BACKGROUND
SETTING
Mongolia is a cold country. Its climate is high and dry, and its short summers and long winters keep the country very cold throughout most of the year (IPSInternational.org). Although Mongolia can get hot during the summertime, this does not last for long and the harsh cold takes over quickly to the point where it causes a climate disaster unique to Mongolia known as a dzud. This occurs when the extreme cold, mixed with drought from the summer, causes the death of livestock across the country, taking the lives of millions of livestock (BBC.com). With such harsh temperatures, staying warm is crucial to the population who live in traditional yurts (also known as gers) across Mongolia. According to National Geographic, “more than half of Mongolians live in gers, including about 61% in the capital of Ulaanbaatar and 90% of the rural population” (NationalGeographic.org). Ulaanbaatar has incredibly polluted air, and since the majority of that pollution is caused by the stoves used in yurts to burn raw coal, it is prevalent that this commonly used method of heating yurts is one that needs to change. The effects of climate change have even worsened the effects of dzuds, forcing many nomadic Mongolians to leave their yurts behind and move to the capital (NationalGeographic.org).
Mongolia is a cold country. Its climate is high and dry, and its short summers and long winters keep the country very cold throughout most of the year (IPSInternational.org). Although Mongolia can get hot during the summertime, this does not last for long and the harsh cold takes over quickly to the point where it causes a climate disaster unique to Mongolia known as a dzud. This occurs when the extreme cold, mixed with drought from the summer, causes the death of livestock across the country, taking the lives of millions of livestock (BBC.com). With such harsh temperatures, staying warm is crucial to the population who live in traditional yurts (also known as gers) across Mongolia. According to National Geographic, “more than half of Mongolians live in gers, including about 61% in the capital of Ulaanbaatar and 90% of the rural population” (NationalGeographic.org). Ulaanbaatar has incredibly polluted air, and since the majority of that pollution is caused by the stoves used in yurts to burn raw coal, it is prevalent that this commonly used method of heating yurts is one that needs to change. The effects of climate change have even worsened the effects of dzuds, forcing many nomadic Mongolians to leave their yurts behind and move to the capital (NationalGeographic.org).
STRUCTURE
The envelope of a yurt is mostly felt, with most yurts sitting on the ground due to their portable nature and only some being set up as permanent residences. While this is able to provide adequate insulation, the yurt still has a way to go before it can be compared to a typical house. A study by by Guoqiang Xu Orcid,Hong Jin, and Jian Kang confirmed this after testing the thermal storage abilities of traditional yurt materials, claiming that “the coefficient of thermal storage of wood and felt is less than a solid wall, which is negative for the thermal environment of Mongolian yurts” (Xu, et al). Sadly, this issue stems from the fact that thermal mass is most effective with heavier materials, and yurts are designed for lightweight transportation. Thermal mass is the ability of any given material to absorb and hold onto heat, letting it back out slowly overtime (YourHome.gov). The higher an object’s thermal mass is, the longer of a delay it will have before releasing the heat, which proves useful for passive heating situations where that heat is needed late at night, after the sun has been gone for hours. In an environment like Mongolia’s, where environmental disasters are making it hard to live in yurts without using pollution-causing methods for warmth, it’s important to search for alternative materials that have high heat storage but a light weight, similar to the layered felt. Otherwise, these traditional dwellings may be lost to history as their owners pack up and leave for the city.
The envelope of a yurt is mostly felt, with most yurts sitting on the ground due to their portable nature and only some being set up as permanent residences. While this is able to provide adequate insulation, the yurt still has a way to go before it can be compared to a typical house. A study by by Guoqiang Xu Orcid,Hong Jin, and Jian Kang confirmed this after testing the thermal storage abilities of traditional yurt materials, claiming that “the coefficient of thermal storage of wood and felt is less than a solid wall, which is negative for the thermal environment of Mongolian yurts” (Xu, et al). Sadly, this issue stems from the fact that thermal mass is most effective with heavier materials, and yurts are designed for lightweight transportation. Thermal mass is the ability of any given material to absorb and hold onto heat, letting it back out slowly overtime (YourHome.gov). The higher an object’s thermal mass is, the longer of a delay it will have before releasing the heat, which proves useful for passive heating situations where that heat is needed late at night, after the sun has been gone for hours. In an environment like Mongolia’s, where environmental disasters are making it hard to live in yurts without using pollution-causing methods for warmth, it’s important to search for alternative materials that have high heat storage but a light weight, similar to the layered felt. Otherwise, these traditional dwellings may be lost to history as their owners pack up and leave for the city.
