Heating

Heat load

Load

4.000W

specific

40W/m²

Heat load estimates the heating power of a room from transmission and ventilation. The method is a simplification in line with DIN EN 12831 and is not a substitute for the full standard calculation. Areas, U-values and air change give the required output.

Heat load

4.000

W

specific

40

W/m²

Method

Guide value

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How it's calculated

Heat load is a simplification in line with DIN EN 12831, not a substitute for the standard. Through the envelope, transmission is the sum of area times U-value times the temperature difference, and ventilation is 0.34 times volume times air changes times the difference. The short path multiplies the floor area by a guide value in watts per square metre. Thermal bridges, reheating and the standard outdoor temperature of the place are not listed separately.

Worked example

30 m² of wall at U = 0.24 and 6 m² of window at U = 1.1, 20 °C inside, −12 °C outside, 75 m³ at 0.5 h⁻¹: transmission 442 W, ventilation 408 W, together 850 W.

FAQ

Can a heat generator be ordered from this?
Only as an estimate. The standard asks for further allowances, the standard outdoor temperature and a calculation room by room.
Can the outdoor temperature be below zero?
Yes. Negative degrees are allowed. An empty or unreadable value is not treated as zero degrees.
What does zero air changes mean?
No ventilation load. That is a deliberate entry. An empty field is different and is flagged.
Where are the thermal bridges?
They are not a separate allowance in the sum. A flat watts-per-square-metre value can only contain them roughly.