Yes. At a basic level, most small companies still need a firewall/router and some switches in a closet. Maybe a local backup server? And a UPS to keep it going

Yes. At a basic level, most small companies still need a firewall/router and some switches in a closet. Maybe a local backup server? And a UPS to keep it going, and now you need to worry about the temperature. Do you own the building? Probably not. Does the building landlord keep the HVAC going on nights and weekends? Probably only at a level sufficient to get things back to normal around 8AM the next work-day. So even if you install your own A/C: do you have sufficient power? Where does the exhaust go? Do you have a drain for the water you take out of the air, or a bucket? A nice bucket full of slightly oily water next to your machines? Better make sure there's nothing on the floor. Add a few temperature sensors and flood-detectors, too. Rig an alert system.