15-1007 v3.X Energy Storage for Resiliency


Hello! hope your doing great. This imperative states that the project must have sufficient battery backup storage for at least 10% of lighting load. However it doesn't specify for how long (time) it must be backed up, only that the amount of energy storage must be based on actual metered lighting energy use for the project. Please let us know for how long does it have to be backed up for us to make sure our batteries sizes are optimum. Thank you!


The storage system must be sufficiently sized to retain the required amount of power (i.e. run 10% of the lights) for a week when the need arises. Note that a project's required energy storage for emergency lighting must be designed to equal or exceed 10% of the project's average lighting load for a week based on the following equation:

[12 months lighting load (kWh)] / [52 (weeks)] x .10 = Lighting Energy Storage Requirement (kWh) 

It is acceptable to use calculations and lighting schedules to determine the probable load of the system. If the energy storage system is undersized, the Auditor will determine if the estimate was made in good faith based on realistic estimates (e.g. solar access, occupancy, etc). If the estimate was realistic, it will be accepted even if slightly low. If the team did not use realistic parameters in their modeling and are also significantly under capacity for energy storage, they may be required to add battery capacity.

Post ID 3283

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