Light and air A long hallway connects the two parts of the house. Here, louvred windows from Stockwells Joinery keep the area well ventilated. The stair treads are made from recycled timber from Ironwood. ECO TIP Louvred windows are great for passive cooling. Up high, they let hot air out while down low they let cool air in. To keep warm in winter, make sure they seal properly to keep out draughts.