Quantitative Infrared Thermography Research Articles

Full-field investigation of dissipative mechanisms and thermoelastic inversion effects within glass-fiber reinforced polyamides subjected to low-cycle fatigue

A comprehensive thermomechanical investigation has been conducted to study the local kinematic and calorimetric responses of wet glass-fiber reinforced polyamide 6.6 subjected to tensile-tensile low-cycle fatigue tests. Digital image correlation (DIC) and quantitative infrared thermography (QIRT) were combined simultaneously to monitor the onset and development of spatial heterogeneities. Fields of strain, strain rates, intrinsic dissipation and resulting thermoelastic sources were successively observed and thoroughly analyzed with regards to the main fiber orientation and water content. Areas of precocious heterogeneities were detected from the very beginning of the loading, roughly propagating along the main fiber orientation. A ratcheting effect induced by the positive mean stress was observed and accompanied by a slight cyclic creep of the specimens. At high water content, the thermoelastic inversion phenomenon appeared and progressively spread along the gage part of the specimen, highlighting both glassy and rubbery behavior of the samples investigated.

Diffusion-compensated correlation analysis of frequency-modulated thermal signal for quantitative infrared thermography

Application of a broadband modulated excitation signal and its cross-correlation with the corresponding thermal response, so-called thermal wave radar or pulse compression thermography, is a well-known technique in active infrared thermography. The technique benefits from both the broadband spectrum and the pulse compression efficiency of excitation signal, providing lag and phase quantities which can be used for characterization of defects. However, the significant distortion of the thermal response due to heat diffusion makes the cross-correlation analysis inefficient, particularly for the detection of deep defects or the inspection of a material with low thermal diffusivity. To tackle this issue, diffusion-compensated correlation analysis (DCCA) of thermal signal is proposed for quantitative infrared thermography, using a frequency-modulated sweep signal as excitation waveform. DCCA is based on the correlation of the measured thermal response with a library of template thermal responses calculated using the 1D analytical solution of the heat diffusion problem. DCCA can then more reliably resolve the thermal response in the presence of measurement noise, and depending on the definition of the library, directly map it to the corresponding depth or diffusivity. Two inspection modes are studied: (i) transmission of heat from defects which act as sub-surface heat sources (e.g. vibrothermography), and (ii) reflection of an externally applied heat flux from sub-surface defects (e.g. optical infrared thermography in reflection mode). Outperformance of DCCA to thermal wave radar is analytically substantiated and verified by finite element simulation on a carbon fibre reinforced polymer plate. Furthermore, the technique is experimentally studied for thermographic inspection of a carbon fiber reinforced polymer (CFRP) coupon including artificial defects, and the advantages as well as limitations of the technique are discussed.

A wrap-film technique for infrared thermography heat-transfer measurements in high-speed wind tunnels

A novel technique for obtaining quantitative infrared-thermography data on metallic (e.g., aluminum or steel) wind-tunnel models is developed. The methodology incorporates a matte-black, thin, wrap-film (3M\ exttrademark Wrap Film Series 1080), which is both commercially available and relatively inexpensive. Compared to painting the model to increase the surface emissivity, using a self-adhesive thin film makes it easier to obtain uniform thickness and roughness and is easier to apply and remove. The relevant surface properties (i.e., thickness, roughness, and directional emissivity) and thermal properties (i.e., thermal conductivity, specific heat capacity, and thermal diffusivity) of the wrap film have been measured and are reported. The high emissivity (0.95) and low thermal conductivity (0.23 W/(m K)) make it an excellent candidate for quantitative infrared-thermography. Using the experimentally measured properties, and the reported data-reduction techniques, stagnation-point heat flux was successfully measured on a blunt 7∘ half-angle circular cone in nominally Mach-6 flow. Fay & Riddell’s theory for calculating heat flux at the stagnation point provided a comparison to verify the effectiveness of the wrap-film technique for quantitative infrared thermography. The heat flux evaluated with the wrap-film technique resulted in excellent agreement with the theoretical solution with a mean error of 4.4%.

