This section covers the heat lost through the walls, floor and roof. Heat Loss through WallsSurface | Wall Area (m2) | U Value Current | Heat Loss (W/K) | U Value Without insulation | Heat Loss (W/K) | | Front, Main | 19.41 | 1.64 | 31.83 | 1.64 | 31.83 | | Front, Extension | 6.48 | 0.32 | 2.07 | 1.47 | 9.53 | | Side, Right, Extension | 16.50 | 0.32 | 5.28 | 1.47 | 24.26 | | Side, Right, Main | 17.36 | 1.47 | 10.82 | 1.47 | 25.52 | | Rear, Extension | 5.02 | 0.32 | 1.61 | 1.47 | 7.38 | | Rear, Pillar | 3.41 | 0.32 | 1.09 | 1.47 | 5.01 | | Rear, Main | 13.95 | 0.36 | 5.02 | 1.39 | 19.39 | | Side, Left | 36.48 | 0.32 | 11.67 | 1.47 | 53.63 | | Total | 118.61 | | 69.39 | | 176.66 |
Heat Loss through FloorHeat lost through the floor is dependent on a proportion being conducted vertically down plus that which flows horizontally via the walls and foundations. As a result, a precise calculation takes into account the floor shape as defined by a ratio of the floor perimeter to area. However, the calculation below is for indicative purposes and so uses a generic values.
Current Insulation| Surface | Area (m2) | U Value (W/m2K) | Heat Loss (W/K) | | Main Building | 42.56 | 0.8 | 34.05 | | Extension | 22.68 | 0.25 | 5.67 | | Total | | | 39.72 |
No Insulation| Surface | Area m2 | U Value W/m2K | Heat Loss W/K | | Main Building | 42.56 | 0.8 | 34.05 | | Extension | 22.68 | 0.8 | 18.14 | | Total | | | 52.19 |
Heat Loss through CeilingWith insulation| Component | Area m2 | U Value W/m2K | Heat Loss W/K | | Main Building | 42.56 | 0.16 | 6.81 | | Extension | 22.68 | 0.16 | 3.63 | Total | | | 10.44 |
Without Insulation| Component | Conductivity (W/mK) | Thickness(m) | Conductance (W/m2K) | Resistance (m2K/W) | Resistance (m2K/W) | Inside Air Layer (In Room) | | | | 0.1 | 0.1 | Plasterboard | 0.16 | 0.0095 | 16.67 | 0.06 | 0.06 | Ceiling Joist | 0.13 | 0.1 | 1.3 | - | 0.77 | Outside Air Layer (In Loft) | | | | 0.04 | 0.04 | Totals | | | | 0.2 | 0.97 | Net Resistance | | | | 0.22 | | Overall U-Value (W/m2K) | | | | 4.55 | |
Percentage of ceiling area occupied by joists = (4/46)x100 = 9%
Net resistance = 1/(0.09/0.97)+(0.91/0.2) = 1/0.093+4.55 = 0.22| Component | Area m2 | U Value W/m2K | Heat Loss W/K | | Main Building | 42.56 | 4.55 | 193.65 | | Extension | 22.68 | 4.55 | 103.19 | Total | | | 296.84 |
Through Uninsulated Loft HatchLoft hatch dimensions = 63cm x 78cm
Loft hatch area = 0.49m2
U Value = 5W/m2K
Heat Loss = 5 x 0.49 = 2.46W/K
Heat Loss Through Doors and Windows
| Total Area of Windows and Doors | 27.81m2 | | Approximate U Value | 2.8 W/m2K | | Overall Heat Loss per deg K | 77.87 W/K |
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