Here is a basic formula for Q (mass storage)= Specific heat of material X density X thickness. Increasing either to the right of the equation increases the lag or delay time. Intake and exhaust rates can vary depending on inertia or better dynamics.

Well, my thread has come a long way from the original topic.
I can say that I am not going to be using min splits to cool my house, it simply isn't cost effective with my lay out and size. However, the radiant is another story. I intend to use it in the slab, the master bath on the second level, the kids bath on the second level and a large mudroom, bathroom, hallway, half bath area on the main level. All will be staple up because GYPCRETE is a pretty foreign product around here. I did research about tile over gypcrete and it's a huge pain and not a fact about what exactly works. So i am going with the staple up from underneath and high water temps from my outdoor wood boiler.

it is dynamics not steady state

Nope, in the middle of the December in Michigan, it's all about steady state in my low solar gain house.

Posted By jonr on 12 Mar 2014 09:50 AM

it is dynamics not steady state

Nope, it the middle of the December in Michigan, it's all about steady state in my low solar gain house.

Not sure what planet you’re on, it's March here daylight savings just changed, but I’m in center MI, USA on temp work assignment. Only steady state here the Antarctic wind/snow blast that rolled in last night, cold past few weeks I been here from CA. Might want to check your center cavity and clear wall R-values @ several locations again for steady state, solar or no solar, report back. ;)

TLP, I just want to say that I hope you keep contributing to this forum. It is so encouraging to see new members join this forum who are intelligent and can actually compose a thoughtful, well written response. We seem to have way too many hacks who seem more motivated to have a high post count than actually contribute any factual and worthwhile info to this GREEN building forum.

Posted By sailawayrb on 12 Mar 2014 03:09 PM
TLP, I just want to say that I hope you keep contributing to this forum. It is so encouraging to see new members join this forum who are intelligent and can actually compose a thoughtful, well written response. We seem to have way too many hacks who seem more motivated to have a high post count than actually contribute any factual and worthwhile info to this GREEN building forum.

Thanks for the welcome, sorry I didn't introduce myself, I am a degreed Aerospace Engr w/30 years experience. Right now working field issues, test lab. My son and I recently launched a storm and restoration co doing well. I am looking and learning to add green technology production homes to our portfolio soon. I got some things to offer and some things to still learn. OP: Other thing the right interior mass can do is absorb and release moisture at rapid rates, preventing mold and mildew causing allergies, also absorb odors.

Thanks for the intro TLP. My dad and founder of our company still works in the Aerospace field (Boeing)…perhaps for 35 years now. I am still in school working on my MBA/J.D degrees. My undergraduate degree majors were IT and English.

Posted By Dana1 on 11 Mar 2014 06:39 PM

Posted By TLP on 11 Mar 2014 05:47 PM
steady state r-values resistance do not apply to thermodynamics anywhere in the world, it is far more complex than that. We don't live in steady state environments, nor do walls. We run it all day, CFD and FEA models, then we validate those models to lab and field data. Q formula has many variations, look it up....then get into aerodynamics, human factors, and equipment correction factors, commercial vs residential, you need a model better than WUFI and HVAC loads.

Read this about DBMS value: http://web.ornl.gov/sci/roofs+walls/research/detailed_papers/thermal/index.html

Read this on the latest how r-value is misleading this industry. If you need help with the test procedures and results let me know it is what I do for a living. I'm doing thermal, pressure, fatigue life cycling on seals now. http://www.buildingscience.com/documents/special/content/thermal-metric/BSCThermalMetricSummaryReport_20131021.pdf

Good read take note: "This article does not address the use of thermal mass inside a building, where it can store heat (or coolth) and even out temperature fluctuations".
http://www.buildinggreen.com/auth/article.cfm/1998/4/1/Thermal-Mass-and-R-value-Making-Sense-of-a-Confusing-Issue/

Of course it's more complicated that that, but just because mechanics is more complicated doesn't mean that gravity doesn't apply. The steady state R is just one element of a more complicated equation, but that fact doesn't mean "...steady state r-values resistance do not apply..."  Of COURSE it applies!

Although R-value is an extremely crude model, at best a first-order approximation,  it's far more than a third-order factor in a building's thermal performance, and more important than the thermal mass factors in most buildings.

