Does Superinsulation "work" in a Hot Climate

[John B]

Conventional Hot and Mixed Climate "wisdom" , Energy Codes and Energy Star guidelines (existing and proposed)seem to indicate that there is really not much need for high R-value (especially in Walls).
I understand that superinsulation and triple glazed windows are expensive and they do not provide the "Big Bang for the Buck" as they might in Fairbanks.

If we ignore the cost and focus on what needs to be done to create Low Energy Homes then I contend that superinsulation and high performance windows "work" in hot climates.

Of course we need to properly shade our structures and windows first and avoid thermal bridges.
AND when nightime temperatures do not go below 75 then we will not eliminate the need for air conditioning...we can only reduce the need.

[Dancing Dan]

It seems hard to argue against it, although the delta is obviously going to be much less in a cooling climate (maybe 40 deg. maximum, whereas even in southern Maine it can easily be 60 degrees). And of course "need" is a relative term. But if you're simply saying that a super-insulated home in Austin will use less energy than a poorly insulated one then I agree.

[John B]

Dan,
I think that it is more than just DeltaT ... You Cold Climate Folks have an advantage.
You can offset with solar gain and internal gain.
Solar Gain and Internal Gain work against us (Hot & Mixed)whenever the outside temperature is greater than 75 ... which can be 24 hours a day for weeks and weeks.
Since we can not "offset"........ all we can do is shade, contain, recover and insulate more.
By the way ... how is your Building Science group going?
Have you had any more meetings?

[Dancing Dan]

Right, your point about night time temperatures is well taken. So what does that mean for super-insulation? There must be some research out there.

Our discussion group has met twice, both good discussions. I think we're going to skip this month (late August in Maine is pretty precious) but we've had a lot of interest, and very little of people pushing product, which was one of my worries.

Our hosts have set up a grill, everyone brings a chair and beer, and we've had about 1/2 hour of socializing followed by 1 - 1.5 hrs of discussion. The foam guys seem to have the most to say and are the most contentious, but it's been a really good mix of theory and practice, and enough interesting case studies to bring real-world experience.

I can't recommend the idea highly enough to anyone interested in starting a group locally. If nothing else it's a mutual support group and you'll meet some potential subs/GC's/arch.s, etc.

[Bluewoodrock]

The foam guys seem to have the most to say and are the most contentious, but it's been a really good mix of theory and practice, and enough interesting case studies to bring real-world experience.

I can't recommend the idea highly enough to anyone interested in starting a group locally. If nothing else it's a mutual support group and you'll meet some potential subs/GC's/arch.s, etc.

Damn uppity foam guys.

As someone who attends these meetings I'll second the notion that it's a great idea. Fun to have a few and talk shop. The discussions have been very informative, and have given me a lot of food for thought and even changed my opinions on a few things. Always good to here other points of view.

[Dancing Dan]

Here, here.

[Dick Seibert]

John:

I always wondered why you were interested in superinsulation being from Texas, the conventional wisdom I always heard was insulate walls in cold climates to keep the heat in, use radiant barriers in hot climates to reflect the heat out, and the problem is in mixed climates where you have to keep the heat in some times, and keep it out other times. I have gone from information I got from both Cardinal Glass and the Berkeley Laboratories' Daylighting Institute. It seems like the scientific principles used for windows should apply to walls as well.

I agree with Dan, isn't there research out there to see how much good insulation does in walls in hot climates?

[Dancing Dan]

the conventional wisdom I always heard

Now you're quoting conventional wisdom approvingly?

[Dick Seibert]

Now you're quoting conventional wisdom approvingly?

Not really, all I'm saying is what I've been told, I'm reaffirming your suggestion that John look for studies on the value of bulk insulation in hot climates. There are parts of this country that don't even require heaters to be installed by code, air conditioning isn't required anywhere.

Just look at Obama's Energy Czar wanting everyone in the country to paint thier roofs white to save energy, people in cold climates should install dark roofs to absorb heat, the proposal so derided by Rush Limbaugh. Are you guys in Maine going to start painting your roofs white? Even people in Berkeley were challenging that one since Berkeley can be cold.

[Dancing Dan]

Dick - I agree that heating is a much bigger issue for our roofs than cooling. Good insulation takes care of most of our summer time issues.

