Does radiant barrier make a huge difference (in Dallas)? (new house, construction)

[Jan08]

Just wondering if anyone has done this (and any other upgraded energy features in attic) and what kind of difference they saw in their heating/cooling bills in this area?

[HockeyDadof2]

We had radiant barrier paint and additional attic fans installed last summer. Based on average temps. and the increase we had in our per kilowat hour charge we did save probably 20% on our electric bills last summer.

Originally Posted by Jan08

Just wondering if anyone has done this (and any other upgraded energy features in attic) and what kind of difference they saw in their heating/cooling bills in this area?

[loves2read]

having radiant barrier installed as part of construction is more energy/cost efficient and just better design

adding radiant barrier is more problamatic because sometimes due to roof lines/height/construction it is difficult to actually install ridiant barrier foil which is better than the radiant spray

the more difficult the physical installation--the higher the cost per sq ft...you have several choices in thickness of radiant foil and in the type of radiant spray--you have to get the roof volumn they will be covering and then figure out how many barrels of spray would be necessary or how many rolls of foil (there is also loss factor to be considered with both applications). Spraying too heavy or too lightly negates the quality of the application--just like not allowing an air envelope with the foil installation is also bad practice...
paying for too heavy a foil barrier is not good ROI--

there is also the issue of air flow--some people think that adding radiant barrier negates the need for improved air flow--that is wrong--in this area if you don't have good air flow, you run the risk of getting no benefit really from adding radiant barrier--so not only do you have to get quality install for the radiant barrier but make sure the company does not block the air flow when retrofitting...
air baffles sometimes need to be installed to protect the intake vents in the eaves (our house has them already installed but older homes usually do not)

some companies also provide extra insulation as a "free" bonus which it really is not since it is cost to installer--this can be blessing and curse--
it also obscures the real payback from the radiant barrier install--

for some people just adding better air flow and extra insulation might be cheaper and obtain almost the same results as the radiant barrier
each project needs to be observed/analyzed on its own merits

we had two companies come out to give us estimates for doing the house we bought in October--since it did not have radiant barrier installed during construction even though it is only 4-5 yrs old...
they did a free energy evaluation for items like weather stripping/insulation/radiant barrier install

both the companies said that we had good air flow through the attic--which was unusual in their experience--both of them said that we would probably get as good a return on our money from having the radiant barrier spay done since the film is more expensive to install and in our attic there were some areas that basically were unreachable
they also said that our windows were pretty basic (which we knew) but there were no real visible problems with poor seals--would take a blower test to really evaluate the whole house envelope
one of them would have included that for free if we had bought the radiant barrier install which would have saved us about 4-500 since they price something like that per sq ft of house...

one of them said that adding soffit vents to our covered patio area--the only part of the roofline not done--might help to improve the air flow but basically it was well-designed--
the other said that because of the way the attic design/construction and how insulation was installed between first/second floor in that area it could make the game room upstairs colder in winter...

we decided since we had no real idea of how expensive it would be to heat/cool the house we would wait a year and just observe--
so far from comfort factor--the house stays very warm (to me) my husband has been wanting to turn the heat up more than I have...
we basically live on first floor--second is for when kids come to visit--we keep the heat set at like 66/67 up there
right now we have windows open and slept that way very comfortably last night...

there is always the issue of pay-back--Oncor has stopped its program of rebates for green-improvements...
if rates stay down (which I doubt) then the payback is extended...
I have been in many new houses where there was no HVAC running--there is a definite difference when you are in attic where there is radiant barrier installed vs none--
I think it should be part of state building code--when you compare the benefit to the cost at installation it is really one of the cheapest things a builder can do...
it is also probably a good idea to use the same type of material around the exterior envelope of the house before the brick/siding goes up--and to have it done to all rooms that have attic exposure...
especially since almost no homes use foam insulation/seal environment construction...

just get several estimates and read up about what makes a quality install...
both the people who came to give me an estimate said that they always come with the foil barrier spray in barrels and wanted the homeowner to inspect the barrels before the job started...
you also need to contact references to see what type of homes they did their installs on and what the payback was--I asked for customers from at least 6 months prior--
winter installs when price is usually less don't really see any benefit until going through a summer cycle...
another factor in air intake/exhause--get turbines vs electric fans and have the wider neck turbines--that really makes difference on amount of air than can be moved--
when the air is hot--and the air flow venting has been done properly--you really are not supposed to need wind to make the turbines operate--having cooler air come in from the bottom and rise to the top of the attic is supposed to pull heated air throught the vents
having electric fans can cause a continuous suction which actually pulls cool air out of the house and into the attic space...not good economics