Please elaborate on how that's responsive to my comment. Again, not really sure a possible 2 year pandemic is especially significant in the 50 year design life of a building. Even if it sits empty for 4% of its life with 100% probability (generous), you still get 96% (48 years) of use out of it.
First, you take an arbitrary probability number that depends on man-made models that are likely much more wrong than right. We've had a lot of hundred- or thousand-year events in the last two decades.
The models depend on predicting an uncertain future, and for this kind of stuff using past data has little meaning. It's not lottery numbers where probability really gives you some hard insights. We also have a lot more people, climate change and with it likely more movement from affected areas and a lot of other stuff going on that makes it hard to use data older than this century to gain insights into what will be.
Next, you interpret said probability as nicely equally distributed over time. I don't know what to say to such an interpretation.
Also, a pandemic is a kind of event that even if it indeed only appears rarely (which we hope but don't know) each time has a huge impact.
You can’t just apply extreme value theory to spectacular events because it supports your argument. Yes, there was a hundred years between the 1918 influenza outbreak and Covid. No, that doesn’t mean you can say that pandemics probabilistically occur once in a hundred years. The world is changing at an extraordinary pace, populations are exploding, humans and animals interact more than ever, and international travel is trivial.
