Heat Transmission Coefficient Measurements in Buildings Utilizing a Heat Loss Measuring Device
1.1. Introduction to Energy Performance Upgrading
1.2. Introduction to U-Value Meter
- If the Meter is taken outdoors from an indoor environment the Meter has to be acclimatized to the outdoor temperature for a minimum period of half an hour. The display will show “Waiting”, until the Meter is in thermal equilibrium with its surroundings. While waiting, the Meter can display the difference between the reference sensor and the heat absorption sensor temperatures.
- After acclimatization the user is prompted to key in the indoor temperature. After that, the user is asked to hold the reference sensor up in the air, and the outdoor temperature is measured for half a minute. During data acquisition these temperature values are given as input to the main processor. In fact, the outdoor temperature is continuously measured by the reference sensor and can be displayed at any time while the apparatus is turned on.
- When thermal equilibrium is reached, the display says “Ready” and the user can initiate the measurement. If the user, by accident, turns the Meter towards the sun or puts his hand on the heat absorption sensor, causing a thermal rise in the heat absorption sensor, the processor will show the message “Waiting…” again, indication lack of thermal balance. Thermal equilibrium is reached when the temperature difference between the heat absorption sensor and the reference sensor is below 0.3 ºC.
- When the user holds the Meter against the test piece, the main processor starts to count the time and the measuring process is going on for the entire measuring period (20 seconds). The display shows “Measuring…” and displays the temperature rise of the heat absorption sensor, while the measurement goes on.
- Immediately after the measurement is finished, the display says “Calculate…” for a few seconds and the U-value is presented afterwards.
- The user can store the results in an internal memory by pressing the button “Memory”.
- The Meter will display “Waiting…” until the heat absorption sensor is back in thermal equilibrium with the outdoor temperature, and after that a new measurement can begin.
1.3. Main Processor
2. EUDP Project
|Id||Object||Tin (°C)||Remark||U-value (W/m2K)|
|1||Parapet||21.9||2 thin wooden boards with air/insulation between. 3 cm thick in total||1.44|
|2||Outer wall||23.0||Measured at 70 cm height||0.80|
|3||Outer wall||22.4||Measured at 1.5 m height||0.84|
|4||Outer wall||23.3||Measured at 1.5 m height||0.88|
|5||Pane||23.3||Measured at the middle of the pane||1.24|
|6||Outer wall||23.3||Measured at 1.5 m height||0.87|
|7||Outer wall||23.5||Measured at 1.5 m height||0.81|
|8||Outer wall||23.5||Measured at 1.5 m height||0.85|
|9||Exterior door||22.0||Door made of 4 cm thick wood (possibly teak)||1.72|
|10||Pane||22.3||Measured at the middle of the pane||1.30|
|11||Outer wall||22.3||Measured at 1.5 m height||0.89|
|12||Beam||22.3||Window lintel (lightweight concrete)||1.12|
|13||Edge of wall||22.3||No significant peripheral effects were measured||0.91|
|14||Exterior door||22.0||Door made of 4 cm thick wood (possibly teak)||1.78|
|15||Wall||22.4||Wall between the garage and living room||0.32|
|16||Outer wall||20.5||Outer wall of utility room/laundry room (facade)||0.26|
|17||Outer wall||20.5||Outer wall of utility room/laundry room (gable)||0.29|
|18||Outer wall||20.5||Outer wall of utility room/laundry room (gable)||0.29|
|19||Socket||21.9||Measured at the center of the base||1.03|
|20||Outer wall||22.7||Built-in cupboard stood up against this wall. Measured at 40 cm height||0.36|
|21||Pane||22.7||Measured at the middle of the pane||1.16|
|22||Outer wall||22.7||Measured at wall section below the window||0.32|
|23||Outer wall||22.7||Measured at 40 cm above socket level||0.20|
|24||Outer wall||22.7||Measured 80 cm above bottom of wall||0.23|
- Outer walls including sockets are insulated with 195 mm mineral wool which is plastered.
- One exterior door replaced by a modern entrance door with low U-value. The other exterior door is removed and the opening closed and insulated as the rest of the façade.
- House entrance was insulated with 100 mm insulation
- Gables and foot of roof were insulated with good connection to the ceiling insulation
- Digging up soil around the concrete foundation and in top, new foundation blocks made of lightweight concrete are established and insulated with phenolic foam (PF).
- The existing windows (with low-energy glazing) are moved out to align with the façade.
- Installation of mechanical ventilation (balanced) aggregate with heat recovery
- Air tightening of the ceiling and between ceiling and outer walls.
- Insulation of bedroom (previously insulated from inside to a certain level).
3. Limitations and Uncertainties
|Examples||Measuring Object||U1||U2||U3||Expected U||Age|
|Example I||Terrace door||1.35||1.33||1.31||1.20||6 years|
|Low E-glazed window||1.24||1.27||1.30||1.20||6 years|
|Outer wall||1.04||0.97||0.94||0.90||32 years|
|Example II||Double-glazed window||3.00||3.12||2.80||36 years|
|Outer wall||0.41||0.42||0.40||36 years|
|Example III||Double-glazed window||2.87 (average of 9 measurements)||2.80||25 years|
References and Notes
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Sørensen, L.S. Heat Transmission Coefficient Measurements in Buildings Utilizing a Heat Loss Measuring Device. Sustainability 2013, 5, 3601-3614. https://doi.org/10.3390/su5083601
Sørensen LS. Heat Transmission Coefficient Measurements in Buildings Utilizing a Heat Loss Measuring Device. Sustainability. 2013; 5(8):3601-3614. https://doi.org/10.3390/su5083601Chicago/Turabian Style
Sørensen, Lars Schiøtt. 2013. "Heat Transmission Coefficient Measurements in Buildings Utilizing a Heat Loss Measuring Device" Sustainability 5, no. 8: 3601-3614. https://doi.org/10.3390/su5083601