High precision isn't usually necessary (and not really possible) to achieve useful and appropriate numbers in these analyses.  U-factors for wall assemblies calculated on the steady state R-values of the components are sufficiently predictive of the heat transfer rates to model annualized energy use and peak energy use of simple buildings like single family homes with corrections for other factors like plug loads, solar gain, etc.  Even a Manual-J or I=B=R tool will get you most of the way there, and a 2-D model like DOE-2 does a little bit better. None of them are capable of factoring out the human-behavior aspects, and all of them are "good enough", for most real-world purposes.   The most perfect thermal modeling of a house is readily undone by a single occupant who didn't understand that they needed to comply with the operating behavior that was modeled.

Now that is information worth quoting. I have never been so happy to be contradicted and applaud your peerless insight and unflagging patience. Shopping for PV panels this afternoon. Thank you Dana.

Posted By easyrider470 on 11 Mar 2014 09:57 PM
Well, my thread has come a long way from the original topic.
I can say that I am not going to be using min splits to cool my house, it simply isn't cost effective with my lay out and size. However, the radiant is another story. I intend to use it in the slab, the master bath on the second level, the kids bath on the second level and a large mudroom, bathroom, hallway, half bath area on the main level. All will be staple up because GYPCRETE is a pretty foreign product around here. I did research about tile over gypcrete and it's a huge pain and not a fact about what exactly works. So i am going with the staple up from underneath and high water temps from my outdoor wood boiler.

Good on ya! Reality sinks in as the pocket book opens and light shows the awful truth! hheheee You won't mind if we go on with the serious work of speculating on advanced building envelope discussions, most of which Dana has already explained to the interested. http://www.ornl.gov/ornl/highlights/advances-in-understanding-durability-of-the-building-envelope And hey; thanks for asking!

Posted By TLP on 11 Mar 2014 08:17 AM
There is no such thing as permanently exhausting a reactive chemical or allergies to air from an inside or outside source.

Maybe not, but many contractors are familiar with OSHA standards, circa. 1999. https://www.osha.gov/dts/osta/otm/otm_iii/otm_iii_3.html

Posted By TLP on 11 Mar 2014 06:52 PM
Nah, I wish I could show you my CFD model, it cost around $15, 000 license decent but not the best, then walk you over to our lab, few million in test equipment, if I were to call thermal mass of a building any other word but dynamics, it be thermal inertia but that be as misleading as r-value....take a while to load, then little to maintain for the materials we are referring to. Very hard to quantify, I think ORNL has a good start using the same lab instrumentation and field data we do, not much theory! Read the test reports on r-value BSC did...it is dynamics not steady state. What matters is the materials specific heat primarily not resistance.

I'm still not sufficiently impressed with your awesomeness, or the per-seat price of the CFD software tool ($15K is a fraction of the cost of some of the design tools I use in my job, but in a different field entirely), or your rilly kewl and expensive lab equipment, given that the simple modeling of DOE-2 works fine for making practical design decisions.

FWIW: I had read and RE-read the BSC material long before you referenced it.  Was there any particular point you want me to focus on the next re-read?

Sometimes the simple models are the right thing to use, even if it's not what's really going on, as long as it gives you the right result with sufficient precision.  The rest may be of some interest to us physics & math types, but when it comes down to the practical aspects of designing building assemblies there is very little to be gained by the more technically correct & precise modeling of what's really happening.  That's as true for heat-transfer issues as it is for moisture transfer- the simple dumb models are all wrong when you get into the weeds on it, but they work, and work pretty well from a practical point of view. eg: If you actually NEED to run a WUFI simulation to know if your assembly makes it or not your design is crap, cutting it too close to the edge.  And even if you designed the moisture transfer issues with margin that's not going to save the house from the occupant who boils pasta all day with the lid off and never uses ventilation.  Building design benefits from knowing the results of the more technical analysis, but doesn't need to (and probably shouldn't) use the same tools.

As a cheap & effective approach to designing performance buildings, modeling using R-values is perfectly fine, whereas it could lead to gross errors in other types of thermal design problems.

Posted By Dana1 on 12 Mar 2014 05:47 PM

Posted By TLP on 11 Mar 2014 06:52 PM
Nah, I wish I could show you my CFD model, it cost around $15, 000 license decent but not the best, then walk you over to our lab, few million in test equipment, if I were to call thermal mass of a building any other word but dynamics, it be thermal inertia but that be as misleading as r-value....take a while to load, then little to maintain for the materials we are referring to. Very hard to quantify, I think ORNL has a good start using the same lab instrumentation and field data we do, not much theory! Read the test reports on r-value BSC did...it is dynamics not steady state. What matters is the materials specific heat primarily not resistance.

