You can always put in a energy/heat recovery ventilator. They use the outgoing stale air to warm/cool the incoming fresh air, so it’s more efficient than leavin

You can always put in a energy/heat recovery ventilator. They use the outgoing stale air to warm/cool the incoming fresh air, so it’s more efficient than leaving a window open. Downside is they need a small amount (20-60w) of power for fans.