Energy efficiency from the ground up (LONG)

woodswellMay 24, 2006

I'm hoping to build a house in the next year or so. This will be my 'forever' house that I will live in until I die or am sent off to a nursing home. I'm in North Florida in an area that has both hot summers (often humid) and cold (for Florida) winters that can be dry OR humid.

So I want to build in energy efficiency from the beginning. Passive solar is one thing that could be a problem. The site is on a north-south ridge and faces east. There is plenty of sunshine from the south, but the main view is to the east and we cannot put the long axis of the house any way but north-south.

I am changing the design to put main rooms on the south side to take advantage of the light. The other rooms will basically extend all the way through the house so they have east and west facing windows and can take advantage of prevailing breezes in spring and fall when the weather allows.

I plan porches along most of the east and south sides, with a smaller porch on the west. We have good shade from trees on the west, southeast and east sides. The major use for the east facing posrch will be for screened porches and maybe eventually a sun room.

I am planning a solar water heating system, but want to consider geothermal for heat and AC. Currently, we have an electric heat pump for both - how would the efficiency of geothermal compare? Is geo effective for AC this far south? Apparently ground temps are between 65-72 F around here. How do you deal with de-humifying with geothermal?

With 60 acres, we've got the space for geothermal - it's whether or not it would pay for itself in the long run.

DH wants radiate floor heating - could that be combined with solar water heating to make it cost effective? Maybe just for limited areas of the house, such as bathrooms?

I'm also considering photovoltaic - with the orientation of the house, if I want that, I would have to change the south facing roof to a hipped rather than a gable. It would cost slightly more and reduce attic/second story space. From what I read, I suspect PV is not cost effective right now, but if I want to add it later, I'd like to plan on it.

PV *could* offset other costs, such as an emergency generator. We are in Hurricane Territory here and even if we don't get hit directly, we get the squall bands that can knock out our power for a day or two. But I've lived without an emergency generator for many decades, so emergency power is not super high on my list of 'must-haves'.

Here is what I will NOT have - any kind of of energy that requires a flame. No propane, natural gas, wood, etc. My house will be all-electric, one way or another.

Any suggestions, ideas, places to go for more info?



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Here is an idea for you that may work better than AC

Here is a link that might be useful: Earth Tubes

    Bookmark   May 25, 2006 at 11:26AM
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Interesting concept but I doubt it would work in this area. They specifically state "Please note that Earthtubing is not meant as a summer cooling system in hot, humid climates where moisture would reach dewpoint and collect in the tubes."

That would be true for months of each year, especially during the cooling season.


    Bookmark   May 25, 2006 at 7:45PM
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Just to reinforce the point - tonight it is 71 F with a dewpoint of 68 F - 90% humidity. And we're in a dry spell during the dry season! While those Earth Tubes may work great in Colorado or out that way, they would not be very good around here in the Deep South.

    Bookmark   May 26, 2006 at 1:52AM
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I applaud your efforts / goals. I'll suggest that radiant heat can do very well when used with either geothermal or solar heat collectors; especially in your climate. It can also supply a very good portion of your hot water needs too. Even up here in central New York state; solar water heating / pre-heating can pay for itself relatively quickly.

I'll point out an issue you may have to deal with . . . . the "no flame" statement. Don't know why you want that; but realize that any appliance / whatever; that creates heat; will require large amounts of electricity to generate. VERY large amounts. You mention the possibility of using PV at some point; all the conserving / efficiency you may build into your place; will be completely SWAMPED by ANY electric heating appliance . . water heater, stove / range etc. Don't know why your aversion to flame; but from PV / electricity usage; you'll be FAR better off using propane / NG or such; to generate the heat required.

I'm solar powered / grid tied . . and I went around the house to find the consumption of ALL my loads . . . the single biggest load in the whole place ? . . . the hairdryer. Followed by vacuum cleaner, well pump, then toaster. You may have your reason(s) for "no flame" . . but realize the implications of doing so completely.

Also know, especially on a large chunk of land you've got; that PV panels do NOT need to go on the roof. That rarely is correct angle for the sun anyway. You could easily do pole mounts at a good location sun / exposure wise; and run cable to the house. Let's you orient your house the way you want; AND could reap great benefits electricity-wise.

I'll also suggest Solatubes or such; as a very good way of bringing in as much light as you want; without introducing any heat; into the areas of your house that will have little window area.

Good luck . . .


    Bookmark   May 26, 2006 at 7:44AM
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On the "no flame" bit - I've had second and third degree burns. I cannot emotionally handle being around flames. And I know the load that it adds, though I do not use a hair dryer Vacuum does not get used much since we now (and will) have wood and tile floors. Most of my cooking is done in the microwave rather than on the stove or in the oven.

Actually, I'd guess that the most "extravagant" load I'd add would be my electric blanket, though using it on winter nights lets me lower the thermostat a lot. The absolute highest load would probably be the clothes dryer.

The way I am laying out the house, there will only be a few interior spaces with no natural light: the laundry room, closets, and one hall - and using Solatubes in them should be easy. The mudroom could benefit from a Solatube since it will extend well into the house.

