Ulaanbaatar is one of the top five cities with worst air quality because of the use of raw coal in the Ger District. The objective of this paper is to analyze the environmental significance of solar heating system with triple heat sources including the solar collector, coal stove, and electric heater for a simple detached house in the harsh cold and dry climate. A long-term measurement was conducted in a Ger district of Ulaanbaatar city, Mongolia. Based on the measurement of the solar thermal system for 8 months, from October 2015 to May 2016, it was found that the average collector efficiency was 49.8% and system efficiency was 37%. The study also reported monthly performance of the system. The dust deposition on the glass tubes of the evacuated tube solar collector considerably decreased the performance, especially during winter season. (C) 2017 Elsevier Ltd. All rights reserved.