Heat Insulation.
UNDER the supervision of Prof. A. Bugge, of the Norwegian Technical Academy, a series of 24 huts were erected, identical as to design and dimensions, but differing as to the materials used in construction. These huts consisted of a single chamber, 6 ft. 6 3/4 in, by 6 ft. 6 3/4 in. by 7 ft. 4 1/2 in., built over a cellar, which, together with the roof, was carefully insulated. Each hut was heated by electricity, automatically controlled by a thermo-regulator. Thermal measurements were taken during l 1/2 winters. These measurements were plotted, the results obtained with a wooden-framed house being taken as 100 for purposes of comparison. The two huts which directly interest our readers were hut 8, built of three-air-duct concrete blocks on the Lean system, fixed by means of tarred dowels, the hollow spaces being filled with coke breeze at floor level to a depth equal to the thickness of the floor, matchboarded
and plastered. This was rated at 140. Hut 18, with walls of High-Rib lathing fixed to wood framing, the external wall with 1 1/4 in. plaster rendering, the inner lathing rendered with 3/4 in. of plaster, a space of 5 in. being left between the two sections. This was rated at 129. The best insulated house was constructed of two walls of matchboard, packed between with sawdust; rated at 96.5. It was found that hollow walls gave better insulation than solid walls, but where these are built of bricks or blocks the mortar between joints should not be allowed to obtrude inwardly or droppings of mortar to accumulate. That in hollow walls, the heaviest and thickest should invariably be the inner one, so as to guard it against damp. It was found that a lightly-burnt brick was a better non-conductor than a hard burnt brick; it was therefore recommended that the bulk of the wall should be built of medium bricks with hard brick outside skin. (Teknisk ukebald.)
Messrs. H. Kreuger and A. Erikson,