There have been attempts at modernizing the yurt over the years to make them easier to heat for those who live closer to the capital, such as foils used in place of felt insulation, and the roof of the yurt being sealed to keep more heat inside (MDPI.com). Although these changes make perfect sense on paper, some side effects of these updates are harder to spot than what meets the eye. A study was done by Tomasz Kisilewicz, Katarzyna Nowak-Dzieszko, Katarzyna Nowak, Sabina Kuc, Ksenia Ostrowska, and Piotr Śliwiński to test the quality of air inside the modern yurt, with the previously mentioned modifications. Surprisingly, they reported that the “conducted measurements and simulations of CO2 concentration in the modified yurt proved that the efficiency of ventilation system is not sufficient and that the air quality is very poor (even for a single user). In the case of a larger number of users, the concentration of CO2 has already reached a level that was dangerous to health” (Kisilewicz, et al). If attempted retrofits to the yurt design have only served to suffocate the interior, this creates a need for not only a material that will trap heat better, but one that will trap CO2 less. According to information from GroovyYurts.com, materials such as sailcloth and polyester fabric have been utilized in some parts of the world for modern yurts, however this information doesn’t come with an indication of the potential benefits or detriments to using such material (GroovyYurts.com).
Literature Review
A Fractional Model for Heat Transfer in Mongolian Yurt
by Hong-Yan Liu, Zhi-Min Li, and Frank K. Ko
This study examines the way heat is transferred through the material of a yurt in order to warm the interior. Although the study references mathematical equations and simulations, rather than a physical experiment, the provided information and conclusions drawn are incredibly valuable information for understanding the properties of a yurt. The study claims that the felt used in a yurt is a large factor in the ways it carries heat, or its thermal functionality. It provides context that the felt of choice is made from layers of fabric and sheep’s wool, traditionally from Mongolian herders. The felt is flexible for storage and wrapping around the structure. These layers of felt are wrapped around the walls and poles of the structure, and typically are between 20 to 30 millimeters in thickness. An interesting fact that was mentioned here was how some areas of Asia actually replaced the layered felt with woven mats made of reeds. That could provide another possible material to compare for my experiment. In the paper, diagrams were provided to show that the inner wall has a much smaller amount of temperature change when compared to the outer layer, suggesting that the felt layering method is indeed successful. However, what was interesting to note was the provided reason. The structure of the felt was compared to that of a silkworm’s cocoon, due to the layers changing in material thickness. The outer layer of felt is explained to have fibers with a notably larger diameter than the inner layer, with the larger fiber diameter resulting in a more solid, less breathable wall of material to keep out cold temperatures. This explains why the temperature changed so much more at the first layer, as cold temperatures were blocked off before the warmer air was able to circulate through both layers easily. The paper used large equations and formulas to explain the science behind this hierarchical structure, however the resulting information lay in proving that the cocoon setup was to thank for the felt’s effectiveness.
