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Old 03-04-2009, 11:32 AM
 
47 posts, read 233,037 times
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When building an energy efficient home, especially in a hot climate, I know that a lot can be done to improve it's energy consumption.

I know also that adding insulation and upgrading areas in the attic is a lot easier to do on a pre-existing home than upgrading walls/windows.

So my question is, what ultimately makes the most impact - the windows/walls, or the attic?
If a home is already built and doesn't have good windows/walls will upgrading the attic alone be sufficient to give the home great efficiency? Or will the quality of insulation with windows/walls make the bulk of the difference?
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Old 03-04-2009, 02:41 PM
 
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If you were buying a newly constructed house, I would suggest looking for an Energy Star rated house - that would get you upgraded attic insulation, windows and building envelope. With the Energy Star inspection process, potential leakage areas are located and fixed.

Since you have an existing home, you may want to consider an energy audit. These can be available free from your electric utility or, if you meet certain income guidelines, from your state weatherization agency.

Your goal is to reduce electric bills. Here are several steps you can take:

1) If your refrigerator is more than 10 years old, use a Kill-a-watt (or similar electricity measuring device) to check its electrical usage. Some older refrigerators can use over $100 a month in electricity - these should be replaced.
2) Replace incandescent light bulbs with compact fluorescent light bulbs. This swap reduces electrical usage by 80% and pays for itself in less than one year.
3) Check attic insulation levels. Find the suggested level for you location here: EERE Energy Savers: Insulation (http://www1.eere.energy.gov/consumer/tips/insulation.html - broken link) Weatherstrip the attic access panel, and insulate the attic side of that panel. I suggest blown in cellulose.
4) Check blinds and drapes on south facing windows. In a warm climate, you don't want the sun to add heat to your house.

In the long term:
1) Plant shade trees
2) Re-roof, when needed, with the lightest color you can be happy with
3) When you replace the AC unit, get the most efficient (Energy Star) model on the market.

In short, attic insulation is much more important than windows, and will provide cost-effective comfort.
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Old 03-06-2009, 01:44 PM
 
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thanks SO much!!
These are great tips!

So, can a pre-existing home be upgraded energy efficiency-wise to match the energy efficiency of a new energy-star home (that has the wrapping, low E windows, etc)
or will a pre-existing home always fall short, even if upgraded to the max?

(I was told by a builder that walls/windows matter a ton, and are too costly to upgrade later)
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Old 03-06-2009, 04:01 PM
 
Location: Eastern Washington
14,217 posts, read 44,878,144 times
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As to which matters more, walls or attic, the attic is more important for the reasons already given, but really the most important heat leak will be whatever you do worst. You can model the different heat conduction paths as a group of parallel electrical resistors, water valves, or even passport control lines - whatever you best imagine. The flow will go to the path of least resistance in each case - so for your house if you essentially do the walls and attic right, the windows in particular become dominant heat conduction paths.

As an old hot-rodder, I have to tell you that anything can be upgraded to any standard as long as you have the money to do it. This may or may not really be practical though.

If you are building from scratch, I would go *at least* to the Energy Star standards, maybe even more. The labor to install the best available windows is essentially the same as installing junk.
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Old 03-09-2009, 02:28 PM
 
Location: Grosse Ile Michigan
26,513 posts, read 62,912,197 times
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The most important thing that you can do is to stop air penetration. You can insulate the heck out of your roof and if the wind blows therough your walls, it will nto help much.

You need to find places where cold air comes into your house and seal them. The easiest places to work on are:

1. Outlets and light switches. Put your hand hear them in teh cold season. If you feel cold coming out get some DAP foam and seal aroound the box, then get those foam things to put underneath the outlet or switch covers.

2. Doors and windows. A lot can be done with weather stripping an caulk. Old windows with decent storms cna be as good or even better than some of the new fangled windows. Again the real trick is ot make sure it is sealed. On a windy day, tape plastic over a winodw. If the plastic fills up with air like a big sail, you have leakage. Doors are harder, but you cna buy materials to help seal doors at any home improvement store.

3. Sills. The sill (where you house attaches to your basement) is often a source of big heat/cold leakage. You can spray the entir sill with foam like Tiger foam, but that is expensive. It may be better to pay someone to come and spray foam for you. Howevre make certain that they doo a good job and get a complete seal. Many insulation companys seem to do a poor job.

