Hi, We are using 100% treated waste water for irrigation. It is not sub metered and therefore we are trying to use the option 2. We are using a baseline case of "Hose without water gun" that is the common mode of watering in this part of the country.
There are 2 problems:
1. How to estimate the irrigation efficiency of the hose without water gun?
2. I think whatever the IE for baseline, we still should achieve 100% water use reduction because we use 100% non potable water. But for some reason online submission form does not calculate it that way. For example if I use 0.5 IE for baseline and 1.0 IE for treated waste water, I get a water use reduction of 50.5%.
Can you please advise me on where I'm going wrong.
Thank you.
Ben Stanley
Senior Sustainability ManagerWSP - Built Ecology
LEEDuser Expert
250 thumbs up
August 30, 2013 - 11:04 am
Hi Magda,
You may not have to worry about the inputs to the theoretical calculation if your treated wastewater is more or less unlimited, like provided through a municipal system. In that case I've seen projects that were able to confirm compliance with a signed letter from the building owner or management confirming that 100% of the water is treated wastewater.
But if it's treated wastewater from the building, and therefore limited, then it becomes more important to estimate the mid summer baseline and show how much treated wastewater is available at the same time.
To your questions above, I haven't seen official guidance for the IE for hand watering, but I have seen a project use a lower efficiency of 0.5 for a similar scenario. Also, to account for the nonpotable water use, rather than adjusting the IE, there is a spot on the form to enter in the non-potable water applied, below the installed case calculation.
Magda Aghababyan
CEOCo-Energi (Pvt) Ltd.
15 thumbs up
August 31, 2013 - 3:15 am
Dear Ben, Thank you for the reply. In our case the treated waste water comes from onsite (toilet flushing and canteen waste water). We are able to theoretically calculate that waste water is actually more than the irrigation water demand.
But my concern is that on the online submission system, there is no provision to show them. And as you said there was the option to indicate non potable water use in the earlier versions of the forms, but version 5 has removed that option it seems.