Infrared thermography for quantitative thermal performance assessment of wood-framed building envelopes in Canada

Since many buildings in Canada were built prior to the advent of national and provincial energy codes and standards, quantifying building envelope thermal performance is an important step in identifying retrofit opportunities in existing buildings. This study aimed to use external quantitative infrared thermography (IRT) to estimate effective U-value of opaque building envelopes (considering the effect of thermal bridging sources) of a conditioned at-scale structure comprised of four wood-framed wall assemblies commonly used in Canada. Furthermore, the effect of vignetting artefacts on effective U-value measurements was assessed, followed by a practical approach to correcting for it to improve accuracy of U-value estimation and calibration of energy models. Additionally, a comprehensive uncertainty analysis was performed to evaluate the impact of input variables on the accuracy and uncertainty of results. Finally, apart from qualitative and quantitative thermal assessment of the building envelope, a novel relative quantitative infrared index (IRI) methodology was proposed as a means to facilitate rapid evaluation and subsequent ranking of building envelope thermal performance. The results indicated that vignetting effect has an adverse impact on the accuracy of results, in particular for well-insulated walls where deviations of −42.31% to −83.33% were observed. However, when the proposed practical approach was implemented, substantial improvements in accuracy of walls’ U-value were obtained, ranging from −2.33% to −12.50% after correction versus −13.95% to −58.33% without correction. Moreover, the results indicated that the energy model was substantially more accurate when the effect of thermal bridges were accounted for, and the adverse effect of vignetting was addressed in the estimation of U-value. In this case, ASHRAE Guideline 14 criteria were satisfied: Normalized Mean Bias Error (NMBE) < 5%, and Coefficient of Variation of the Root Mean Square Error (CVRMSE) < 15%. The findings of the uncertainty budget demonstrated that the influence of parameters on U-value depends on the type of wall assembly. Ultimately, wall thermal performance rankings based on IRI were consistent with their U-value rankings, implying that IRI can be a reliable metric for relative quantitative comparison of building envelope thermal performance, regardless of boundary conditions.

Hydration-induced thermal behavior of crystalline and amorphous dispersed alumina

• The high-throughput express diagnostics realized using quantitative infrared thermography (QIRT) allows us to identify the amorphous phase in polymorphic alumina by the analysis of hydration-dehydration-induced thermal effects. • Unlike crystalline alumina, the amorphous one produces a pronounced excess heating in the hydration process. • In a humid atmosphere, the solid-state exothermic chemical reaction of the oxide transformation into crystalline hydroxide takes place • The pseudoboehmite phase formation during the rehydration process occurs exclusively due to the amorphous alumina interaction with water. Dispersed alumina is one of the main materials used in adsorption and catalytic technologies. However, some poorly controlled factors (exposure to the atmosphere, etc.) can change the oxide phase composition and morphology. Hence, it follows that the development of robust approaches to characterizing the material structure is a topical problem. In this study, the ability of high-performance quantitative infrared thermography (QIRT) to identify the amorphous phase in polymorphic alumina by the analysis of hydration-dehydration-induced thermal effects is demonstrated. The QIRT-obtained findings were verified by a comparison with the XRD patterns measured on the same samples. It is revealed that, in a humid atmosphere, the solid-state exothermic chemical reaction of the oxide transformation into crystalline hydroxide takes place, and, unlike crystalline alumina, the amorphous one produces a pronounced excess heating in this process. Moreover, it is found that the pseudoboehmite phase formation during the rehydration process occurs exclusively due to the amorphous alumina interaction with water. It is shown for the first time that the high-throughput express diagnostics realized using QIRT allows us to determine the amorphous phase content in dispersed alumina and, potentially, in other materials for which this problem is relevant.

Impact of Stationary and Dynamic Conditions on the U-Value Measurements of Heavy-Multi Leaf Walls by Quantitative IRT

Infrared thermography (IRT) has become a commonly applied non-destructive testing method for assessing building envelopes. Like any diagnosis tool, IRT requires an appropriate experience and principle understanding, mainly when the method is used for quantitative analyses. The challenges of the IRT often deal with the dynamic properties of building partitions. Climatic conditions have a certain variability, and the accumulated energy storage in the building components can affect their temperature as well as the calculated thermal performance. This paper aims to analyze how stationary and dynamic regimes of a quantitative IRT test could impact the measured thermal transmittance of heavy multi-leaf walls. Investigation in two European countries with different climatic conditions are reported. In this way, it is discussed which boundary conditions should be guaranteed to provide reliable information about a building envelope using quantitative IRT. In order to check the quality of the measurements, the heat flux meter (HFM) method was also implemented, following the ISO 9869. The research revealed that it could be possible to use short-lasting tests in the climatic conditions of Southern Europe, while long-term tests should be implemented in Northern European countries where climatic conditions are less regular.