I'll have to think about where I could put pole mount PVs - close to the house, though not actually shading most of it, are a lot of trees. There is an open pasture to the northeast of the house site - wonder if the horses would be tempted to mess with the panels?

I'll try to post a link to the current house plan and an aerial of the house site and surrounding land. Not tonight, though, we spend half the day halter breaking foals and it is late!


    Bookmark   May 31, 2006 at 12:10AM
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Gary, I've downloaded some of the info you suggested - been lurking here a while reading old posts. But I'll need to do some homework on the other stuff you've pointed to!

Locally most of our power is from a LP plant and a hydroelectric dam (built in the 30s and revived in the early 80s). A company is talking about building a coal gasification plant in a nearby county, but the electric coop I am in is not going to participate in that project, though the only city in this county has signed on.

As I told Bob, I will try to post the current iteration of our house plan and a site aerial.

Thanks - I'll be back with more questions.


    Bookmark   May 31, 2006 at 12:27AM
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I'm not sure how many horses you have. If you built a low level stable, and put the house over the stable, you could gain heat from the horses in winter. The grass uses sunlight to make food for the horse, the horse eats the grass, and some of the metabolic heat is released. You can still see some older farmhouses in New England, connected directly to the barn, designed and constructed to take advantage of metabolic heat derived from farm animals.

    Bookmark   May 31, 2006 at 12:02PM
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Look into an induction cooktop. They are twice as efficient as regular radiant or gas cooktops and much safer since they don't heat up -- I've used bare fingers to pick up spilled items from active "burners". See the Appliance forum for lots of information.

Also, you might want to consider super-insulating your house. My parents have a new Energy Star house and they rarely run the heat in the winter since most of the heat for their mild climate house is supplied by lightbulbs and their own bodies with a little help from the dogs! Heat recovery is also viable. It is fairly inexpensive to recover heat from waste water as it goes down the drain and use it to pre-heat incoming water or to recover heat as air is vented from the house.

    Bookmark   June 1, 2006 at 1:45PM
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I've thought about a mattress heater - two reasons I have not tried one yet: when my old electric blanket has gone out, no one had a mattress heater in stock and I just bought an off the shelf electric blanket for a quick replacement. Second - I've worried about how lumpy the pad might be. I'm the classic "Princess & the Pea" type and hate any sort of lump or uneveness/ You're the first person I have discussed a mattress heater with that owns one - are they at all lumpy?

    Bookmark   June 2, 2006 at 1:34AM
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Here in Florida, the inconvenience of dealing with the heat, insects and smells produced by the horses in the summer would far out weigh the heat gained in the winter. In fact, one major aspect of planning a barn in Florida is a high rate of air exchange to keep the horses cool in the summer. The relatively few cold nights we get in the winter are not worth sealing up a barn sufficiently to gain heat from the animals.

In the old days they used to do what is called "deep bedding" of the stables and barns. They'd put down a thick layer of bedding material (straw) then not clean out the manure and soiled bedding for the entire winter. It was not just the heat of the animals that heated the living quarters above, it was the composting of the organic material, too. While that can be done in cool, dry climates, in Florida it just makes a nasty, smelly mess with millions of insects and lots of disease.

Also, in the last 40-50 years it has been found that sealing a barn tightly leads to many respiratory problems in horses (I don't know much about other livestock), so I'd want good airflow no matter what.

These days, if I had enough horses being kept up I'd consider building one of the setups to collect the methane and use that for heating - if I could find a way to never have to deal with the flame, that is.

Some dairy operations are participating in collecting methane and providing it to local electrical power plants. Other than short bits on the news, I don't know much about these projects. I want to say they were in the Pacific Northwest.

Thanks for the thought, though.

    Bookmark   June 2, 2006 at 1:44AM
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I've read about the induction cooktops, but so far have not seen one at a price I'd be willing to pay. But I am keeping an eye on the new technologies, so will watch out for lower prices as the inductions become more common.

I talked to a builder yesterday that builds ICF houses. His price per square foot range is within my budget and I like some of the other things he does. I'm going to look at one of his houses in progress, maybe this weekend. If I do not go ICF, I will probably go 2x6" with Icynene insulation (which I will probably use to insulate under the roof, no matter what). I plan to spend more money on building a well insulated and tight envelope than on any other aspect of the house.


    Bookmark   June 2, 2006 at 1:49AM
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Hi Anne,

On the mattress pad heater, we have not found it to be lumpy. I think we are using a regular mattress over it.
I guess you could always order it from a place with a good return policy?

On another part of the electric appliance front, we are in the process of replacing our frig. We are finding that the lowest use energy ones seem to be the conventional freezer above frig without the through the door icemaker (icemaker inside instead). We have found a 21 cubic foot one at 420 KWH per year. I measured our old one over a week -- its right around 1100 KWH per year -- quite a difference.
Anyone know of a better than 420 frig (without getting into the very exotic and expensive ones)?



    Bookmark   June 2, 2006 at 10:03AM
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