[lemma=envelope] □
[lemma=envelope] [□]
[lemma=envelope] □ □
It focuses on measuring the air leakage flows to outside at operating conditions that are required for envelope infiltration impacts and energy loss calculations for duct systems . The simulation results showed that for the prototype tested here , the excess return leakage tended to decrease envelope infiltration flows by about 20 % but the total infiltration load including return duct leaks more than doubled during system operation .