Division (11) ‘seasonal space heating energy efficiency in active mode’ (ηson ) means

for fuel boiler space heaters and fuel boiler combination heaters, a weighted average of the useful efficiency at rated heat output and the useful efficiency at 30 % of the rated heat output, expressed in %;

for electric boiler space heaters and electric boiler combination heaters, the useful efficiency at rated heat output, expressed in %;

for cogeneration space heaters not equipped with supplementary heaters, the useful efficiency at rated heat output, expressed in %;

for cogeneration space heaters equipped with supplementary heaters, a weighted average of the useful efficiency at rated heat output with supplementary heater disabled, and the useful efficiency at rated heat output with supplementary heater enabled, expressed in %;