Emergency sites serve as additional locations you can land the drone in the event that it is beyond range of a launch site. They generally are not intended to be manned locations, and instead are places that have been identified ahead of time in the event of an emergency to avoid damage to equipment or other risks with UAV operations.
You can configure emergency sites to be automatically flown to when needed.
As with general launch sites, be sure that any emergency site can be physically secured with manageable access limits.
Also, be especially mindful of any RF interference in the area - cell towers, power lines or utility infrastructure, and so on.
For emergency sites that your organization does not control or otherwise has explicit access rights, be sure you know the owners of the location and communicate with them your intended use of the location as an emergency site.