Design of ventilation, air conditioning and heating systems

The design of ventilation, air conditioning and heating systems is regulated by SNIP 2.04.05-91. In accordance with the principles of construction, design decisions should not:

• Violate the purity of air;
• Create excessive noise or vibrations in the premises, in particular, at the installation site, the noise level should not exceed 110 dBA;
• Be fire hazardous.

In addition, the design of ventilation and heating systems should provide for the maintainability of the equipment. This may surprise the owners of private cottages, but typical project documentation includes the calculation of the number of personnel who must operate the equipment. Otherwise, everything is pretty obvious: the presence of corrosive media in ducts requires corrosion resistance from pipelines and ducts, and hot surfaces are inevitably isolated, what the idea of fire safety, already mentioned above, is realized. If the insulation does not help to reduce the temperature of some parts of the system to a safe design, then it is strictly prohibited to place them in rooms where there is the possibility of the presence of flammable aerosols or gases. And such premises should be taken into account separately, performing the design of ventilation systems. Any non-standard elements of the system should be made of materials approved for use in construction.

General calculation for the premises where people work, is conducted:

• In summer - based on the maximum permissible temperature in the rooms with the formation of excess heat. In the absence of such an economically feasible temperature is selected from the permitted range. Estimates are indicated in the annexes, and not everything is so obvious. The temperature can not exceed 28 ° C, but at lower values, the environment starts to vary accordingly. The design of air conditioning and ventilation systems is aimed at fulfilling the above requirements.
• In winter - based on the economic feasibility of maintaining in the room of a particular temperature within the permissible range. With a minimum temperature is simpler, it should not be below 14 ° C.

In this case, the flow velocity and relative humidity are also selected from a number of acceptable values.

For fully automated premises where people are not permanently, the rules prescribe a slightly different approach:

• In warm weather, operation is allowed at ambient air temperature, and if excess heat is generated in the room, the design of ventilation systems should aim to force the temperature difference to 4 degrees. At the same time, the temperature in the room should not be lower than 29 ° C, otherwise the difference in temperature inside and outside can be ignored. These conditions are correct, unless additional heating of air is required.
• In the cold period, if there is no excess of heat, it is necessary to maintain a temperature of 10 ° C, if there are excess heat, the design of ventilation systems should be aimed at maintaining an economically feasible temperature.

Climatic conditions of operation should be taken in accordance with the application of SNIP II-3-79.