Hi LEED experts, It is difficult to find rainfall data of 10 years in my country. I'm just lucky to find an international source for that long data. But they just recorded the average rainfall and rainy day numbers in each month, not specific rainfall in any specific day. My question is Can I calculate the average daily rainfall by dividing the rainfall in a month by the rainy day numbers, and use those in the calculator? Every line will be every different month and the total precipitation column is the average daily rainfall in that month.
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Bipin Karki
Project Manager - Sustainability Division84 thumbs up
May 31, 2019 - 8:38 am
Hello Hieu,
In general, a 30-year period of rainfall record is preferred for the percentile of rainfall analysis. The Reference Guide (RG) for LEED v4 says at least 10 years of data must be included if available. The rainfall events of less than 0.1 inch (2.5 mm) are removed in calculations. Since RG states - "The amount of precipitation from these small events generally produces no measurable runoff because of absorption by permeable surfaces and interception and evaporation by impermeable and vegetated surfaces." The day with no rain has 0-inch rainfall event so they are automatically excluded. The approach you explained may be acceptable, as there is no way to get daily rainfall data. I would suggest you explain your case in special circumstances (SC) box in LEED form or provide clear narrative explaining your case, so the GBCI may consider your SC. Also, make sure to check local airport data, as always raw data are collected by most airport.
Hope it helps! Thank you.
Victoria Rios Esteve
3 thumbs up
May 31, 2021 - 2:35 pm
Hi everyone! In our project we are having the same problem as Hieu. We believe that is important for the Calculator to have the rainfall time-lapse to know if there is risk of flooding or not. We do not have this information neither. So, if we do as Hieu suggests, will the calculator work correctly?
Thank you for your time!
Simon Joubert
Terao2 thumbs up
July 14, 2021 - 10:12 pm
Hi Hieu,
What is important is to have different different values, an average wont be usefull for this credit. This credit is based on percentile and not on average. If you take V4.1 target, we have to based our calculation on the 80th percentile, 85th percentile and 90th percentile, which gave for Shanghai for exemple 18mm, 21mm, 27mm. 95th percentile of V4 should be maybe 45mm... it is not at all linear because this credit is aiming to control heavy rain. so a daily average of monthly monthly wont be accepted i think because it is not in line with percentile methodology. Maybe you can try to find data from a similar climate in an other country, and extrapolate according to monthly average data (IWMI). You can also try to see with IWMI how they give 75th percentile results on their website. maybe they have some data you can buy and after calculate 80th percentile, 85th percentile...
PARITALA sudhakar
March 13, 2022 - 12:18 pm
Hai. I am new user. Where can i get the Leed Form to apply for special case.