No, I don’t think it is good for you ‘to be a little bit cold’ on the whole. It might burn calories, but older folks are more susceptible to cold related illness if they do not keep warm, particularly if they already have underlying health issues - high blood pressure, asthma, arthritis, high cholesterol, other heart conditions, copd, cancer, mobility issues, et, etc. Young children, too, are vulnerable if continually cold. If you are physically fit, relatively young and in good health, then being ‘a little bit cold’ now and then is probably ok, but we’re talking here about people not heating their homes sufficiently for lengthy periods of time ( usually due to affordability) and that is certainly not good, and means they are not just ‘a little bit cold’ but chilled for unhealthy periods of time which leads to all sorts of life threatening conditions, including hypothermia and potentially death.