Getting silly with energy savings...

[charby]

Composting toliet.

[grampster]

Probably 20 years ago, I saw some plans in Outdoor Life or Field and Stream for a log house.  The outside walls were 24" long logs laid end to.  I don't remember how they chinked them, but I do remember they had some special material to be used.  

[Balog]

That.  Many of these fringe technologies would be mainstream if this were not the case.

Most homes are mass produced to be as cheap and modular as possible while appealing to the widest demographic. 2' thick concrete walls and a 50 ton thermal mass stove in the basement may not have wide appeal or be easy to churn out a hundred of; but that doesn't mean it can't be a good option or economically feasible to have constructed.

[Firethorn]

Most homes are mass produced to be as cheap and modular as possible while appealing to the widest demographic.

Bingo, and unlike cars and appliances, most don't require any estimate on what it'll take to heat/cool them.  Thus, many builders will do the minimum insulation allowed and simply let the homeowners such up the costs.

[Balog]

I've also got to thick some styles of construction are far more suited to being self-built. Maybe I'm way off, but I'd think concrete form would be a style favoring the guy doing it on his own.

[Hawkmoon]

I want a Foyer/cloak room area - Reason being, the semi-isolated area reduces hot/cool air loss when entering/exiting the building.  Bonus - Good spot to leave the bulky northern coats and snowy/muddy boots.

a.k.a. "mud room"

Massive construction - I've read nothing but good things about having a home with a good deal of thermal mass to the walls.  They help moderate temperatures and prevent you from wanting the heating system on at night and the AC during the day.  Insulation, lots of it, covering the TM on the outside, before whatever siding material is used.  You want a material that isn't too conductive to heat, but still has a lot of mass.  Concrete and dirt are frequent choices.

You might want to rethink that, depending on the climate. If the thermal mass is entirely within the insulation envelope, it doesn't provide much (if any) benefit unless it is artificially infused with heat. One example is houses that use a solar greenhouse on a south exposure, with a "tromb wall" to separate the solarium from the main house. During the day, solar energy pumps heat into the wall, and at night the wall gradually releases the heat into the building. If the side facing the solarium were insulated, the solar energy would not reach the wall for storage.

Thermal mass works both ways. Ever been inside an unheated concrete or masonry building on a cold, damp morning? The sun can be shining and the birds singing, but it'll be 10 to 20 degrees colder inside the building than outdoors, and very uncomfortable, because the thermal mass of the structure has nothing to bring up its temperature. Thermal mass slows the transfer/exchange of heat, but it doesn't eliminate it. Any mass you put inside the thermal envelope has to be heated, or it's cold.

[Brad Johnson]

If the thermal mass is entirely within the insulation envelope, it doesn't provide much (if any) benefit unless it is artificially infused with heat.
...
Thermal mass slows the transfer/exchange of heat, but it doesn't eliminate it. Any mass you put inside the thermal envelope has to be heated, or it's cold.

You WANT the mass inside the insulated envelope.  Once the desired temp is reached it takes less to maintain it, hot or cold, because the thermal mass stabilizes everything within that volume of air.  The insulation keeps heat migration (in or out) at a minimum.  Less heat migration = less temp variance.  With the mass inside, and the insulation keeping heat migration down, once you reach or your personal desired indoor temp it tends to stay that way. 

Shorter version ... In the summer the heat stays out, in the winter the heat stays in, and inside the house it's still 78 degrees.

Brad

[Headless Thompson Gunner]

Most homes are mass produced to be as cheap and modular as possible while appealing to the widest demographic. 2' thick concrete walls and a 50 ton thermal mass stove in the basement may not have wide appeal or be easy to churn out a hundred of; but that doesn't mean it can't be a good option or economically feasible to have constructed.

Things like cost and appeal are important factors, too, and cannot be ignored.  I think if that sort of construction offered a significant advantage at a reasonable price, while still providing everything else people expect in a home, then lots more people would use it.  The fact that virtually nobody wants it enough to actually build it is informative.

I think Nick is right.  The appeal of unusual construction techniques like massive concrete walls and huge stoves might diminish somewhat once you actually see the prices.  The appeal might diminish even further once you consider the resale value of such a home.