4. Baseboards. The best thing to do with leaking baseboards, is to pull them off in put insulation in behind them. Another less expensive and less effective option is to caulk them.
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Old 03-09-2009, 05:39 PM
 
Location: Maine
502 posts, read 1,566,333 times
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i agree with the previous post - stop air leakage first. Find the locations that air is escaping or coming in. The best insulation in the world won't help if air is leaking under doors and around windows.

Then - start ceiling. Hot air rises. It is relatively easy to add insulation.

Windows can be pretty easily replaced. My brother had a 200 year oldish farm house, and just changing the windows cut the oil heating bill in half. There were days when you could see the curtains move from the cold air coming through. They then removed the old horsehair walls, insulated and put up new sheetrock. The tried to do one room each month - tear out, insulate and install in one weekend. I helped a couple times. Lots of messy work, but they now use about 1/4 of the oil as before for heat.
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Old 03-14-2009, 01:34 AM
 
Location: Northglenn, Colorado
3,689 posts, read 9,447,940 times
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Quote:
Originally Posted by Jan08 View Post
thanks SO much!!
These are great tips!

So, can a pre-existing home be upgraded energy efficiency-wise to match the energy efficiency of a new energy-star home (that has the wrapping, low E windows, etc)
or will a pre-existing home always fall short, even if upgraded to the max?

(I was told by a builder that walls/windows matter a ton, and are too costly to upgrade later)
upgrading an existing home to meet energy star ratings, or HERS ratings is possible, but it has the potential to be extremely costly.
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Old 03-14-2009, 08:01 AM
 
234 posts, read 1,150,959 times
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I have a question - I have cathederal ceilings in the dining room, living room and hallway of my home. The home was built in 1991 so I don't think it is insulated up to the par as houses are today.

How can I insulate these cathederal ceiling areas?

thanks
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Old 03-14-2009, 08:28 AM
 
48,516 posts, read 83,890,268 times
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It will have to be blown in.But if the home walls don't breathe you can creat a moisture problem ;especaily in colder climate. that is why its important to know what you are doing in older homes with DIY.
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Old 03-15-2009, 02:28 PM
 
Location: Charleston, SC
5,615 posts, read 12,826,401 times
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Quote:
Originally Posted by Jan08 View Post
So my question is, what ultimately makes the most impact - the windows/walls, or the attic?
If a home is already built and doesn't have good windows/walls will upgrading the attic alone be sufficient to give the home great efficiency? Or will the quality of insulation with windows/walls make the bulk of the difference?
IMO, after moving to a hot climate I'd say if you're building (and especially if you have windows facing the south/southwest), go for better windows and wall insulation first. Radiant barrier next (can be a real pain to install later), followed by going above and beyond on the blown-in insulation last since the radiant barrier will cut down on attic temperatures significantly.

Existing houses are a bit different since you can't get into the walls easily and replacing windows can be much more difficult. I'm working on making my 16-year old house more energy-efficent right now. I did an experiment on adding a radiant barrier to the attic space above my garage, pantry and laundry room with a north/south exposure and it brought a 30-40 degree temperature difference after I installed it. I was in the mid-140s before, low 100s to 110 after. I chose that area because it wasn't that large and already had plywood installed as a floor. I can really feel the difference in the garage because there's no insulation above the sheetrock, but now there's less heat trying to get into that part of the house through the insulation and ducting too. The only downside - it's a huge pain to install in areas where you only have the beams in the ceiling to stand on. My goal is to finish the southern-facing part of my attic before the middle of the summer but it won't be easy.

Of equal importance if you have southerly-facing windows is to get some kind of solar screen up. Even in March my IR thermometer showed the blinds (closed) to be over 100 degrees in one room. Letting the light through the windows whether it hits your blinds or stuff in your house is like having giant radiators heating up the place. The only way to address the root cause is to keep the energy from coming indoors, so that means screens, trees, tint or something to reflect it back out. In another month or two I should have some hard data on what kind of difference that makes.

Adding more insulation will help some too - you can use an IR thermometer to find gaps and thin spots a lot more effectively than you can with a hand. It'll also tell you whether you actually need more insulation or not.

In my opinion there may be something to cleaning up dusty HVAC ducting. When it's new there's nothing coating the reflective surface but as time goes by dust settles up there and more IR energy gets absorbed since it's not as reflective anymore (and more energy gets transfered inside your living space through air that's not as cool as it would've been). The ducts themselves I don't think are actually insulated that well to begin with... they might be R-6? I'm not sure what kind of difference cleaning them makes - it's another experiment I'm trying later this summer once I can get a couple of weeks worth of data points before and after.
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