Grey-box Modeling to Evaluate Heat Loss in Mongolian Ger
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Hakkarainen, Max
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Abstract
Ulaanbaatar, Mongolia, is currently facing an unprecedented air pollution crisis. The main cause of this is residents of ger (or “yurt” in Russian) burning solid fuels for domestic heating during the winter. To combat this problem, the Ger of the 21st Century project was launched with the goal of decreasing the amount of energy required for domestic heating in ger. As part of that project, several interventions were designed to target the specific pathways of heat loss in ger. In the fall of 2018, six unoccupied test ger were constructed on a ranch near Ulaanbaatar to test these interventions. Each of these ger was fitted with a package of thermal monitoring equipment and heated for the 2018–2019 winter heating season. A lumped-sum thermal model was developed to describe the anticipated pathways of heat loss within ger, namely conduction through the building envelope, air infiltration, conduction through the edge of the floor, and conduction to the ground. The log-normalized extended Kalman filter (LNEKF) was then used to simultaneously estimate the thermal state of the ger and the parameters of the thermal model. The converged parameters were used to estimate the heat loss to each of the previously mentioned pathways. Based on this analysis, it was concluded that conduction through the building envelope accounted for 53.9 percent of all heat loss in ger and adding an additional layer of horsehair felt insulation to the ger envelope was shown to decrease the thermal transmittance of the ger envelope by 43 percent. Additionally, conduction at the floor edge accounted for 26.6 percent of all heat loss in the ger. None of the tested interventions targeted that pathway of heat loss. While conduction from the floor to the ground accounted for 16.7 percent of the heat loss in the ger, the four types of floor interventions tested in this study did not appear to have a meaningful impact on the thermal transmittance between the floor and the ground. Finally, air infiltration accounted for a negligible amount of heat loss in the ger (0.183 percent), and the interventions to decrease air infiltration appear to have been ineffective. However, there still appears to be significant amounts of unaccounted for heat loss in the model for some of the ger. Future development of these models could yield higher fidelity results.
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2025-03
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