Can you justify cathedral ceilings?
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| Posted in Green Building Techniques on
We are building a house with a 28×42 footprint. The kitchen, dining room and living room are open plan. Aesthetically a cathedral ceiling would look best and make the room look bigger. But how can I justify a cathedral ceiling due to energy loss, even with insulation? Or am I making too big a deal of this? Heat will be via woodstove and/or hydronic radiant heat (propane based) coming from cement floors.
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If you're properly insulation and air sealed (do not neglect the air sealing!) then it seems like your main issue would be stratification forcing you to overheat the space to keep the occupied zones comfortable. Ceiling fan to the rescue!
Just be sure to shop around for the fan: most of them are extremely inefficient, and the unit will likely be running for long periods of time.
Galia,
Unlike Brent, I don't recommend a ceiling fan. With proper air sealing and insulation, the room shouldn't need one. In fact, a fan is likely to use more energy than it saves.
Proper air sealing and insulation details are far more important than ceiling height. Be sure your R-value is high enough, and the added room volume will not add significantly to your heating or cooling bill.
Aha, but if you are "air sealed" then don't you need an air exchange? We are going to be off grid so I don't want to have an air exchange due to further energy drain. (We were just going to crack open a window)
Every new house should be built as airtight as possible.
If you are off-grid, you will be watching your electricity use closely. It's possible to live off-grid without mechanical ventilation; I do. It's also possible to use a Panasonic WhisperGreen exhaust fan (11.3 watts, 80 cfm) when desired for mechanical ventilation.
But whatever you do, don't build a deliberately leaky house.
If you use radiant heat the coolest part of the room will the ceiling. Radiant heat heats the objects not the air so that the warm air does not rise to the ceiling. I have houses with 17' ceilings and have found this to be true. Of course the roof has to be air tight.
With the woodstove burning, you will get heat stratification because of the bouyancy of the superheated air from the stove surface and you will need a recirculation fan to bring the heat down to the living level and reduce unnecessary heat loss through the ceiling/roof assembly (which could result in ice dams).
On-grid or off, you should have some form of mechanical ventilation system both to provide the fresh air required for human health and to control indoor humidity and the potential for mold and decay. An efficient bath fan on a 24-hour timer (as well as intermittent switch) with passive make-up air inlets in bedrooms and living space will both evacuate moisture at the source and guarantee the minimum 0.25 ACH required for a safe indoor environment.
As a general rule, I avoid cathedral ceilings because of heat stratification potential, difficulty in insulating well (R-60), difficulty in ventilating the roof assembly, and increasing the heated volume and heat-loss/heat-gain surface area.