This nominal square footage amount is then multiplied by a factor associated with the roof s pitch.
Runoff produced per square foot of roof.
Although this calculation is simple in principle the units can make it a headache.
1 of rain on 1 000 sf roof will yield 623 gallons roof area m2 x precipitation amount mm amount collected liters other water conservation calculators.
Because of the variables pinning down exact numbers is tough.
Step 1 determine the footprint of your structure f in square feet.
Roof pitches in.
You have to admit that whether you re in a drought situation or not it s hard to pass up that much of a free thing.
Use our metric system version.
But at 20 watts per square foot a system rated to produce 2 kilowatts would cover roughly 150 square feet while a 3kw system would take up about 225 square feet.
The basic calculation is a x r 231 g where a is the area of your roof in square feet r is the amount of rain in inches and g is the amount of runoff in gallons.
Multiply the two figures together to obtain the square footage of your roof step 2 determine the percentage of water collected from each downspout p.
As an example if your overhang is 12 inches you ll add 2 feet to the overall length and 2 feet to the overall width of the house.
Roof area ft2 x precipitation amount in x 0 623 amount collected gallons easy formula to remember.
0 gallons per minute gpm 0 cubic feet per second cfs peak runoff volume.
However calctool s unit menus remove this issue doing all the unit conversion for you.
0 inches per hour data source.
Measure your house at ground level then add in the roof s overhang for greater accuracy.
Automatic overflow control directs water back to downspout when barrel is full.
So how many square feet of your roof will your pv solar system cover.
Count the number of downspouts coming from your roof.
Measure along the length of the house or building and along the width of the house or building in feet.
So a 50 x 20 roof is 600 x 240 multiply the roof dimensions by the number of inches of rainfall.
Here you can easily find how much rainwater you can collect from you roof how much you need to remove from a courtyard or how much runoff you can expect from an area of land.
Rainfall calculator english units how much water falls during a storm.
In this example 600 x 240 x 1 144 000 cubic inches of water divide by 231 to get the number of gallons because 1 gallon 231 cubic inches.
Take the dimensions of the footprint of your roof and convert them to inches.
Divide 100 by the number of downspouts in order to obtain the percentage of water collected from each downspout.
The answer is about 623 gallons.
It is the middle of july in georgia and both you and your tomatoes are wilting in your yard both looking to the sky and hoping for rain.
Drainage pipe required minimum diameter.
