At present, the heat loss of energy-efficient buildings through transparent partitions – windows, make more than 40% of the total heat loss. Since most of these partitions (70-80%) are covered by the insulating glass unit (IGU), it accounts for the largest part of the heat loss. These losses increase with the lifetime of the building as the heat transfer coefficient of the IGU increases with decreasing argon gas concentration in a cavity of glass unit, due to the aging of the seals. As a result, the heat loss through 1 sq. m of IGU is about 21 kWh per year. The number of residential houses built in Lithuania until 2010 is about 35K with a window area of about 10M sq. m, which leads to heat losses up to 200 GWh per year. A similar situation exists in many other countries. At present, there are no non-invasive methods of measuring gas concentration in glass unit without disassembling of the IGU. As a result, windows are usually operated until their mechanical-use limits. However, measuring argon concentration could make targeted decisions on replacing of IGU, thus significantly reducing the heat loss of the building and the CO2 pollution. The aim of the project is to develop and investigate method for estimation of thermal conduction of IGU based on ultrasonic adaptive and non-invasive measurement of argon gas concentration.
Project funding:
KTU Research and Innovation Fund
Project results:
Non-invasive, adaptive ultrasonic method and special device for assessment of Ar gas content in cavity of the IGU based on sound velocity measurements was proposed and verified. The approach ensures high measurement accuracy by combining ultrasonic and electromagnetic field phase shift measurement methods that allow to estimate the overall thickness of IGU and Ar content in gas mixture at any position over the surface of IGU. The technique was verified on the samples with known Ar gas concentrations and compared with commercial systems and gas chromatography in Ar content range of 27-93%. Experimental verifications demonstrated, that estimated measurement accuracy of proposed technique is ±3.15 % in comparison with gas chromatography and exceeds the accuracy of market available plasma emission Ar analysers. To date, such measurement accuracy of Ar concentration in the cavity of IGU has not been reported with ultrasonic measurements. The proposed technique offers a cost-effective approach, that is suitable for laminated and coated double glazing units that are frequently used in houses build over the last decade. The widespread use of such a device by building maintenance and supervision would contribute to the energy savings and the reduction of CO2 emissions during the life cycle of a building.
Period of project implementation: 2020-04-14 - 2020-12-31