I'm still not sufficiently impressed with your awesomeness, or the per-seat price of the CFD software tool ($15K is a fraction of the cost of some of the design tools I use in my job, but in a different field entirely), or your rilly kewl and expensive lab equipment, given that the simple modeling of DOE-2 works fine for making practical design decisions.

FWIW: I had read and RE-read the BSC material long before you referenced it.  Was there any particular point you want me to focus on the next re-read?

Sometimes the simple models are the right thing to use, even if it's not what's really going on, as long as it gives you the right result with sufficient precision.  The rest may be of some interest to us physics & math types, but when it comes down to the practical aspects of designing building assemblies there is very little to be gained by the more technically correct & precise modeling of what's really happening.  That's as true for heat-transfer issues as it is for moisture transfer- the simple dumb models are all wrong when you get into the weeds on it, but they work, and work pretty well from a practical point of view. eg: If you actually NEED to run a WUFI simulation to know if your assembly makes it or not your design is crap, cutting it too close to the edge.  And even if you designed the moisture transfer issues with margin that's not going to save the house from the occupant who boils pasta all day with the lid off and never uses ventilation.  Building design benefits from knowing the results of the more technical analysis, but doesn't need to (and probably shouldn't) use the same tools.

As a cheap & effective approach to designing performance buildings, modeling using R-values is perfectly fine, whereas it could lead to gross errors in other types of thermal design problems.

I respect your point of view and experience. Mine is aircraft design and manufacturing. Interesting since I remember the days about 20 years ago when hand calculations and outdated AutoCAD/NCAD was considered 'good enough'. Today our models are EXTREMELY accurate since we have feed them with empirical data for decades. Impressed or not next time you fly if you do chances are I helped design some portion of the plane you are in, or some of this country’s best fighters/bombers. We have come a long way with modeling, dropping a lot of ground and flight test cost to compete with the world as a country. I use CATIA/ENOVIA V6/NASTRAN/PACTRAN. Of course this industry is not selling products that cost 750 million, 30 billion in program cost, with Engineers modeling across the globe, so my point was the software used here is nowhere close to being certified by the FAA or NASA. As far as modeling everything you mentioned in a house to a tee, we did that 20 years ago. I’ve seen mass designs go south, read of the horror stories of people too hot or cold from bad designs that were told by engineers there HVAC bills would go down not up as they did. BSC did limited testing to show the effect of induced air/moisture in wall cavities. Very low budget compared to what we do. Same with ORNL. Both recognize it was just a start and there were budget constraints we rarely see in my world. But a BASIC step in the right direction, quantify mass with DBMS and a 10 climate zone c-mass calculator based on prototypes and 1900 models, realizing corrections need to be made at an industry level to whole wall r-value by knock down factors from air/moisture infiltration in wall cavities when thermally cycled over time. Nothing I did not explain in more detail above. Specific heat, density, thickness, pressure, inertia are the main parameters. Inner and outer wythes that thermally cycle with a respective designed in lag time. You I am sure will use R-value in your designs I will not, we can agree to disagree, no prob! Sorry OP your thread is getting off topic, with that note I'm out. Good luck to all! :)

Looks like some thermal mass salesmen are joining the radiant barrier and thermal paint salesmen with their "R value doesn't matter" claims.

For most new builds and US climates, the weighting is going to be closer to 10% thermal mass, 15% air infiltration and 75% R value.

When houses cost 750 million a pop to build or heat/cool there will be an argument for that level of thermal analysis, eh? :-)

I'm still curious as to what special insight in the BSC document indicates completely tossing the use of R value out the window. There's very little in the way of truly new news there, but it's being quantified a bit better. The same with ORNL's dynamic mass modeling stuff too. The better understanding of how it really works is of academic interest, but doesn't materially affect the overall designs when looking at the thermal performance of a house. Even crummy heat load calculators are predictive of peak loads and average fuel use within low double-digit percentages for homes without any dynamic modeling of ANY aspects. DOE-2 isn't a very complex tool either, but does a bit better than simple-minded load tools, gets the error down to high single digits. And the statistical noise of occupant behavior is higher than the error of these simple tools. Sure, you don't want to resort to using a rock for a hammer, but you don't need to use a precision stamping machine with air-bearings do drive that nail either.

