Lately we have been involved with "mission critical" projects which take the word redundancy and introduces a whole new meaning for backup of building systems. Over the years, design engineers have incorporated standby equipment on a regular basis. Now we are seeing "N plus N," where every piece of equipment has a matching piece of equipment.
If design-builders were to research the various strategies facility managers apply when it comes to exercising and/or using this standby equipment, they may be surprised at the feedback they get from operators. Redundancy doesn't come without a price.