The Homebox line does not come equipped with active ventilation. It has passive intakes located near the bottom... and "ports" that you can hook duct work/fans to near the top. The Homebox will not exchange or ventilate air by itself. You will, most likely, need to purchase appropriate exhaust equipment in order to keep the temperature under control.

Without proper air exchange/circulation... your plants will be subject to heat stress and insufficient CO2, which will increase your chances for hermaphrodites and decrease your yield potential.

With the Homebox XS, since it is small... you won't need an extremely strong fan to pull hot air out, but it will also depend on what type of lights you want to use and if you are going to use a carbon scrubber. CFL's are probably the best bet given your situation in the Homebox XS.

Where are you looking to buy from? I'm checking some tents out too. Just trying to find one that doesn't say "INDOOR GROW TENT."