As a strategic national asset ensuring the security of China’s energy resources, the summer extreme heat environmental condition and complex air flow composition of the ocean drilling vessels have become one of the key challenges in the design and construction. By establishing the balance formula of air volume inside a galley, this study sorts and analyzes the airflow parameters such as air conditioner air supply, air intake outside and inside the cabin and air mechanical exhaust. Based on the cooling capacity calculation method for fresh air conditioners specified in ISO 9943:2009, and incorporating personnel comfort requirements, this study proposes a solution for adjusting air conditioning cooling capacity parameters under extreme heat conditions exceeding standard environmental design specifications. Using an ocean drilling vessel as a case study, calculations were performed to develop recommended cooling capacity parameters for such extreme conditions on this vessel. This provides a reference for engineers to clarify air flow composition in complex cabins and to select appropriate cooling equipment under extreme heat environments.

The design ideas of ship epidemic prevention and safety heating ventilation and air conditioning （HVAC）systems are provided by summarizing the characteristics of the onboard infection outbreak and comparing the requirements of classification societies on the arrangement of isolation cabins and the HVAC technology, in order to mitigate the onboard infectious disease transmission. The results show that the isolation cabins equipped with epidemic prevention and safety HVAC system can effectively mitigate the transmission of virus through contact and air. The epidemic prevention notation of each classification society has different requirements for the design of HVAC system. The BIOSAFE SHIP is a notation developed for onboard epidemic prevention by RINA, which is accumulatively evaluated and scored according to the biosafety risk factors of the HAVC system and other systems. The notation Infectious Disease Mitigation-Arrangements（IDM-A）of ABS provides three kinds of negative pressure isolation cabins capable of being switched from its normal operation mode to an outbreak operation mode, with specific requirements of the ventilation system layout, pressure differential, air changes per hour, pipe fitting and operational measures for negative pressure cabins. The notation Epidemic Prevention and Control （EPCN）of CCS presents requirements of the ventilation system layout, airflow organization, pressure differential, air filtration, pipe fitting, operational measures and exhaust outlet for negative pressure rooms. It can provide references for the epidemic prevention and control on board marine and offshore assets.