A Comparative Case Study of the Impact of Square and Yurt-Shape Buildings on Energy Efficiency
by Valeriya Tyo and Serikbolat Yessengabulov
In this study, the energy usage of a yurt’s design is examined and compared to a rectilinear building footprint. Like the previous study, it was conducted with mathematical equations and digital simulations rather than with a physical experiment. Two hypothetical buildings were designed to be extremely compact and space-efficient, with one being circular and the other being square. Aside from the differing shapes in floor plans, the other factors such as location, rooms, single stories, and climate remained identical across both simulations to establish a control variable. The buildings were designed to go in Astana, a city in Kazakhstan known to be the second coldest capital city in the world. Two experiments were run with slight changes to the simulated materials. The first time around, the materials met Kazakhstan’s minimum building code requirements for thermal performance, and the second time they were upgraded to meet the passive house standard. Among the formulas used were ones that related energy consumption to a building’s compactness, as well as its shape and even window types, as well as a formula to optimize said compact layout. Through the simulations, it was found that the yurt was more energy efficient than the square building, using 23 to 27% less energy for heating and cooling the structure. Corner conditions inside the rectilinear building were to blame for some of this energy loss, with the envelope and heat infiltration claiming more energy than in the yurt. Also worth noting was that the shape of the building had no impact on the solar radiation and the internal heat gain of either building, rather only the consumption of that energy was impacted.
Experimental Study on the Indoor Thermo-Hygrometric Conditions of the Mongolian Yurt
by Guoqiang Xu, Hong Jin, and Jian Kang
Unlike the previous experiments I looked at, this one did have a physical model that was studied. Better yet, it was a full-size yurt! For this study, a group in China constructed a yurt as accurately as they could to traditional Mongolian standards, replicating the lattice wall segments (Khanas), uni (poles), bagana (supporting poles) and felt/canvas covers. They used wool felt pieces, and the canvas layer was applied to prevent deterioration from water and moths. The experiment here was to find out how well yurts stored heat, and after constructing the home, the team outfitted it with equipment for recording data. Thermal imaging cameras were used to see the surface temperature of the inside wall, and temperature and humidity recorders were used for the conditions inside the structure at different locations. An oil radiator was utilized for heating the yurt, placed in the center. What the team discovered was that the center of the yurt ended up being the coldest, compared to the perimeter of its interior. Most of the heat that escaped the structure did so through the lower parts in the curtain/wall, as well as the structure’s joints, where the envelope was interrupted and air could escape easily. They blamed this on the roof and felt’s poor thermal stability, which is interesting to note since the first study I examined suggested the felt was great at holding heat and keeping the interior warm. Regardless of the outside temperatures, however, the Khaalga (front door and its frame) was a constant source of heat loss. There was no recorded point at which the door had more heat gain than loss. They also made note that the ground itself was helping to warm the yurt, citing the ground’s heat storing ability as an important factor.
by Hong-Yan Liu, Zhi-Min Li, and Frank K. Ko
This study examines the way heat is transferred through the material of a yurt in order to warm the interior. Although the study references mathematical equations and simulations, rather than a physical experiment, the provided information and conclusions drawn are incredibly valuable information for understanding the properties of a yurt. The study claims that the felt used in a yurt is a large factor in the ways it carries heat, or its thermal functionality. It provides context that the felt of choice is made from layers of fabric and sheep’s wool, traditionally from Mongolian herders. The felt is flexible for storage and wrapping around the structure. These layers of felt are wrapped around the walls and poles of the structure, and typically are between 20 to 30 millimeters in thickness. An interesting fact that was mentioned here was how some areas of Asia actually replaced the layered felt with woven mats made of reeds. That could provide another possible material to compare for my experiment. In the paper, diagrams were provided to show that the inner wall has a much smaller amount of temperature change when compared to the outer layer, suggesting that the felt layering method is indeed successful. However, what was interesting to note was the provided reason. The structure of the felt was compared to that of a silkworm’s cocoon, due to the layers changing in material thickness. The outer layer of felt is explained to have fibers with a notably larger diameter than the inner layer, with the larger fiber diameter resulting in a more solid, less breathable wall of material to keep out cold temperatures. This explains why the temperature changed so much more at the first layer, as cold temperatures were blocked off before the warmer air was able to circulate through both layers easily. The paper used large equations and formulas to explain the science behind this hierarchical structure, however the resulting information lay in proving that the cocoon setup was to thank for the felt’s effectiveness.
