Thanks.
In the vault.
Thermal bridging of metal studs is real issue and is well proven. Metal is 300 times more conductive than wood. The r-value of wood is 1 per inch and metal is .04. Metal stud manufacturers build dimples or channels into the studs to reduce contact with the wall surface to help reduce this problem. Even if it wasn’t I would suspect you would see the studs due to lack of perfectly installed cavity insulation. Depending on when the house was built or the exterior cladding I would suspect there was something done to reduce the thermal bridging. Possibly an exterior layer of insulation, which is required under the 2009 Energy Code and also suggested by ASHRAE in certain climate zones.
Good conclusion Robert.
The conductive material also has a*** rapid conductive behavior*** and will emit energy signatures on wall board…
Let me explain.
My residence is mental studding.
I have made many mental notes during my infrared observations within my home.
Question I have asked myself is manufacturing Delta T adventitious to a degree weighing time as a factor and when is the best time?
Using manufactured Delta T, my interior H-VAC, I can control the best conditions to extract some very good images. Materials emissivity is now the educational subject.
Question, can Delta T be artificially produced in other building?.
I suspect we know the answer.
In Montreal Stack Condos are still the biggest real estate property investment in Montreal. NOTE: It is not that much time consuming due to the conductivity of the material.
Of course during adverse exterior temperature differences it a joy for all of us.
As summer approached I will being continuing to replicate conditions in hopes of advancing my theory.
It will be my first season when I have to take the time of day and manufacturing an optimum Delta T condition.
Thanks ROBERT E.
Please prove it (without the internet hype).
I don’t care what others “think”. I did not believe this either.
Again: This is** not **about the “Rate” of transfer, it is about the “Quantity” of energy involved.
For Plumbers: If you have 1 psi on a water line, one is 1.5" and one is 1/4", which one will have the most volume discharge in 1 hr.?
For Electricians: If you apply 120VAC to a conductor, one is 10ga and one is 28ga , which one will deliver the most wattage in 1 hr.?
Then if you add length to the wire or pipe, what happens to the flow?
Didn’t John McKenna go through all this in IR Certification?
This is just Level I stuff straight from the ITC Level I training manual.
There are additional design features employed in metal stud design and use to further reduce the heat transfer rate. Even with wood studs, they try to reduce heat conductance by placing them 24" OC so there are fewer studs.
As few can do the math, Show me the scans!
Thermal Imaging can measure and record R-Values, K-Values U-Values etc. Actual testing is the only way to determine performance. Just because heat flows faster, does not mean the total over time will be greater.
Show me your IR R-Value comps between the two materials.
Will be a great training exercise for Certified Thermographers.
If you want to learn more about this, it will be discussed at NACBI Commercial Training (after hours training sessions).
Evening 3: http://www.nachi.org/forum/f53/commercial-building-onsite-training-soon-available-80552/index3.html
David the hypothetical bridging material makeup being part of the equation.
I see no reason to reference John’s course.
Weather you have taken the course or not is not what the discussion is about.
As long as a passion is sparked the student will do the rest.
Thank you David.
The two of you insist on pulling in Internet Opinion.
I thought you may be able to relate to something you “invested in”.
I didn’t say anything about the course for you to be scolding me on. I simply asked if that was not covered. My posted example came from the same book John was trained from…
Thus you should have been, also.
So in theory, the length of time at a certain deltaT could result in a completely different IR image as heat transfer occurs through the metal stud? What I mean is there may have been a point much further into Charlie’s test where the loss of heat from the drywall and plywood was greater between studs than at the studs and they would have begun to appear?
This would occur because heat was continuously transferring through the studs from the outside at a relatively steady rate and quantity, assuming consistent outside conditions, but the absorption rate at the interior wall would overtake the rate of heat transfer through the studs if enough cool air was being pumped into the room by the AC unit.
And if the wall was wood framed, even though wood doesn’t conduct heat as rapidly as metal the cross-sectional area of the wood stud is so much greater that the quantity of heat transfer would occur faster?
I will be prepared when you can attest to your investment in humility.
I see you personal association fellowship emissivity David, A pride we all share. Look closely beneath these posted words.
Can’t you see it?
Nor can I:p
Of course it would have my image was just a moment in time as I have never ran across this type of wall. If the outside ambient had been up near 100 degrees and the A/C had been on constant and kick the delta T up near 30 degrees very possible to see the studs. I did not stick around that long I was just playing with the camera.
You guys that are just getting into IR will have a passion for it and will take your camera to McDonalds with you and scan everything in sight it will be an extension of your arm or you will sell your camera and profess to the world that no one in your area wants or will pay you for IR work.
