Super Simple Heat Loss

Explore the difference between custom measured assumptions and those typically used from the CIBSE domestic heating design guide.

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Name Material Area U-value Heat Loss CIBSE
Exteral Walls {{ elements["external wall"]["area"] | toFixed(1) }} m2 {{ elements["external wall"]["uvalue"] | toFixed(2) }} {{ elements["external wall"]["heat_loss"] | toFixed(0) }} W {{ elements["external wall"]["cibse_heat_loss"] | toFixed(0) }} W
Party Walls {{ elements["party wall"]["area"] | toFixed(1) }} m2 {{ elements["party wall"]["uvalue"] | toFixed(2) }} {{ elements["party wall"]["heat_loss"] | toFixed(0) }} W {{ elements["party wall"]["cibse_heat_loss"] | toFixed(0) }} W
Windows {{ elements["windows"]["area"] | toFixed(1) }} m2 {{ elements["windows"]["uvalue"] | toFixed(2) }} {{ elements["windows"]["heat_loss"] | toFixed(0) }} W
Doors {{ elements["doors"]["area"] | toFixed(1) }} m2 {{ elements["doors"]["uvalue"] | toFixed(2) }} {{ elements["doors"]["heat_loss"] | toFixed(0) }} W
Floor {{ elements["floor"]["area"] | toFixed(1) }} m2 {{ elements["floor"]["uvalue"] | toFixed(2) }} {{ elements["floor"]["heat_loss"] | toFixed(0) }} W
Roof {{ elements["roof"]["area"] | toFixed(1) }} m2 {{ elements["roof"]["uvalue"] | toFixed(2) }} {{ elements["roof"]["heat_loss"] | toFixed(0) }} W
°C
°C
°C
°C
°C
°C
ACH
Heat loss

{{ totalHeatLoss*0.001 | toFixed(1) }} kW

Heat loss per m2

{{ Wm2 | toFixed(0) }} W/m2

Heat pump size*

{{ totalHeatLoss*0.001*1.4 | toFixed(1) }} kW

Number of 1200x600 K2 radiators
{{ rads40 | toFixed(1) }}x @ 40°C
{{ rads50 | toFixed(1) }}x @ 50°C

* Heat pump sizing based on 40% margin to account for lower than datasheet average heat output during defrost conditions (typically 10-30%). Careful consideration based on available real world defrost output data required. Optimal margin will vary from one heat pump make & model to another and may vary in the 10-50% range.

CIBSE Heat loss

{{ totalHeatLossCIBSE*0.001 | toFixed(1) }} kW

Heat loss per m2

{{ totalHeatLossCIBSE/total_floor_area | toFixed(0) }} W/m2

Heat pump size

{{ totalHeatLossCIBSE*0.001 | toFixed(1) }} kW

Number of 1200x600 K2 radiators
{{ rads40_cibse | toFixed(1) }}x @ 40°C
{{ rads50_cibse | toFixed(1) }}x @ 50°C