In the beginning of chapter 1 what is the effect of the juxtaposition at the beginning of the section?

Can you elaborate on the juxtaposition? THe beginning has Winston climbing to his flat. Everything is grey, cold, and void of hope.

The fact that they smell bad and that they are grey and cold shows the juxtaposition in this part of 1984. It shows the  difference between Winston's reality and the Party's reality. 

We have no idea about the inner party's reality at this point. Everyone in the outer party lives like Winston does.