planning:thermal_protection:thermal_protection_works:insulation_increases_comfort_-_evidence_no.3_outdoor_thermography
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planning:thermal_protection:thermal_protection_works:insulation_increases_comfort_-_evidence_no.3_outdoor_thermography [2012/02/27 16:57] – Angela | planning:thermal_protection:thermal_protection_works:insulation_increases_comfort_-_evidence_no.3_outdoor_thermography [2022/01/25 13:17] (current) – ggrosskopf | ||
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+ | ====== Outdoor thermography ====== | ||
+ | |||
+ | Outdoor thermographies provide independent evidence that insulating buildings allows for considerable energy savings and increases the level of comfort.\\ | ||
+ | \\ | ||
+ | ===== Infrared thermography with insulation / without insulation ===== | ||
+ | |||
+ | The infrared imaging technique or [[http:// | ||
+ | \\ | ||
+ | |{{ : | ||
+ | |//**PHI member Oliver Kah taking a thermal image**// | ||
+ | |||
+ | This image shows a member of the passive House Institute taking a thermal image. The camera is mounted on a stand. It produces a colour image of the infrared radiation with a wavelength between 8 and 15 µm which allows for conclusions to be drawn regarding the objects’ temperatures. This image shows a blue spot where a fresh layer of plaster has just been added below the window sill. The plaster is still wet – moisture evaporates cooling the area. This example shows that cold spots aren’t necessarily caused by thermal bridges. Preparing and evaluating IR images requires a great deal of expertise.\\ | ||
+ | \\ | ||
+ | |||
+ | ==== Applying exterior insulation ==== | ||
+ | |||
+ | The following infrared image was taken during the application of exterior insulation to a Nuremberg building. The modernisation was planned and carried out by the architect [[http:// | ||
+ | \\ | ||
+ | |{{ : | ||
+ | |//**IR image taken during the application of the insulation: | ||
+ | The insulation at the exterior walls of the ground floor is nearly finished, | ||
+ | unlike that of the upper floors. New quality windows have been installed\\ | ||
+ | A scaffolding has been put up in front of the facade with packages of\\ | ||
+ | insulation panels attached to them (see regular picture).\\ \\ \\ **// | ||
+ | The picture clearly shows the filling on the old plaster (light\\ | ||
+ | grey) as well as the insulation panels (dark grey) which have\\ | ||
+ | already been applied from the bottom to the ground floor\\ | ||
+ | window. The scaffolding and the bags allow a good view of\\ the wall and will serve as points of reference for comparisons\\ later on.**//|\\ | ||
+ | \\ | ||
+ | |{{ : | ||
+ | |//** This image is identical to the thermal image above, the areas of particular\\ interest have been labelled. Note the white boundary line between the\\ uninsulated and the insulated areas.**\\ | ||
+ | |||
+ | // | ||
+ | The temperatures depend on the radiation intensity of the materials\\ | ||
+ | as well as their emissivity. This value varies very little for all the\\ | ||
+ | materials in this picture (except for the glass surfaces), with emissivity\\ | ||
+ | values ranging 0.93 and 0.96.**\\ | ||
+ | //|\\ | ||
+ | \\ | ||
+ | These IR images are rather revealing: | ||
+ | |||
+ | * ** The outdoor air temperature is approx. 6.46 °C ** as measured at the surface of the bags hanging from the scaffolding. The surfaces of these bags have reached a temperature equilibrium with the outdoor air; therefore they neither give off heat nor do they absorb heat. | ||
+ | |||
+ | * ** The temperatures measured for the areas of the facade that have already been insulated are very uniform** and rather similar to that recorded for the bags – rendering the bags barely noticeable in the thermal image. Nevertheless, | ||
+ | |||
+ | * ** The facade areas of the heated upper floor which have not yet been insulated have a much higher average temperature of 9.14 °C. Moreover, their temperatures are not uniform.** This is due to a number of reasons: In some areas, significant heat losses are caused by thermal bridges – e.g. at the edge of the window where the heat only travels a short distance the masonry. In other areas, furniture is positioned along the external walls serving as partial interior insulation and reducing the temperature in these areas. | ||
