Line 11: |
Line 11: |
| *''R<sub>a</sub>'' = The average annual rainfall depth (mm) | | *''R<sub>a</sub>'' = The average annual rainfall depth (mm) |
| *''e'' = The efficiency of the pre-storage filter}} | | *''e'' = The efficiency of the pre-storage filter}} |
| + | Filter efficiency (e) can be reasonably estimated as 0.9 pending manufacturer’s information.<br> |
| + | In a study of three sites in Ontario, STEP found the annual ''C<sub>vol, A</sub>'' of the rooftops to be around 0.8 [http://www.sustainabletechnologies.ca/wp/home/urban-runoff-green-infrastructure/low-impact-development/rainwater-harvesting/performance-evaluation-of-rainwater-harvesting-systems-toronto-ontario/]. This figure includes losses to evaporation, snow being blown off the roof, and a number of overflow events. |
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− | Filter efficiency (e) can be reasonably estimated as 0.9 pending manufacturer’s information.<br>
| + | Five percent of the average annual demand can be estimated: |
− | In a study of three sites in Ontario, STEP found the annual C<sub>vol, A</sub> of the rooftops to be around 0.8 [http://www.sustainabletechnologies.ca/wp/home/urban-runoff-green-infrastructure/low-impact-development/rainwater-harvesting/performance-evaluation-of-rainwater-harvesting-systems-toronto-ontario/]. This figure includes losses to evaporation, snow being blown off the roof, and a number of overflow events.<br>
| + | <math>D_{0.05} = P_{d} \times n\times 18.25</math> |
− | | + | Where: |
− | {{textbox|{{plainlist|
| + | {{plainlist| |
− | *Five percent of the average annual demand can be estimated:
| + | *''D<sub>0.05</sub>'' = Five percent of the average annual demand (L) |
− | *<strong>D<sub>0.05</sub> = P<sub>d</sub> × n × 18.25</strong>
| + | *''P<sub>d</sub>'' = The daily demand per person (L) |
− | *D<sub>0.05</sub> = Five percent of the average annual demand (L) | + | *''n'' = The number of occupants}} |
− | *P<sub>d</sub> = The daily demand per person (L) | |
− | *n = The number of occupants}}}} | |
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| Then the following calculations are based upon two criteria: | | Then the following calculations are based upon two criteria: |