Your best bet is likely to be conventional construction done right.  Good insulation, reflective roof, proper windows and doors, and efficient heating and cooling will prevail.  The devil is in the details, and if you get all the details right then conventional construction works remarkably well.

[Balog]

There is a remarkable inertia in things like homes, I believe. "Because that's how all the other houses are" is a stronger motivator than you may realize. This is largely a regional thing. As was mentioned thermal mass stoves are very popular in some places.

Additionally, different needs can drastically change the cost benefit ratio. If you intend to build it yourself then ease of do-it yourself is higher. Plan to be off the grid? Energy efficiency is king. Just like in automobiles. Small fuel efficient cars are great, but if you have 10 kids your priorites change. The fact that wooden A-frame construction is common and works "well enough" for most people's needs is hardly a ringing endorsement.

[Balog]

Also, a prime determining factor in the design of a lot of modern homes is "Can Joe Contractor swing by Home Depot, pick up a load of semi-skilled guest workers and some 2nd rate materials, then slap a dozen of these together in a month or two?" If you want a house built to your specs why settle for something designed to be mass produced?

[cassandra and sara's daddy]

its a tossup for me on log home or concrete with the styrofoam forms.  the forms i like have built in nailers in the styrofoam and that saves you much time in finishing em off. they also incorparate "chairs" for all the rebar. toss in a  few bags of those fiberglass fibers and you get an incredibly strong fire and bug proof house.  you do need to plan em to a fair thee well  no way to just pop a window in or move a door over a bit.   i'm doing the roof on this place this spring and its gonna be metal over a foam board layer with another layer of sheathing oner the foam.  and the foam is gonna cost darn near as much as the metal. at least i can do the labor myself and save.

[drewtam]

In our region (central Illinois) natural gas is about 1/3 the cost per joule than electricity. This makes combined heat and power very enticing for winter months. The natural gas generator would provide electricity. The motor's coolant is radiated inside the home and the exhaust can also pass through an air-to-air heat exchanger inside the home. Thus one can achieve ~80% energy efficiency from the NG.

So this has several major advantages:
Cut the (gas + electric) utility bill by up to 50% during the winter.
Very reliable power during winter.
Built in backup power anytime of year.


I don't know the capital cost so I don't know the ROI. The most expensive material is the generator. Heat exchangers (radiators) are pretty cheap. The electrical work would be tricky so that power is not put back into the incoming service line.
Also realize, that during the summer the efficiency drops below the utilities electric price. Because your no longer using the waste heat. So during the summer you would switch back to retail electricity.

[Firethorn]

In our region (central Illinois) natural gas is about 1/3 the cost per joule than electricity. This makes combined heat and power very enticing for winter months. The natural gas generator would provide electricity. The motor's coolant is radiated inside the home and the exhaust can also pass through an air-to-air heat exchanger inside the home. Thus one can achieve ~80% energy efficiency from the NG.

This is very, very neat tech.

I don't know the capital cost so I don't know the ROI.

I've been looking at this stuff; but I do know the cost is such that you need to place a high value on the backup power portion in order to make the ROI worth it.

The electrical work would be tricky so that power is not put back into the incoming service line.

There's a couple ways to do this.  Some sort of automatic transfer switch is one option, but so isn't leaving the main power on ala many green power systems to run the meter backwards such even during low electric demands the generator runs at optimal efficiency and during high the generator isn't overloaded.

Hmmm... 

Thermostat turns on generator.  Power is fed to a rectifier->powerline inverter system. 
In addition, possibly separate due to low demand for integrated systems, an automatic transfer switch is also hooked in.

Situation Normal, heat needed:
Generator kicks on, feeds power through the rectifier to inverter system.  You need the inverter to ensure phase matching.  Waste heat proceeds to help heat house.
Situation:  generator on due to heat demand, power goes out.
For power line safety, inverter system cuts out as designed.
ATS works as designed, isolates house electrical from wire, finds the generator already on and starts providing power using direct AC from generator.  You'd want the computers and sensitive equipment on a UPS, and you might notice the lights blink.
Situation: generator off, no heat demand.  power goes out
Inverter not functioning, not an issue.  ATS kicks in.  If it's during the summer, you'll want some ducting to direct the radiated heat outside, and a bypass for the exhaust heat exchanger.  Since the generator isn't running, the time until the house has power again is a bit longer, depending on the exact nature of the generator and switch.

