Thermal Infrared Cameras

8/4/2019 Thermal Infrared Cameras

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THERMAL IMAGINGUSING INFRARED CAMERAS

TANEL PRANK

VIA UNIVERSITY COLLEGE DENMARK

Bachelor of Architectural Technologyand Construction Management

Consultant Henrik Jean BlytNov 2009

(01) HLC Home Inspections, 2008) (02) Cool Cosmos bio)


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Thermal Imaging Using Infrared Cameras Tanel Prank2

ACKNOWLEDGEMENTS

I would like to thank Mr Toomas Rhmonen from Termopilt O(the company is active since 2004) and Mr Indrek Kasekamp from

Termoproff O (the company is active since 2007). Both men are therepresentatives of the mentioned companies in Estonia and are activelyworking in the field of thermal infrared inspections. They were kindenough to spare their time to have small interviews and share theirknowledge with me during summer 2009.

I am also very grateful to my teacher Henrik Jean Blyt, whoorganised a meeting with a thermal imaging companys representative

in order to give me a possibility to see an infrared camera in real-lifeaction.


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TITLE PAGE

DISSERTATION TITLE: Thermal Imaging Using Infrared Cameras

CONSULTANT: Henrik Jean Blyt

AUTHOR: Tanel Prank

DATE/SIGNATURE: Week 49

STUDENT IDENTITY NUMBER: 2005858

NUMBER OF COPIES: Three copies on paper and one copy on CD

NUMBER OF PAGES: 31

WRITING STYLE: Font 12 Verdana; line spacing 1,15

All rights reserved no part of this publication may be

reproduced without the prior permission of the author.

NOTE: This dissertation was compiled as part of an Architectural

Technology and Construction Management degree course no

responsibility is taken for any advice, instruction or conclusion

given within!


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SUMMARY

This report is about thermal infrared cameras and their usage onthe building industrys field. It gives an overview of the history of

thermal imaging equipment and explains the working principle of athermal imaging camera in simple terms. In addition, there is anexplanation of the nature of infrared radiation.

The report is mainly based on information found on variouswebsites (mentioned in the list of reference), but also on two inerviewswith representatives of comapanies dealing with termal imaging servicein Estonia. Moreover, there is some information of an experimentalmeasuring that took place on the VIA University Colleges property inNovember 2009. The report is also enriched with colorful pictures and

charts.

KEYWORDS

Absolute zero Advantages of

thermography Colorful Cooled infrared detectors Digital camera Disadvantages of

thermography ECOlab Emissivity Fire fighting FLIR Focal lenght Infrared Invisible light IR Monochrome NEC Night vision Passive house Photograhpy

Price of thermal imagingequipment

Price of thermal imagingservice

Radiation Resolution Selling or buying real

estate Sir Frederick William

Herschel Spectrum Thermal imaging Thermal imaging cameras Thermography Uncooled infrared

detectors Vietnam War Visible light Wavelenght Wolrd War Two


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INTRODUCTION

The subject of Thermal Imaging Using Infrared Cameras waschosen, because I wanted to link the investigations with everyday

photography, which happens to be one of my dearest hobbies. Before Istarted collecting information about thermal infrared cameras andtechnology, I knew more or less nothing of the subject, so this was acompletely dark field for me. Nevertheless, it was interesting to learnand write about a totally new topic.

I am not plannig to work with thermal infrared cameras orthermography in my future career. On the other hand, there is always apossibility that I could share the research information and knowledgeaccumulated at some point of my working career when a question

about it arises. I find the infrared technology to be a very necessarycomponent in todays building indurstry.

This dissertation gives an insight to the following subjects: Basic answer to the question: What is infrared?. Brief overview of the history of thermal imaging equipment. Difference between the first generation night vision

equipemnt and modern thermal imaging technology workingprinciples.

How does a thermal imaging camera work? Brief introduction about the term emissivity. Difference between cooled and uncooled infrared cameras Approximate price range of thermal imaging equipment and

service in Estonia. What kind of constructional failures is a thermal imaging

camera able to detect? When should one consider hiring a thermal imaging

specialist? Things to be watchful about when choosing a company who

performs thermal imaging on your building.


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PROBLEM STATEMENT

The main objective for this dissertation is to give informationabout thermal imaging and answer the questions: What can thermal

infrared technology do for people wanting to erect a new building orrestaurate an old one? and How beneficial is to hire a professional to

take thermal pictures of your building?. Many people might have heardthe word infrared, but they do not really know what it is. This piece of

writing gives an insight and a casual explanation to that matter as well.

