Changes

*R_a = The average annual rainfall depth (mm)

*R_a = 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.

Filter efficiency (e) can be reasonably estimated as 0.9 pending manufacturer’s information.

In a study of three sites in Ontario, STEP found the annual C_{vol, A} 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 number of overflow events.

In a study of three sites in Ontario, STEP found the annual C_{vol, A} 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 number of overflow events.<br>

<blockquote>Five percent of the average annual demand (D_0.05) can be estimated:

 

<br><strong>D_0.05 =  P_d × n × 18.25</strong>

<br>D_0.05 = Five percent of the average annual demand (L)

*Five percent of the average annual demand (D_0.05) can be estimated:

<br>P_d = The daily demand per person (L)

*<strong>D_0.05 =  P_d × n × 18.25</strong>

<br>n = The number of occupants </blockquote>

*D_0.05 = Five percent of the average annual demand (L)

*P_d = The daily demand per person (L)

*n = The number of occupants}}

 

Then the following calculations are based upon two criteria:

Then the following calculations are based upon two criteria:

#A design rainfall depth is to be captured entirely by the RWH system.

#A design rainfall depth is to be captured entirely by the RWH system.