i've got fluorescent lights... the door is open. I did open a window but sadly it felt just as hot outside as it was inside. We've got central heating & air. I think it just must be body heat and movement warming up the room. I'm okay with it warm. I like it warm but I felt bad for my friends. We'll just plan to wear short sleeves.. I started off with long sleeves and was ready for short sleeves very quickly. I have to remember to dress in layers. When my guild has Sewing Saturdays I dress in layers because you just never know...