Analysis of the Applicability of Non-Destructive Techniques to Determine In Situ Thermal Transmittance in Passive House Façades

Within the European framework, the passive house has become an essential constructive solution in terms of building efficiency and CO2 reduction. However, the main approaches have been focused on post-occupancy surveys, measurements of actual energy consumption, life-cycle analyses in dynamic conditions, using simulation, and the estimation of the thermal comfort. Few studies have assessed the in situ performance of the building fabric of passive houses. Hence, this paper explores the applicability of non-destructive techniques—heat flux meter (HFM) and quantitative infrared thermography (QIRT)—for assessing the gap between the predicted and actual thermal transmittance of passive house façades under steady-state conditions in the Mediterranean climate. Firstly, the suitability of in situ non-destructive techniques was checked in an experimental mock-up, and, subsequently, a detached house was tested in the real built environment. The findings revealed that both Non-Destructive Testing (NDT) techniques allow for the quantification of the gap between the design and the actual façades U-value of a new passive house before its operational stage. QIRT was faster than the HFM technique, although the latter was more accurate. The results will help practitioners to choose the most appropriate method based on environmental conditions, execution of the method, and data analysis.

Verification of quantitative infrared thermography heat-flux measurements

Stagnation-point heat flux was measured on 7° half-angle circular cones with spherical nose diameters of 5, 10, and 25 mm using infrared thermography in hypersonic flow. All models were machined from polyether ether ketone (PEEK). A nominal freestream Mach number of 6 with varying initial stagnation conditions allowed for testing at length Reynolds numbers based on nose diameter ranging from 5×104–5×105. Fay & Riddell’s theory for calculating heat flux at the stagnation point provided a comparison to verify experimental data-reduction methods. Excellent agreement was obtained. Sources of deviation were investigated and best practices for obtaining heat-flux values most similar to theory are presented. Heat flux calculated using a one-dimensional assumption had a mean error of 8.9% from the theoretical expectation. To improve upon this, an implicit, finite-difference approximation was used to solve the axisymmetric heat equation in spherical coordinates, assuming a known surface temperature and isothermal back face. The axisymmetric calculation yielded steady-state heat-flux magnitudes 1–10% greater than the one-dimensional approach, as expected. Correcting for longitudinal heat transfer yielded heat fluxes more nearly proportional to 1/D, and the mean error decreased to 4.8%.

Thermographic 2D U-value map for quantifying thermal bridges in building façades

Thermal bridges accounted for 30% of the impact on the energy performance of European residential building stock. Nevertheless, European countries and their standards do not take into account the influences of this type of anomaly. Furthermore, current methods for quantifying thermal bridges have three main drawbacks. Firstly, most of approaches consist of complex models based on fluid dynamics or finite elements as calculation procedure. Secondly, the disturbances of a thermal bridge can’t be assessed along the vertical and horizontal axis of a wall surface area, since the current methods only allow to perform local measurements. Thirdly, the stratigraphy and morphology of wall is unknown in most cases. Hence, this research proposes the implementation of a 2D U-value map to quantify the influence of thermal bridges in three heavy walls by internal quantitative infrared thermography (QIRT). The measurement campaigns were conducted on a walk-in climatic chamber to monitor and evaluate full-scale building elements. The results demonstrated that the use of 2D U-value maps could help to delimit the geometry of a thermal bridge as well as its area of greater influence, to quantify the U-value in any point of an entire wall with acceptable reliability and, to provide real information about the thermal behaviour of air voids inside opaque façades. Indeed, the U-value results measured by HFM and QIRT were similar in the inhomogeneous wall areas (from 0.08 to 8.55% of difference in most cases). In this way, the operational life of a building could be enhanced with specific refurbishment procedures.

U-value time series analyses: Evaluating the feasibility of in-situ short-lasting IRT tests for heavy multi-leaf walls

A gap in standardization of quantitative infrared thermography (IRT) directly leads to a lack of measurement pattern for determining in-situ U-values of heavy multi-leaf walls. Three groups of causal factors might influence the estimation of this build quality indicator: operating conditions, thermophysical properties and technical conditions. Focusing on the last one, previous studies underlined the difficulties of measuring below 3 h. In contrast to active IRT, no algorithms have been found to process images, despite playing an important role in the effectiveness and robustness of IRT. The traditional approach involves analysing from 120 to 7200 thermograms with a data acquisition interval of 1 min up to 1 s respectively. The aim of this paper was to critically assess the test duration that is traditionally used. Six real heavy multi-leaf walls were tested under a stationary regime as a stochastic process of underlying data. For the first time, a research based on two U-value time series analyses (statistical tests and a signal modelling technique by MATLAB) demonstrated the feasibility of short-lasting IRT tests. Moreover, this research posed an innovative data management tool to automate this non-destructive testing (NDT) in mid-term, stopping IRT tests in real time once the right level of accuracy was achieved.

