Looking for natural cooling ideas

[Highbeam]

Strength isn't the issue and 2x6 walls are just fine for strength. I am looking for the thermal mass of concrete along with a place to run my wires. Lots and lots of commercial buildings are constructed with block walls in washington so I know there isn't a seismic issue. I wonder how tilt up concrete wall construction is in residential sites. That is the current craze in commercial construction.

HVAC ducts within the floor slab? I would have never thought it. I need to also consider non-ducted heating such as radiant slab heat. I plan to use a woodstove for heat. Perhaps HVAC is not necessary with adequate thermal mass? Our climate is very moderate most days even though we break 90 today and 95 tomorrow the ground temp is nice and cool and we dip into the 50s most summer nights. Whoa, no heater vents.

 

[Phils]

"Perhaps HVAC is not necessary with adequate thermal mass? "

Just be sure that you have a "primary" heat source OTHER than a woodstove. No one will monitor which you primarily use but getting insurance on a home with woodstove heat is expensive and not readily available.

Phil

 

[Paddy]

True, IFCs are tight on air leaks, that can be done with and without concrete.
You don't need IFCs to glue Foam on to poured concrete walls.
Also, you can't play the card "good insulation and thermal mass at the same time with IFCs". The Thermal mass IS INSULATED from it's source of heat gain/loss outside and location of deposit inside if it is so well insulated. Choose one card or the other.

Point is, choose where you want that insulation wisely.

The western adobe has no isulation, just massive amount of thermal mass, 2-3' of earth. You can open the door for one hour and let all the heat in of the mid day. When you close the door, the heat will be absorbed in the the walls. If those same 2-3' adobe walls had the same fine foam insulation of IFCs inside, well it would just be hot and steamy. The less foam you had the quicker the room would return to pre door open temp. Another example; an empty frige at 45 deg will heat up once the door is opened in short order. The same frige filled with water jugs will maintain the 45 deg starting temp for quite some time.

The number one advantage of IFC was "home owners can stack foam legos and fill them will concrete and think they are saving money"

Sorry for my rant, but I'm just not sold on them

 

[dmccarty]

Regarding the wood stove and getting insurance. I'm sure it depends on your location but we got insurance on our house with the stove. Did it raise a flag? Yes. But the cost of insurance for the new house which is twice the size of our old house and worth far more, was about the same as the old. We eventually went with Farm Bureau insurance and drastically cut the cost of insurance for the same coverage.

Insurance and mass. Based on the questions asked by the insurance company the one thing that helped us with the insurance and the wood stove was the finished concrete floor. Its hard for the floor to catch on fire. Course the insurance company did not have a check box for Finished Concrete Floor so we had to use tile instead. Since we don't have carpet, can't stand the stuff, the slab acts as a huge thermal mass. It works. The wood stove sits on a brick and granite hearth. The brick is doubled so that the hearth is seen in the master bedroom and the study so that the heat from the stove can radiate directly into those rooms. The hearth is a fair amount of mass in the house.

We went through the idea of ICFs but we could not justify the cost, we kept bumping into a cost of an extra 5% over stick construction. Plus we knew we where putting in huge area's of wndows. Why have this expensive wall that is supposed to be energy efficient but then punch 8'x6' holes into it? We wanted the ICFs to protect the house against falling trees but in the end we went with 2x6 walls with the 1 inch foam. This got us about the same R value as ICFs and some strength but at less cost. Given the window holes maybe we should have just kept 2x4 walls but I think we made the right decision.

You can add mass to the house without having to involve the exterior walls. One of our earlier designs had a sun space that ran the length of the southern side of the house. We wanted an eight foot "room" for solar gain. The idea was to grow some plants as well has the passive solar design. The "room" would have had extra mass built into the interior wall to hold the solar heat. But that idea was just to expensive. There is a NC Solar Center at NCSU. We went there in December a few years ago after we had days of temps dropping into the teens and 20's overnight and not getting out of the 30s. The NC Solar Center house had a bunch of passive and active technique/technologies. It is bermed into a hill for instance so the first floor has roughly half the house covered by grade. The house was so hot inside we had to take off our coats and sweaters. The porch that was enclosed by glass was 90 degrees while the outside temp was in the 20/30s. The downstairs was built out of CMUs if I remember correctly. The upstairs was stick built.