METHODS

Material for this dissertation is primarily based on three types offindings: two interviews in Estonia, measuring results in Horsens andinformation found in the internet.

DELIMITATION

This dissertation does not cover: Terms passive thermography andactive thermography. Price of the thermal imaging equipment and service in

Denmark. Scientific information about infrared wavesphysics. Scientific working pirnciples of thermal imaging equipment.


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TABLE OF CONTENTS

ACKNOWLEDGEMENTS ................................................................ 2

TITLE PAGE................................................................................. 3

SUMMARY ................................................................................... 4

KEYWORDS................................................................................. 4

INTRODUCTION.......................................................................... 5

PROBLEM STATEMENT ................................................................ 6

METHODS ................................................................................... 6

DELIMITATION ........................................................................... 6

RESULTS AND FINDINGS ............................................................ 8

What is infrared? ........................................................................... 8

History of infrared ......................................................................... 9

History of invisible light detection equipment .................................. 10

Seeing in dark before the modern thermal imaging equipment .......... 10

Modern thermal imaging technology basic working principles ............ 11

Comparisson between a digital camera and infrared thermal camera . 13

Cooled and uncooled infrared cameras ........................................... 15

Price of the thermal imaging service .............................................. 17

Time, precision and trial measuring ............................................... 18

Who can perform thermal imaging? ............................................... 20

Emissivity ................................................................................... 22

Some advantages and disadvantages of thermography .................... 23

When to order a thermal infrared inspection? .................................. 24

SUMMARY OF THE WORKING PROCESS..................................... 26Collecting information .................................................................. 26

CONCLUSION............................................................................ 27

LIST OF REFERENCE ................................................................. 28


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RESULTS AND FINDINGS

What is infrared?

Most of the people who have an up to date picture of todaysworld, have heard or read the word infrared or IR in one place oranother. Infrared technology is used in such everyday equipment as TVremotes, computers and cellphones, just to bring out a few. Since manypeople do not have an idea of the nature of infrared radiation, it wouldnot be a big surprise, when a person asked you:Who inventedinfrared?. Of course the right answer to that would be: It was notinvented it has always excisted!. The correct question would instead

be: Who discovered the infrared

excistance?.Infrared (IR) radiation is

electromagnetic radiation whose wavelengthis longer than that of visible light (400700nm), but shorter than that of terahertzradiation (100 m 1 mm) and microwaves.Infrared radiation spans more than threeorders of magnitude (roughly 700 nm to 300m).(03) Wikipedia/Infrared)

The picture on the left side of this pagegives an idea what the technical definitionabove is saying. In simple terms, everyobject or body is radiating electromagneticwaves, which have different wavelenghts. Forexplanation of the wavelenght, see the sketchon the bottom of the page.

The above mentioned interval ofwavelenghts is called infrared and is invisible

to human eye, as are the majority of otherwavelenghts, thathave beendiscovered andnamed by people.The visiblewavelenghts arein between 380 to750 nm and arejust under(04) Imagine the Universe!) (05) The Free Dictionary)


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infrared. The visible wavelenghts are registered by human eyes ascolorful lights. (06) Wikipedia/Visible spectrum)

History of infrared

The first person todiscover lights invisibleto human eye was SirFrederick WilliamHerschel. He did it backin year the 1800. Herschel passed sunlight through aglass prism to create a spectrum and measured the

temperatures of each color. He discovered, that thetemperatures are rising when moving up on the

spectrum. A spectrum contains all of the visible colors that make upsunlight.(09) Cool Cosmos) While measuring the temperatures of eachcolor, he found out that after the last visible color red thetemperature waseven higher. Fromthis knowledge heconcluded, that there

must be a lightinvisible to humaneye. Since it wasplaced after the redcolor, he named itinfrared.(02) Cool Cosmos bio)

The wordinfracomes from

the Latin languageand means below.To explain, one couldsay that the visible red color has the longest wavelenght (out of allvisible wavelenghts) meaning the smallest frequency - the frequency ofinfrared is even lower, so it is below red.

(08) WilliamHerschel)

(07) Cavendish Science)

(10) MIVIM)


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History of invisible light detection equipment

Originally the invisible light detection equipment was invented toenable military forces to see in such light conditions, where it is nearly

impossible for the naked eye to distinguish a clear picture of a subject.(11) Bullard)

Current thermal imagers are based on technology that wasoriginally developed for the military. Thermal imaging technologyprovides the ability to see and target opposing forces through the darkof night or across a smoke-covered battleground. The properties thathave made infrared detection valuable to military services around theworld also make it valuable to fire services and law enforcement.

