A financial services firm is designing a private cloud hosted in its own data center to run a payment processing platform that must remain available even during scheduled maintenance of power and cooling systems. The architecture team wants a facility that provides concurrently maintainable power and cooling paths (N+1 redundancy) so any single component can be taken offline for service without disrupting the IT load, but they do not require the cost of fully fault-tolerant (2N) infrastructure. Which Uptime Institute data center tier best matches this requirement?