I'd like to hear more about "...mass designs go south, read of the horror stories of people too hot or cold from bad designs that were told by engineers there HVAC bills would go down not up as they did." though, especially in regard to how much of the horror can be attributed to the poor modeling and simulation, and how reliance upon steady state R value numbers as a parameter in that modeling was the root of the problem.

I have nothing against high-mass building systems, and clearly the mass effects with rammed earth or CIC walls, etc is more than the 3rd order effect the way it is with the stick-built US paradigm, but so what? Clearly dumb heat -oad tools based purely on steady state U-factors/R-values of the dirt will not be super-useful in those designs, and I'm sure badly done attempts would (and do) lead astray. (Electronic filter analysis tools sometimes can do a pretty good job of modeling many mass-wall designs though.)

Even the best models use delta T and R-value (or U-factor). The models just divide the problem into a finite number of elements to apply this heat transfer principal. The better models largely use more elements to improve accuracy and better address temp time lags. It is usually more important to account for all the heat gain/loss items in the building (solar heat gain often being neglected and infiltration often being inaccurate and significant) and correctly book keep all the BTUs.

Posted By BadgerBoilerMN on 12 Mar 2014 04:42 PM

Now that is information worth quoting. I have never been so happy to be contradicted and applaud your peerless insight and unflagging patience. Shopping for PV panels this afternoon. Thank you Dana.

It looks like the PV deal going forward is now a known commodity in MN (unlike most locations), now that the Minnesota Public Utilities Commission just passed a state-wide VOST!

With that legal structure in place it's now possible to use a more rational basis for the investment in PV.  In many states the utilites are challenging the traditional dumb net-metering deal with some good arguments and a whole bunch of bad ones and in many cases getting concessions that aren't clearly warranted (the payback on all of that lobbying, advertising and whining in AZ was pretty good for the  utility, not so much for the small scale PV owner.) 

It'll take awhile for the dust to settle, but it looks like having a state-wide standard puts MN ahead of the game, and it should be possible to figure at what price point (with or without subsidy) rooftop solar will make financial sense.  I expect MN is poised for a huge solar boom in the wake of this decision, but we'll see pretty soon how the number shake out. Grid power is  pretty cheap in MN, but the VOST is probably going to be substantially better than residential retail net-metered deals.

"A Passive House home in europe costs only 10-15% more and uses 90% less heat than a home built to code."

Given their cost of fuel, it is little wonder.

I work with many "Architects and Builders" most have LEED credentials and are not lacking in any respect, save customers willing to pay a premium for triple-glazed windows.

We designed a radiant floor system for a sun room three years ago. The Architect asked us to confirm the surface temperature of the $8000.00 German windows to confirm the comfort promised would be delivered. After advising that original specification would result in very dark glass--more appropriate for Dubai than Minneapolis--and that Krypton was not worth the considerable up-charge, we determined the interior surface of the glass would be 66°F during design conditions -13°F. You would do better to sell the comfort than the quite questionable ROI.

Windows are a poor place to hang your hat and the last place to invest in GREEN technology, be it in new and more especially in old construction/renovation.

http://www.greenbuildingadvisor.com/blogs/dept/qa-spotlight/are-high-performance-windows-worth-their-high-cost

Naturally this article is "in the bag" for any high performance window (while its author routinely discounts the wisdom of radiant floor heating in GREEN home building) the arguments for triple-glaze demonstrate more the weakness than the strength of triple glazing.

Paraphrasing;

First, that energy prices are going up.

That is what I told my customers in the 80's when I installed my first condensing boiler--at three times the cost of the old atmospheric boilers. Didn't happen.

Second, that the triple-glazed house will not cool off as fast as a house only double-glazed.

Never heard of shutters or thermal curtains I guess.

The third point speaks to comfort and correctly points out that sitting next to a lowly double-glaze window when the outdoor temperature is below zero can be uncomfortable. Maybe if depending on how close you are sitting, the quality of the window, the wall assembly and the MRT. If you have radiant floors, walls or ceilings you likely wouldn't know the house had windows.

Comment #13 by Mr. Koerber is the reasonable reflection of a passive house builder pointing out the obvious relationship of climate and current construction practice.

Don't get me wrong, I love triple-glaze windows, and Mercedes cars, just about any airplane, most can't afford them. If you have to be rich to be GREEN you have lost 99% of your potential market.