be opened or closed at will. In order to prevent ingress of the warmer outside air if the door is opened it is usual to provide a small air lock, with a door at each end. One of these doors should always be closed before the other is opened. In this way, any large quantity of cold air is prevented from escaping and no hot outside air may enter.”
"Brewing Theory and Practice" by E. J. Jeffery, 1956, pages 339 - 340.
And here’s another consideration: a room at freezing point wasn’t the most pleasant environment in which to work:
“The question of the discomfort of working in a cold store is being dealt with in some modern plants by having the tanks separately insulated and cooled, so that the working space in the cold room can be at a comfortable temperature. The tanks are covered with six-inch cork insulation (or similar material). Special arrangements are then necessary to prevent loss of heat at the manhole. Cork insulation needs painting with a waterproof finish to prevent absorption of moisture from the air which would impair its insulating properties. In some recently built plants this has been avoided by supplying the cold room with dried air, thus obviating the necessity for any special waterproofing of the cork insulation.”
"Brewing Theory and Practice" by E. J. Jeffery, 1956, page 340.
There must be some sort of regulations about that now. How cold your workplace can be. Come to think of it, most small breweries I’ve visited in Bavaria have a closed, refrigerated room with their open fermenters. They aren’t quite as cold as freezing point, but they are pretty chilly. The lagering cellars at Pilsner Urquell aren’t exactly a tropical temperature either.
Still using natural cork for insulation. How quaint. I’m sure than would be far too expensive today.