Insulation, Radiant and Vapor Barriers - cold

My house was originally constructed out of concrete blocks, even the inside walls are block. I have done major remodeling twice, but until recently I didn't realize how much of the house was not originally insulated. We added a second story which exposed the top layer of blocks completely around the frame of the house, while it is covered with the new addition we won't be finishing that area for a long while. My main question is how do I air seal the down stairs living area until I can complete the second level and what can I use in the blocks or on the blocks to seal the air off and hold the heat in the downstairs area? Thanks in advance, Msfixit