Message Board Thread - "Thermal Index/efficiency of an attic."

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Thermal Index/efficiency of an attic. Mobius01 12/22/2011
Does anyone know the thermal efficiency of an attic?

For example, we know that for the coldest day in the year, the thermal efficiency of an exterior wall should be 75% - 80% (resistance to outside temp)

So I want to know the same for an attic.

 
Re:Thermal Index/efficiency of an attic. Mobius01 12/26/2011
Mobius01 wrote:
yone know the thermal efficiency of an attic?

For example, we know that for the coldest day in the year, the thermal efficiency of an exterior wall should be 75% - 80% (resistance to outside temp)

So I want to know the same for an attic.

I can not believe that this post did not warrant a response and/or a feedback. WOW
 
Re:Thermal Index/efficiency of an attic. chicago infrared 12/28/2011
Mobius01 wrote:
I can not believe that this post did not warrant a response and/or a feedback. WOW
Which climate zone are you in? What type of insulation does the attic have? The ideal thermal efficiency would be 100%.
 
Re:Thermal Index/efficiency of an attic. Mobius01 12/28/2011
chicago infrared wrote:
Which climate zone are you in? What type of insulation does the attic have? The ideal thermal efficiency would be 100%.
Southern Ontario (same as Chicago), fiberglass loose fill.

I assume the thermal efficiency should be between 85 - 90% because it is not exposed to outside temperature. I am basing this based on an thermal efficiency of 75 - 80% of an exterior wall which is exposed to the outside temperature.
 
Re:Thermal Index/efficiency of an attic. chicago infrared 12/28/2011
Mobius01 wrote:
Southern Ontario (same as Chicago), fiberglass loose fill.

I assume the thermal efficiency should be between 85 - 90% because it is not exposed to outside temperature. I am basing this based on an thermal efficiency of 75 - 80% of an exterior wall which is exposed to the outside temperature.
If the attic is vented, it is exposed to the outside temperature. http://www.buildingscience.com/documents/digests/bsd-102-understanding-attic-ventilation
 
Re:Thermal Index/efficiency of an attic. Mobius01 12/28/2011
chicago infrared wrote:
If the attic is vented, it is exposed to the outside temperature. http://www.buildingscience.com/documents/digests/bsd-102-understanding-attic-ventilation

Ok that did not answer my original question but we can discuss your point. The attic might be exposed to the outside temp. but the temp. in the attic is always a bit higher than the outside temp. BTW, your link does not support the argument that the temp in the attic is higher than the outside temp in cold weather which is what I am trying to say.


I am very surprised that all the hot shots on this forum have no clue as to why am I asking for the thermal efficiency of an attic. So let me play a scenario for your understanding.

I get a call from a customer complaining that he thinks that the insulation in his attic is not enough.
I go to the site and turn on my IR camera, its set to auto focus. Lets say that the insulation in the attic is uniformly not enough (i-e it is R25 instead of R50 - just for the argument).

If you are doing qualitative analysis, your camera sets temperature of an area with R25 as the max and all areas in the attic lower than R25 are going to show as 'deficiencies' which is not right because your IR camera should be showing the entire attic as 'deficient' OR cold.

If you know the thermal index of an attic which is what I have been trying to figure out, you can put the values for the inside temp, outside temp (which is the temp of the attic) and the thermal index % which is 75% for an exterior wall in the coldest day of the winter and get the accurate thermogram on your IR camera.

If you put the correct thermal index (%) in the camera for the attic in question, you will be able to clearly tell if the ENTIRE attic was low in insulation.

Hope that helps answering my question.

Regardless of what people say, I think 90% would be a good # to use considering that its 75% for an exterior wall (R17). Whereas an attic is usually R40 so the thermal efficiency will be much higher.
 
