必须交换流通。The rate of this exchange depends on the purpose of the b

the rate of this exchange depents on the purpose of the building. For example, for recidential houses this rate is about 8 cycles/hour.

Here it is this amount of air moved out of the house per hour that determines the loss of cooling and heating.

Of cause it is important to have the house properly insulated - I will discussed this maybe in another posting.