i was on the 20th floor overlooking times square. The window doesnt open and only gets about 1.5 - 2 hours of direct sunlight depending on the time of the year but the area itself is sort of cold due to the chill from the glass and also the air conditioning during the summer.
Point worth making, i only use a drop or two at a time each week. The container used was only a quart from a chinese take out so use this sparingly. You can likely use more in a larger container but start small and go from there. I never changed the water and only topped up. I think i may have done a 100% water change when i had taken a few days off and decided to restart the container with fresh water and a drop of the fertilizer. i use the same fertlizer on all my other desk plants so i know this stuff works. It has completely restored my porthos which were otherwise yellowing and going bald. new leaves are huge and deeply green.
to answer your question. i suppose room temp. nothing too hot or cold.