i have designed the eco-safe top slider window which allows for safe and cool ventilation in any home or office space. the eco-safe top slider window safely allows hot daytime air to escape and cool evening air to enter. the two side by side windows shown have an opening that is approximately 15×20, small enough to be safely left open. the design works best when there are two windows within close proximity so that the naturally rising hot indoor air can escape to be replaced by cooler outdoor air. the windows are in my home in ca & i am able to keep my electric bill down to $10-12 per month because i only have to turn on the ac when it remains in the 90s for several days.