[BLDG-SIM] On-site U-value measurement

[David S Eldridge]

I would imagine it to be difficult to do with a hand held instrument.  Aside from how this hand held instrument would be designed, or if you could use some combination of the fluke product and some thermocouples, you'll have to account for the thermal storage effects that are occurring in any in-situ measurements....so even if you had the necessary instrument, you might not be able to get accurate results (or more accurate than from estimating based on the material properties) depending on the construction.
 
As part of my masters research we built a guarded hot box to measure the thermal conductivity of a wall assembly, but that was most definitely not a hand held instrument.  During that process you are subjecting the assembly to a steady state flux which you wouldn't necessarily have in-situ.
 
I guess it depends on how badly you need these measurements, or if you can quantify the constructions in some other way to accomplish your goals.  
 
David
 
 


________________________________

	From: BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of Brandon Nichols
	Sent: Tuesday, May 08, 2007 12:58 PM
	To: BLDG-SIM at gard.com
	Subject: [BLDG-SIM] On-site U-value measurement
	
	
	Hello,
	 
	You may find an infrared thermal imager to be a powerful tool, useful for the application you have indicated and many others.  Here's a link to Fluke Corp. thermal imaging notes for building systems, there are many other manufacturers...
	 
	http://us.fluke.com/usen/support/appnotes/default?category=AP_TH_BM(FlukeProducts)&parent=AP_THERMO(FlukeProducts)
	 
	For building systems, the thermal imager is useful for finding voids in insulation, infiltration losses, calculating the overall heat loss correction due to framing framing elements, etc..
	 
	Using the thermal imager, you will have to "tune" heat loss equations based on observed temperature differential data to derive U-values. These instruments typically have the ability to scan large areas and quickly calculate a weighted average and other statistical factors for each image.  
	 
	Unfortunately they are not cheap, and probably overkill for just measuring the U-values of specific materials.  Personally I don't know any way to measure U-values directly with a hand-held instrument, but it seems such a device wouldn't be hard to put together with a data acquisition unit and a couple of thermocouples.
	 
	 
	Regards
	 
	Brandon Nichols, PE
	Mechanical
	HARGIS ENGINEERS
	600 Stewart St
	Suite 1000
	Seattle, WA 98101
	d | 206.436.0400 c | 206.228.8707
	o | 206.448.3376 f | 206.448.4450
	www.hargis.biz
	

________________________________

	From: BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of Gunes Inan
	Sent: Tuesday, May 08, 2007 7:46 AM
	To: BLDG-SIM at gard.com
	Subject: [BLDG-SIM] On-site U-value measurement
	
	

	Dear All,

	 

	We are looking for a hand-held instrument for on-site measurement of the U-value or thermal conductivity of walls. Any experience about the measurement techniques and recommendations about instruments and brands are greatly appreciated. 

	 

	Thank You,

	 

	Gunes Inan

	 

	R&D Engineer 

	Betek Paint and Chemical Corp., Inc. 

	Kavakpınar Mah., Tandoğan Cad. No: 175, 

	Kaynarca, Pendik 

	Istanbul, Turkey 

	Tel: +90.216.396.2070 / Ext: 177 

	Fax: +90.216.396.6989

	 

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