Charley, your remarks have always held weight on this subject for me.
Yourself peaked my interest in the education and science of thermography.
Your point of view is an excellent narration for configuring Delta T within a given situation using a H-VAC system. Sticking around long enough being the time one will/may spend creating a hypothesis through discovering components.
As always you represent yourself as the candidate that many InterNACHI members strive to be.
All the best.
Charley,
McDonald’s you say.
Does Ronald MacDonald have any emissivity to speak of, or is he a “black body”? Like the foods and nutrient value “considered zero?”
I remember someone saying once that when the sun is shining on the side of the house it will negate any readings you take with the camera. Is that true, is it just in winter or does it also apply to summer when the outside is already hot?
In my opinion that would not be true you control the temps within your enviroment to obtain a delta T however furnace or A/C. If I had actually been trying to see a difference in the temp between indoor and outdoor on the wall with the plywood I would have cranked the A/C down as low is possible hours before hand.
@ 84 degrees outside ambient the first image I posted is a prime example of how little heat is actually being tramsmitted from the exterior to the interior.
How much heat the wall studs metal or wood have retained from the exterior is irrelavant it is not being transmitted to the interior and that is all that should be considered
As compared to -20 as the outside temperature is what I think Cameron was asking.
Also imaging from the exterior at the envelope.
If I am mistaken than excuse me.
My IR is only rated for -20. I have tried on colder days.
With the temp @84 and the envelope being fully saturated with the same temperature, the timing to have a good Delta T condition artificially manufactured from the H-VAC is dependent up time as you expressed.
Have the exterior envelope at minus 20 as in winter and you have prefect condition except for below grade and dependent upon ground frost.
Yes you folks with the capability of -20 degrees exterior and 70 degrees interior have a gold mine concerning IR. I perfer to do my imaging from the side of the envelope that I can control the temp the conditions on the exterior are beyond control we just have to be aware of them and the result they can create, sun, wind, and temp. Not to say you don’t have to be aware of indoor conditions because you do the sun shining through a window A/C or furnace blowing on a wall its all about being aware of conditions and understanding your enviroment
All the above play a well orchestrated game in infrared thermography.
Yes a cold exterior climate and normal habitual interior space are wonderful to image.
As for the side of the envelope that I can control, it is not always that easy in every given circumstance. From reflective materials and following guests heat signatures and agents over your shoulder peering at the screen make it difficult to say the least.
Thanks Charley.
My pic in post #16 was solar loaded.
It doesn’t always negate anything, it mostly just makes things a little more difficult because there are a lot of extra things to consider and adjust.
If the picture in #16 was not solar loaded and it was hotter outside than inside (which it was) the stud would be yellow instead of blue. In Charley’s scans you can calculate the R-value, you can’t in mine.
Solar loading as well as evaporative cooling are similar to a heavy reflection which could totally washout any anomaly that you happen to be looking for. If you’re not looking for missing insulation (as in my picture), rather you’re looking for wall fasteners, you won’t find them. Were not always looking for what is most apparent in our thermal scans. Thus you can’t operate your camera in the “auto mode” much of the time.
As for this OP, solar loading may provide the increased energy required to identify metal studs in Charley scans, but that’s not what he was looking for.
90% of what you do with building thermal imaging requires proper timing/conditions. When you are looking for moisture under a flat roof you may be looking for something hot or you may be looking for something cold or you may see both at the same time! That is why your training is more important than the camera you own.
I am working on a report right now where I was hunting down a building leak. During my initial site assessment the outdoor air temperature was the same as the indoor wetbulb temperature.
I had both air leakage and water intrusion occurring in the same place. I have air leakage anomaly signatures and water leak anomaly signatures overlapping one another. I spent several hours separating the two.
This job is going to require window removal, exterior brick siding removal and interior ceiling removal. You had better have called it right before you start!
It’s not always as easy as it seems by using a moisture meter to verify your thermal anomaly between moisture or air leakage. Air leakage very often causes elevated moisture. It could be recessed lighting in the kitchen ceiling just as easy as it could be a leaking roof or flashing!?
Thank you Cameron.
Wonderful explanation.
As for solar loading that terminology is new. I will be looking into the term tonight.
I mostly use auto but if the image is not what I want or expect, I instantly manual focus to see what I can extract from the walls or components surface.
The three D image is what will emerge myself into and yes C. training is everything.
All the best.
I wish. That was David Anderson.
Come see me in ten years and I might know all that.