Hi all,
I'm struggling to calculate the percentile of rainfall events. I gathered over 10 years of daily precipitation data and entered all values day by day into the calculator. My concern is: should I enter days without precipitation (slightly over 50% of all daily data I gathered) into the calculator? Or should I enter only days with rainfall?
It has significant impact on the 98th percentile rainfall amount we are targeting. I calculated both variants and actually we are compliant with the stringent one, but I would like to be sure about the documentation.
Thanks!
Bipin Karki
Sustainability Project Manager87 thumbs up
July 24, 2020 - 3:51 pm
Hello Prawda,
Rainfall Events Calculator should not include rainfall events of less than 0.1 inches (2.5 mm) in the historical rainfall data. You can refer to the LEED v4 BD+C Reference Guide, Further Explanation, Percentile of Rainfall Events section detailing the calculation of percentile of rainfall events for more information.
Hope it helps!
Aleksandra Prawda
Sustainability ConsultantJacobs
12 thumbs up
July 27, 2020 - 1:27 am
Thank you Bipin, this is very helpful indeed! I missed this in the reference guide. Fortunately the design of my project is still compliant.
Queenie Lee
July 27, 2020 - 11:33 pm
Hi Prawda,
You may want to explore LEED V4.1 criteria instead which are less stringent. If I am not mistaken, 90th percentile would earn you 3 points. You can do credit substitution if your project is already registered under V4.
Aleksandra Prawda
Sustainability ConsultantJacobs
12 thumbs up
July 28, 2020 - 7:37 am
Thanks! I'm aware of that, but actually we're aiming at 98th percentile and 3 points + exemplary performance. Is it possible to achieve exemplary performance with LEED v4.1 credit substitution? If so, do you know the EP threshold?
Monte Li
2 thumbs up
November 17, 2020 - 1:45 am
Hi, I would like to follow up on the original question. What is the rationale for removing days with less than 2.5mm precipitation (apart from being stated in the LEED details)?
For my project located in Asia, considering 11 years of data, I have 4,018 daily data points. If I exclude days with less than 2.5mm precipitation, I am left with 954 data points only. Given that my location is prone to typhoons and is a coastal city, my 95th percentile and 98th percentile precipitation is 90.29mm and 145.61mm respectively, which is extremely difficult to tackle.
It seems unreasonable and illogical that I have to exclude over 75% of the time. To think of this scenario differently, if our project designs to tackle 95th percentile rainfall event, we are designing to cater for almost 99% of the calendar days. Similarly for a project at a different location, say if they only have 50% of the time with precipitation of less than 2.5mm, then by tackling 95th percentile rainfall even, they are effectively designing to cater for 97.5% of the calendar days only. Any advice on how I could address this matter for my project?