Indoor design parameters are related to indoor comfort standards and sanitary requirements, including indoor dry bulb temperature, relative humidity, fresh air volume, flow rate, noise and dust content in the air.

1. Indoor dry-bulb temperature: 22 ~ 28℃ should be used for air conditioning in summer. High-grade civil buildings or buildings with long stay time can be taken as low values, while general buildings or buildings with short stay time should be taken as high values. Winter air conditioning should be 18 ~ 24℃. High-grade civil buildings or buildings with long stay time can be taken as high values, while general buildings or buildings with short stay time should be taken as low values.

2. Indoor relative humidity: 41% ~ 65% should be used for air conditioning in summer, and a higher value is recommended for general buildings or buildings with short stay time. Air conditioning in winter should be 31 ~ 61%. Commercial central air-conditioning systems are generally used in high-grade apartments, villas and small offices, shops, restaurants, entertainment and other public places. For the owner, it is hoped that the air conditioning system can provide a comfortable indoor environment, and at the same time, it is hoped that the operating cost of the air conditioning system will be as low as possible. On the calculation surface of air conditioning load, the indoor temperature will increase by 1℃, the relative humidity will increase by 5%, and the air conditioning load will decrease by 6% ~ 8%, so the standards of indoor design parameters such as temperature and relative humidity should not be too high.

3. Indoor air velocity (people's activity area): Indoor air velocity also has a certain impact on human comfort. If the velocity of cold air in summer or hot air in winter is too large, there will be uncomfortable blowing feeling. Generally, the air velocity is required to be no more than 1.3m/s in summer and no more than 1.2m/s in winter.

4. Noise: Excessive noise will be harmful to human health, so the noise index is also an important index, and air-conditioning designers should effectively control the noise of air-conditioning systems.

5. cleanliness: for civil buildings, the requirement for dust content in the air is not high, so it is generally enough to install a primary filter in the air conditioning system. For demanding occasions, the medium efficiency filter can be used.

6. Fresh air volume: The storey height of a general residence is low (about 2.8m), so it will be difficult to arrange fresh air treatment equipment (such as fresh air units) and fresh air ducts. Moreover, in residential buildings, the personnel density is very low, so it is often necessary to rely on the infiltration of doors and windows, or intermittently open windows to introduce fresh air to dilute the indoor carbon dioxide concentration, thus ensuring the minimum standards required by personnel health. For high-rise houses (such as villas), there are higher comfort requirements for residents.

for crowded offices, shops, restaurants, entertainment and other public places, the indoor air has a high concentration of carbon dioxide, which is mixed with strong human body odor and smoke generated by smoking, so it must be sent into the treated fresh air in an organized way.