Re:Thermal Index/efficiency of an attic. chicago infrared 12/28/2011
Mobius01 wrote:

Ok that did not answer my original question but we can discuss your point. The attic might be exposed to the outside temp. but the temp. in the attic is always a bit higher than the outside temp. BTW, your link does not support the argument that the temp in the attic is higher than the outside temp in cold weather which is what I am trying to say.


I am very surprised that all the hot shots on this forum have no clue as to why am I asking for the thermal efficiency of an attic. So let me play a scenario for your understanding.

I get a call from a customer complaining that he thinks that the insulation in his attic is not enough.
I go to the site and turn on my IR camera, its set to auto focus. Lets say that the insulation in the attic is uniformly not enough (i-e it is R25 instead of R50 - just for the argument).

If you are doing qualitative analysis, your camera sets temperature of an area with R25 as the max and all areas in the attic lower than R25 are going to show as 'deficiencies' which is not right because your IR camera should be showing the entire attic as 'deficient' OR cold.

If you know the thermal index of an attic which is what I have been trying to figure out, you can put the values for the inside temp, outside temp (which is the temp of the attic) and the thermal index % which is 75% for an exterior wall in the coldest day of the winter and get the accurate thermogram on your IR camera.

If you put the correct thermal index (%) in the camera for the attic in question, you will be able to clearly tell if the ENTIRE attic was low in insulation.

Hope that helps answering my question.

Regardless of what people say, I think 90% would be a good # to use considering that its 75% for an exterior wall (R17). Whereas an attic is usually R40 so the thermal efficiency will be much higher.
I don't understand what you are asking, and I don't claim to be a hot shot.

Thermal efficiency-In thermodynamics, the thermal efficiency is a dimensionless performance measure of a device that uses thermal energy, such as an internal combustion engine, a steam turbine or a steam engine, a boiler, a furnace, or a refrigerator for example.

Thermal index-A thermal index is a measure of atmospheric stability/instability.
 
Re:Thermal Index/efficiency of an attic. chicago infrared 12/28/2011
chicago infrared wrote:
I don't understand what you are asking, and I don't claim to be a hot shot.

Thermal efficiency-In thermodynamics, the thermal efficiency is a dimensionless performance measure of a device that uses thermal energy, such as an internal combustion engine, a steam turbine or a steam engine, a boiler, a furnace, or a refrigerator for example.

Thermal index-A thermal index is a measure of atmospheric stability/instability.
Now that I read over your question several times I figure you need to get some formal training. What is your background? How long have you been a thermographer?Do you have any formal infrared training?
 
Re:Thermal Index/efficiency of an attic. chicago infrared 12/28/2011
Thermal imdex is valid where you have a continous conductive path only. If there is any air gap as part of the construction then it cannot be used.
 
Re:Thermal Index/efficiency of an attic. chicago infrared 12/28/2011
You may want to start with this class. They will be in Canada in the near future. I recommend you bring your camera so you can become proficient with all the functions.
http://www1.infraredtraining.com/calendar/classDescription.cfm?Classname=39931
 
Re:Thermal Index/efficiency of an attic. Mobius01 12/28/2011
chicago infrared wrote:
I don't understand what you are asking, and I don't claim to be a hot shot.

Thermal efficiency-In thermodynamics, the thermal efficiency is a dimensionless performance measure of a device that uses thermal energy, such as an internal combustion engine, a steam turbine or a steam engine, a boiler, a furnace, or a refrigerator for example.

Thermal index-A thermal index is a measure of atmospheric stability/instability.
OMG, seriously?

Ok - I would highly recommend you to upgrade your camera to the one that has insulation alarm, humidity alarm, above, below alarms etc.

I have an insulation alarm on my camera which my customers just love it.

When I turn on that alarm, my camera asks me to enter the
1) Outdoor temp,
2) Indoor temp. and

3) Thermal Index in %. Thermal Index in this context means, "how efficient (in %)do you expect an exterior wall to be in terms of resisting outdoor temp?" This magic % is 75 for an exterior wall. When you enter these values in your camera, it will tell you where you have voids in insulation. (The 75 % came from the Building Investigations Book - so lets not just go there).