In the late 1950s and 1960s,

Texas Instruments, Hughes Aircraft,and Honeywell developed singleelement detectors that scannedscenes and produced line images.The military had a lock on thetechnology because it wasexpensive and had sensitive militaryapplications. These basic detectorsled to the development of modern thermal imaging.. (11) Bullard)

The thermal imaging technology was first demonstrated to themilitary in 1979. At first it was quite expensive, but after 1991 theproduction quantities of the equipment went up and the price of eachpiece decreased remarkably. It was then, the thermal imagingequipment was also introduced to fire fighters. First thermal imagerspecifically designed for fire fighting was introduced in 1998. (11) Bullard)

Seeing in dark before the modern thermal imaging equipment

Before the modern thermal imaging (that is based on collectinginfrared information and translating it to visible picture) was invented,military forces used first generation night vision equipment.Nightvision devices were first used in World War II, and came into wide useduring the Vietnam War.(13) Wikipedia/Night vision device) The firstgeneration night vision devices had a much different working principle,than those of todays world knows and uses.American soldiers usedimage intensifiers called Star-Tron scopes in the Vietnam War(similar

to the

(12) Woodbury Minnesota)


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device shown on right). The scopeswere almost as heavy as the riflesthey were mounted on, and wereextremely expensive to manufacture.

They worked by focusing the dim nightscene onto a photo-cathode inside atube. The photo-cathode acceleratedand multiplied the electrons from theambient light, and focused them into avisible image. The Star-Tron scope permitted a soldier to see in thedark about 400 yards ( 366 m), but it had several unfortunatedrawbacks. The scope would shut down if it was exposed to a suddenbright light, and the device emitted a high-pitched whine that was often

loud enough to give away its users (sic) position, thus cancelling outthe stealth effect.. (15) Bookrags/Night Vision Devices)

There was a lot of work done to eliminate the mentioned problem.The scientists successfully removed the malfunction from the devicebefore the next generation was announced. (15) Bookrags/Night VisionDevices)

Modern thermal imaging technology basic working principles

A thermographic camera, sometimes

called a FLIR (Forward Looking InfraRed), or aninfrared camera less specifically, is a device thatforms an image using infrared radiation, similarto a common camera that forms an image usingvisible light. Instead of the 450750 nanometerrange of the visible light camera, infraredcameras operate in wavelengths as long as

14,000 nm (14 m).(17) Wikipedia/Thermographiccamera)

Modern technology used to see otherwise invisible light is mainlybased on thermal infrared imaging and in many references is calledinfrared thermographyInfrared thermography is not the same asnight vision. Night vision operates on the principle of light amplification,so in a totally dark environment light amplification would yield no imagewhere as a thermal imager would.. (16) About.com/Origins of ThermalImaging or Infrared (IR) Imaging, 1977) A thermal imaging device gives the

ability to see targets in darkness or smoke.. (16) About.com/Origins ofThermal Imaging or Infrared (IR) Imaging, 1977)

(14) Utah Gun CollectorsAssociation)

(16) About.com/Originsof Thermal Imaging orInfrared (IR) Imaging,

1977)


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All bodies above the absolute zero oftemperature absorb and radiate infraredradiation.(18) The Free Dictionary/infraredradiation)By international agreement, absolute

zero is defined as precisely 0 K on the Kelvinscale, which is a thermodynamic (absolute)temperature scale, and 273.15 on the

Celsius scale.. (19) Wikipedia/Absolute zero) So,figuratively speaking, if one took a thermalpicture of an object, which was surrounded bynothing, and had a temperature of absolutezero, the resulting image would be blank. Ofcourse that kind of a situation is imaginary,

and could not happen in everyday life.A thermal imaging camera consists offive components: an optic

system, detector, amplifier, signal processing, and display.(21) Thermalimaging camera) When a commonly used digital cameras sensor is able tocreate a picture if light that is visible to human eye is projected througha lens to the sensor, then thermal imaging cameras sensor is able to

generate an image using light that is invisible, such as infrared light.Picture taken with a thermal imaging camera can be monochrome

or colorful. That depends on the camerassensor. Images from

infrared cameras tend to be monochromatic because the cameras aregenerally designed with only a single type of sensor responding tosingle wavelength range of infrared radiation. Color cameras require amore complex construction to differentiate wavelength and color hasless meaning outside of the normal visible spectrum because thediffering wavelengths do not map uniformly into the system of colorvision used by humans. Sometimes these monochromatic images aredisplayed in pseudo-color, where changes in color are used rather thanchanges in intensity to display changes in the signal.(17)Wikipedia/Thermographic camera) Most of the thermal camera sensors, thatare able to create colorful pictures, can also do it in monocrome, but

not the other way around. Asimilar parallel could bedrawn between black &white and color film used ineveryday photography.When projecting images toa photo paper, the lattercould, in principle, be

