In order to protect the domestic agricultural industry from the much cheaper imports of agricultural products, it is essential for the Korean farmers produce high quality and year-round agricultural products. As one of the solutions, agricultural structures such as greenhouses and livestock houses have been widely used, and, they have been larger and larger for the consideration of automation and high productivity. Accordingly, the environmental control became more difficult, and especially, ventilation design should be effectively improved because the airflow itself is the main mechanism for the physical phenomenon of all the main environmental factors. To overcome the shortcoming of field experiment for the study, such as very limited measuring points and artificially uncontrollable and unpredictable weather condition, some additionally aerodynamic latest technologies have been used such as a large-sized wind tunnel, particle image velocimetry (PIV), Computational fluid dynamics (CFD), etc. Moreover, the heating and cooling loads periodically are computed using TRNSYS simulation because the ventilation and energy load are strongly related with each other. The theories of ventilation efficiency such as LMR/LMA, Tracer gas decay, etc have been also studied effectively including their interfacing technologies.