How to insulate basement ceiling between beams

[jazzman]

Hi everyone,

During the winter, the wide-plank flooring on the ground floor of my house is absolutely freezing.

This is due to a variety of factors:

1. external air infiltration through the above-grade portion of the foundation
2. gaps between wide-plank flooring
3. no insulation between the basement beams

I've attached a photo - you can actually see daylight between the floor boards, when looking up from the basement.

Obviously there are various things in and around the beams, such as plumbing and electrical. Above-grade foundation issues will not be solved any time soon.

Any thoughts about how to mitigate this situation?

Thanks in advance

[jazzman]

Wanted to add that this situatino is causing us to burn a lot more oil/wood than would otherwise be the case.