planning:thermal_protection:thermal_protection_works:insulation_works_-_evidence_no.1_measurements_at_a_highly_insulated_wall
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| planning:thermal_protection:thermal_protection_works:insulation_works_-_evidence_no.1_measurements_at_a_highly_insulated_wall [2015/01/02 15:23] – [Magnified view] wolfgangfeist@googlemail.com | planning:thermal_protection:thermal_protection_works:insulation_works_-_evidence_no.1_measurements_at_a_highly_insulated_wall [2022/01/25 10:53] (current) – ggrosskopf | ||
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| * just below the inner surface of the interior plaster (red dash line) | * just below the inner surface of the interior plaster (red dash line) | ||
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| * in the center of the brickwork (purple square) | * in the center of the brickwork (purple square) | ||
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| * in between the insulation layer and the brickwork (light red cross) | * in between the insulation layer and the brickwork (light red cross) | ||
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| * inside the insulation layer (12 cm below the outer surface, yellow diamond) | * inside the insulation layer (12 cm below the outer surface, yellow diamond) | ||
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| * just below the outer surface of the exterior plaster (blue square) | * just below the outer surface of the exterior plaster (blue square) | ||
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| * outdoor air (green curve). | * outdoor air (green curve). | ||
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| * Throughout the entire period of time outdoor air temperatures are well below the room temperature: | * Throughout the entire period of time outdoor air temperatures are well below the room temperature: | ||
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| * Room temperatures mostly correspond with those measured at the internal wall surfaces. These temperatures are between 22.9 and 25.3 °C (nice and warm!); the mean temperature is 24 °C. Note that the heating system was not turned on in this room throughout the entire period of time. The heat is provided exclusively by the sun entering through the windows facing south. | * Room temperatures mostly correspond with those measured at the internal wall surfaces. These temperatures are between 22.9 and 25.3 °C (nice and warm!); the mean temperature is 24 °C. Note that the heating system was not turned on in this room throughout the entire period of time. The heat is provided exclusively by the sun entering through the windows facing south. | ||
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| ===== Very low heat flows ===== | ===== Very low heat flows ===== | ||
| - | Since all three temperature curves are very close together we can see that little heat escapes from the exterior surface of the brick wall: If that were the case the exterior of the brick would be a lot colder than the center of the brick and even more so than the interior surface. Yet, the temperature measured at the exterior of the brcik is hardly below that of the interior plaster: at an average of 23.4 degrees Celsius on the outside and 24.1 degrees on the inside. | + | Since all three temperature curves are very close together we can see that little heat escapes from the exterior surface of the brick wall: If that were the case the exterior of the brick would be a lot colder than the center of the brick and even more so than the interior surface. Yet, the temperature measured at the exterior of the brick is hardly below that of the interior plaster: at an average of 23.4 degrees Celsius on the outside and 24.1 degrees on the inside. |
| These findings can even be used for a rough estimation of quantitative results: The mean temperature decrease in the brick part, including the layer of interior plaster, amounts to 0.63 degrees, and to 19.4 degrees between the exterior surface of the brick wall and the external plaster on the insulation layer. This means that the insulating effect provided by the insulation layer is increased by a factor of 19.4/0.63 ≈ 31 compared with that of the brick wall. This result is even better than the theoretical value of approx. 28.5 resulting from a simple U-value calculation: | These findings can even be used for a rough estimation of quantitative results: The mean temperature decrease in the brick part, including the layer of interior plaster, amounts to 0.63 degrees, and to 19.4 degrees between the exterior surface of the brick wall and the external plaster on the insulation layer. This means that the insulating effect provided by the insulation layer is increased by a factor of 19.4/0.63 ≈ 31 compared with that of the brick wall. This result is even better than the theoretical value of approx. 28.5 resulting from a simple U-value calculation: | ||
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| This magnified view illustrates both the fact and the reason for temperature changes within the brick wall. The change in temperature does not occur due to heat flowing from the wall to the exterior – after all, this is where the insulation layer does an excellent job of shielding the wall from the environment. It mostly occurs at the internal wall surfaces (red lines -): This is where the temperature changes are greatest and where they occur first. This can be explained quite simply (data from 12 October): | This magnified view illustrates both the fact and the reason for temperature changes within the brick wall. The change in temperature does not occur due to heat flowing from the wall to the exterior – after all, this is where the insulation layer does an excellent job of shielding the wall from the environment. It mostly occurs at the internal wall surfaces (red lines -): This is where the temperature changes are greatest and where they occur first. This can be explained quite simply (data from 12 October): | ||
| - | * First, between 12am and just before 6am, the temperature decreases in all brick layers of the wall: The wall gives off heat (to the interior and exterior). Inside, the heat is radiated towards the window surfaces which have cooled down during the night. | + | * First, between 12am and just before 6am, the temperature decreases in all brick layers of the wall: The wall gives off heat (to the interior and exterior). Inside, the heat is radiated towards the window surfaces which have cooled down during the night. |
| - | * From 6am on, solar radiation through the windows increases (12 October was a clear day). All internal surfaces, including the interior wall surfaces, are heated by the sun. The wall on the west side of the building is even directly hit by the sun until 9am, hence the rapid increase (at 7:30 the window frame causes a shadow; the same happens on 13 October). Later on, radiation occurs only indirectly by heat radiating from the floor which is now directly hit by the sun. Yet, even then the temperature at the internal surface continues to increase and peaks at 25.3 degrees Celsius at 1pm. | + | |
| + | * From 6am on, solar radiation through the windows increases (12 October was a clear day). All internal surfaces, including the interior wall surfaces, are heated by the sun. The wall on the west side of the building is even directly hit by the sun until 9am, hence the rapid increase (at 7:30 the window frame causes a shadow; the same happens on 13 October). Later on, radiation occurs only indirectly by heat radiating from the floor which is now directly hit by the sun. Yet, even then the temperature at the internal surface continues to increase and peaks at 25.3 degrees Celsius at 1pm. | ||
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| * This rapid increase in temperature is passed on to the next layer fitted with a sensor, 88 mm below the surface. However, this increase occurs with a certain delay and at a lesser rate: The temperature “only” increases by 0.75 degrees and only peaks at 6pm. | * This rapid increase in temperature is passed on to the next layer fitted with a sensor, 88 mm below the surface. However, this increase occurs with a certain delay and at a lesser rate: The temperature “only” increases by 0.75 degrees and only peaks at 6pm. | ||
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| * The most outward layer of the brick wall only reaches its maximum temperature at 7pm and doesn’t exceed 23.8 degrees Celsius. At this level, there is also some influence from the exterior which is largely reduced by the thermal insulation but is noticeable nevertheless. This is mostly due to the fact that the temperatures on the outside of the brick wall are always below those at the internal surfaces.\\ | * The most outward layer of the brick wall only reaches its maximum temperature at 7pm and doesn’t exceed 23.8 degrees Celsius. At this level, there is also some influence from the exterior which is largely reduced by the thermal insulation but is noticeable nevertheless. This is mostly due to the fact that the temperatures on the outside of the brick wall are always below those at the internal surfaces.\\ | ||
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planning/thermal_protection/thermal_protection_works/insulation_works_-_evidence_no.1_measurements_at_a_highly_insulated_wall.txt · Last modified: 2022/01/25 10:53 by ggrosskopf