room_heat_loss

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Calculate the design heat loss of a single room in watts, following BS EN 12831 as MIS 3005-D applies it. This is the figure a heat pump is sized from and the figure the radiator in that room must be able to deliver. BS EN 12831 is a room-by-room method. Run this once for each heated room and add the results; sizing a heat pump from floor area alone is what produces the oversized installations that cycle all winter. Internal design temperatures come from Table 1 of MIS 3005-D and follow from the room type: 22 for a bathroom, 21 for living and dining rooms, 18 for bedrooms, halls, kitchens and toilets. These are minimums, so a higher figure is accepted and a lower one is refused. External design temperatures come from Table 2, for eight locations, in two columns: 'a' is the 99% figure and 'b' the colder 99.6% one, which needs no uplift for intermittent heating. Each element needs an area, a U-value, and a kind. The kind matters because it fixes which temperature difference applies. Walls, windows, doors, roofs and suspended floors lose heat to the outside design temperature. A SOLID FLOOR ON THE GROUND loses heat to the local annual average air temperature instead, which is far warmer, and getting this wrong is the commonest error in a heat loss calculation. Window and door areas belong to the window and the door, not to the wall behind them. Method from MIS 3005-D. These calculators follow the published MCS methods, for understanding a system and checking a quotation. Anything that gets installed still needs a design and a site survey from a certified installer.