(20) Flir.com/FLIR i5 andi7 Infrared Camera)

(17) Wikipedia/Thermographic camera)


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successfully used with either color orbalck & white paper, but not the black& white film.

Some thermal imaging

cameras, that are used in the buildingindustry, are able to take usual digitalpictures as well. When makingcomparisons, this additional functionsaves both time and money for the people making thermal analysis of abuilding, because a thermal image shows aspects of the photographedobject that a usual digital photo does not and vice versa. When placedside by side, two different pictures of the same object give a betterunderstanding of the situation or possibly a problem of the object.

These cameras, which do not have the ability to take usualphotographs, do not lacktoo much value, when weare talking about the finalresult of thermal analysis,but for a non professionalclient, for example, it iseasier to understand thesituation, when two images

are put side by side. Withthermal cameras, that arenot able to take picturesvisible to human eye, aseparate digital camera isused.

Comparisson between a digital camera and infrared thermal

camera

One of the important things in nowadays digital photography isthe resolution of the sensor. The bigger it is, the larger the picture.High resolution can not be directly related to better image quality,because there are several other importances to the quality of theimage. For example the size of pixels on the sensor and the quality ofthe materials used in the lens. Therefore, one of the questions duringboth interviews I had past summer, I asked: What is the resolution of

(22) Developing problem, or X-rayfogging?)

(23) Abrioux Home Inspections)


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a thermal camerassensor?. Having

photography as one of myhobbies, but at the same

time knowing very littleabout thermography, Iwas expecting an answercomparable to thenumbers that one couldread from a digitalcameras instruction

manual 2 to 8 megapixels for lower end cameras, 8 to 24 megapixelsfor medium and semi-professional cameras and 24 plus megapixels for

professional studio work cameras. Turns out that my assumptions werereally far off from the correct answer. Both of the companies that Ivisited, are using a thermal imaging camera from a company calledFLIR. The resolution of sensors of the cameras that these companiesare using is 320 x 240 pixels, whichequals to about 0,08 megapixels.Compared to a usual didital camera,it is a really low resolution, but theimportant thing to note here, is that

in thermography the well knownsaying a picture is worth a thousand

words does not apply.When in photography the

outcome is just a picture, then inthermography the picture has only an illustrative function. Since visionis one of the most important senses of a human being, then seeing apicture on a thermal imaging cameras screen helps to recognise the

things one is looking for. In the building industry these things would, in

many cases, be heat- and moisture leaks. Besides the illustrativepicture, the outcome of taking a thermal image is a great amount ofinformation about every singel pixel of the image. When phrased thisway, the 320 x 240 pixels does not seem like a small number anymore.A simple calculation shows that 320 times 240 is 76 800. That is thenumber of analysis the thermal imaging camera does with ervey singlepicture taken at that resolution. On the FLIRs homepage I was alsoable to find more sophisticated thermal imagers with more functionsand larger sensor resolutions. One example is the model called FLIR660, which has a resolution of 640 x 480 pixels

(24) flir.com/ThermaCAM B4)

(25) FLIR/FLIR IR Camera Range forthe Building Industry)


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totaling 307 200 measuringpoints.

When a usual digitalcamera, depending, of course,

on the quality and type, couldbe bought for few hundredkroner, then thermal imagingcameras prices are, so to

speak, form another world. Forexample, FLIR B4 (see a pictureof the device from previouspage) costs around 100 000

Danish kroner. The mentioned model is by far not the highest end and

best thermal infrared camera in theindustry, but still the price speaks foritself. More advanced devices costhalf a million or even more. (26)Kasekamp, 2009)

The camera pictured on theright is one of the best FLIR modelsone could use. Besides the alreadymentioned high resolution it features

several other modern technologies,that help the operator to achievebetter results in less time.

Cooled and uncooled infrared cameras

Yet another way to distinguish infrared cameras is if theirdetectors are cooled or uncooled. There is a difference in between the

construction of the sensors used in either kind of the systems. Bothhave their own pros and cons.

