INSULATION IN THE DEEP SOUTH

[DONKUMPUNEN]

I dont think that people in the deep south[mississippi gulf
coast] understand that insulation and at least double pane
windows are necessary because of the intense heat from may
through the end of october.
I used to live in Wisconsin and i had 12 inches of insulation in my attic,double pane windows,and larsen storm doors.
When i bought an older home here i put 6 inches of rolled
insulation over the 4 inches already there in the attic.I replaced the old single pane windows with new double pane
windows and installed a larsen storm door.
I definitely believe that double pane windows,12 inches of
insulation in the attic,etc.are necessary in the south for
energy efficiency and comfort[from the intense heat vs cold].Any thoughts out there on this? DON KUMPUNEN

 

[imok2]

This is from the dept of Energy:

First check the ductwork for air leaks. Repair leaking joints first with mechanical fasteners, then seal any remaining leaks with water-soluble mastic and embedded fiber glass mesh. Never use gray cloth duct tape because it degrades, cracks, and loses its bond with age. If a joint has to be accessible for future maintenance, use pressure- or heat-sensitive aluminum foil tape. Then wrap the ducts with duct wrap insulation of R-6 with a vapor retarder facing on the outer side. (If you live in the deep South or southern California, you can use R-4 insulation.) All joints where sections of insulation meet should have overlapped facings and be tightly sealed with fiber glass tape; but avoid compressing the insulation, thus reducing its thickness and R-value. In many parts of the country, this type of insulation will pay for itself in energy saved. Hope this helps
Roger

 

[amorrison]

Consider this:

Twenty five years ago(~1975) the heat bill in Canada and the heat bill in Florida were the same - $600.

Unbelieveable ! ! you say -WHY ?

Homeowners in Canada had double pane windows, 3.5 inches of wood shaving/fiberglass in the walls and ceiling and the house was reasonably airtight to keep out the -20F drafts to make the house comfortable.

Homeowners in Florida had .....insulation and even less airtightness (what is a "draft" on Florida??).

Bottom line -- People build houses that are adequate (and nothing more) for their physical and financial comfort.

 

[DONKUMPUNEN]

When talking about CANADA and FLORIDA I would compare the
heating bill in CANADA vs the cooling bill in FLORIDA.
My a/c bill in the summer[everything is electric]is about
200 dollars a month here in mississippi.My house is about
1700 sq/ft.When i lived in northern wisconsin i didnt need
air conditioning.The last winter i lived in wisconsin 1990 to 1991 i used about 300 gallons of heating oil.
A lot of people try to say its cheaper to live here but
thats hog wash.You use your a/c a lot here and another
item to consider is a/c in your car which is a necessity.
In wisconsin its nice to have but its not a necessity.Also
on the average your auto a/c isnt going to last as long as the home unit and when it goes out thats big bucks.
DON KUMPUNEN

 

[imok2]

Don the humidity is the problem!
Roger

 

[chicopee]

DOUBLE GLASS PANES IN MISSISSIPPI MAKES SENSE BUT MAKE SURE THAT YOU HAVE TREES AND OVERHANGS TO BLOCK SUNLIGHT RADIATION BETWEEN THE PANES, OTHERWISE, YOU WILL HAVE EXTREMELY HOT AIR SPACES WHICH SHOULD HAVE AN OTHERWISE TEMPERATURE RANGE BETWEEN THAT OF AMBIENT AND OF THE LIVING SPACE.

 

[billygoat22]

I found "Builder's Guide to Mixed Climates" to be very informative. The deep South is called a hot,humid climate, as opposed to the cold climate of Wisconsin. Down there,the vapor barrier is installed on the OUTSIDE of insulation envelope, as opposed to the interior.
Of course, insulation helps greatly, but reflective roof colors, shading, controlling air infiltration(humidity) and moisture sources in the building can affect energy use as much as the r-value.
Here in central Va, its a mixed climate. Better off without a vapor barrior, since 1/2 cool and 1/2 heating through the year. I have shading, r-30 in attic and a conditioned crawl space. elec bill runs about 60/mo in summer

 

[BravoCompany]

billygoat:

I would be interested to know why you believe this, only for my own purpose not to necessarily chalange your position on this matter. You have brought up an interesting point about vapor barriers. I would disagree however about not requiring a vapor barrier here in VA

The use of vapor barrier and where to locate it seems to be an issue of debate here in Va. Based on an article I had previously read from ASHRAE Journal, it was my understanding that a vapor barrier should be installed on the outside of insulation assembly, in hot humid environments to keep outdoor humidity from entering the wall cavity protecting against mold; on the inside of the wall cavity in cold, dry climates, to keep moisture from entering the wall cavity then turning to ice and damaging the insulation within; and never on both sides as this is a sure way to trap moisture within the insulation.

In a climate such as Va I don’t know that there is a set of rules on placement, however, I would imagine that one should be in place to prevent the moisture travel between conditioned spaces and the outdoors. Remember moisture will travel against air pressure gradients as it is affected only by the partial pressure of water vapor present. This means building pressurization does nothing to protect against moisture gain, hence the need for vapor barrier.

 

[billygoat22]

I have to agree with you on the barrirs,I've been reading several books on the subject and had to go reread some. In the Moisture Control Handbook there are actually wall assemblies with the vapor barrier on the inside or the outside, depending on the construction materials.
It seems most of the buildings I've been in either have no vapor barrier or only the kraft paper vapor ratarder, and many times the aluminum backing on the insulation product was installed sometimes in ,sometimes out. One would expect to see mold in 1/2 these applications, but it isn't so. Apparenly (according to building scientists) the mixed climate doesn't promote continous wetting of the wall cavity so the materials can dry quickly enough without moisture problems.
I'm not for vapor barriers, since no one installs them anyway, and the backing on insulation (vapor retarder)isn't installed lapped to get the proper performnce. Couldn't find it right off, but because a single air leak in a room will bring in more moisture than an entire wall assembly by diffusion, it might be a better strategy to air seal the envelope (which you would do with a vapor barrier anyway.

 

[Warpspeed]

The problems of keeping heat in and keeping heat out are totally different.

In a cold climate all you need is a sufficient thermal insulation barrier, and an internal vapor barrier to prevent the insulation from icing up. Heat losses through the floor might also be very significant.

In a hot climate quite obviously the insulation does not suffer from icing, but there is the problem of direct solar gain. As has been previously said external reflective surfaces are excellent, as is shading. It also well worth ventilating roof space to reduce the thermal load on ceiling insulation. Wide eaves and shade trees also become a big part of comfortable living.

Planting deciduous trees works well, summer shade, but you can still get the winter sun.