Carpeting is considered unhealthy by todayÂs standards for indoor air quality. Wall-to-wall carpeting is a poor choice, particularly for those with repertory problems, due to its out-gassing and collecting of allergens and pathogens.

I would suggest the wood option for carpet replacement for health reasons as well as resale value as carpets add nothing. There should be no difference between the two regarding energy efficiency, however carpets do feel more comfy to bare feet.

SR

Here is a link that might be useful: CMHC-About Your House

It seems that your change from vinyl to wood in the kitchen resulted in a warmer feel in the kitchen floor. That suggests to me that perhaps the new floor is what they sometimes call a floating floor that feels a bit bouncy underfoot, or they put in some kind of subfloor over the slab before putting in the engineered wood. In either case, it could be what's under the engineered wood that's providing additional insulation against the cold slab.

Now, the comparison in the kitchen floor is a before-after comparison. But you're asking a different question: Will a new carpet be as effective as the wood floor installation in providing insulation. That's not an apples to apples comparison. My guess is that, if you put in some kind of subfloor over the slab, sort of like the one you had put in on the kitchen floor, and then put carpeting over that, you would get the kind of warmer floor underfoot that you want.

The issue about indoor air quality and carpeting is valid. But if you prefer carpeting and have had not problems with it ( no asthma or other breathing problems ) then get carpeting, but keep it clean. Vacuum it often with a vacuum cleaner equipped with a HEPA filter, and shampoo it often, and you should be all right.