These cameras that use cooled detector systems can, in mostoccasions, produce infrared images with higher quality than theuncooled ones.Without cooling, these sensors (which detect andconvert light in much the same way as common digital cameras, butare made of different materials) would be 'blinded' or flooded by theirown radiation.(17) Wikipedia/Thermographic camera)Additionally, thegreater sensitivity of cooled cameras also allow the use of higher F-

number

(25) FLIR/FLIR IR Camera Range for theBuilding Industry)

(27) flir.com/FLIR B660)


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cooled cameras also allowthe use of higher F-numberlenses, making highperformance long focal

length lenses both smallerand cheaper for cooleddetectors.(17)Wikipedia/Thermographiccamera)

On the other hand,there are some drawbacks.

Cooled infrared cameras are relatively expensive both to produce and torun. Cooling process uses a lot of energy and is also time-consuming.

Cooling down might take several minutes. (17) Wikipedia/Thermographiccamera) Cooling system last only 8 000-10 000 hours, when uncooledcameras might not need servicing for years. (28) Richards) There are twocommonly used cooling systems - rotary stirling engine cryocooling andgases bottled at high pressure. (17) Wikipedia/Thermographic camera)Eventhough the cost of a cooled camera core is much higher than anuncooled core, the system cost (core plus lens) for uncooled surpassescooled system cost at a focal length on the order of 350mm.(28)Richards) From the previous one could deduce, that in the building

industry there are mainly uncooled systems used, because normallythere is no need to use a lens with a focal lenght of 350mm or more. Anapproximate measuring distance from a building, which is 5 meter highand 10 meters wide, is 25 meters. (26) Kasekamp, 2009)

Uncooled thermal infrared imaging devices are physically smaller(because there is no need to reserve space for cooling mechanisms)and also cheaper to produce and maintain. (17) Wikipedia/Thermographiccamera)However, their resolution and image quality tend to be lowerthan cooled detectors. This is due to difference in their fabrication

processes, limited by currently available technology.(17)Wikipedia/Thermographic camera)Modern uncooled detectors all

use sensors that work by thechange of resistance, voltage orcurrent when heated by infraredradiation. These changes arethen measured and compared tothe values at the operating

temperature of the sensor.(17)Wikipedia/Thermographic camera)

(28) Richards)

(28) Richards)


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Price of the thermal imaging service

Since thermal imagingequipment is so expensive, in most

cases, the service of taking thoseimages is bought from a specialisedcompany. In Estonia the average feefor thermal analysis of a single familyhouse is worth around 1 500 Danishkroner. This price includes both takingpictures of the building and making adetailed report with the measuringresults. If there are any problems with

the house, then the report alsoincludes suggestions for repairs. (26)Kasekamp, 2009)

Some firms offer the service fora remarkably lower cost, than

mentioned above. The ones, who needto use the service, must thereforewatch out not to have a trick playedon them. As described previously,

seeing a thermal picture alone, giveslimited information of the situation. Itdoes not help the one, ordering themeasuring, enough to take relevantaction for eliminating theproblem/problems. It would not bewise to set all the companies, offeringthe thermography service with a costlower than 1500 kroner, aside just

because of the low price some mighthave discount campaigns going on.Nevertheless, before buying theservice, one should make a thoroughinvestigation of what one actually gets for the money. During one of theinterviews I was told, that some of the firms, who offer the thermalimaging service, do the following: take the pictures of the givenbuilding, charge the client few hundred kroner and present him/her witha CD of the pictures. There are neither analysis nor suggestive ideas for

fixing the problems included. Unless one wants just the thermal

(29) Crawford, 2006)

(29) Crawford, 2006)


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pictures - which usually is not the case these kind of companiesshould be avoided. (30) Rhmonen, 2009)

Time, precision and trial measuring

Another photography related question, that I asked during theinterviews in Estonia, was: How long is the exposure time for takingone thermal image?. When taking a usual digital image, the exposuretime can vary from approximately 1/8000 of a second to several hours.It depends on the type of picture and the type of effect one wants toachieve. However, to get one decent thermal image with enoughinformation for analysis it takes about 50 seconds. An average time

spent on completing a thermal imaging process for a single familyhouse, for example, is 1,5 hours. That includes setting up theequipment to proper places and taking images. Post analysis takessome additional time. Of course every building is different and has itsown characteristics, so the precise measuring time depends on variousfactors. (26) Kasekamp, 2009)

