Real Decreto 138/2011, de 4 de febrero, por el que se aprueban el Reglamento de seguridad para instalaciones frigoríficas y sus instrucciones técnicas complementarias, this is Spanish regulation and shows interesting developments concerning cold storage and access systems, we quote verbatim:
"Cameras in low temperature, the temperature decrease must be carried out with the door ajar, locking it in order to prevent its closure, until it has reached normal operating temperature, in order to avoid depression caused in the cooling operation. The duration of decrease depends on the total mass of the construction must be between three to ten days.
They are provided within the prescribed safety measures in the IF-12
It must be keep out hot and humid outside air through the gates during opening. For cameras with more than 500 cubic meters internal volume shall be provided for a heated antechamber or equivalent system."
What we gather that the air curtain systems are the best option to install and comply with existing Spanish regulations.