This % is true for walls and I wanted the same % for an attic. Do you understand me now?

I just played a scenario above for you. How would you find with the help of an IR camera if insulation in the ENTIRE attic is not enough (R20) ?

I am asking you how would you trouble shoot this?



 
Re:Thermal Index/efficiency of an attic. chicago infrared 12/29/2011
Mobius01 wrote:
OMG, seriously?

Ok - I would highly recommend you to upgrade your camera to the one that has insulation alarm, humidity alarm, above, below alarms etc.

I have an insulation alarm on my camera which my customers just love it.

When I turn on that alarm, my camera asks me to enter the
1) Outdoor temp,
2) Indoor temp. and

3) Thermal Index in %. Thermal Index in this context means, "how efficient (in %)do you expect an exterior wall to be in terms of resisting outdoor temp?" This magic % is 75 for an exterior wall. When you enter these values in your camera, it will tell you where you have voids in insulation. (The 75 % came from the Building Investigations Book - so lets not just go there).

This % is true for walls and I wanted the same % for an attic. Do you understand me now?

I just played a scenario above for you. How would you find with the help of an IR camera if insulation in the ENTIRE attic is not enough (R20) ?

I am asking you how would you trouble shoot this?



I own a FLIR T400, it has all the features you mention. If you are doing an inspection to determine attic insulation deficiencies, a scan of the ceiling area from the inside of the home will help you determine areas of insulation deficiencies. You will also need to do a visual inspection to verify your findings. A blower door test is also recommended to determine air leakage. I've done hundreds of inspections over the last 5 years, maybe someone else will chime in and fill us in on other procedures. Taking figures from your "Buildings Investigations Book" and plugging them into your expensive thermal imager to impress your client with images you/they know nothing about, to activate the insulation alarm, is not the way to conduct an infrared inspection. You are fooling yourself and the public and doing a disservice to the infrared industry if you are providing your clients with bad information. I would recommend a good training course for starters. I know you are new to the business and learning, but you need some FORMAL TRAINING to help you along:

http://www1.infraredtraining.com/calendar/classDescription.cfm?Classname=39931

Hope this helps.
 
Re:Thermal Index/efficiency of an attic. Mobius01 12/29/2011
chicago infrared wrote:
I own a FLIR T400, it has all the features you mention. If you are doing an inspection to determine attic insulation deficiencies, a scan of the ceiling area from the inside of the home will help you determine areas of insulation deficiencies. You will also need to do a visual inspection to verify your findings. A blower door test is also recommended to determine air leakage. I've done hundreds of inspections over the last 5 years, maybe someone else will chime in and fill us in on other procedures. Taking figures from your "Buildings Investigations Book" and plugging them into your expensive thermal imager to impress your client with images you/they know nothing about, to activate the insulation alarm, is not the way to conduct an infrared inspection. You are fooling yourself and the public and doing a disservice to the infrared industry if you are providing your clients with bad information. I would recommend a good training course for starters. I know you are new to the business and learning, but you need some FORMAL TRAINING to help you along:

http://www1.infraredtraining.com/calendar/classDescription.cfm?Classname=39931

Hope this helps.
You are a shame to thermal imaging industry. You are one of those people who are old school and simply rely on what they see on their camera when they turn it on and have no clue how to use technology like using alarms to be more productive in what they do.

You dont walk into a doctor's office and ask the doctor for their resume and ask how many patients they have seen before they can see you for illness. If they are a doctor then the govt. has authorized them to practice. You are not the judge of whether or not they should be in the business.

Similarly, If i am certified, you can not judge me whether or not I can do thermal imaging based on the # of inspections that I have done. I dont report to you.

Oh also, I am also a home inspector not just a thermal imager like yourself.

Now, let me prove to the world how ignorant you are.

