Retrocommissioning Findings – Applied Psychrometrics–The Question

A while back, I posed the following question to some students in a year long EBCx class.

You are scoping out a new facility in Miami, Florida, walking through it with the Director of Engineering. One of the things she is anxious to show you is an issue that is occurring in the entry lobby.

On occasion, water runs out of the duct system and the ceiling is generally stained, as can be seen in the picture you took, which is reproduced below.


Being as you are totally enthralled with building commissioning and data, you always carry several data loggers and an assortment of probes in your backpack. So, you deploy one in the lobby ceiling to monitor the temperature and humidity above the ceiling as well as the temperature about a foot below the ceiling.

About two weeks later, the DOE mails your logger back to you, and you export the data to Excel for further analysis, saving it initially as a file named lobby_above_Ceiling.csv.

A.       Take this file and start by making a plot of the data. Do you see an issue?
B.       Do you need additional data to make a meaningful assessment?
C.       If so, what do you need and how might you find that data?
D.      What would your recommendations be to the DOE?

The idea was that I would develop the answers to the question on the blog;  that turns out to have taken a while, but here we are and I am about to do that.  If you want to try this, the file I mention (lobby_above_Ceiling.csv) is available on my Google Drive.

The question, and the string of blog posts associated with it, actually have their roots in the real world.   Specifically, there were inspired by a e-mail conversation I was having with a friend who is the DOE (Director of Engineering) in a hotel in a hot and humid environment.  The data and picture are real and come from Joe’s facility.  In fact, Joe is still working on the issue, so it is likely that more data will be forthcoming and I may even be able to share the results of any corrective action he tries

In the meantime, as I corresponded with him about it, I realized the issue provided a good way to discuss psychrometrics in a real world application, so that is were I am heading initially, starting with the basics. So for some of you, the initial posts in this string may be too fundamental, but I am hoping that for others who are not comfortable with psychrometrics, they may prove helpful.  But bear with me;  eventually I will work my way through the questions above.  

To make these posts easier to find, I will use the words “Applied Psychrometrics” in the title.  For example my next post, and the first post in the string is titled Applied Psychrometrics – Dew Point;  A Critical Parameter in a Hot and Humid Environment.

I have also added a Psychrometrics category so that you can find posts on that topic by using the “Categories” drop down on the right side of the opening page of the blog.



David Sellers
Senior Engineer – Facility Dynamics Engineering

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