At first, I calculate cold and hot load in this design, then sure air conditioning system forms, selected and layout terminal device equipment. hydraulic calculation after identifying pipe and duct diameters, then complete plan design. Then I design  cooling, heating station. At first we select cold, heat source , technology used compared to determine the equipment scheme. Then we design the equipment room, choose equipments. Air conditioning system design have heat preservation and anti-corrosion design, sound insulation and shockproof design, etc.
The following is the design concept of this design.
Office buildings usually include both peripheral and interior zone spaces. The peripheral zone extends 3 to 3.6 m inward from the outer wall toward the interior of the building, and frequently has a large window area. These zones may be extensively subpided. Peripheral zones have variable loads because of changing sun position and weather. These zones typically require heating in winter. During intermediate seasons, one side of the building may require cooling, while another side requires heating. However, the interior zone spaces usually require a fairly uniform cooling rate throughout the year because their thermal loads are derived almost entirely from lights, office equipment, and people. Interior space conditioning is often by systems that have VAV control for low- or no-load conditions.
Most office buildings are occupied from approximately 8:00 am to 6:00 pm; many are occupied by some personnel from as early as 5:30 am to as late as 7:00 pm. Some tenants’ operations may require night work schedules, usually not beyond 10:00 pm. Office buildings may contain printing facilities, information and computing centers, or broadcasting studios, which could operate 24 h per day. Therefore, for economical air-conditioning design, the intended uses of an office building must be well established before design development.
Occupancy varies considerably. In accounting or other sections where clerical work is done, the maximum density is approximately one person per 7 m2 of floor area. Where there are private offices, the density may be as little as one person per 19 m2. The most serious cases, however, are the occasional waiting rooms, conference rooms, or directors’ rooms, where occupancy may be as high as one person per 2 m2.
The lighting load in an office building can be a significant part of the total heat load. Lighting and normal equipment electrical loads average from 10 to 50 W/m2 but may be considerably higher, depending on the type of lighting and amount of equipment. Buildings with computer systems and other electronic equipment can have electrical loads as high as 50 to 110 W/m2. The amount, size, and type of computer equipment anticipated for the life of the building should be accurately appraised to size the air-handling equipment properly and provide for future installation of air-conditioning apparatus.
Total lighting heat output from recessed fixtures can be withdrawn by exhaust or return air and thus kept out of space-conditioning supply air requirements. By connecting a duct to each fixture, the most balanced air system can be provided. However, this method is expensive, so the suspended ceiling is often used as a return air plenum with air drawn from the space to above the suspended ceiling.
Miscellaneous allowances (for fan heat, duct heat pickup, duct leakage, and safety factors) should not exceed 12% of the total load.
Building shape and orientation are often determined by the building site, but some variations in these factors can increase refrigeration load. Shape and orientation should therefore be carefully analyzed in the early design stages.
Along with the social progress and economic development, ecological environment and energy problems appear increasingly. People have become increasingly aware of the importance of sustainable development. The central air conditioning system is a vast and complex systems, energy consumption is very big. So energy saving has plenty of room. In system design process, about system selection and equipment selection, this design considered the energy requirements. And for HVAC system design, every link has been in strict accordance with the national, regional or industry standards and specifications for implementation, achieves the elaborate design. 十二层公司办公楼中央空调系统设计+CAD图纸(2):http://www.youerw.com/gongcheng/lunwen_1890.html