20-0702 Emergency Power Systems - Toilet Flushing


Given the information below, it is our understanding that we may use a natural gas generator using the 18-0326 update to I06: E6 Emergency Power Systems.
Our project, pursuing the Energy Petal, is required by our city's Land Use Code to use nonpotable water (greywater) for toilet flushing. In case of a power outage, the toilets would be unusable (no water for flushing) without a back-up means of toilet pumping power, deeming the building un-occupiable. Our goal is to have this building serve as a hub of "resiliency for communities in times of crisis" (per pg 8 Energy Petal Handbook v3.1) and maintain occupancy during emergencies.
We have investigated the use of battery to support toilet pumping during a power outage, however one day of pumping toilets alone would be ~400 kWh battery that could not be re-charged. The on-site PV array would not be a reliable charge to ensure adequate and consistent flushing.
Please confirm our approach.


The project team may use I06-E6 Emergency Power Systems for the use of a natural gas generator to allow toilet flushing in the case of a power outage. Note that this Exception requires the following:
"... backup generators may be used if the generator:

  • is not included in the project’s strategy for operation and any use during the 12-month performance period is offset through the project’s renewable energy generation.
  • does not impact adjacent properties through noxious emissions or noise."

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