Objectively assess the work done on the insulation of a private house can be on a number of grounds. In most cases, this is the amount of electricity consumed for heating and thermometer readings. But if the insulation was ineffective, it is difficult to find the reasons without special equipment.
In such situations, use a thermal imager for construction. In the article submitted by us, the principle of operation and design features of the device are described in detail. The rules for using and processing the data obtained during thermal survey are given.
The content of the article:
- Why do thermal imaging?
- Device and principle of operation
- Types of thermal imaging devices
- Thermal imaging application rules
- Interpretation of the data
- Conclusions and useful video on the topic
Why do thermal imaging?
Inspection by a building thermal imager of a cottage, cottage or a residential house provides an opportunity to see on the thermogram what is happening inside various objects and structures of the building without touching them at all. This is called non-destructive testing.
This kind of inspection will show the state of the heating pipes in the walls and floor heating without opening plaster or tile.
The basis of thermal diagnostics is the principle of fixing heterogeneities of the thermal field, which allows to judge the state of the objects under study.
The sensitivity of some models reaches hundredths of a degree, so you can not only see the thermal footprint on the surface of structures, but also find out what happens inside.
The unique advantage of modern thermal imagers over other controls is precisely the ability to look inside objects without violating their integrity. Even a minimal deviation of temperature indicators from the norm will indicate the presence of problems, for example, in the electrical network.
Checking a private house with a thermal imager will help solve a variety of tasks:
- localize the places of heat leakage and determine the degree of their intensity;
- monitor the effectiveness of the vapor barrier and identify the formation of condensate on various surfaces;
- choose the right type of insulation and calculate the required amount of insulation material;
- to detect the flow of the roof, pipelines and heating mains, leakage of the coolant from the heating system;
- check the air tightness of window glass and the quality of installation of door blocks;
- to diagnose ventilation and air conditioning systems;
- to determine the presence of cracks in the walls of the structure and their size;
- find places of blockages in the heating system;
- diagnose the condition of the wiring and identify weak contacts;
- detect the habitat of rodents in the house;
- Find sources of dryness / high humidity inside a private building.
Building thermal imager allows you to quickly verify the compliance of the parameters of the erected building with technical requirements, assess the quality of an immovable object before its purchase and diagnose the work of internal communications.
A home inspection by a thermographic scanner before laying insulating materials will help to correctly calculate the cost of insulation
And after the completion of the work, thermal imaging will allow you to control the final result and detect the installation faults that create heat loss. The check will also show cold bridges that can be quickly eliminated in preparation for the winter season.
Before reconstruction or repair of old buildings, a device with an infrared camera will come to the rescue in order to identify the most cold areas and places of leakage, problems with warm floors, and objectively assess the amount of planned construction works
Device and principle of operation
The sensitive element of any thermal imager is a sensor that transforms the infrared radiation of various objects of inanimate and living nature, as well as the background, into electrical signals. The obtained information is converted by the device and reproduced on the display in the form of thermograms.
As a result of metabolic processes, all living organisms produce thermal energy, which is perfectly visible to the equipment.
In mechanical apparatus, the heating of individual components occurs due to constant friction at the junction points of the moving elements. In equipment and systems of electrical type, conductive parts are heated.
After pointing and shooting an object, the IR camera instantly forms a two-dimensional image containing complete information about temperature indicators. Data can be stored in the memory of the device itself or on external media, or it can be transferred using a USB cable to a PC for detailed analysis.
Some models of thermal imagers have built-in interfaces for instant wireless transmission of digital information. The recorded thermal contrast in the field of view of the thermal imager allows you to visualize the signals on the device screen in semitones of a black and white palette or in color.
Thermograms show the intensity of infrared radiation of the structures and surfaces under investigation. Each individual pixel corresponds to a specific temperature value.
The heterogeneity of the thermal field reveals errors in the engineering structures of the house and defects in building materials, thermal insulation deficiencies and poor-quality repairs.
On the black-and-white screen of the thermal imager, the lightest zones will be displayed. All cold objects will be virtually indistinguishable.
On the color digital display, the areas that radiate the most heat will turn red. By reducing the intensity of the radiation, the spectrum will shift toward violet. The coldest zones will be marked in black on the thermogram.
To process the results obtained with a thermal imager, it is sufficient to connect the device to a personal computer. This will reconfigure the color palette on the thermogram so that the required temperature range is best seen.
Modern multifunctional devices are equipped with a special detector matrix, which consists of a huge number of very tiny sensors.
Infrared radiation captured by a thermal imager lens will be projected on this matrix. Such IR cameras are able to detect a temperature contrast equal to 0.05-0.1 ºC.
