Sweeps by trained fire marshals are often the best way to ensure buildings are clear.
I've even seen very hi-tech systems 'fall over' in live plays on large COMAH sites,

In the past on complex old buildings, I had marshals put signs on final doors saying do not enter - this was as the alarm wasn't immediately audible.

In reality - drill and see what happens, then sit and discuss, try something else and drill again - repeat until YOUR system works.

We have large site with about 700 people on it. Anybody entering the site either has to sweep in (including vehicles) or be registered as a visitor assigned to a host.
There is only one way into the site and it is manned 24/7.
If there is a fire alarm only the block where the fire is detected is evacuated. There are two assembly areas on opposite sides of the site.
As there are no restriction on coming and going from the site and on moving about the site between the blocks there is no point having any sort of register.
Instead we use a sweep system (which is not too difficult as usually they would only do one block)
There have been attempts to “standardise” our system to match the one they use in Whitehall but we have to explain to them that our site is completely different form the ones down there.

At our main office (about 700 people) we use chipped ID badges. These are linked to the entry points from reception, anybody with a chip can walk in (and is logged), everybody without a chip has to sign in and be manually cleared to get through the doors. The system also logs people as they leave,

John

Interested in some of the auto logging devises that some of you use. How long does it take to get a list of people off the system and if there was a real fire would you be happy with someone staying in the building to get that list rather than evacuating at the earliest opportunity? I appreciate that sweepers are the last to leave so there is a lag in evacuation time there, but thinking about our IT system I just think this would be a nightmare interested to know how others cope.

Brian

Our roll call system is linked to the fire alarm, when the fire alarm sounds the roll call is automatically printed out in our reception area and also at our Security hut at the entrance to site. This works well for us as our large, one area, production line with lots of blind spots would be impossible to sweep quickly

I'm going to say again - whatever your system - ensure you drill and drill again!
Try planting someone in the building and see if the sweepers find them.
Try presenting a 'casualty' and see what happens.
Ask the fire brigade if they'd like to come and play (unless you're COMAH etc and get billed for it :) )

This is the only way to ensure a system works.

Then on that day we hope never comes, you can say with confidence to the fire chief, you need to commit a crew (who might not come out), or the buildings clear (no crew committed, so lets hope we were right)

This was the most stressful moment I had when running silver command (in an exercise) on a COMAH site - the fire officer pointed out the above and asked "are you sure - if not and people die its on you" it was then I realised, despite a hi-tech system I wasn't sure!!!

Our confusion came as the ambulance service reported that they 'with a casualty' and the fire brigade said they were 'extracting a body' - we counted two people - there was only 1!
Mass confusion - doubt over system... As everyone has said above - no system is perfect, not even sweeps!
But practice goes along way!

Can only echo what has already been said, training warden to sweep dedicated section of the building, and report to a Lead Warden that there section is clear.

Train enough to cover comings and goings/ holidays and sickness, Get them some shinny hi-vis vest,

Communicate fire procedure to all staff, training the warden then have your drill and review from there. Better to find the shortcoming now than alter.

Good luck,

Oli