Let's get some numbers:
Guardian 17 kW Home Standby Generator, $4k  71 Amps capacity, should be plenty.  183 ft^3/hr, 1.61 gallons propane, at 50% load.
Briggs & Stratton 100-Amp Automatic Transfer Switch w/ Load Shedding  $500
Solectria PVI 15KW 15KW Gridtie Inverter 208VAC , $10,166 (ouch, and only 208VAC)
SMA America SB7000US, $4k * 2 (cheaper, actually does 220/240VAC)

Call it $13-14k for the equipment alone?  Things we'd still need:  A way to tie the thermostat into turning the generator on.  If you can somehow set it to turn the generator on, you might drop the largest expense - the inverter system.  That would reduce the efficiency of the system though, especially if you're like me and don't use much electricity at night.

[Boomhauer]

Underground house for me, thank you very much.

Big fireplaces with buck stove inserts for part of the heating.

Only 1 or 2 levels...I live in a 2 story house with a full basement now...climbing up and down stairs gets old...

Concrete construction is a favorite of mine.

No carpet.

Large kitchen. If the house was above ground, I'd want the kitchen separate from the house. I want a kitchen where I can hose it down and easily clean it, too. If the kitchen must be attached in the underground house, I want it isolated and have some big firedoors that can be closed, just in case. I don't want a walk in freezer or anything, but I do want industrial grade appliances that will last.

I want the house to be built as fireproof as possible.

I want to be able to easily access stuff like plumbing and wiring for the inevitable repairs.

Easiest way to get lots of mass is to use insulated concrete forms.  Four to six inches of reinforced concrete with two inches of polystyrene foam on either side.  It's like living in a bank vault.  A side benefit is the home is also severe weather resistant.

My uncle is building a house with interlocking foam blocks filled with concrete.

[Regolith]

I alternate between wanting an underground "bunker" and a tower.  Sometimes I decide it'd be best to combine the two. 


Ah....if only I had $1,000,000,000....

[drewtam]

I alternate between wanting an underground "bunker" and a tower.  Sometimes I decide it'd be best to combine the two. 


Ah....if only I had $1,000,000,000....

Just borrow to build your proposed Barad-Dur. When you can't make the payments, ask the government to help. Failing that, try to enslave the world.

[roo_ster]

Just borrow to build your proposed Barad-Dur. When you can't make the payments, ask the government to help. Failing that, try to enslave the world.

Well, those that pay the taxes that will eventually pay off the debt of both gov't and the schmoes who bought more house than they could afford are already enslaved to the degree that their wages are taken by threat of force.

[drewtam]

Thermostat turns on generator.  Power is fed to a rectifier->powerline inverter system. 
In addition, possibly separate due to low demand for integrated systems, an automatic transfer switch is also hooked in.

Situation Normal, heat needed:
Generator kicks on, feeds power through the rectifier to inverter system.  You need the inverter to ensure phase matching.  Waste heat proceeds to help heat house.
Situation:  generator on due to heat demand, power goes out.
For power line safety, inverter system cuts out as designed.
ATS works as designed, isolates house electrical from wire, finds the generator already on and starts providing power using direct AC from generator.  You'd want the computers and sensitive equipment on a UPS, and you might notice the lights blink.
Situation: generator off, no heat demand.  power goes out
Inverter not functioning, not an issue.  ATS kicks in.  If it's during the summer, you'll want some ducting to direct the radiated heat outside, and a bypass for the exhaust heat exchanger.  Since the generator isn't running, the time until the house has power again is a bit longer, depending on the exact nature of the generator and switch.


Solectria PVI 15KW 15KW Gridtie Inverter 208VAC , $10,166 (ouch, and only 208VAC)

Call it $13-14k for the equipment alone?  Things we'd still need:  A way to tie the thermostat into turning the generator on.  If you can somehow set it to turn the generator on, you might drop the largest expense - the inverter system.  That would reduce the efficiency of the system though, especially if you're like me and don't use much electricity at night.

You're over thinking this... #1 engineering principle: Keep It Simple Stupid.

