As accurate house heat load calculations need to be done in professional heat load simulation software, if you have a team of engineers, it is recommended to simulate the calculations based on local climatic conditions, usage scenarios and other data, using EnergyPlus, OpenStudio and SketchUp together is recommended.
To facilitate the calculations, we only use simple mathematical formulas for the calculations, which have a large error but do not deviate much from the actual use. According to the heat transfer equation as follows.
Qnp=Qn(tn-tp)/( tn-twn)
Where.
Qnp – average heating heat load, KW.
Qn – heating design heat load, kW;
tn – interior design temperature, °C, 18 °C is preferred
tp-average outdoor temperature during the heating period, °C
twn – calculated outdoor temperature during the heating period, °C.
In general, the doors and windows of a house, the walls dissipate heat in winter, and how much heat is lost must be compensated, otherwise the room temperature will drop.
In the case of general insulation, i.e. where there is no special insulation in the house, where the doors and windows are closed in general, and where the indoor air flow is general, the following empirical values are obtained.
1) Average winter temperatures in the range -30°C to -11°C: the average heat load per square metre can be taken as 80-120W
2) For an average winter temperature of -10°C to 15°C: the average heat load per square metre can be taken from 60 to 100W
(Also: the average heat load factor is the ratio of the average heat load to the maximum heat load for a year or a heating period)
For example: if you live in Prague, Czech Republic, then we know that the average winter temperature in Prague ranges from -3°C to 3°C, we can take the value of 100 W/m2. to heat a 120 m2 house you need a total heating capacity heat of 100*120 = 12 kW, which means that you need a rated heating capacity of 12 kW or even more than 12 kW for your residential heat pump. This means that you need a heat pump with a rated heating capacity of 12 kW or even more.
