To be ecact, Kaltmiete means rent for a house or apartment exclusive of heating and other additional costs. It does not mean, as the term might imply, only excluding the heating. In the leo dictionary and google you find some explanations. In English you say base rent.

"Kaltmiete" means only the rent without the costs of heating the apartment.

In Germany, 'Kaltmiete' (ltrl. cold rent) refers to the basic rent cost for your flat/house. On the other hand, 'Warmmiete' (ltrl. warm rent) includes not only heating and warm water expenses but also cleaning, garbage disposal, and elevator electricity, and so on. So, when renting a flat in Germany, it's essential to pay attention to the 'Warmmiete' because that's the total amount you'll pay your landlord. Keep in mind that you need to pay internet and electricity in your flat separately.