+ | |||
+ | * ** The heat emitted by an object is roughly proportional to the temperature difference between this object and the outdoor air temperature**. \\ In this case, the difference is:\\ | ||
+ | for the uninsulated wall: 9.14 – 6.46 = 2.68 degrees | ||
+ | for the insulated wall: 6.81 – 6.46 = 0.35 degrees | ||
+ | These figures allow for a rough estimation of the heat losses through the wall: those occurring at the insulated wall are reduced by a factor of 8 compared with the uninsulated wall. | ||
+ | \\ | ||
+ | The thermal image doesn' | ||
+ | The white line in the second thermography reflects the edge where the insulation ends and where the bare brick wall starts to show behind the insulation which has already been applied. Even at some distance the brick wall is losing less heat and has become somewhat warmer – reaching a temperature of over 18 °C. This is good as moisture build-up is reduced and structural damage is prevented even if furniture is placed next to the exterior wall. Increased temperatures behind the insulated wall also promote cross-heat-flow upwards through the wall. As a result, the temperature increases at the edge where the bare wall shows behind the insulation. This effect is clearly reflected in the thermal image with an orange-coloured strip running closely to the edge of the insulation. As the image is taken from an upward angle the brick wall is somewhat covered by the front edge of the insulation; otherwise the effect would be even more obvious.\\ | ||
+ | \\ | ||
+ | |||
+ | ==== The complete insulation ==== | ||
+ | |||
+ | The following thermal image shows the fully insulated facade. | ||
+ | \\ | ||
+ | |{{ : | ||
+ | |//**The completed facade with insulation and plaster; image taken by PHI \\ (Dr. W. Feist) on 17 December 2002 at 7:52. Background: a uninsulated \\ building, partly hidden by trees.**// | ||
+ | \\ | ||
+ | That morning, the outdoor air temperature is approx. 3.5 degrees Celsius. The uninsulated wall of an old building is shown on the left side in the background of the thermal image (colourful). Lots of heat is conducted towards the outer surface of the wall and radiated into the surroundings. This is reflected in high surface temperatures between 6 and 7 °C. | ||
+ | On the right side in the foreground of the image, the new insulated facade is shown in dark blue colours: the insulation considerably reduces the amount of heat flowing from the inside to the outside of the building. The new plaster surface has a uniformly low temperature of approximately 3.7 °C which is hardly any different from the temperature of the surrounding trees. This shows that the heat loss is extremely small. Higher heat losses at the windows and the colours around the tilted window (above left) prove that the house is indeed heated.\\ | ||
+ | | ||
+ | |||
+ | \\ | ||
+ | |||
+ | ==== Note on the tilted window ==== | ||
+ | |||
+ | The following images illustrate the thermal effects around the tilted window in this building. They are both the same image, displaying different temperature ranges: | ||
+ | * The image on the left only shows temperatures between 2 and 10 degrees Celsius, higher temperatures are displayed as white areas. | ||
+ | |||
+ | * The image on the right shows temperatures between 2 and 20 degrees Celsius revealing the tilted window as well as the window sill (light purple). The temperature at the interior surface is close to 19°C. | ||
+ | This example illustrates just how well the insulation works: Even with the window open, the interior surface of the wall stays warm even right next to the thermal bridge due to the window installation.\\ | ||
+ | \\ | ||
+ | |{{ : | ||
+ | |// | ||
+ | \\ | ||
+ | |||
+ | What about tilting a window in a Passive House? Well, it's possible, as the pictures show. Does it change the Passive Houses performance? | ||
+ | |||
+ | ===== Conclusion ===== | ||
+ | |||
+ | The analyses presented in this article highlight that improved insulation works and that it considerably reduces heat losses, and that the generally accepted scentific calculation methods apply.\\ | ||
+ | \\ | ||
+ | |||
+ | ===== See also ===== | ||
+ | |||
+ | [[planning: | ||
planning/thermal_protection/thermal_protection_works/insulation_increases_comfort_-_evidence_no.3_outdoor_thermography.txt · Last modified: 2022/01/25 13:17 by ggrosskopf