As building science evolves to give us greater control over our built environment, modern structures are made ever more airtight. (When was the last time you saw a new office building with windows that could open?) While this solves one problemthe intrusion of outdoor air and the moisture it can bringit creates another, which is that these modern buildings require mechanical systems to circulate fresh air.A Vancouver-based company called VanAir Design has come up with a unique assistance method. Their VanAir Door contains staggered ventilation slots, allowing airflow rates of up to 170 CFM. (For scale, your average bathroom fan moves 50 to 100 CFM, so this door is like having a couple of bathroom fans going at once.) There are no internal fans; the air exchange is passive. As air circulates through a space, a closed door creates a pressure difference and temperature variation within the space it's enclosing. Air naturally seeks to even this out, and the door's ventilation channel allows it to flow through. Part of the reason you close an office door is that you want acoustic privacy. In terms of the Sound Transmission Class rating, the VanAir door (25 STC) stacks up between a solid-core door (28 STC) and a hollow-core door (22 STC). The company also envisions domestic applications for the door, in bathrooms and laundry closets. The door comes in standard sizes, and can also be ordered with custom dimensions. And yes, you could achieve the same as their product with a louvered door; the company reckons you can get the same airflow with a 12" by 12" louvered panel. VanAir's product, however, is designed to be easier on the eyes.