Infrared Thermography for energy recovery

The energy audit may make use of infrared thermography (IR) as a technique to define better the real situation of the property Thermal.

Introduction
Part of a policy aimed at reducing energy consumption in full construction, the lion's share will, more and more, the retrofit of existing building heritage.
But we must consider that, to date, the 90% of the buildings is in a very bad situation from the point of view of energy consumption.
The current state of crisis in the construction sector production should not, however, obscure the fact that the crisis also means change. If the construction of the new model is rapidly slowing construction, It must reflect on the fact that there is a real and huge building park all to be redeveloped and this could be a great opportunity to be seized.
Work on the existing assets can be summarized in three great voices:
– maintenance
– redevelopment
– demolition and reconstruction of entire urban areas.

thermography
The ’ importance of diagnosis
Any maintenance and cleansing you should go through a diagnosis of the current state of ’ estate where the diagnosis will cover mainly the housing ’, but not excluding the ’ plant that aspect will have to adapt to the new housing needs.
While it is true that an expert technician, Classic issues (such as thermal bridges, disturbances, etc.) are not found, It will be only through a correct diagnosis which will identify the real weak points. Especially with ’ thermography can detect irregularities that do not appear to the naked eye and assess the ’ entity in relation to the structure of ’ building.
The diagnostic phase of the ’ property should be preceded by a reconnaissance in the visible spectrum detecting system ’, the quality of doors and Windows, vertical and horizontal partitions of the ’ estate by highlighting the sensitive nodes can scatter, the positioning of the boiler and heat providers terminals.

The power of thermal imaging in rehabilitation stage
If properly used, thermography has considerable potential to provide information to the designer already in the design phase, and the ’ energy is just one aspect of these.
Other, no less important, are:

1. check the ’ property degradation due to presence of infiltrations;
2. checking status of accession of outer garments: plaster or ceramic and stone tiles;
3. definition of homogeneous structure differences;
4. presence of moisture ski lifts;
5. verification of the presence of thermal bridges;
6. check the Thermo-hygrometric regime, the presence of areas with concentrations of humidity to check whether the surface temperatures comply with the conditions imposed by the current regulations (UNI 13788 and from the d.lgs. 311/06).
This information acquired fundamental importance especially in situations where there is the presence of a historic constraint that prevents the ’ direct action on one or on both sides of the structure, allowing then to consider carefully any other interventions.

In this article we will enter into the operational aspect of the technique ’, but we will focus on the evaluation of Thermographic surveys run before making a speech to retrofit.
Diagnostic phase so it's certainly possible to determine the presence and severity of any thermal bridges, but it will be equally important to determine the presence of any leakage or humidity up in order to eliminate or mitigate their deleterious effects.
If you present these issues, might go to compromise throughout the ’ effectiveness of insulation materials and at the same time also cause further damage (could cause damage to the insulating structures to the degradation of the adhesives due to the thrust of migration and crystallization of sali).

Equally important is to define the presence of leaks or losses from. The study of thermal behavior of building is substantially ’ on determination of verification of thermal bridges and ’ analysis of the causes which they determine in order to correctly evaluate the remedies.

As anticipated, thermal bridges can be of different nature and can be generated by the presence of a discontinuity of material, by thickness variation of housing ’, from a geometrical variation, or even by the presence of a phenomenon called thermal bypass (that you check when the external air tends to penetrate the thickness of building envelope).
When this occurs, the outside air tends to transit within the hollow spaces in the walls or in the roof (even by natural convection or by pressure difference) causing a cooling of gaps, internal surfaces and a decay of the thermal performance of the building, with the aggravating circumstance of ’ create additional issues such as the formation of interstitial condensation or superficial to the possible formation of fungal microorganisms in ’ of them all.

Other interventions that often are not considered, are relative to the ’ mapping systems, allowing you to highlight the location of the pipes but also some abnormalities, especially in homes with too old and not sufficiently insulated.

In the case of buildings where there is found the need for a full renovation, It could be shown, already in the diagnostic phase, perform a "blower door test” aimed at determining the sources and the casing air leakage. During the ’ run the blower door test, thermography, allows you to highlight, with great speed and reliability, searching for points of discontinuity of housing ’.

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Not only thermal bridges
In summary, we believe that the action ’ thermography Diagnostics is not limited to simple highlighting of thermal bridges, being able to provide the following information:
• of rising damp phenomena of capillary effect.
• phenomena condensation
• thermal bridges
• Installations
• Thermal bypass
• Verification of the works
• Determination of the internal conditions of the building in relation to the UNI 13788.

The requirements of proper thermal test
The ’ operator, they must possess the certification UNI EN 473 level II to operate and sign relations, must also possess a specific preparation in order to be able to evaluate any false positives (UNI 13187 to evaluate the response and ’ interpretation of results).

For the sake of brevity we will assess what are thermal irregularities already mentioned:
• air flows from the inside out
• insulation defects
• moisture
• thickness variations
• of material variations

But there are additional General requirements of proof to be met depending on:
• machine specifications
• characteristics of the thicknesses of the insulating materials
• radiant properties of the coating materials
• climatic factors
• ease of access to the object to be detected
• environmental influence (as wind and weather)

The Thermographic Analysis ’ should never be carried out in the presence of direct irradiation (that would generate false readings due to solar accumulations); unless there is a great deal of experience of ’ operator who would be able to seize critical points. This is valid in particular for heavy structures where it is necessary to consider the capacity of heat accumulation of materials.

The report
The final report should contain at least the following information

A personal analysis (with detailed identification of the causes and the causes of the problems):
• Air infiltration
• Lack of insulation
• Moisture
• Thermal bypass

Highlighting irregularities (with the definition of cases which mainly can be accounted to the four cases listed):
• uniform temperature with values ​​significantly different from those expected.
• Structural thermal bridges.
• Highlighting ΔT between the different thermal areas.
• highlighting any deviations from the requirements for testing.

What does not allow thermography and operating limitations of the standard

Although there are such trials, with infrared thermography technique you can't, to date, determine the transmittance of the elements. To obtain such information is cosigliato employ other techniques (termoflussimetriche, ’ it also subject to potential errors of measurement, or analytic calculation, starting from tabular data).

The rule requires therefore some testing conditions found only in few cases in professional practice. The tension to the ’ excellent, laid down in accordance with, should not be seen as an obstacle, but as an indication of proper operation.
The norm, for example,  indicates that before you begin detection operations, you have already submitted the projects property ’, (not always possible for privacy reasons to objective difficulties of access to documentation).  It is also recommended to compare the thermograms of relief with the thermograms of reference performed on structures that have known defects (difficult especially for the considerable amount of architectural details present in the building scope ’).  It also asked to have the walls of houses or furniture sgombere furniture (difficult conditions as well as in contrast to the normal conduction of ’ estate).

The presence of such rigid requirements therefore must not think one non-applicability of the legislation operating in practice, go instead it highlighted how the rule constitutes a precise reference point for a quality standard in an industry that unfortunately view very little professionalism and high improvisation at the expense of those who will support the work.
The diligent operator you will ’ to consider carefully the possibility of applying the specifications from the norm and, While some of these were not applicable, will indicate in detail the reason.

This will also allow you to an expert reader of to evaluate correctly the data reported in the final report and Thermographic Analysis.

 

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taken from an article of ’ bell ’ Arch. Carlo Di Pillo

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