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markincalgary on October 7, 2005 - 11:56am Permalink | Subthread | Parent | Comments top
"Not making houses out of wood would be a great start to making them more efficent and better insulated. Brick and concrete is much more efficent and has way less maintanice."

Wrong!

First, concrete really stinks as an insulator.  Concrete gets 0.08 R/inch.  Compare this with fiberglass batt at 3.14 R/inch. Brick is even worse than concrete. (Numbers come from http://coloradoenergy.org/procorner/stuff/r-values.htm).

Second, concrete and brick have large embodied energies compared to wood products.  (Numbers at http://www.greenhouse.gov.au/yourhome/technical/fs31.htm.)

I participate in a couple of mailing lists that focus on natural, green, and straw-bale construction. Much of the discussion at those sites is on minimizing concrete use because of its massive embodied energy.

Concrete and brick have their places in construction (footings, basement walls) and there are new concrete products (like autoclaved concrete foam) that are really interesting, but conventional concrete is definitely not a good replacement to wood as it is used in conventional north-american homes.

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flankp on October 7, 2005 - 12:48pm Permalink | Subthread | Parent | Comments top
Not just concrete, with nothing on the inside of it. You'd have insulation between the concrete and whatever was the inside wall. Foam, fiberglass, or whatever and then your drywall or whatever was the inside wall.

I'd be a concret shell, but the inside wall on the living space would not be concrete.

That would not be more efficent than wood? And last a whole lot longer?

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ChrisPhoenix on October 7, 2005 - 2:03pm Permalink | Subthread | Parent | Comments top
Concrete doesn't always last well. I was just in Chicago, and saw quite a few highway overpasses with chunks literally falling off the bottom of the concrete girders.

By contrast, there are 200-year-old wood houses that are still in great shape.

As far as light bulbs: Most of the non-dimmed lights in my house are fluorescent. When dimmable fluorescents or LED's become available, I'll gladly switch to them. I have looked, and even with Google and Ebay, they're near-impossible to find; I'd have to buy a 12-pack for $150 or something like that.

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fum on October 7, 2005 - 8:42pm Permalink | Subthread | Parent | Comments top

Dimmable CFLs currently don't work that well based on the one I purchased. On top of that, they are $13 each.

Concrete in housing will last longer than concrete that is subjected to the stress of being part of the road system.

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markincalgary on October 9, 2005 - 2:34pm Permalink | Subthread | Parent | Comments top
My impression is that it wouldn't be more efficient than wood, but that's mostly because of the embodied energy of concrete (not to mention the drywall).  If you were to forego the concrete and drywall, and just use a lime (ok) or earthen (ie. clay, hopefully from onsight) plasters, both inside and out, over a modern post-and-beam frame infilled with strawbales or cellulose, well then you've got something to talk about.

Some of the most environmentally fundamentalist straw-bale and natural home builders (ie. my friends) still use concrete but only for footings.  Even then, they often use rubble (field stone, miscellaneous rock, recycled pieces of concrete) to minimize the amount of new concrete they use.  But as a footing material, concrete is hard to beat.

Seriously, you really don't need a concrete slab for a home.  A well done earth floor is beautiful, functional, has a low environmental impact, and inexpensive.  You can even insulate an earth floor (underneath and on the sides) to use it for passive heat-storage or passive cooling, not to mention active heating.

And concrete isn't necessarily as long-lived as you might think.  Like all building materials, improperly used, installed, or maintained, it's rather short-lived.

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Magnus Redin on October 7, 2005 - 6:34pm Permalink | Subthread | Parent | Comments top
The currently most popular way to build small houses in sweden is from the bottom up:

A concrete slab with tubes for water heating on 0,2 - 0,3 m (8-12") layer of plastic foam.
The floor heating uses low water temperatures with is favorable for a heat pump or deep cycling of a heat accumulation tank connected to a wood or pellet boiler.
Walls made of wooden framework with crossed beams to avoid heat leakage thru the wood, insulated with 0,2 - 0,25 m (8-10") mineral or glass wool giving a u-value of about 0,22.
Two or three pane often argon filled and IR-surface treated windows with a u-value of about 1.3, summer cottages etc often use old style two pane windows with u-value 2.5.
And below the roof very often about 0,5 m of loose fiber isulation.

The most popular ventilation system is to have a fan sucking out air and most often a heat pump to recover the energy in the ventialtion air and heat hot water with it and take some of the general heating load. Fresh air is sucked in thru vents in most rooms, it is often combined with old style radiators. I suspect that ballanced mechanical ventilation with a heat exchanger will get more common since they use much less electricity.

Most new small houses have 1 or 1,5 floors and cellars have become uncommon since they are a little to expensive to build. The living area is usually between 110-200 m2. (1200 - 2100 square feet? )

The current main heating systems for small houses are with VERY rough
numbers:
Direct electricity  40% (shrinking fast)
Heat pumps  23% (growing fast)
Oil  9%  (shrinking fast)
District heating 9% (growing)
Wood and wood pellets 18%  (growing fast)

The abnormal ammount of electric heating is due to overinvestment in nuclear power during the 70:s and 80:s giving a long lasting dumping of cheap electricity. This is ending now due to increasd onsumption and export to other european countries.

Air conditioning is uncommon but is becomming more popular, mostly as a feature on air-air heat pumps for heating during spring, autumn and not so cold winter days.

The achilles heel is the electrical heating and electrical water circulation. The heavy concrete floor stores enough heat for about 24h during cold winter days before the house freezes. Long lasting grid breakdowns during cold spells is the most likely major disaster.  The building standard has been driven by a wish for comfort and energy efficiency. Comfort is important since people have invested to have the houses comfortable during very cold -20 C (-4 F) days when most of the winter is more like -5 C ( 25 F)  (Varies between locations. )

(I hope I got all the "funny units" right)

How do this compare to new built housing in different parts of USA?

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fum on October 7, 2005 - 8:55pm Permalink | Subthread | Parent | Comments top

State code in Oregon requires as a minimum: (R = 1/U)
Walls R-21 via 2x6 walls
Ceilings R-38
Floors R-25
Windows U-0.40

There might be additional codes for each city.

The State encourages building or renovating a house beyond the minimums specified.  They also provide tax incentives to add solar hot water, solar PV and/or wind if appropriate.

The radiant floor system you mention is becoming somewhat more popular, but still a novelty.

The majority of houses are wood framed. 2300 sqft average? (but you see lots of the 3000+ sqft on 5000 sqft lots)
Some of the 3-5 story multi-family bldgs are using steel instead of wood.

Heating is mainly electrical, with older houses using oil and usually converted to natural gas (also prevalent in new homes as well).

There is only one district heating system I know of in the state.  

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Magnus Redin on October 8, 2005 - 4:13am Permalink | Subthread | Parent | Comments top
I think the radiant floor heating system mostly is popular due to comfort reasons, people figured out it was comfortable in a bathroom and concluded "hey, lets have it in the whole house". You also dont get any ugly radiators but that require well insulated windows. It can save some energy compared with radiators but manny turn up the floor temperature instead of using 2$ slippers. It gives more potential savings then actual savings.

There has recently been some downward trends in insulation thickness, house customers have to keep asking for thick insulation or the house builders build with less to get better margins or a lower price. I suspect one of the limiting factors are the banks, they often include the running cost in the calculation on giving a loan or not and they know that a better built house is worth more to them if their customer defaults.

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