TB Infection Control

Hi, David. Interesting question. A 3 m ceiling is pretty good, and a 4 m ceiling has some advantages, but not dramatic. In Lima, for example, 4 m ceilings in colonial style hospitals have tall ceiling to (near) floor windows, bringing in light to deep rooms before electric lighting, and also providing huge amounts of natural ventilation when open. There is more air volume per patient, but in a steady state production/removal situation, room volume drops out of the equation. Local dilution is only important in a non-steady state situation, which of course is reality. So, if you enter a low ceiling, low volume room after a bout of coughing your short-term risk might be double that of entering a room with half the volume.

However, you are talking about a much smaller difference in ceiling height. Other ceiling height issues are thermal comfort - more room for hot air to rise out of the living zone, room for paddle fans, and room for UV. Your 3m ceilings provide plenty of room for all of those issues. Conclusion: Would I spend a lot more on 4m ceilings? No, but I might spend a moderate amount more if airborne infection is ...

Hi, David. Interesting question. A 3 m ceiling is pretty good, and a 4 m ceiling has some advantages, but not dramatic. In Lima, for example, 4 m ceilings in colonial style hospitals have tall ceiling to (near) floor windows, bringing in light to deep rooms before electric lighting, and also providing huge amounts of natural ventilation when open. There is more air volume per patient, but in a steady state production/removal situation, room volume drops out of the equation. Local dilution is only important in a non-steady state situation, which of course is reality. So, if you enter a low ceiling, low volume room after a bout of coughing your short-term risk might be double that of entering a room with half the volume.

However, you are talking about a much smaller difference in ceiling height. Other ceiling height issues are thermal comfort - more room for hot air to rise out of the living zone, room for paddle fans, and room for UV. Your 3m ceilings provide plenty of room for all of those issues. Conclusion: Would I spend a lot more on 4m ceilings? No, but I might spend a moderate amount more if airborne infection is the issue. You are probably not going to have huge windows like in Lima, but they should be as big as possible, and not sliders - so that they open up fully.

Hope that helps.

Ed

Merry Christmas and Happy New Year every one.
I fully agree with ED, the benefits of a 4m space over a 3m one is not very clear. However, when a designer has the opportunity to create a taller space, they will probably provide taller windows, ventilators or clerestory windows. These will make a difference.
also the added height will aid in convection currents being created, when the room is occupied. These have added benefits especially when it is hot. i would have the architects and engineers give a cost comparison between the spaces. If the increase is bearable, i would go for the taller height. Just a point of note, windows cost more per surface area than block and mortar. And larger opening windows are required.
TAQ