A method of designing a dry pipe residential fire protection system using hydraulic demand criteria of a wet pipe residential fire sprinkler system, the dry system being for a residential dwelling unit having a plurality of compartments and a fluid supply source defined by a flow and pressure, the method comprising: determining a minimum quantity and location of residential fire sprinklers (40A,40B) required to determine a hydraulic demand calculation of the residential fire sprinklers of a piping network filled with water in a wet pipe fire sprinkler system arranged to protect the plurality of compartments, the determining of the minimum quantity and location of the residential sprinklers (40A,40B,40C) being based upon hydraulic demand design criteria for the wet system, such that the determining the minimum quantity includes: determining a wet design area; determining a number of sprinklers (40A,40B,40C) for the wet system so as to comply with a sprinkler coverage requirement for each compartment; determining a hydraulic demand for each compartment in the wet system including determining the highest hydraulic demand for the wet system; determining that the flow and pressure of the fluid supply source satisfies the highest hydraulic demand of the wet system; and specifying the minimum quantity and location of residential fire sprinklers(40A,40B), as determined, for the dry system having a dry design area that is the same as the wet design area, the dry system having a piping network filled with a gas to protect the plurality of compartments. determining a minimum quantity and location of residential fire sprinklers (40A,40B) required to determine a hydraulic demand calculation of the residential fire sprinklers of a piping network filled with water in a wet pipe fire sprinkler system arranged to protect the plurality of compartments, the determining of the minimum quantity and location of the residential sprinklers (40A,40B,40C) being based upon hydraulic demand design criteria for the wet system, such that the determining the minimum quantity includes: determining a wet design area; determining a number of sprinklers (40A,40B,40C) for the wet system so as to comply with a sprinkler coverage requirement for each compartment; determining a hydraulic demand for each compartment in the wet system including determining the highest hydraulic demand for the wet system; determining that the flow and pressure of the fluid supply source satisfies the highest hydraulic demand of the wet system; and specifying the minimum quantity and location of residential fire sprinklers(40A,40B), as determined, for the dry system having a dry design area that is the same as the wet design area, the dry system having a piping network filled with a gas to protect the plurality of compartments. determining a wet design area; determining a number of sprinklers (40A,40B,40C) for the wet system so as to comply with a sprinkler coverage requirement for each compartment; determining a hydraulic demand for each compartment in the wet system including determining the highest hydraulic demand for the wet system; determining that the flow and pressure of the fluid supply source satisfies the highest hydraulic demand of the wet system; and specifying the minimum quantity and location of residential fire sprinklers(40A,40B), as determined, for the dry system having a dry design area that is the same as the wet design area, the dry system having a piping network filled with a gas to protect the plurality of compartments.