With FLIR B4 temperature is measured on every point on thethermal picture with an accuracy of 0,1C (30) Rhmonen, 2009) On theFLIR website the number of accuracy is said to be even as low as

0,08C (24) flir.com/ThermaCAM B4). The best temperature of the workingenvironment for the thermal camera FLIR B4 is between -20C and+55C. (24) flir.com/ThermaCAM B4) For best measuring results indoor anoutdoor temperature difference should be about 15C for a constantperiod an occasional night frost during autumn or spring does notcount. The best time to run a thermal imaging would be a cold period preferably during the winter season. (30) Rhmonen,2009) 20C difference in indoor and outdoortemperatures would be the ideal condition (26)Kasekamp, 2009) and 10C would be the minimum (31)Trial Thermal Measuring in Horsens, 2009)

The trial measuring, that was scheduled to takeplace on 24th of November in Horsens on the VIAUniversity Colleges property, did notsucceed 100%. The building, that was to be takenthermal images of, was still under construction andtherefore not warm enough from the inside to makeup the metioned temperature difference of at least

10C. The attempt to heat up the building with an (32) ECOlabHorsens, 2009)


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electrical hot air blower failed, because it couldnot have been left turned on overnight due to therisk of burning down the buliding if anything wentwrong. According to the thermal imaging

specialist, who was on the site taking thepictures, the building should have been underconstant heating for about a week to heat up the

walls and achieve the insidetemperature acceptable fortaking decent thermal images.(31) Trial Thermal Measuring inHorsens, 2009)

The building itself is being

built for a scientific project andmeant for that kind ofmeasurings and tests. The insidearea of it is only about 10m2. Ithas thick well insulated walls.The roof is covered with solarpanels.

Although the conditions forthermal imaging were far from

perfect, some pictures weretaken just to demonstrate howthe camera works. Modelnumber of the camera used isNEC TH7800. The resolution ofthe cameras thermal picture sensor is thesame as it is in FLIR B4 320x240 px (pixels).This camera has the ability to take both

thermal and usual digital

images simultaneously.(33) Thermo Tracer TH7800320x240 Pixels)

The original idea,why ECOlab building waschosen for the measuring,was to check the housewith a professional thermalimager aginst any flaws in

the construction quality.One of the

(32) ECOlab Horsens, 2009)

(32) ECOlab Horsens,2009)

(32) ECOlab Horsens, 2009)

(32) ECOlab Horsens,

2009)

(33) Thermo Tracer

TH7800 320x240Pixels)


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possible problems with the building that I had inmind and would have wanted to have beencontrolled, was the tightness of the heat proofingaround the windows and doors. Since the ECOlab

is being built as a passive house using all themodern materials to make it sustainable itshould, according to the calculations, workthat way once finished. Nevertheless, takingthermal images of the building would give anadditional security and peace of mind thateverything was done properly. As mentioned,this time the measuring did not succeed due totoo small temperature differences between

inside and outside, but I sincerely hope, that thiskind of measuring will take place in the futurewhen the building construction has beencompleted. Of course, if done, it will be a subjectof another report or dissertation but this one.

Who can perform thermal imaging?

Since a thermal imaging specialist is not an easy profession tohave, one could think, that to become one, he/she would need to,figuratively speaking, go through fire and water to get a certificate for

that. Some part of this thought istrue, but some is not. Sure, athermal imaging specialist musthave great amount of knowledgeabout the thermography field todo the work properly and

effectively, but at least in Estoniaone does not need a paper ordiploma for doing that kind ofwork. This being said, peopleshould be aware of who theyreally hire to do the inspection ontheir house. There are someservice providers out there, whohave just bought a thermalimaging camera to make some



(34) Viewport enables closed-door IR

scans of electrical panels.)


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money by using the equipmentfor taking bare infrared picturesand presenting their client withthese. They are including very

vague analysis thogether with thethermal images, if any at all.Therefore, trusting companies orindividuals with proper educationand long experience pays off,even if their service costs a pennymore.

