How to spend the winter in a house with no heating and only air conditioning in Beijing?

When I sleep at night, I cover myself with two quilts. Sometimes it's very cold. Cover your feet with a down jacket. As long as you protect your feet, you won't feel cold. Don't sit in the dormitory for a long time. I used to wear a down jacket and a hat when I was playing computer in the dormitory, and I had to wrap it up. Or go out for a walk and exercise. Anyway, the temperature inside and outside the house will not be cold.