co2 and ventilation?

Wondering if anyone has any good advise on how to use c02 and ventilation at the same time. I have a co2 monitor that keeps things at 1500 perfect but my heat issue is getting to the point that i have to ventilate the room. My monitor does not have any fan control so just thinking about doing short bursts on the blower to clear the room with the c02 running but it seems like a waste. I am pulling from the top of the room which seems to me would be pulling more hot air and less of the heavier Co2 but just dont want to waste it. Suggestions?
THanks in advance