If you're going to run nat-gas gen-set during the winter to provide power; then it has to be on all the time to provide standby and primary load power. (Probably a C-tier rating, but I digress).
 
So while idling and providing just enough juice to light a light bulb (or CFL), you can also provide continuous heat to the house at low levels (~3kW). The furnace can kick on and off as a separate beast. Any electric load put to the generator as a result, also produces more heat for the house. The furnace can be a separate system on NG; since the furnace will be 90-95% efficient.

Its the electric load from the washer, dryer, dishwasher, lights, computer, refrigerator, guitar amp, tv, vent blowers, welding equip, etc that will create 3x more heat input to the house because of recovered waste heat from the gen-set.

Since all power comes from the gen-set, the wiring to the service line can be permanently disconnected all fall+winter+spring.

[Waitone]

Look into rammed earth building.  All the thermal efficiencies of an underground house but with a view.

http://www.lowimpact.org/factsheet_rammed_earth_building.htm
http://www.terrafirmabuilders.ca/what_next.htm

[Firethorn]

Since all power comes from the gen-set, the wiring to the service line can be permanently disconnected all fall+winter+spring.

Good point.  Still, the generator wouldn't be as efficient at producing heat than a high efficiency furnace; nor is it likely to be as efficient as the power company.

I think we'd need a lot more charts/efficiency equations with cost estimates to do a good job of it.

Oh, yeah, and if you're running the generator all the time you might not be able to get by with a 'standby' generator, you'd need a much tougher system, increasing the cost of the generator system.

Can't forget maintenance and replacement costs for the generator when it wears out.

[K Frame]

One of the things I'm going to buy this summer is a pellet stove.

I have a heat pump, and while it does OK at keeping the place sort of warm, I'm sick and tired of the cool breeze.

[Desertdog]

2X6 walls with R19 insulation, double pane windows, 2 - R19 layers of insulation in attic, running 90 degrees of each other, single floor, 8 foot ceiling, conventional gas heat, evaporative cooling (good only in dryclimate), and exterior painted white to reflect the sun.  Warm in the winter and cool most of the summer with an average of about $150 a month for gas, lights and water (no plush lawn).

[drewtam]

I've done some the math. Your right, it wouldn't be as efficient at producing direct heat since we are talking about ~80% thermal efficiency. Thats why I suggest still having an additional but undersized NG furnace at 90+% thermal eff.

So the gen-set will divide energy like this:
1/3 mechanical work -> electrical production
1/3 exhaust energy -> air to air heat exchanger and recover ~70%
1/3 coolant heat rejection -> water to air heat exchanger and recover ~95%
(diesel gen-sets are more efficient, but the diesel is more expensive that it defeats the purpose.)

So if each joule of NG is 1/3 the price of each joule of retail electricity, then we can produce electricity via NG genset at the same price as retail electricity. (We need 3x the input NG joules because we are 1/3 efficient with them)

Where we really gain is on the back end of the equation. While our electricity production cost remains flat, for each joule we buy we get 2 "free" joules in heat added to the house. The business case is then made based on the cost opportunity of cutting all required heating (whatever the yearly heating bill runs). Multiply by 3 or 5 to determine your maximum allowed capital for a 3-5yr ROI.

One thing you can also subtract is the cost of a cheap backup generator. Since most people buy these anyway for power outages, this can be subtracted as an assumed sunk cost.

This is why its only viable during cold months. Without the recovered "free" heat, the whole scheme loses economic value.

A Prime tier rating might be ideal because the house will rarely use full load. You would need to run every major appliance to do that. So a  continuous rating might be overkill. But when comes time to design, the supplier can help figure that out with you. Remember NG doesn't have the soot loading that gasoline and diesel will have.

http://www.cat.com/cda/layout?m=39300&x=7

[Nick1911]

(diesel gen-sets are more efficient, but the diesel is more expensive that it defeats the purpose.)

Question:  Can't the diesel cycle be applied using Natural Gas as a fuel?  I haven't researched it, but I don't see why it wouldn't work...

[Nick1911]

Also, if I were looking at generating power 24/7, I wouldn't buy a standby unit.  I'd try to find something designed around a compact gas-turbine; like an APU.

Much less maintenance.