Analysis and discussion on determination method of outdoor design conditions for summer air conditioning

 At present, Chinese HVAC design code determines outdoor design conditions for summer air conditioning and generates the design day based on 50 non-guaranteed hours in the air conditioning system design and equipment selection. The determination system of outdoor design conditions for summer air conditioning can not reflect the effect of air conditioning system on indoor thermal environment. Selects Guangzhou, Shanghai and Tianjin as representative cities with typical climate characteristics, and establishes corresponding office building models. Takes the non-guaranteed hours of indoor cooling load as the index of indoor thermal environment risk level. The results show that in the three cities, the non-guaranteed hours of indoor cooling load are lower than 10 hours when outdoor design conditions for summer air conditioning are selected based on 50 non-guaranteed hours. There are similar results for other non-guaranteed hours. There is a linear relationship between the two non-guaranteed hours in the three examples. The simulation of different building models confirms the universality of the magnitude difference and linear relationship of the two non-guaranteed hours.