Most models of thermal imagers are equipped with a liquid crystal control display to display information. However, the quality of the screen does not always indicate a high level of infrared equipment in general.
The main parameter is the power of the microprocessor used to encode the received data. The speed of processing information plays a major role, as pictures taken without a tripod can be blurred.
The operation of thermal imaging devices is based on fixing the temperature difference between the general background and the object, and converting the data into a graphic image visible to the human eye.
Another important parameter is the resolution of the matrix. Devices with a large number of sensitive elements give better two-dimensional images than thermal imaging devices with a lower resolution matrix detector.
This difference is due to the fact that one sensitive cell has a smaller surface area of the object under study. In high-resolution graphics, optical noise is almost imperceptible.
Types of thermal imaging devices
Checking a private house for heat loss with an IR camera makes it possible to conduct the most accurate measurements and qualitative analysis of all temperature indicators. And after that, on the basis of promptly obtained data, competently carry out repair work and / or modernization of a residential facility.
For thermal imaging diagnostics involve two types of devices:
- stationary thermal imagers;
- portable infrared cameras.
Stationary devices are mainly used in manufacturing plants. They are intended for regular checking of the state of power grids and constant monitoring of complex technical equipment. Stationary thermal imaging systems are made on semiconductor arrays of photodetectors.
With the help of portable thermal imagers hold an energy audit of residential apartment buildings and private buildings. These devices are used for a one-time local inspection, and for a comprehensive diagnosis of homes.
Portable thermal imagers are based on silicon uncooled microbolometers and are excellent for use in hard to reach places.
Thermal imaging is an effective non-contact survey method, which is advisable to combine with the use of aerial door to measure and control the air permeability of buildings
Depending on the functionality, there are three types of thermal imagers:
- Observation devices - provide only visualization of various warm-contrast objects, often in monochrome.
- Measuring devices - create a graphic image within infrared radiation and assign each point of the light signal a certain temperature value.
- Visual pyrometers - designed for contactless temperature measurements and visualization of the thermal field of specific objects in order to detect areas with deviations from normal values.
The price of good functional heat radiation receivers starts from $ 3,000. Their purchase for a one-time survey at home is simply unprofitable. Many companies today offer building thermal imagers for rent for a day. This is a very convenient service.
You can also order a full professional thermal imaging survey of the cottage / house. The average cost of imaging with a thermal imager is $ 5 per 1 square meter of private residential area.
As a rule, the cost of thermal imagers is an indicator of their functionality. But even low-end models effectively perform infrared diagnostics. Therefore, when choosing, one should focus on basic technical characteristics and the ability to solve specific tasks.
The functionality of thermal imaging cameras depends on the resolution of the infrared sensor, its sensitivity and operating temperature range.
A big plus is the presence of additional functions, namely: digital zoom, laser pointer, compilation of annotations to thermograms, customizable color alarm, identification of sections with maximum and minimum temperature indicators.
Considerably simplify thermal imaging at home and various accessories - removable optical wide-angle lenses for general views and telephoto lenses for detailing critical areas, folding tripods, storage containers batteries.
Thermal imaging application rules
The main task of a thermal imaging survey is to accurately identify heat loss and defects in the operation of engineering systems, as well as to detect possible weak points of a residential facility during the construction phase.
Thermal imaging diagnostics of buildings includes:
- examination in the long-wave infrared region of the spectrum in the range of 8-15 microns;
- building a temperature map of the objects and surfaces under investigation;
- monitoring the dynamics of thermal processes;
- accurate calculation of heat flow.
Verification of a residential object is carried out both outside and inside the building. In the first case, infrared imaging allows you to detect gross defects in the infiltration of air flow through the building envelope and insulation defects. In the second - to identify errors in the functioning heating system and power supply networks.
It is better to carry out thermal imaging diagnostics in cold weather, when the difference in temperature in the street and in the house is more than 10 degrees Celsius
The higher the temperature difference, the more accurate the test results. In addition, in order to obtain correct data, the surveyed residential object must be continuously heated for at least 2 days. In the summer period, it is practically useless to inspect the building with a thermal imager due to the minimal temperature difference.
Inspection of buildings with thermal radiation detectors shows the distribution of temperature fields on the surfaces of objects or structures at a particular point in time. Therefore, conducting an infrared camera shooting is highly dependent on a number of conditions, compliance with which is crucial for obtaining correct results.
Strong wind, sun and rain affect the device. Under their influence, the house will be cooled or heated, which means that the test can be considered ineffective. Examined structures and surfaces should not be in the zone of contact with bright direct rays of the sun or reflected radiation for 10-12 hours before the start of thermal imaging diagnostics.
