Although it seems like they should both be mutually exclusive, there are several ways Bi-fold doors achieve this. For one, bi-fold doors can be designed to have good ventilation options, such as top-hung vents, trickle vents and louvres. This allows you to control the airflow, meaning you can outright cut off ventilation. As far as insulation goes, bi-fold doors are designed to have thermal breaks, insulated glass, and weatherstripping. Our bi-fold doors are created to suit your individual needs and can be as energy efficient or inefficient as you, please.