Be creative and “This was in the age of chivalry!!!!” huh? It sounds like almost any answer could be judged correct.
The queen has two choices, in the way that chivalrous royal marriages go, either marry your brother or marry a prince foreigner. So she comes up with a riddle to present to her own countrymen, to stall and avoid either option, hopfully someone rich and clever will come along in the meantime.
“Your Majesty, be it upstairs or down, winter or fall, when and wherever you are, your radiance gives comfort to us all.”
It was just a dream after all…...
So promise the queen, “If I would be your husband, then I would help keep you warm upstairs and down, in your heart and mind, during the winter and summer both, because I would be a loving husband to you.” Is that dreamy, chivalrous, and creative enough?
If not keep it strait, upstairs will never get colder than the winter, so upstairs is not colder.