When we were designing the house I wanted a recirculating duct from the living room on the parlor floor to the bulkhead 4 flights up. I figured in the winter we could pull the hot air from the top of the stairs down to the parlor, and in the summer we could push cool air up where it was hot.
Problem was, the architect wasn’t too enthusiastic about the idea, and his mechanical engineer told me air in buildings didn’t work that way – that the hot air wouldn’t rise. That contradicted everything I had been taught in grade school. He said hot air only rises when there’s moving air. The air in a well-sealed house with the windows shut doesn’t move.
I didn’t believe him and when we got to the end of the project the recirculating duct was one of a short list of things I felt like I would have done differently if I could do it all over again.
Well, who’d have guessed – but the mechanical engineer was right. It’s winter and the top floor is at least 5 degrees cooler than the lower floors. It’s not because of poor insulation – we’ve got an R62 roof and R22 walls and great windows. At first I thought it might be just be that the room where I was when it struck me had had the door closed. But then I moved into the stairwell and it was the same there.
In the summer the area up in the bulkhead would get incredibly hot, but apparently that was because of solar heat gain from the large bulkhead windows (and glass door). But in the winter there’s less solar heat gain even – though the bulkhead is designed to capture winter light and discourage solar heat gain in the summer.
Now I’m perfectly happy the recirculating duct wasn’t put it. The air is cold up in the bulkhead – there’s no point of pulling cold air down into the living space in the winter. And likewise with the summer – we don’t need the bulkhead air conditioned.
The moral of the story is engineers know what they’re talking about. Who’ve guessed? lol