If you have access to a Wool blanket, you could wet the blanket out and then use it as a radiant heat barrier between yourself and the source of the heat. Removing synthetic clothing materials such as Polyester fleece would be a good idea or if an a business environment its best to stick to a wool suit rather than the cheaper mass produced polyester ones . But it is usually hands and face that get the worst of the radiant heat burning. A silk or wool balaclava and gloves weigh nothing (leather gloves are preferable) and are easily kept in the inside pocket of a good wool business suit. If these are not available and time allows it might be preferable to remove your wool socks are use them as improvised gloves.

Heat rises along with hot toxic flammable combustible fumes which can flame out and roll along the roof spaces so its best to keep near to the ground where the air is somewhat cooler and cleaner. Chances are the smoke will get you before any fire will so a commercial smoke hood may make sense if you life or work in buildings higher than 5 stories. (higher than this and a Fire truck Ladder isn't going to get you down to safety)

As with everything else, paying attention to your surroundings and being prepared will greatly increase you chances of survival. If the fire alarm goes off then leave the premises immediately without having to seek permission from superiors, management or the seeking permission from the social group mentality. Knowing where the fire escapes are and how to navigate to them in the dark costs nothing and may just save your life well before having an ex SEAL stating his name to you and him saying how he going to save your life by rappelling from floor to floor with Ethernet cable. (even Chuck Heston and John McClane knew to use a fire hose reel)