Non-Destructive Testing for Building Diagnostics and Monitoring: Experience Achieved with Case Studies

Building inspection on site, in other words in-situ examinations of buildings is a troublesome work that necessitates the use of non-destructive investigation (NDT) techniques. One of the main concerns of non-destructive testing studies is to improve in-situ use of NDT techniques for diagnostic and monitoring studies. The quantitative infrared thermography (QIRT) and ultrasonic pulse velocity (UPV) measurements have distinct importance in that regard. The joint use of QIRT and ultrasonic testing allows in-situ evaluation and monitoring of historical structures and contemporary ones in relation to moisture, thermal, materials and structural failures while the buildings themselves remain intact. For instances, those methods are useful for detection of visible and invisible cracks, thermal bridges and damp zones in building materials, components and functional systems as well as for soundness assessment of materials and thermal performance assessment of building components. In addition, those methods are promising for moisture content analyses in materials and monitoring the success of conservation treatments or interventions in structures. The in-situ NDT studies for diagnostic purposes should start with the mapping of decay forms and scanning of building surfaces with infrared images. Quantitative analyses are shaped for data acquisition on site and at laboratory from representative sound and problem areas in structures or laboratory samples. Laboratory analyses are needed to support in-situ examinations and to establish the reference data for better interpretation of in situ data. Advances in laboratory tests using IRT and ultrasonic testing are guiding for in-situ materials investigations based on measurable parameters. The knowledge and experience on QIRT and ultrasonic testing are promising for the innovative studies on today’s materials technologies, building science and conservation/maintenance practices. Such studies demand a multi-disciplinary approach that leads to bring together knowledge on materials science and building science.

Non-Destructive Testing for Building Diagnostics and Monitoring: Experience Achieved with Case Studies

Building inspection on site, in other wordsin-situexaminations of buildings is a troublesome work that necessitates the use of non-destructive investigation (NDT) techniques. One of the main concerns of non-destructive testing studies is to improvein-situuse of NDT techniques for diagnostic and monitoring studies. The quantitative infrared thermography (QIRT) and ultrasonic pulse velocity (UPV) measurements have distinct importance in that regard. The joint use of QIRT and ultrasonic testing allowsin-situevaluation and monitoring of historical structures and contemporary ones in relation to moisture, thermal, materials and structural failures while the buildings themselves remain intact. For instances, those methods are useful for detection of visible and invisible cracks, thermal bridges and damp zones in building materials, components and functional systems as well as for soundness assessment of materials and thermal performance assessment of building components. In addition, those methods are promising for moisture content analyses in materials and monitoring the success of conservation treatments or interventions in structures. Thein-situNDT studies for diagnostic purposes should start with the mapping of decay forms and scanning of building surfaces with infrared images. Quantitative analyses are shaped for data acquisition on site and at laboratory from representative sound and problem areas in structures or laboratory samples. Laboratory analyses are needed to supportin-situexaminations and to establish the reference data for better interpretation of in situ data. Advances in laboratory tests using IRT and ultrasonic testing are guiding forin-situmaterials investigations based on measurable parameters. The knowledge and experience on QIRT and ultrasonic testing are promising for the innovative studies on today’s materials technologies, building science and conservation/maintenance practices. Such studies demand a multi-disciplinary approach that leads to bring together knowledge on materials science and building science.

