The air change rate (ACR) of naturally ventilated dairy buildings (NVDBs) plays an important part in the design and control of the ventilation system, as well as in the estimation of the gaseous emission rate. The objectives of this research were to model the ACR based on a quantitative investigation of the relationship between the ACR and its potential influencing factors, including the opening ratio (r), the building length to width ratio (α), the wind speed (U), and the wind direction (θ). The investigations were performed using the response surface methodology integrated with the Box-Behnken design and Computational Fluid Dynamics (CFD) simulations. Three response surface models of the ACR of NVDBs were established for three opening ratio ranges of 5%–42.5%, 42.5%–80%, and 5%–80%, respectively. It was found that the selection of the opening ratio range had almost no effect on the developed response surface models. The results showed that the ACR of NVDBs was not influenced by α, but was significantly affected by r, U, θ, and interaction effects between every two of the three factors. The highest ACR was 6.7 s⁻¹, 6.0 s⁻¹, and 4.0 s⁻¹ when θ, U, and r was at their respective medium value while the rest parameters were at the highest values, indicating that the r played an important role in the value of ACR. It was concluded that in the prediction of the ACR of a building, the influences of both individual and interactional effects of θ, U, and r should be considered.

自然通风的奶牛场（NVDB）的空气变化率（ACR）在通风系统的设计和控制以及气体排放率的估算中起着重要的作用。这项研究的目的是基于对ACR及其潜在影响因素之间关系的定量研究，对ACR进行建模，包括开口率（r），建筑物长宽比（α），风速（U））和风向（θ）。使用与Box-Behnken设计和计算流体动力学（CFD）模拟集成的响应面方法进行了研究。建立了NVDB ACR的三个响应面模型，分别针对5％–42.5％，42.5％–80％和5％–80％的三个开口率范围。发现开口率范围的选择对已开发的响应表面模型几乎没有影响。结果表明，NVDB的ACR不受α的影响，但受r，U，θ以及三个因素中每两个因素之间的相互作用的影响显着。最高ACR为6.7小号^-1，6.0小号^-1和4.0小号当θ，U和r分别为中值而其余参数为最高值时为^-1，这表明r在ACR值中起重要作用。结论是，在预测建筑物的ACR时，应考虑θ，U和r的个体效应和相互作用效应的影响。