At this point I find itnecessary to mention, that the

previous applies only for takingthermal images. Drawing anenergy audit together, is a wholedifferent story. One needs to have

a special licence for doing energy audits. (26)Kasekamp, 2009)An energy audit is an inspection,survey and analysis ofenergyflows forenergyconservation in a building, process or system toreduce the amount of energy input into the systemwithout negatively affecting the output(s).Whenthe object of study is an occupied building thenreducing energy consumption while maintaining orimproving human comfort, health and safety are ofprimary concern. Beyond simply identifying the sources of energy use,an energy audit seeks to prioritize the energy uses according to thegreatest to least cost effective opportunities for energy savings.(37)Wikipedia/Energy audit)

At the same time, in The United Stated

there are extensive educational training coursesprovided for specialists working withing the fieldof thermography.Advances in technology haveprovided infrared equipment that is user-friendly; however, infrared thermography is nota "simply point and shoot" technology. Inaddition to understanding the object or systembeing inspected, thermographers must also

understand common error sources that can influence observed thermal

data. Typically, infrared training courses should cover the topics of

(35) npiweb.com)

(36) ITC - BuildingScience

ThermographyCertification)

(38) The Academy OfInfrared Training Inc(AIRT))
http://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/Energy_conservationhttp://en.wikipedia.org/wiki/Energy_conservationhttp://en.wikipedia.org/wiki/Energy_conservationhttp://en.wikipedia.org/wiki/Energy_conservationhttp://en.wikipedia.org/wiki/Energy


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infrared theory, heat transfer concepts, equipment selection andoperation, how to eliminate or overcome common error sources, andspecific applications.(39) Wapedia/Thermographic camera)Structuralthermal imaging professionals can properly interpret readings and

recommend cost-effective measures to improve building efficiency.(39)Wapedia/Thermographic camera) To reach the highest - third - certified level,it takes a lot of work and time.

A Level 3 must: Meet all the requirements for a Level 2 thermographer. Complete a further 40 hours training under an approved

program and pass an exam with at least 75%. Work for at least 48 months as an active thermographer. Have at least 1920 hours of cumulative experience in

thermography. Submit proof of this.

(39) Wapedia/Thermographic camera)A Level 3 qualified thermographer is "qualified to perform and/or directall types of thermographic measurements and analysis."(39)Wapedia/Thermographic camera)Certification is written proof of qualification, and a well trainedthermographer will not only be trained, but properly certified. ISO18436 lays down the criteria for certification.(39) Wapedia/Thermographic

camera)

Emissivity

Another term that is important, when talking aboutthermography, is emissivity. Emissivity is a term representing amaterial's ability to emit thermal radiation.(40) Wikipedia/Emissivity) Oneof the most important part of thermography specialists work is to know

how to estimate emissivity. Each material has a different emissivityand it can be quite a task to determine the appropriate emissivity for asubject. A material's emissivity can range from 0.00 (completely not-emitting) to 1.00 (completely emitting); the emissivity often varies withtemperature.(40) Wikipedia/Emissivity)

Emissivity is related to the theory of Black Body. A black body isa theoretical object which will radiate infrared radiation at its contacttemperature.(40) Wikipedia/Emissivity)Since there is no such thing as aperfect black body, the infrared radiation of normal objects will appear

to be less than the contact temperature. The rate (percentage) of


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emission of infrared radiation willthus be a fraction of the truecontact temperature. This fractionis called emissivity.(40)

Wikipedia/Emissivity)To make a temperaturemeasurement of an object, thethermographer will refer to theemissivity table to choose theemissivity value of the object,which is then entered into thecamera. The camera's algorithmwill correct the temperature by

using the emissivity to calculate atemperature that more closelymatches the actual contacttemperature of the object.(40)Wikipedia/Emissivity)There is anexample of a basic emissivitytable on the left. Of course, thereare more complex tables withmore information for actual

infrared thermography.

Some advantages and disadvantages of thermography

Advantages Disadvantages

It helps to prevent problems priorto their occurrence

The cameras cost a lot (often overUS$ 6000)

It can be used to observe areas

inaccessible or hazardous for othermethods

For getting accurate temperatures,

emissivity must be determinedcorrectlyIt can be used to find defects inshafts, pipes, and other metal orplastic parts

Most cameras have 2% accuracyor worse and are not as accurateas contact methods

It can be used to see better indarker or completely darkenvironment

Thermography is only able todirectly detect surfacetemperatures

It makes catching moving targetsin real time easy

It is a non-destructive test method(42) Wikipedia/Advantages of thermography)

TABLE OF EMISSIVITY -METALS

MaterialTemp.(C)

Normalemissivity,

En

AluminumUnoxidized 100 0.03Unoxidized 500 0.06Oxidized 200 0.11Oxidized 600 0.19

Monel, Ni-CuUnoxidized 200 0.41Unoxidized 600 0.46

Nickel

Polished 40 0.05Oxidized 40 0.31Oxidized 250 0.46

SteelUnoxidized 100 0.08Oxidized 100 0.80Stainless

SteelPolished 100 0.22Polished 425 0.45

(41) Infrared ir thermal imaging camerasfor thermographic applications;emissivity)


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When to order a thermal infrared inspection?

