SCIENCE AND WARMTH

Evening Star, Issue 20252, 13 August 1929, Page 2

SCIENCE AND WARMTH

ENGLISH EXPERIMENTAL HOUSE PERTINENT HOME PROBLEMS The man who sits shivering because his back is radiating heat to" the wall behind him may now be informed, if it is any com tort to him, that his shivers have become the object of thoroughgoing scientific research. i was conducted yesterday (writes a representative of the London 4 Observe/' •’) over the experimental house which has been erected by the Building Ik'search Board at Watford, and which is perhaps the only house in the country where the great frost has been welcomed. “ It’s just what we want 1 It gives us extremes,” said one of the experimenters.)

From the technical aspect the first object in life of the experimental house is to replace the rough-and-ready formula by which heating engineers compute “ the contribution of a wall to the loss of heat from a room,” with a formula (yet to be discovered) which shall have a true .scientific basis. But even for us, to whom the Heat Transmission Coefficient ”• is a dangerous animal not to he meddled with, this research into tho problem of keeping warm is interesting. The experimental house is about the size of the ordinary subsidy house. Though from the outside it looks innocent enough, it is built in a steel frame in such a way that the walls and the roof can bo replaced by walls and roof of other materials. At present the house has 9in brick walls and a tile roof. In the next stage of the experiment it will have cavity walls. Indeed, it was intended that the house should have changed its face some time ago, but when experiment had fairly begun it was found that the problems of heating were so com plicated that the duration of the first—the brick—stage of the experiment had to be continued indefinitely. COMFORT AT 75 DEGREES. The house is heated throughout by electricity—for reasons which will be dear hereafter. In each room there is an electric stove and near the middle of the room a (lummy man. This person is interesting. * Ho is a black--painted hollow copper cylinder, inside which is an electric heater which dissipates twenty watts. “ That,” said my guide, “ represents his breakfast.”) Now it is required to keep this dummy man “ comfortable,” and for the purposes of tho experiment his comfort has been postulated as a temperature of 75 deg. Fahrenheit, and ho is to lose heat at tho rate of 17.5 British Thermal Units per square foot per hour. Tin’s is held to ho a condition of comfort for a sedentary occupation. Tho dummy is sensitive to surrounding objects, to draughts, and to sunshine, and whenever his temperature rises above 75 degrees he automatically switches off the stove, la some of the rooms, where there is little draught and little sunshine the dummies seem to load fairly regular lives and tho chart shows that they switch the heat on and off at regular intervals. In other rooms tho graph is more erratic. It is surprising how much difference winter sunshine makes in tho temperature of a room. When in tho direct sun tho dummy is naturally comfortable with a much lower air temperature; but it has been found that sunlight radiated from the walls makes a very great difference too. The dummy _ makes great play with his switch in the sunnier rooms. MASTERIES OF RADIATION. Thewhole question of the transfer of heat is intensely complicated. From any surface maintained at a temperature higher than that of its surroundings, heat escapes both to the contiguous air—a process known as convection—and by radiation to relatively cooi surrounding surfaces. Tho mail with his back to a cold wall with whom wo began, is losing heat for the most part by radiation. Radiation has some odd effects. It is found, for instance,' that somctimes_ at night a wall will be radiating heat into tho room instead, of

out of it oven though tho temeprature ot the room is considerably higher than that of the air outside. The explanation is that one of the walls on which the sun has been shining during the day is warmer than the opposite wall and the inward radiation from this wall to the cooler wail is greater than the normal radiation from the centre of the room outwards. Some building materials delay tho passage of tho sun’s heat by eight or nine hours, and it is suggested that it may be possible to build houses in the tropics in such a manner that one room will not let th • heat through till night, when it is more bearable, and another room will he adapted for use during the day. In the experimental house delicate instruments record the heat radiation and convection of each wall. Radiation from windows presents a still more complicated problem, which is receiving special attention. At the present stage of the experiment the vontilation_ factors are kept at the simplest possible. Tho windows are never opened. THE RADIATING PANEL. The investigation is only at tho beginning. Later, the house will bo heated with coal and coke fires, and there will be many variations in the experiment, Dr Margaret Fishenden, who lias been making researches into fuel, is co-operating with Mr A. 8. Duflon, who is working on the experimental house. Many homely questions may in th© end receive scientific answers. It may he possible to discover exactly what is the economy in heating made by building houses in rows like barracks. In a block of flats which is tho warmest? The ground floor, the first, the second? Certainly not the attic! Already strong scientific-support is being given to the common sense of onr ancestors, who covered their walls witti wood panelling. It has been found that with double the rats of heating which- serves to maintain warmth, the time taken to warm the surface ;of a 9in brick wall is six hours; for a lin wall of wood the time is ten minutes. The moral is surely that there should bo wood panelling in all dining-rooms!