Casement windows are one of the best types of windows for ventilation. Casement windows feature a single large sash that can be opened outward and secured in place with a crank handle or lever. This provides maximum air flow and ventilation, making them perfect for areas such as kitchens and bathrooms where increased air circulation is necessary. Sliding windows may also provide good ventilation, depending on how many panels there are, how wide they open and what material they are made from.