A model for the improvement of thermal bridges quantitative assessment by infrared thermography

The intervention on the existing building envelope thermal insulation is the main and effective solution in order to achieve a significant reduction of the building stock energy needs. The infrared technique is the methodology of the energy diagnosis aimed to identify qualitatively the principal causes of energy losses: the presence of thermal bridges. Those weak parts of the building envelope in terms of heat transfer result not easy to treat with an energy efficiency intervention, while they are gaining importance in the buildings total energy dispersion, as the level of insulation of opaque and transparent materials is continuously increasing. It is generally possible to evaluate the energy dispersions through these zones with a deep knowledge of the materials and the geometry using a numerical method. Besides, authors proposed in the past a methodology to assess the flux passing through thermal bridges with an infrared image correctly framed. The analysis of surface temperatures of the undisturbed wall and of the zone with thermal bridge, allows to define the Incidence Factor of the thermal Bridge (Itb). This parameter is strongly affected by the thermographic image accuracy, therefore, this paper deals with the development and validation of an innovative mathematical algorithm to enhance the image resolution and the consequent accuracy of the energy losses assessment. An experimental campaign in a controlled environment (hot box apparatus) has been conducted on three typologies of thermal bridge, firstly performing the thermographic survey and then applying the enhancement algorithm to the infrared images in order to compare the Itb and the linear thermal transmittance ψ values. Results showed that the proposed methodology could bring to an accuracy improvement up to 2% of the total buildings envelope energy losses evaluated by quantitative infrared thermography. Moreover, the proposed algorithm allows the implementation of a further process applicable to the images, in order to extract the physical boundaries of the hidden materials causing the thermal bridge, so revealing itself as a useful tool to identify exactly the suitable points of intervention for the thermal bridge correction. The application of the imaging process on the quantitative infrared thermography is an innovative approach that makes more accurate the evaluation of the actual heat loss of highly insulating buildings and reaching a higher detail on the detection and treating of thermal bridges.

SERS Investigation of Cancer Cells Treated with PDT: Quantification of Cell Survival and Follow-up

In this study Surface Enhanced Raman Spectroscopy (SERS) data recorded from mouse mammary glands cancer cells (4T1 cell line) was used to assess information regarding differences between control, death and viable cells after Photodynamic Therapy (PDT) treatment. The treatment used nanoemulsions (NE/PS) loaded with different chloroaluminumphthalocyanine (ClAlP) photosensitizer (PS) contents (5 and 10 µmol × L−1) and illumination (660 nm wavelength) at 10 J × cm−2 (10 minutes). The SERS data revealed significant molecular alterations in proteins and lipids due to the PDT treatment. Principal Component Analysis (PCA) was applied to analyze the data recorded. Three-dimensional and well reproductive PCA scatter plots were obtained, revealing that two clusters of dead cells were well separated from one another and from control cluster. Overlap between two clusters of viable cells was observed, though well separated from control cluster. Moreover, the data analysis also pointed out necrosis as the main cell death mechanism induced by the PDT, in agreement with the literature. Finally, Raman modes peaking at 608 cm−1 (proteins) and 1231 cm−1 (lipids) can be selected for follow up of survival rate of neoplastic cells after PDT. We envisage that this finding is key to contribute to a quick development of quantitative infrared thermography imaging.

U-value assessment by infrared thermography: A comparison of different calculation methods in a Guarded Hot Box

The thermal transmittance (U-value) of the vertical opaque building envelope plays a key role for the evaluation of the thermal performance of a structure.In order to speed up the assessment procedure and to investigate wider portions of buildings directly in situ, new methods based on the use of quantitative infrared thermography have been proposed during the last years.Although the studies agree about the influence of the operative conditions, a detailed report, based on measurements effected on a large wall in a controlled environment and at different boundary conditions, is still missing in literature.The aim of this work is to assess the validity of thermographic methods by using different operative conditions in a controlled environment. The results obtained by different IR methods in a Guarded Hot Box have been compared with heat flow meter measurements and theoretical values.

Active IR-Thermal Imaging in Medicine

In this paper we summarize results of several research projects devoted to development of new diagnostic methods and procedures based on quantitative infrared thermography in medical applications. First, basics of active dynamic thermography are presented. Described are both, instrumentation and software comprising measurement procedures including collection of series of IR-images after external excitation, data treatment with displacement corrections, reduction of noise and artifacts and finally presentation of parametric diagnostic images. The thermal tomography method is also shortly discussed. As the most important for medical diagnostics parametric images of thermal time constants are discussed. For illustration of the value of presented methods chosen research and clinical applications performed in several clinics of Gdansk Medical University are presented. In vivo experiments on animals, mainly domestic pig, as well as clinical diagnostic procedures are discussed in skin burn and cardiosurgery applications. Specific requirements of IR-thermal investigation in medical applications are discussed in comparison to IR-thermal imaging in technical non-destructive evaluation. It should be underlined that medical applications of IR-diagnostics seem to be the most difficult among other applications as heat transfers in living tissues are far more complicated comparing to technical evaluation where nondestructive testing methods based on thermal IR-imaging are already well developed.