The Enertia homes I mentioned in an earlier post use the 6x6s and other large diminsion lumber as thermal mass in the interior.

Later,
Dan

 

[Haoleguy]

Stumpfield - You have many good ideas. The 4 that come to my mind are1) ICF construction from base to roof..available in different wall thicknesses, (2) the porch overhangs on the sunniest sides, (3) air flow in attic/crawl space, &(4) key placement of trees and bushes. The bushes are designed to keep the ground from heating up and warming the structure.

 

[SPIKER]

haloguy mentioned one good thing was landscaping, thermal mass needs to be effective, having a big ole hot stone in the sun will soak up a lOT of heat and let it go through the night, same with a house, this is good in winter, bad in summer, so you need to plant fast growing shading plants that drop their leaves in winter, shades the home in summer and exposes it to the sun in winter. other things are that using light water spray to feed these plants helps inhot summer and none is needed in winter... solar heating is good solar cooling can also be effective. useing the sun to move the air past water cooled medias can caluse a good temp drop which can be moved into the home...
anyhow lots of good info here and else where on the net.

markM

 

[dfkrug]

ICF construction is a proven method with thousands of houses all
over the US now. There are over 80 US vendors of ICFs from what I hear.
The advantages are clear and proven. In my own 2100 sf house I
have the smallest forced-air furnace (40KBTU) and a 34KBTU wood
stove, either of which can easily heat the whole house by itself. The
thermal mass, strength, and lack of leaks works amazingly well to
save me 50%+ in heating costs vs my old frame house. I eliminated
central AC in my mild climate. THERE is a significant savings right there.

In my DIRECT experience with 2 dozen projects, the main downside to
ICF construction is the difficulty getting contractors to build with it
and engineers to do the calculations. Both trades are extremely
resistant to changes and most benefits to ICF construction go to the
owner, not the builder.

 

[3RRL]

....the main downside to
ICF construction is the difficulty getting contractors to build with it
and engineers to do the calculations. Both trades are extremely
resistant to changes and most benefits to ICF construction go to the
owner, not the builder.

You would think that is the way it's supposed to be? ...for the homeowner's benefit. Why are they so "resistant" to that, I wonder?

 

[dfkrug]

You would think that is the way it's supposed to be? ...for the homeowner's benefit. Why are they so "resistant" to that, I wonder?

Well when you fixed-bid a project and you are learning a new method,
it is understandable that you are taking risks with how much time/effort the
new method will require. There is an inherent resistance by contractors
or engineers to changing ANYTHING. Historically, there was extreme
resistance to the use of plywood after WW2, ABS plastic drain pipes,
and other materials/methods taken for granted today. The only real
benefit to the builder is a better house, and that only affects the bottom
line in a market where the builder builds on spec and has to market his
house in competition with other conventionally-built houses. Ususally,
ICF houses are custom-built for particular customers who have done
their research and demanded ICF construction.

 

[Tom_H]

Thermal mass mainly helps when outside temp swings above and below inside desired temps DAILY. For example, in the MN twin Cities, ave winter temp fluction never get above inside desired temps. Same can be true for FL, hot all 24Hr. In AZ, you get nice temp swings and you can stored the heat of the day for use in the chilly night.

This is very true. We have good thermal mass with our log home. In the summer it can get into the hundred + teens during daytime, yet usually cools off nicely at night. The solar gain from the day re-radiates back outward at night. During this recent heat wave, however, we had a bit of humidity which acted as a thermal blanket at night, which kept the outside temp. in the 80s. Instead of radiating outward, the solar gain all radiated inward all day long. The AC ran 24 hr./day. The logs usually function to save on elec. usage, but for that week and a half, they cost us a bundle. It would have been more efficient to have had a traditionally insulated home then. Thank goodness we are back to normal now.