A Comparative Case Study of the Impact of Square and Yurt-Shape Buildings on Energy Efficiency
by Valeriya Tyo and Serikbolat Yessengabulov
In this study, the energy usage of a yurt’s design is examined and compared to a rectilinear building footprint. Like the previous study, it was conducted with mathematical equations and digital simulations rather than with a physical experiment. Two hypothetical buildings were designed to be extremely compact and space-efficient, with one being circular and the other being square. Aside from the differing shapes in floor plans, the other factors such as location, rooms, single stories, and climate remained identical across both simulations to establish a control variable. The buildings were designed to go in Astana, a city in Kazakhstan known to be the second coldest capital city in the world. Two experiments were run with slight changes to the simulated materials. The first time around, the materials met Kazakhstan’s minimum building code requirements for thermal performance, and the second time they were upgraded to meet the passive house standard. Among the formulas used were ones that related energy consumption to a building’s compactness, as well as its shape and even window types, as well as a formula to optimize said compact layout. Through the simulations, it was found that the yurt was more energy efficient than the square building, using 23 to 27% less energy for heating and cooling the structure. Corner conditions inside the rectilinear building were to blame for some of this energy loss, with the envelope and heat infiltration claiming more energy than in the yurt. Also worth noting was that the shape of the building had no impact on the solar radiation and the internal heat gain of either building, rather only the consumption of that energy was impacted.
Experimental Study on the Indoor Thermo-Hygrometric Conditions of the Mongolian Yurt
by Guoqiang Xu, Hong Jin, and Jian Kang
Unlike the previous experiments I looked at, this one did have a physical model that was studied. Better yet, it was a full-size yurt! For this study, a group in China constructed a yurt as accurately as they could to traditional Mongolian standards, replicating the lattice wall segments (Khanas), uni (poles), bagana (supporting poles) and felt/canvas covers. They used wool felt pieces, and the canvas layer was applied to prevent deterioration from water and moths. The experiment here was to find out how well yurts stored heat, and after constructing the home, the team outfitted it with equipment for recording data. Thermal imaging cameras were used to see the surface temperature of the inside wall, and temperature and humidity recorders were used for the conditions inside the structure at different locations. An oil radiator was utilized for heating the yurt, placed in the center. What the team discovered was that the center of the yurt ended up being the coldest, compared to the perimeter of its interior. Most of the heat that escaped the structure did so through the lower parts in the curtain/wall, as well as the structure’s joints, where the envelope was interrupted and air could escape easily. They blamed this on the roof and felt’s poor thermal stability, which is interesting to note since the first study I examined suggested the felt was great at holding heat and keeping the interior warm. Regardless of the outside temperatures, however, the Khaalga (front door and its frame) was a constant source of heat loss. There was no recorded point at which the door had more heat gain than loss. They also made note that the ground itself was helping to warm the yurt, citing the ground’s heat storing ability as an important factor.
Sources
Anthony. “WHAT IS MONGOLIA’S CLIMATE LIKE?” Ipsinternational.org, 27 Nov. 2021, https://www.ipsinternational.org/what-is-mongolias-climate-like/.
Kisilewicz, Tomasz, et al. “How to Adapt Mongolian Yurt to the Modern Requirements and European Climate—Airtightness versus co2 Concentration?” Energies, vol. 14, no. 24, 2021, p. 8544., https://doi.org/10.3390/en14248544.
Liu, Hong-Yan, et al. “A Fractional Model for Heat Transfer in Mongolian Yurt.” Thermal Science, vol. 21, no. 4, 2017, pp. 1861–1866., http://www.doiserbia.nb.rs/Article.aspx?id=0354-98361700081L#.YgvpIt_MKUl. Accessed 10 Feb. 2022.
National Geographic Society. “Yurt.” National Geographic Society, 9 Oct. 2012, https://www.nationalgeographic.org/encyclopedia/yurt/.
Reardon, Chris, et al. “Thermal Mass.” YourHome, Australian Government Department of Industry, Science, Energy, and Resources, 2013, https://www.yourhome.gov.au/passive-design/thermal-mass.
