Sage
Staff Emeritus
- 12,533
- United States
- GTP_Sage
Huh? Black absorbs heat quite well. I don’t know whether or not it would make a relatively small difference on the overall heat within the house (depends on how many windows you have, and you also have to do some icky calculations about thermodynamic equilibrium), but it cannot possibly block all of the heat from entering the room (even white curtains won’t do that).[…] probably by a pretty small percentage, since they still block the heat from entering the room completely.