This study proposes a method for determining summer outdoor design parameters and design days using the current code. Based on the method from the current code in China

four typical cities are selected according to the adaptation zone of evaporative cooling technology

forming outdoor design parameters for evaporative cooling air conditioning with wet bulb temperature as the primary factor and dry bulb temperature as the secondary factor. Based on the historical long-term meteorological data

a new method for determining the design days is proposed. The characteristics and trends of outdoor climate change in typical cities in summer are extracted

and the data of the summer design days are obtained using the hourly coefficient method. The results show that the new method reduces the temperature difference between dry and wet bulbs and the evaporative cooling potential. Guiding the design according to the method in the current code results in an insufficient design. The design days in the current code cannot accurately reflect the variation trend of the outdoor climate in summer in different regions. However

the design days obtained by the hourly coefficient method proposed in this study are more consistent with the measured data of typical cities.