Consider the whole home
Describe existing ventilation arrangements and any rooms with moisture or stale air. Discuss air supply, movement between rooms and extraction together. Window choices can then be coordinated with the current system and any improvements planned for the property.
Choose suitable provisions
Window vents, opening sections and mechanical systems serve different functions. Ask which combination suits your home and applicable local requirements. Include noise, operation and maintenance when ventilation components are proposed as part of the window specification.
Operation and upkeep
Ask for a demonstration of how the chosen provisions are operated and cleaned. Keep openings accessible and discuss signs that attention is needed. Store instructions with the window documentation so ventilation remains part of everyday use after handover.