You said in your post above, “If the attic is vented, it is exposed to the outside temperature”

No, you are wrong, the attic is not exposed to the outside temperature. If it was, then it would read the same temp. as the outside. I test every case before I draw a conclusion. The temp in the attic is always higher than the outside temp in cold weather. This is mostly because the attic is not exposed to the wind chill factor. The roof above the attic acts as an air barrier.

You said, “If you are doing an inspection to determine attic insulation deficiencies, a scan of the ceiling area from the inside of the home will help you determine areas of insulation deficiencies.”

No, it will tell you insulation deficiencies only if the attic is missing insulation in certain areas. I was asking how you would know if the ENTIRE attic is low in insulation level. You have to read my question at least 10 times before opening your mouth.

You said, “you will also need to do a visual inspection to verify your findings”

NO, you don’t need to do a visual inspection of the attic and physically measure the insulation level with a measuring tape if you use the correct values in your IR camera which is why I was trying to get that % for the insulation alarm. You need to work smart not hard.
What if the attic hatch is locked or not accessible? I see this at home inspections all the time. What do you then tell your client? Oh, I am sorry maam, I can not stick my head into your attic to measure the insulation level because the hatch is not accessible. But I would like for you to get my check ready.
This is why you need to use your insulation alarm on your camera to find out the insulation level without a visual inspection.


You said, “A blower door test is also recommended to determine air leakage.”

NO, you are wrong. You don’t need a blower door to determine air leakage. You can determine air leakage as long as you have enough temp differentials. In most cases, all you need is a smoke pencil to show air leakage. Blower door is needed for Energy Audit and it’s a different type of inspection.

You said, “Taking figures from your "Buildings Investigations Book" and plugging them into your expensive thermal imager to impress your client with images you/they know nothing about, to activate the insulation alarm, is not the way to conduct an infrared inspection.”

That’s a very bold statement to make and actually, you should be penalized for saying something like not following the procedures. I test everything and I have tested that if you put the correct values in your alarm, you get the right results. ITC should challenge you because you are challenging the procedures defined in the FLIR IR camera and its manuals.

You said, “You are fooling yourself and the public and doing a disservice to the infrared industry if you are providing your clients with bad information.”

Actually, you are wrong again, I provide my clients GOOD information. Just because you are old school and does not know how to use your camera does not mean that other people are doing something wrong.
 
Re:Thermal Index/efficiency of an attic. chicago infrared 12/29/2011
Wow. You need help.
 
Re:Thermal Index/efficiency of an attic. Wieslaw 12/29/2011
IMHO : as I understod question, it depends of "heat transfer coefficient" which depends on heat flux direction : horizontal is 0.14, vertical up is 0.10, vertical down 0.17 (for internal spaces). Then if you want alarm at the same built isolation as 75% for wall, you'd set it for say 97% for ceilling, or 58% for floor..
It is of course theory and sure not so true eg. in corners. Sure it is not very usable to change settings to often when investigating room, since probably differences/anomalies are much more important for client...
 
Re:Thermal Index/efficiency of an attic. Top Gun 12/31/2011
"Mobius01": I have some observations for you. "chicago infrared" was earnestly trying to help you. Instead of humbly accepting the help,
you challenged it, even though you do not take into account your own wording of your question/issue. In this case the wording is open
to interpretation in different ways. Obviously you were not happy with the interpretation of others. Your alluding to "Hot Shots" was
inappropriate and disrespectful. You have peppered this forum with basic level queries that really should be addressed in the forum of
a Level I ITC training class. There are six of them, from 8/4/11 through 12/22/11. In this thread, you stated,: "I can not believe that this post did not warrant a response and/or a feedback. WOW". This displays a lack of
patience. The exchanges of 12/28 and 12/29 descend into a disgusting level that is not warranted on this forum nor appreciated by the
rest of us who use this forum. We don't need your line-by-line evaluations of your helper's statements. You mostly revealed your own
deficiencies rather than those of others. You need to follow the advice offered to you and get some more infrared experience and more
importantly, training. You asked for it.
 
