This study looks at static air pressure change for a variety of ventilation comp0nents used in agriculture buildings. Ventilation is very important in agriculture as it must remove harmful aerosols and not let the temperature change inside the barn even though seasonal changes can be extreme. This study used twenty-one ventilated wall claddings and ten roof ventilation arrangements for tests. To measure the rate of air pressure change, the air was recorded on the speed at which it moved per meter. The pressure drop characteristics of the items measured were able to be described as a pressure lost coefficient, k. The paper provides the values of k for the various items tested and describes how the use of k simplifies the calculation of pressure losses in complex ventilation paths.