Could this be true

Greg Gibbs

Thanks guys.....for your help! -Greg

Greg Gibbs

Could this be true…

or is this smoke and mirrors.

This “cinder block” manufacturer claims a very high R-Vale for his product.
Every chart I have, including the old ASHRE tables show MAYBE a R-3 to R-5 (with cores filled with insulation).
I have a plan for a large warehouse in front of me…I would hate to design for R-14, if the true R-value is 3 -Greg

Charles G.

Cinder blocks

I don't think you'll get R-14 if you fill the blocks w/smoke...

Boilerpro_5

Maybe...

I have heard of very high R-values for aerated concrete products, but I sure would look closely. In fact I believe aierated concrete can be used as insualtion between studs. Most concrete block walls have R-values equal to that of thermopane windows...about R-2.

Boilerpro

Brad White_9

Precisely, Boilerpro

People are surprised -and no less than my architectural students- when I tell them that concrete block walls have an R value close to that of double-pane glass. In fact, we have an historic building under design in Maine (Historic meaning we cannot touch the facade), where the window R-value is double that of the wall....

The objection I have to the notion of insulated concrete blocks is, yes, you can insulate the cores, better than nothing. But every block has at least two or three positive thermal bridges, the block webs, to conduct heat at a rate enviable by radiator manufacturers. (Exaggerating here, but, you know what I mean.)

Weezbo

ok..so somewherewhen i was going to fire up an old block plant..

there is some material that is fired at different temps with less structural strength that will allow a block plant to make blocks with some real R value...however, not many would do it as it has different parameters to the manufacturing process.

the cost ,providing you can get the materials is close to price except the blocks have to be built into a structure and wet waterproofed ...the old guy who passed on,sold the block plant to another who ran the place a couple ten twelve years and unfortunately sank his snowmachine in a river a few years back. He had changed something about the firing process and was begining to make more money moving houses and basically his work died with him.

you can be sure that anyone making blocks of that nature have more money wrapped up in standards than making any specialty blocks with 10 times the r value of normal cinder blocks.

the blocks are somewhat like wood that has to be inclimated,... meaning timing is everything with them




do your homework ....

GMcD

Like the window sales literature

Was the thermal resistance measured at the insulated core or as the "overall" U-value? 99% of all the window guys out there sell "high" performance windows based on the "centre of glass" U value, which is about 20%-30% better than the actual "overall" U value when you factor in the thermal bridging, framing and mullion systems. I'm having a "discussion" with an Architect who claims he is providing "high" performance double glazing with a "U value of 0.29", and when I run it on my trusty Window 5.2 software, with a thermally broken frame, the overall U value is actually 0.41. Pretty significant if you are sizing the perimeter heating and cooling systems. I'm told my standards are too onerous and expensive....then I simply show the Owner the energy cost per SF with that glass vs the energy cost per SF with the better glass, and apply whatever inflation rate on energy costs they want, and it's a no-brainer. Institutional clients that live in a building for 50 years plus are a little more open to the on-going operating costs of their buildings. Homeowners ought to be similar, but first cost always seems to override common sense.

Brad White_9

Your experience, Geoff

Mirrors our own for the same reasons. 0.29 center of glass generally does go to the low 0.40's when amortized over the whole.

Also, argon fill? Sorry, it leaks out and does not add much when it is there, a point if that in my experience.

Use manufacturer's literature alone at your peril.

BTW: If no good glass data is given, we use 0.45 as a U value for double-pane low-E as a default/place holder until better information comes along.

Thanks for the validation.

Brad

Mike T., Swampeast MO

This appears to be a realistic r-value table for concrete block and other masonary materials. The block in question here (10" thick; 80#@ cu.ft. density) with cavity insulation is said here to have an r-value of 7.46

Nice discussion here about thermal performance in real-world concrete walls. Note that mortar substantially reduces the effective r-value.

Autoclaved aerated concrete blocks (usually solid) are however, pretty good insulators. A 10" block has an r-value of about 12.5

Rigid exterior insulation substantially increases the thermal performance of masonary walls.

MMI6

Block

Greg, I would say that this is correct maybe even a little on the reserve, one block that I have seen (Eco block)
http://www.eco-block.com/ touts that they can achieve the same value of a standard framed wall insulated to an R-40.

thank you

GMcD

Based on what standardized testing?

All this talk of "effective R value" is just words if all of these concrete block suppliers aren't using a standardized, repeatable test. Where and how do they generate their "effective" R value data? Is it based on a standard whole wall area? Just a single block? Air temperature differences on either side of the block in what conditions? I checked the ASTM site and did a search on insulation testing for concrete and there isn't, as far as I could find, and standardized testing method for the "effective R value" of concrete products, blocks, etc. So it's like bubble foil insulation, it's sales hype unless it's referenced to standardized testing and measurement methods.

Brad White_96

Just like the Low E glass R values...

Not sure what you have found, Geoff, but the Low-E R values seem to also be "effective" numbers allowing for reflected radiant flux. I have measured the surface temperatures versus double-pane and found no appreciable difference. I am surmising that the "radiant effect" is an add-in.

The reason I tested the surface temperature was my concern that in a swimming pool, the dewpoint/surface temperature of the glass would not be significantly different than standard glass, and I was right.

GMcD

Same issue found here

Yep - good thing I visit buildings with surface temperature sensors as well as doing my due diligence on "Overall" thermal resistance values. The problem in the past is that the "all air systems" being designed had enough safety factors built into the calculations that the variables like the published data for envelope components vs the "real operating data" got washed out in the mix. Now that more folks are trying low energy. sized "right to the load" systems, with minimal added safety factors, more and more of these building thermal physics issues are occuring. The current state of the art of building design has the HVAC designer being made responsible for the "energy efficiency" of the building, but all of the energy required to keep that building comfortable is a direct relationship with the quality of the building envelope.

So now, the old conventional building envelope products are being "tarted up" with a few bells and whistles to enhance their "energy efficiency" performance at low cost, but the standardized testing and measurement protocols haven't kept up to the sales hype.

Brad White_96

Well said and appreciated, Geoff.

Indeed here in the states, we on the HVAC engineering side calculate envelope compliance (often as a courtesy to the architects for whom we work), largely because we already have the breakdowns of materials and areas for our calculations. The architect, not the HVAC designer as you well note, is responsible for policing the construction and insuring the integrity. How many times have I seen brick masons responsible for installing the insulation board? No offense to them as a group but this was not their area of expertise. I have seen one inch or greater gaps, boards flopping in cavities... if the system does not perform it would be my fault.

Not venting too much I hope, but your call for progress in standardized testing is well-placed.

Mike T., Swampeast MO

Insulated concrete forms have both physics and common sense behind them. By their very nature you must build in a manner that maintains thermal efficiency throughout the entire wall. Thermal bridging is a non-issue. Don't forget that wood studs in a highly insulated frame wall are the weak link.