It does not advocate but it gives certain numbers so it proposes that one could go below 18C. If I keep my flat at 18C or below I get loads of condensation and mold. I don't need some special clothes to feel comfortable between 19C - 20C sweatpants and sweatshirt are cozy enough. That said - if someone needs 24C to feel comfortable it might be useful to get some thermal underwear and turn heat down to 20C.