If previously there was a topic about the price of thermal infraredinspections, then this paragraph is listing the main reasons why to

order the service.If one has a problem with his/hers

heating bill showing too large numbers, thenit would be a good idea to have his/hershome examined by a thermographyspecialist. It does not necessarily have to bea private house, that the thermal imagescould be taken of. Semi-detached houses orapartments can be investigated as well.

Thermal images can reveal constructionalproblems invisible to human eye, such aspartly or totally missing insulation in someparts of the wall as well as moisturedamages. (26) Kasekamp, 2009)

The fact, that a house is recently builtor only a few years old, does not give anyguarantee for the building to be in goodorder. During one of the interviews in Estonia I had a severe story

shared with me. When the handing over time for a building was gettingclose, my interviewee had heard a builder shouting harsh wordstowards the site manager, because the latter had not warned thebuilding crew for the coming thermal inspection. That was all, what myinterviewee told me about this case, but it is fairly easy to readbetween the lines and understand, that clearly some parts of the

building had not been insulated properlyto cut down on the cost of buildingmaterials. Again, the problem could not

have been discovered without a thermalinspection. (30) Rhmonen, 2009)

If there are any mistakes foundinside the construction of a building, then,in most cases, some advice is given to theowner of the building or to the person,who ordered the inspection, how toeliminate those problems. Sometimessimple replacement of windows orexternally insulating some walls can do

(43) Ebuilding EnvelopeForum)

(44)frenta)


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SUMMARY OF THE WORKING PROCESS

Collecting information

During the summer 2009 I collected some information aboutthermal imaging from different web pages, after which I had twointerviews with two companies dealing with infrared cameras in Estonia.Since the whole thing was new to me, I started from the very beginningand gathered some basic facts from those meetings. Questions likeWhat can the infrared cameras be used for? and What is the best

distance to take a thermal picture of a house? got easy, but thoroughanswers. I even had a chance to see an infrared camera and have somefunctions of its menu introduced to me.

I also had an opportunity to take part in an experiment on apassive house in Horsens that was specially being built for tests. Withthe help from my consultant, who organised a meeting with a companydealing with thermal imaging in Denmark, I got to see a thermalimaging camera in action. Reading about a subject is one thing, but tosee it working in real life is a whole different story.

Collecting decent information about the subject was not easy,because there are so many informative sources, with somewhatdifferent facts, out there, so it was hard to choose one and rely totally

on that. On the other hand, having enough options to choose betweenand having specialists of thermal imaging with years of experienceconsulting me, made writing the dissertation a great learningopportunity. It also gave me security and piece of mind when thepeople working with infrared cameras daily, confirmed some facts that Ihad read from a page or another.


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CONCLUSION

Based on infrared (invisible light discovered more than 200 yearsago) the mankind has invented a high end technology that is both

extremely helpful and a necessary part of nowadays building industry.Using thermal infrared inspection service to find out

constructional flaws of a building is a very good idea. There is no needto open up any inaccessible sections of the house, becausethermography is a non-destructive test method. Thermographic camerais able to measure temperatures of surfaces without having a physicalcontact to them. It is relatively cheap to use this service and tracedown the defects compared to the price of repairing the possible errorsmade during the erection of the building later.

However, a piece of thermographic equipment costs a fortuneand, in most cases, is not affordable for a regular individual. At thesame time, the unattainability is good in a way that handling a thermalinfrared camera requires a lot of knowledge and experience anyway. Toavoid miscalculations and wrong conclusions it is better to leave the jobof thermal inspections to the professionals.

As well as there is a large number of thermal infrared cameramanufacturers, there are many companies offering the service ofthermal inspections. To find out the best relation between the price and

the quality, a thorough investigation, of what one acctually gets for themoney, must be made, before buying the service.

The best time of the year for running thermal imaging is winter.As the trial measuring in Horsens also showed, this type of cameracannot be properly used, when the temperature differences betweenindoor and oudoor are not great enough.

There are number of conditions which have to be fulfilled forusing an infrared thermal imager. There conditions are not only physicalor weather related, but also depend on the knowledge of the cameras

operator. One of these importances is knowing how to correctly applyemissivity.

To sum up, this study gives a thorough insight to thermal imagingand good bases for somebody looking for further information on thesubject.


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Thermal Infrared Cameras