bayarhuu has been cultivating vegetables from spring to autumn for more than 30 years. she produces about ten types and starts growing saplings in march. her annual sales exceed $50,000. the greenhouses bayarhuu uses sit empty in the winter. >> in other seasons she hires around 15 workers. but after harvest time there isn't any work available during the three months of winter. she put up two winter greenhouses with $130,000 government loan in january 2015. buhbat is responsible for temperature control, a vital element of winter cultivation. the boiler that heats the winter greenhouses is run on coal. buhbat checks the temperature and wind conditions to determine how much coal needs to be burned. >> the fire heats the water inside the boiler. the steam flows throughout the greenhouse through pipes, keeping the interior warm. she regularly checks whether the temperature inside the greenhouses is appropriate. it's a delicate process, as tomatoes can be ruined by temperatures below 15 degrees or above 35. bayahuu can now keep four workers on staff throughout the whole year.