20' of half-inch poly foam tubular insulation

The temperature in my windowless office can be as low as 63 deg f. even when it's pressing 100° outside. This is too cold for me to work effectively. I need temps in the 70's or I have to wear a sweater or jacket. (Even bundled up my fingers get too chilly for efficient typing.). I've put this foam rope around the offending light-fixture vent and brought the temp up to 69° and 70° most of the day. You'd think the government would wish to keep the temp. higher in the summer to save energy, and I suppose you'd be right; they would if they could. However, the local engineers say the system can't be corrected without making the temp too high in the room on the floor below me.