Energy Loss: Air Exfiltration

[David A. Andersen]

you have to have a minimum of 18 deg F temperature differential

I would not say that you "have to have" but the more the better!

Down here in the South it can be very difficult to get temperature differential.

This does not mean the camera will not work for you.
The quality of the scan will substantially degrade and air movement, sunlight, HVAC etc. will substantially affect the capacity to detect thermal anomalies. The camera is capable of temperature differentials below 1°C. That's all you need to get an anomaly to show up.

I would highly recommend that the 18°F temperature differential not be disregarded if it can be achieved.

I also recommend that your report documents if testing was conducted outside of the 18°F temperature differential recommendation. As this is an industry standard, any deviation from it warrants explanation.

[David A. Andersen]

The delta T that you are talking about is that outside temp from mid day to night or are you talking from inside to outside?

Inside/outside.

[lolsen]

Thanks for clarifying David.

In Canada we were taught delta T of 10C to 15C. Conversion tells me that 18F is about 8C. Close enough! I do not know the Delta T because I was just playing with the camera that night and shooting houses for the fun of it. Normally houses inside temp is 20C so I am guessing that I would have a Delta T of 40C or 104F. That should be enough .

Thanks
Lawrence Olsen

[David A. Andersen]

It just performed this test at my office on a known "minor" thermal anomaly under these conditions:

Indoor/outdoor air temperature differential: 21.6°C/21.2°C = .4° temperature differential C.

Apparent wall temperature scale in thermal scan: 21.6°C/23 .5°C = 1.9° temperature differential C.

Outdoor air temperature 21.6°C. Windspeed 14 mph with 25 mph gusts. Dewpoint temperature 17°C. Relative humidity 76%.

The indoor/outdoor air temperature was taken with a calibrated thermalcouple.

The apparent wall temperature scale was determined by the BCAM and quick report software.

The palate was "mid-green" with the scale set at 23.8°C - 21.5°C.

Under no circumstances would I consider conducting a thermal scan under these conditions, however this is an example of the BCAM's capabilities under actual conditions.

[lolsen]

David

That is ugly. Sure glad I did not go with the BCAM.

Lawrence

[David A. Andersen]

Post us a scan with your camera with a 1.9°C scale across the scan and let's compare. For you to duplicate these crappy conditions, it may take you till summer!

This is the same camera. Different temperature differential. Except for the sky, this is still < 10F degree differential.

Does it look familiar?!

[Peter C. Russell]

Here's some from today's heat loss survey on a warehouse with offices.

Any opinions?

[lolsen]

David

I was not trying to avoid you but I had to go to work. Trying to get ready for a trade show. I am curious to see how my images do turn out and will try as soon as I can. I will post them even if I shoot myself in the foot. We all need to learn somehow.

The last Picture you posted is way better. Yes it does look familiar but from where I don't know off the top of my head.

Lawrence

[David A. Andersen]

Lawrence,
That's what we're all doing here! You're not alone. We have all been passing things around (even behind the scenes on the bulletin board). Some of these reports are just too big for some of us to get posted here.

Yes it does look familiar but from where I don't know off the top of my head.

John McKenna is using it on much of his marketing materials and educational website (as am I).

[lolsen]

David

This is why I like NACHI. People help People and everybody wins.

By the way nice cover page. I like it.

Lawrence

[David A. Andersen]

This is why I like NACHI. People help People and everybody wins.

Raising the international standard of home inspectors makes this industry more professional and worth more to the public.

I hate the perception of home inspectors that currently exists. Real estate agents, appraisers, structural engineers that do the same work all get paid more for their time and expertise (or lack of).

By the way nice cover page. I like it.

Thanks, I'm still working the kinks out of the template for the rest of the report.

[Peter C. Russell]

Dave, glad you made through the night OK, I guess all that weather is heading my way, Damn.

The pictures I posted above are from a warehouse I started a heat loss survey but cancelled because we couldn't get access to most of the building.

Here's my question to everyone. When I got to the inspection it was raining, I put my camera in a zip-lock bag and started, the problem I was having was it started to rain really hard and I could not tell if the images were in focus. Any suggestions for taking images in the rain, by the way the bag worked great.

[David A. Andersen]

http://www.nachi.org/forum/f58/tips-focusing-your-bcam-25038/

[Peter C. Russell]

Dave, what I was referring to was any good tips on taking images in the rain with your camera in a zip lock bag or under other adverse weather conditions such as snow.

I'm glad the inspection got delayed it was brutal. I guess I should pick my days.

[Peter C. Russell]

Here's some pictures of the commercial building I did last week, any thoughts?