Re:Thermal Index/efficiency of an attic. Mobius01 12/31/2011
Top Gun wrote:
01": I have some observations for you. "chicago infrared" was earnestly trying to help you. Instead of humbly accepting the help,
you challenged it, even though you do not take into account your own wording of your question/issue. In this case the wording is open
to interpretation in different ways. Obviously you were not happy with the interpretation of others. Your alluding to "Hot Shots" was
inappropriate and disrespectful. You have peppered this forum with basic level queries that really should be addressed in the forum of
a Level I ITC training class. There are six of them, from 8/4/11 through 12/22/11. In this thread, you stated,: "I can not believe that this post did not warrant a response and/or a feedback. WOW". This displays a lack of
patience. The exchanges of 12/28 and 12/29 descend into a disgusting level that is not warranted on this forum nor appreciated by the
rest of us who use this forum. We don't need your line-by-line evaluations of your helper's statements. You mostly revealed your own
deficiencies rather than those of others. You need to follow the advice offered to you and get some more infrared experience and more
importantly, training. You asked for it.

First of all, who invited you to the conversation? Second of all, instead of telling me where I was wrong in my line-by-line evaluation that I did above, you are giving me a vague response on how i was wrong in my evaluations. Huh? I don’t like vague statements. I am not here to socialize, i am here to get the answers.

I had to do a point by point evaluation, so the readers could totally understand what exactly I am responding. I do this because I am sick and tired of people telling other how GOOD they are just because how long they have been in business. If you are inviting yourself to the conversation, instead of lecturing me, go back to my line by line evaluation and tell me where I was wrong so I can actually learn from it. Use quotes.

Also this is a building science forum and I asked a building science question, it really did belong to this forum.

Yes, I said, "I can not believe that this post did not warrant a response and/or a feedback. WOW" because it was a time critical issue and I was expecting a response from the 'experts' before I actually go to the call. I waited 4 days before I followed up on my initial post. Whats wrong with that? Do you have a timeline that I had to wait before following up? If not, then you can not say that I have 'lack of patience' and this is because there were not standards of patience that I broke? You see what I am saying? Dont be judgemental.

'Chicago Infrared' kept bragging about his experience and how I needed help and I have seen his website and it says it all. If you are in a business for such a long time with so many inspections then you should have spend a few hundred dollars to do a proper website. I would never hire someone with such a poor website presentation. All he said at the end was “WoW, you need help”. This tells me that he had nothing to say to my line-by-line evaluation which was pathetic and I wanted to leave it at that but then you invited yourself to this.
If you have a response to my line-by-line evaluations then go ahead so I can actually see where I was wrong, else buzz off.
 
Re:Thermal Index/efficiency of an attic. Top Gun 12/31/2011
"Mobius01": you cannot hope to gain anything by criticizing others. You reap what you sow. I suggest you solve your lack of respect problem for others as a first priority BEFORE addressing anything infrared. I am finished addressing you.
 
Re:Thermal Index/efficiency of an attic. chicago infrared 12/31/2011
Top Gun wrote:
01": you cannot hope to gain anything by criticizing others. You reap what you sow. I suggest you solve your lack of respect problem for others as a first priority BEFORE addressing anything infrared. I am finished addressing you.
This one is a classic:
http://www.infraredtraining.com/community/boards/thread/10497/

Got a website we can critique Hotshot. LOL
 
Re:Thermal Index/efficiency of an attic. qhinspect 12/31/2011
"No, you are wrong, the attic is not exposed to the outside temperature. If it was, then it would read the same temp. as the outside."

The vented attic IS exposed to the outside temperature and also to other influencing temperature sources which is why there is not thermal equilibrium of the attic space and the exterior temperature.

This is just one instance showing your arrogant incorrect thinking. Oh, by the way, "chicago infrared" is also a home inspector, commercial building inspector along with many years as a thermographer.

