Disclaimer: This is for your novel.
The more you know, the better. Share those pictures with the would-be arsonist if possible.
Does your company store any flammable liquids? Does it have ventilation?
Remember the triangle:
Burning down a modern building without experience is not easy.
Places that would be easy to burn down usually come with stringent security. How do I know? Hazard assessment and risk minimization are part of safety and security plans.
But do you actually need it to burn down? Or is it enough to do substantial damage to one area? How many entries and exits are there? If your aim is to be out of work, would it be enough for the reception area to be fire damaged?
Clearly define your goals.
And go through the plan step by step in your head.
- What would you do if you were in the other people's shoes? What steps might they take to put out the fire?
- And then counter them: What steps could your mystery arsonist take to prevent or discourage them from taking those steps? How can you reduce their effectiveness?
Adapt the plan.
If that person manages to collapse your building, I would be very surprised.
On another note, if your organization has dedicated security, I would not recommend arson. They will know it was arson. They will have security footage backing up offsite in real time. They will identify your arsonist. They will check his messages.
If I were to send a potential arsonist pictures of a building, I would use a difficult to trace method.