It is recommended to keep the door and window units in a fixed position for 12 hours before shooting with an infrared camera and during the building inspection process.
Prior to the start of the home survey, it is necessary to set the basic settings on the device, namely:
- set the lower and upper temperature limit;
- adjust the range of thermal imaging;
- select the intensity level.
Other indicators regulate depending on the type of insulation, materials of walls and floors. Energy audit of a private house begins with a check of the foundation, facade and roof of the building.
At this stage, it is very important to conduct a thorough diagnosis, since the areas on the same plane are significantly different and the receivers of thermal radiation will definitely show this.
After checking the exterior, proceed to diagnostic activities inside the residential building. About 85% of all construction defects and faults in engineering systems are detected here.
The survey is carried out in the direction from the window blocks to the doors, slowly exploring all technological openings and walls. At the same time, the doors between the rooms are left open to stabilize the flow of heated air and minimize the likelihood of errors in the measurements.
Thermal imaging control involves the phased inspection of different zones of enclosing structures, which must be open for shooting with an infrared camera. To do this, you need to free up the sub-window space, to organize unhindered access to the plinths and corners.
The walls at the time of internal thermography of the building must be freed from carpets and paintings, peeled off old wallpaper and other objects that interfere with the direct visibility of the object under study.
Houses equipped heating radiators, taken taken only from the outside. Diagnostics of facades is carried out under favorable weather conditions - the absence of wet fog, smoke, precipitation.
Interpretation of the data
Thermal imaging devices record the temperature difference from 3 ºC, and this will be displayed on the thermogram as an anomalous zone in the characteristic color spectrum. However, the spectral image itself is not a sufficient justification to consider the area being diagnosed as defective.
For all anomalous zones it is necessary to make heat engineering calculations and then already draw conclusions about the state of the objects under study.
Therefore, complete with portable thermal imagers, instrumental software is supplied for qualitative and quantitative analysis of thermograms, as well as for creating reports.
All this means that to work with an infrared camera does not require special training. Having studied the user manual, it is easy to independently conduct a thermal inspection and processing of the results in the proposed program. After analyzing the obtained indicators, the application will give an expert assessment of the images.
In addition, the information collected by the equipment can be transferred to programs for processing statistical data - tabular processors or special engineering utilities, for example, MathLab.
It is also worth noting that the imager may produce incorrect results in case of incorrect settings. Similar situations occur when examining surfaces such as glass, gloss tile, mirror.
Infrared radiation of nearby objects will be reflected in these surfaces, which will lead to a distortion of the thermograms. To correctly determine the temperature of the mirror surfaces in thermal imaging devices, it is necessary to additionally adjust the correction factors.
It is also necessary to take into account cold radiation, which may be reflected from the windows and roof of a residential object. The resulting thermogram can be much colder than the actual state of the house.
The quantitative method of analyzing the distribution of temperature fields over the surface of structures does not take into account the coefficient of emission and the background radiation of the environment. And it does not matter whether the shooting is performed by an infrared camera on site or the results obtained are processed by the software.
When carrying out diagnostic activities inside the building, more reliable results are obtained, since external climatic conditions do not affect the surfaces under study. The final thermograms after processing the corresponding programs correspond to reality.
The use of a building thermal imager makes it possible to objectively assess the quality of the thermal protection of a building, detect cold bridges and subsidence insulation, as well as to find hidden damage and defects in the installation of window blocks, doorways, poorly made joints of the roof, walls and overlaps.
Infrared diagnostics makes it possible, correctly, and therefore economically, to perform work on minimizing heat loss in a residential facility, to reduce the cost of floor insulation and thermal insulation of other structures.
Conducting research procedures will provide an opportunity to correctly select insulation for walls and ceiling private construction. As a result, the cost of heating a private house will decrease.
Conclusions and useful video on the topic
The principle of operation of the imager, checking the building after insulation for defects and correct interpretation of images in infrared rays in the video:
Thermographic scanners functionality:
Video on how to analyze and create a technical home diagnostic report using a thermal imaging device using the Testo IRSoft software module:
Today, infrared camera thermal imaging is an advanced technology for non-destructive monitoring, which allows you to monitor the state of various structures, communication networks and electrical equipment.
The study of heat loss using a thermal imager is carried out in order to prevent emergency situations, to detect defects in heat and waterproofing, to identify faults in engineering systems at home.
Do you have experience using a thermal imager to study the weak points in your country house / apartment? Perhaps you can share useful information on the definition of heat loss building structure? Please write comments, ask questions, post a photo on the subject of the article in the block below.