Have a Happy New Year and try to not be so rude next year and you might get faster help to your questions.
 
Re:Thermal Index/efficiency of an attic. Mobius01 1/1/2012
Top Gun wrote:
01": you cannot hope to gain anything by criticizing others. You reap what you sow. I suggest you solve your lack of respect problem for others as a first priority BEFORE addressing anything infrared. I am finished addressing you.
What do you know about what am I hoping for? Just because you know my screen name does not mean that you know me.

Did you go to college at all? Did they not teach you not to be judgmental about others?

You are finished addressing me? really? You should not have started this to begin with.
 
Re:Thermal Index/efficiency of an attic. Mobius01 1/1/2012
chicago infrared wrote:
This one is a classic:
http://www.infraredtraining.com/community/boards/thread/10497/

Got a website we can critique Hotshot. LOL
Good stuff but I am still waiting for your response on my line-by-line evaluation above.

Can you bring something to the table?
 
Re:Thermal Index/efficiency of an attic. Mobius01 1/1/2012
qhinspect wrote:
u are wrong, the attic is not exposed to the outside temperature. If it was, then it would read the same temp. as the outside."

The vented attic IS exposed to the outside temperature and also to other influencing temperature sources which is why there is not thermal equilibrium of the attic space and the exterior temperature.

This is just one instance showing your arrogant incorrect thinking. Oh, by the way, "chicago infrared" is also a home inspector, commercial building inspector along with many years as a thermographer.

Have a Happy New Year and try to not be so rude next year and you might get faster help to your questions.
You are wrong.

Also, dont worry about me finding answers to my questions. I know how to get answers to my questions.

You dont need to speak for Chicago Infrared, he can speak for himself.

I go to home inspectors' conferences all over the country and we all learn from each other in those conferences and if someone asks an 'odd' question we just dont start recommending further training and/or start questioning his/her credibility. Thats not how it works. Its because of this 'Chicago Infrared' is on the bottom of my 'good list'.

 
Re:Thermal Index/efficiency of an attic. Bob Berry 1/1/2012
"Chicago Infrared" YHBT.

Mobius01.

I don't recommend the use of this tool without fully understanding it, and you don't seem to have fully grasped it. From your post, it appears that you want to use this in an attic, and I assume that you want to view the ceiling below the attic, to check for the insulation. It also appears that the building has a cold roof design. The tool is not really valid in this instance, as you don't have a continuous conductive path to the outside. I am not sure that it has any validity in the USA anyway, but it is a nice tool, and customers do like it. However it is only a tool and must be used correctly. It is an invalid tool in about 95% of buildings where I am.

Also, you are incorrect about your statement that thermography can be used to locate air leakages with ONLY a temperature difference in place. You will find some of them, but not them all. I would strongly recommend a blower door when looking for air leaks, particularly if you want to find all the leaks. This is basic building physics.

Also, if you want people to be more responsive to your posts (particularly over a holiday period), I would suggest a more relaxed response be adopted. To be honest, given the deterioration of the thread, I was reluctant to post myself.
 
Re:Thermal Index/efficiency of an attic. Linas 1/1/2012
Thanks for chiming in Bob,
Our technology has come a long way in the last 5 years, but it is not just "point and shoot" technology. You actually have to have a grasp on the equipment capabilities and some knowledge of thermal science to intrepet the images. As you mentioned, a blower door is needed to determine the location of air leakage. Climbing into the attic and getting dirty is part of the job too, you need visual confirmation of your findings if the area is accessible.
 
Re:Thermal Index/efficiency of an attic. qhinspect 1/1/2012
Not defending "chicago infrared, just stating that he is also a inspector as am I.

I am not wrong.

I go to conferences also and talk with many people that have varying degrees of formal/hands on education about many different subjects. I may not always agree with what they say but I understand they may have a different perspective.
Odd questions are what facilitates learning as long as responses to those answers are not as rude as yours are.
 


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