Sensible heat ratio is the ratio of sensible cooling capacity and total cooling capacity. The total cooling capacity of air conditioning is sensible cooling capacity and latent cooling capacity of and, where sensible cooling is used to cool down, and latent cooling is used for dehumidification. The main room is heat sensible heat, so the CRAC sensible heat relatively high, generally above 0.9 (normal comfort air conditioning is only about 0.6). Amount of wind, the small difference is the essential difference between Han and other air-conditioned room air conditioners. Strong wind, air temperature will not be resorted to low, and increase the number of room ventilation, which is the operation of servers and computers are beneficial. Conference room temperature is too short causing the server operator error, room humidity is too low will cause static electricity (20% of the time the humidity can reach 10,000 volts electrostatic). Since CRAC with high sensible heat ratio, enthalpy difference in the design laboratory room air conditioning, pay special attention to the accuracy of special wet bulb temperature, a simple error of 0.05 ℃ had a 1% error.