Does the energy efficiency of a home change if the plate height changes (moves from 8 ft. to 9 ft.)?
Our company has recently converted all of our plans from a 8-ft. plate height on the first floor to 9-ft. plate height. The upper floor plate height is remaining at 8 ft. We are trying to figure out if the added volume will affect the overall energy efficiency of the home.
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Of course it will. It increases the heated volume, it increases the square footage of exterior shell, it is more likely to cause temperature stratification with warmer ceilings and cooler floors, and it increases the stack effect pressure which causes natural infiltration.
In short, it wastes energy and materials for the sake of completely unnecessary aesthetic ambiance. If the ceilings are painted white, they are perceptually higher and no one but a 7' tall basketball player needs anything more than 8' ceilings.
Wow Robert, please get off the fence & tell us how you feel about this.
In short yes it does, but the changes are minimal (and not as dire as listed above), especially if you pay attention to the details as you build it. By paying attention to how it is built, you can end up with not only a more spacious feeling house, but a more comfortable one. If you are curious about what the real "diffrences" will be, you might consider getting a RESNET Rater, ENERGY STAR Rater / Verifier like me to model the plans for you.
it does increase surface area, and thus leads to slight increase in heat loss.
however, it's hardly a waste to increase ceiling heights - aesthetic ambiance and architectural delight are benefits to the homeowner and can make for a more livable home.
Sorry, but a higher ceiling adds nothing of value to the essential functions of human shelter. It satisfies only human vanity and the realtors.
Contrary to Mike's assertions, it may make a house more marketable, but in no way does it make it a better house.
And contrary to Sean's assertions, every one of the issues I listed are very real impacts on energy efficiency, resource efficiency and even potential human comfort. Increasing temperature stratification does not improve comfort and it makes a house less efficient to heat. Increasing both surface area and stack effect pressures causes more air exfiltration, more wasted energy, and potentially more moisture problems.
As a designer/builder/consultant/educator who has modeled energy efficiency and pioneered super-efficient building for more than 30 years, I can assure you that these are very real effects.
... Unless of course Mr Wyatt is building in a Zone where traditional houses engaged passive cooling with 12-foot ceilings to provide a space for cool air down at the level where people live. In fact, we'uns feel bad that it freezes from September to May in some parts of the world, but it was 63 here today and we had the windows open.
Thank you for your responses. We will have someone do some energy modeling for us to help determine what the impact will be.