3　Heating

3.1　General Requirements

3.1.1　For the production buildings and auxiliary buildings located in regions where normal daily mean temperature is stably below or at 5℃for at least 90 days，central heating systems shall be provided if the buildings are frequently occupied or specified room temperature is required by a process.

3.1.2　For production buildings and auxiliary buildings located in regions where normal daily mean temperature is stably below or at 5℃for 60 days-89 days or the normal daily mean temperature is stably below or at 5℃for 45 days-59 days but the average value of mean relative humidity in annual coldest months is equal to or larger than 75%，central heating systems may be provided through techno-economic comparison if the buildings are densely and frequently occupied and waste heat is available in the plant.

3.1.3　For production buildings and auxiliary buildings located in regions other than those covered in Articles 3.1.1 and 3.1.2 of this Specification，central heating systems may be provided if special room temperature is required by a process.

3.1.4　For production buildings located in regions where central heating systems shall be provided，if special room temperature is not required by a process and the floor area occupied by each worker exceeds 100m2，general heating should not be used，but local heating shall be provided at fixed workplace.If workplace are not fixed，heating rooms shall be provided.

3.1.5　Heating medium served for central heating systems shall be selected through techno-economic comparison based on heat supply conditions in the plant.Priority shall be given to the waste heat from process units，and hot water should be served as the heating medium.If steam is used for process service in the plant，it may be served as the heating medium，provided that health，technical and energy-efficient requirements are met.

3.1.6　For central heating systems，the indoor design temperature in winter shall be determined with considerations to building services，process characteristics，labor intensity，automatic control and automatic operation levels，maintenance requirements and occupancy.The indoor design temperature for general production buildings and auxiliary buildings where central heating systems are designed may be determined with reference to Appendix A of this Specification.