The Groovy Yurts Team. “How Yurts Have Evolved Throughout History.” Groovy Yurts, The Groovy Yurts Team Http://Groovyyurts.com/Wp-Content/Uploads/2018/02/Groovy-Yurts.png, 15 June 2021, https://groovyyurts.com/the-evolution-of-yurts/.
“The Slow and Deadly Dzud in Mongolia.” BBC News, BBC, 14 May 2016, https://www.bbc.com/news/world-asia-35983912.
Xu, Guoqiang, et al. “Experimental Study on the Indoor Thermo-Hygrometric Conditionsof the Mongolian Yurt.” Sustainability, vol. 11, no. 3, 2019, p. 687., https://doi.org/10.3390/su11030687.
Tyo, Valeriya, and Serikbolat Yessengabulov. “A Comparative Case Study of the Impact of Square and Yurt-Shape Buildings on Energy Efficiency.” International Journal of Environmental and Ecological Engineering, vol. 9, no. 10, 2015, https://publications.waset.org/10002403/a-comparative-case-study-of-the-impact-of-square-and-yurt-shape-buildings-on-energy-efficiency. Accessed 10 Feb. 2022.
Xu, Guoqiang, et al. “Experimental Study on the Indoor Thermo-Hygrometric Conditionsof the Mongolian Yurt.” Sustainability, vol. 11, no. 3, 28 Jan. 2019, https://www.mdpi.com/2071-1050/11/3/687/htm. Accessed 10 Feb. 2022.
Kisilewicz, Tomasz, et al. “How to Adapt Mongolian Yurt to the Modern Requirements and European Climate—Airtightness versus co2 Concentration?” Energies, vol. 14, no. 24, 2021, p. 8544., https://doi.org/10.3390/en14248544.
Liu, Hong-Yan, et al. “A Fractional Model for Heat Transfer in Mongolian Yurt.” Thermal Science, vol. 21, no. 4, 2017, pp. 1861–1866., http://www.doiserbia.nb.rs/Article.aspx?id=0354-98361700081L#.YgvpIt_MKUl. Accessed 10 Feb. 2022.
National Geographic Society. “Yurt.” National Geographic Society, 9 Oct. 2012, https://www.nationalgeographic.org/encyclopedia/yurt/.
Reardon, Chris, et al. “Thermal Mass.” YourHome, Australian Government Department of Industry, Science, Energy, and Resources, 2013, https://www.yourhome.gov.au/passive-design/thermal-mass.
The Groovy Yurts Team. “How Yurts Have Evolved Throughout History.” Groovy Yurts, The Groovy Yurts Team Http://Groovyyurts.com/Wp-Content/Uploads/2018/02/Groovy-Yurts.png, 15 June 2021, https://groovyyurts.com/the-evolution-of-yurts/.
“The Slow and Deadly Dzud in Mongolia.” BBC News, BBC, 14 May 2016, https://www.bbc.com/news/world-asia-35983912.
Xu, Guoqiang, et al. “Experimental Study on the Indoor Thermo-Hygrometric Conditionsof the Mongolian Yurt.” Sustainability, vol. 11, no. 3, 2019, p. 687., https://doi.org/10.3390/su11030687.
Tyo, Valeriya, and Serikbolat Yessengabulov. “A Comparative Case Study of the Impact of Square and Yurt-Shape Buildings on Energy Efficiency.” International Journal of Environmental and Ecological Engineering, vol. 9, no. 10, 2015, https://publications.waset.org/10002403/a-comparative-case-study-of-the-impact-of-square-and-yurt-shape-buildings-on-energy-efficiency. Accessed 10 Feb. 2022.
Xu, Guoqiang, et al. “Experimental Study on the Indoor Thermo-Hygrometric Conditionsof the Mongolian Yurt.” Sustainability, vol. 11, no. 3, 28 Jan. 2019, https://www.mdpi.com/2071-1050/11/3/687/htm. Accessed 10 Feb. 2022.