A biorepository running 30 -80°C ULTs draws 15-25 kW continuous and cannot tolerate a 4-hour outage. In Tampa Bay that is not hypothetical — it is annual. Real continuity is layered: utility, ATS-switched generator, UPS for monitoring, CO2 backup on the highest-value freezers, and a written runbook that names people and decisions, not just equipment.
Hillsborough, Pinellas, and Pasco counties see at least one named storm threat per season and on average one major utility-disturbing event every 3-4 years. The continuity question is not "if the power goes out" — it is "when it goes out for 36-72 hours, what stays cold." That framing rewrites the spec sheet.
Hospital research at Moffitt, Tampa General, USF Health, and Johns Hopkins All Children's already runs against this assumption. Independent biorepositories and pharma-services labs need the same posture even if they cannot match the budget.
The base layer is a permanent diesel or natural-gas generator on an automatic transfer switch (ATS) sized for the entire refrigeration load plus the room HVAC that keeps ULTs from heat-soaking. Sizing rule of thumb: 1.5x the steady-state ULT draw to cover startup inrush after a transfer, plus the connected HVAC and monitoring loads. A 30-ULT room typically lands at 60-100 kW.
Diesel sites need 48-72 hours of on-site fuel for hurricane season, with a refueling contract pre-signed (post-storm fuel is rationed). Natural-gas avoids the fuel logistics but depends on TECO Peoples Gas pressure staying up — which is not guaranteed during a major storm.
An ATS takes 8-15 seconds to transfer. ULT compressors handle that fine. Network-attached monitoring gateways and controllers do not — they reboot and lose state. Put the ColdSentry™ gateway, the building monitoring server, and any controller PLCs on a 30-minute UPS so the audit trail does not break across a transfer event.
This is the cheapest part of the stack and the one most often skipped. A monitoring gap during a storm is the artifact a regulator or sponsor will ask about first.
For irreplaceable specimens (CAR-T material, NIH-funded cohort biobanks, Moffitt clinical trial samples), liquid CO2 backup systems hold a ULT at -70°C or colder for 4-8 hours after total power loss. The freezer is plumbed to a CO2 cylinder bank with a solenoid that opens on temperature rise. This is the only redundancy that survives total facility power AND a generator failure.
CO2 backup is appropriate for the top 10-20% of inventory by replacement cost or scientific value — not the full freezer farm. Sizing: a 50-cu-ft ULT consumes roughly 50 lbs of CO2 per hour of backup at Tampa ambient temperatures.
For every 8-10 ULTs in production, keep one empty and energized as a hot spare. When a unit fails (compressor, contactor, controller — not just power), the recovery is to transfer racks rather than chase a parts ETA at 3 a.m. during a storm response. The cost of one extra freezer is trivial against the cost of a -80°C box drifting into specimen-loss range while you wait on a service call.
Co-locate the most critical inventory in two ULTs in two rooms on two ATS branches if facility design allows. Write a manifest of which racks are duplicated and which are not, and update it quarterly. The decision to duplicate a sample is a research and budget call, not a facilities call — but the facilities team has to make duplication possible.
T-72 hours: top off generator fuel, verify ATS exercise log, confirm CO2 cylinder bank is full, run a test transfer if the schedule allows. Notify the on-call PI list.
T-48: pull a manifest of irreplaceable inventory and confirm it is in CO2-backed units. Move what is not. Stage portable generators and shore power cables.
T-24: lock down loose equipment in the freezer room (a flying ULT lid is a real failure mode in shutter-rated rooms with the door cracked). Pre-position spare contactors, controllers, and probes.
T-0 to T+24: monitor remotely via ColdSentry™. Do not enter the building during a hurricane. Document every alarm and every transfer event.
T+24 to T+72: rotate fuel. Verify the audit trail reconstructed cleanly. File any USP, FDA, or sponsor-required incident notifications within the windows their protocols require.
After any major event, expect requests for: continuous monitoring logs across the event window, ATS transfer event logs, generator runtime hours, fuel consumption records, the runbook with timestamps showing it was followed, and an excursion report for any unit that drifted out of range. ColdSentry™ + ArcticOS™ produce most of this automatically; the rest needs a written process.
For a 30-ULT biorepository in Tampa Bay: generator + ATS sized for the load runs $80K-150K installed. UPS for monitoring is $5K-10K. CO2 backup on 6-8 priority units is $25K-40K capex plus $300-600/month fill contracts. One hot-spare ULT is $12K-18K. Total continuity capex lands at $130K-220K — meaningful, but small against a single ruined cohort.
We design the refrigeration and CO2-backup layers, coordinate the generator and ATS work with the electrical contractor of record, install ColdSentry™ across the freezer farm with UPS-protected gateways, and put the whole site under ArcticOS™ so the runbook, asset registry, and excursion log live in one place. For service-contract customers we negotiate written response SLAs by site-tier and severity rather than relying on best-effort dispatch.
A well-sealed full ULT holds -50°C for roughly 24-36 hours and -70°C for 4-8 hours. Specimens that require strict -80°C will start to drift within hours. CO2 backup is the only way to extend that meaningfully without restoring power.
For research biorepositories and high-value clinical inventory, yes — at the building level via an ATS, not per-unit. Single-unit pharmacy refrigerators can sometimes ride out a brief outage without a generator if the inventory value supports the risk, but ULTs essentially always need backup power.
Diesel runs without external utility dependence but needs fuel logistics. Natural gas avoids fuel storage but assumes Peoples Gas pressure stays up during a storm. Many Tampa Bay hospital systems run diesel for exactly this reason. The right answer depends on building code, fuel contracts, and acceptable risk.
The sensors are battery-backed and the gateway runs on UPS in our standard install — so monitoring continues through transfer events and short outages. For multi-day outages a second cellular gateway with an extended UPS is available.
The electrical contractor of record handles generator and ATS work; we handle refrigeration, CO2 backup, monitoring, and runbook integration. We coordinate the two scopes during design and during commissioning so the refrigeration load matches what the generator was sized for.
Suncoast Cold Systems handles exactly this kind of commercial refrigeration issue across Tampa, St. Petersburg, Clearwater, Brandon, Riverview, Temple Terrace, and Wesley Chapel. 24/7 dispatch. Licensed Class A A/C Contractor (FL #CAC1824642), EPA 608 Universal, OSHA 30 Construction.
N+1, hot-spare, and CO2 backup compared by inventory value and risk profile.
The first 30 minutes — quarantine, document, contact manufacturers.
How cascade compressor systems actually fail.