protect PC against noise
Apparently your system is suffering from susceptibility to EMI and low immunity to transients. Obviously your overall setup (with all USB devices and associated USB cables) was never tested to IEC 61000-4-x standards, especially to 4-4 EFT (fast transient) section.

The position of your building manager is understandable. Before installing some extra equipment, you need to find the root cause of your issue.

If the interference is coming from AC power mains, a battery-powered UPS is an easy solution. But if your PC doesn't reboot, the power is not likely the cause.

If USB is disrupted, you might want to look into the scale of communication disruption, whether any individual USB devices are disrupted, or the entire PC root hub gets reset and/or massive disconnects are happening. 

If the interference (fast transient) is coming in a radiated way (coupling into USB cables), the simple ferrite blobs on USB cable coming to PC might help. However, most regular PCs have the shielding routed in completely wrong manner (shield is usually directly connected to signal ground plane on most mainboards at USB connectors), the ferrite beads might be not enough. In this case a good total (optical) isolation will solve the problem, see USB3.0 optical cables from Corning Communication. This would be the best, although a bit pricey.

[CORRECTION: The Corning cable does not provide galvanic isolation between grounds on connectors, as some audiophiles have discovered, and tolerance of data signals to common-mode is not specified or known. Corning didn't return the request for clarification]

USB has a limited range of how much of common-mode shift it can tolerate (officially about 1-2V, or less for HS). If the disruption comes from excessive bouncing of common ground across multiple power sources supplying your USB devices, you may want to reduce the ground loop area by consolidating all power bricks into one area if possible, and use another local UPS to power them.

Overall, fighting Electromagnetic Interference is always a challenge, so good luck to you.