Validation of size estimation of debonds in external wall’s composite finishes via passive Infrared thermography and a gradient algorithm

This paper aims to present a study on validating a passive and quantitative infrared thermography (PQIRT) methodology to estimate the size of debond in rendered and tile composites in external walls of high-rise buildings. The accuracies of the PQIRT methodology were evaluated under four conditions, including (i) nine depths of debonds, (ii) three temperature ranges, (iii) two types of composites and (iv) changes of heat flux during a 2-h diurnal and continuous monitoring. The method processed infrared images with a simple spatial pixel differentiation algorithm to determine temperature gradients, where the absolute temperature value was no longer required. The methodology was validated by comparing the estimated and the actual sizes of the debonds by statistical error analysis. In the rendered composites, the percentage error was at most 15% for cover depths of debond up to 20mm for all temperature ranges. In the tile composites, the error was at most 30% for cover depths of debond up to 9mm at all temperature conditions, while the estimation was erroneous for cover depths beyond 9mm. These results will form the basis to develop guidelines for using PQIRT for inspection of high-rise building envelops in densely populated cities, which supplement the current qualitative inspection adopted by a handful of few accredited laboratories in Hong Kong and elsewhere.

A comprehensive experimental approach for the validation of quantitative infrared thermography in the evaluation of building thermal transmittance

Quantitative thermography is now mostly accepted as a reliable method to measure energy performance of existing buildings, in particular the thermal transmittance U-values of opaque elements. Some researches have been conducted in this field, each presenting a different procedure verified by the application on simple case studies. Anyway, a comprehensive approach, based on a parametric analysis of walls with different typologies and exposure, but same boundary conditions, is still missing. This study proposes a systematic approach to the problem, based on a three years research activity carried on an experimental building where timber (light) and brick (heavy) structures were tested simultaneously with Infrared Thermovision Technique (ITT), also equipped with heat flow meter (HFM) sensors and a nearby meteo station. Standard deviation of U-values measured with ITT is given as well as absolute deviation against values calculated following international standards and measured with HFM method. Parameters having high significance for the achievement of good results compared to the expected U-values are assessed through a sensitivity analysis. Influence of weather conditions during the survey are also considered and a repeatable procedure is finally set up. The findings presented in the study show that the method gives good results for heavy constructions, while further studies are still needed for light and super-insulated walls.

In situ examination of structural cracks at historic masonry structures by quantitative infrared thermography and ultrasonic testing

The key concern of the study was the in situ assessment of cracks in historic masonry structures by quantitative IR thermography (QIRT). To better understand the potentials and/or limits of QIRT for that purpose, the non-destructive in situ survey composed of QIRT and ultrasonic testing was conducted on a sixteenth century monument, suffering from structural cracks that had occurred in recent years. Its aim was to discover the thermal behaviour and ultrasonic characteristics of cracks in relation to depth and moisture content. The superficial and deep cracks were found to have different thermal responses to exposed conditions which made them easily distinguishable by QIRT analyses. The results of thermal monitoring during the exposure of heating conditions were promising in giving hints of methods for the depth assessment of deep cracks in masonry. The in situ ultrasonic data taken in indirect transmission mode provided knowledge on the depth of cracks that enhanced the accuracy of the non-destructive in situ survey.

Humidity and air temperature measurement by quantitative infrared thermography

Quantitative infrared thermography is used to measure the humid air conditions in equilibrium with a building surface. The method is based on accurate temperature measuring as the driving parameter of the physical process. At the same time, the thermographic system produces images of the wall surface behind the device and so can measures the wall's temperature, as well. This is a part of a project dealing with the full monitoring of the indoor environment on thermodynamic basis. The use of a special ancillary device called IRpsicro and a dedicated procedure allows the measurement of the air temperature, relative humidity and speed using only IR thermography. This knowledge is fundamental to know and quantify the moisture exchange process between the porous material and the boundary. As a consequence thereof the evaporative process can be studied on quantitative basis. Essentially, IRpsicro enable the wet and dry bulb temperature measurements needed by the psycrometric method. Equations to achieve indirectly the hygrometric quantities of air are presented. Results obtained in laboratory-controlled conditions are compared with standard measurements of temperature and relative humidity. The paper illustrates a current application of the system in order to evaluate the decay of a heritage building covered by frescoes. An accurate global view of the building envelope is produced with images corrected for the geometric and radiometric distortions.