John - isn't Austin the center of warm-climate green building?

[John B]

Dan, you are correct....
Austin is very progressive when it comes to Hot climates and low energy.
I have learned a lot from my Austin neighbors.
The publicly owned power company is extremely involved with helping citizens save energy.
Austin Energy has education events 4 times a year and Holds a Cool House Tour every Year and nearby Fredricksburg hosts an Energy roundup every year.

The "conventional wisdom" message concerning insulation from Austin...."After about R-13 you are really reaching a point of diminishing return"
I believed this myself until I started building my own Low Energy Home.
I employed many of the strategies that I learned from Austin....Window orientation, shading,extreme air tightness,modular framing, light colored roof, simple shape, roof overhangs..yada,yada

I was not too concerned about wall r-value ...
Before construction I had the Design modeled for Energy Star and got a pretty decent HERS score.

In order to avoid having any plumbing on exterior walls... I had created several double wide exterior walls.
Not really intending to juice up my r-value...why bother?
Spray foam is not cheap ... but at the last minute I decided to just go for it... I went ahead and filled those double walls with open cell foam.
When the Energy rater came out to inspect.. he made note of the extra foam and then updated my HERS score.... For some strange reason there was a dramatic improvement in the predicted Energy Use and the HERS rating....hmmmmm
There must be something wrong with the RESNET software....R-value is not important in my Climate??? or is it?
My final HERS rating was 51 ... not too shabby.
Projected Energy use was about 50 percent of a built to code reference house.

After living in the house for a year .. the actual usage was below the projected usage.
I believe now that if I would have insulated the edge of my slab, used triple glazed windows and juiced up the wall r-value of all of my walls that my home would have performed much better.

[Dick Seibert]

You ask the $64 question, a question that should be studied before anymore money is thrown into insulation, bulk or radiant, and money not supplied by an stakeholders in the insulation industry or the Green Building industry.

You say that in Texas R-13 is the point of diminishing returns, I think that should be studied everywhere in the country. When the scientists at the Daylighting Institute in Berkeley told me that it was a waste of money to insulate a wall to a greater level than the window, I suggested that we stop rating walls and windows, but start rating wall assemblies including all fenestrations, this seemed to throw them stating that the manufacturers would just give them "gold plated" assemblies to test that wouldn't be anything like the assemblies built in the real world.

From what I'm reading New Orleans, of all places, is adopting a combination or radiant barriers and soy based foam insulation, I can't find article where I read about it, but Googled and came up with this.

[Bluewoodrock]

From what I'm reading New Orleans, of all places, is adopting a combination or radiant barriers and soy based foam insulation, I can't find article where I read about it, but Googled and came up with this.

"soy based" foams is a misnomer. What it really should be called is spray foam with soy polyol content. It's still a petroleum product, the maximum soy content of these foams tops out at about 5%. Most spray foams contain some vegetable based polyol content, some use sugar beets or corn or sugarcane based polyols and some use soy.

"soy based" is a marketing thing (and a good one judging by all the people I talk to who want the "green" soy bean stuff), but it is just that: marketing. Dick I just don't want you starting to like foam because the manufacturer gives the impression that they are maing the stuff entirely out of soybeans.

our experience with the soy bean stuff is that it's finicky to work with and doesn't produce really good foam. Save the soy beans for edamame and tofu.

[Dancing Dan]

Dick - I think rating wall assemblies sounds cool but seems entirely unworkable - a gazillion variations.

John - it's hard to believe that R13 would be the point of diminishing returns for a hot climate. Doesn't seem like enough to keep the heat out effectively. How are you drying out your house? I was exchanging e-mail with someone who made that point - that if you're lowering your AC usage you need another source of dehumidification. Do you have an ERV? OR dedicated dehumidifier?

[John B]

You say that in Texas R-13 is the point of diminishing returns,
came up with this.

Dick,
I did not say that.

I said that it was the "conventional wisdom" in Texas.
To be fair it is not touted by everyone in Texas ... but the concept is widely believed here.
Peter Pfeiffer for one has been saying it for years.

The problem is that he is talking about diminishing return on DOLLARS invested to change away from the way that we are building now.

R-13 is based roughly on what people THINK they are getting with a standard 2x4 wall.