Prepare a building’s MEP systems before hurricane season starts, not when the warning arrives. Protect the equipment that fails first, decide which loads run on emergency power, load-test the generator, and write the shutdown and restart sequences. A forecast cone gives 72 hours; by then the generator either starts under load or it does not.

How do you test a standby generator before a storm?

Preparation of the building’s MEP systems for hurricane season needs to be done prior to the beginning of the hurricane season, not at the warning stage.

That is, the measures are to include protecting equipment that is prone to premature failure, determining which systems should be operating on the emergency power, conducting a load test on the generator, preparing a shutdown procedure, and planning the restart. Forecasting cones are provided with seventy-two hours’ notice; by that time the generator will either start under load or not.

The key preparatory measures should be taken in June, on a quiet day.

Under load, not at idle, because the failure is hidden until it matters. NFPA 110 calls for a monthly exercise of at least 30 minutes at no less than 30% of nameplate rating, and where the monthly run cannot reach that load, an annual load-bank test.

Running a diesel only at light load glazes the cylinders, “wet stacking,” unburned fuel fouling the engine, so the load test protects the unit as much as it proves it. A generator that starts cleanly at no-load can still quit under building load.

Then check the four things that actually strand a unit in a storm:

• The battery – Battery failure is the most common cause of a no-start.Test it, clean and tighten the connections, and confirm the charger breaker is on, it is often left off after service.
• Fuel – Top the tank, and know how many hours of runtime you have at load.NFPA 110 rates generators by exactly this, a “Class 48” unit carries 48 hours of on-site fuel, so match the class to the storm you are planning for.

  Humidity and ethanol drive condensation and microbial growth in stored diesel, clogging filters mid-storm, so fuel polishing belongs on the pre-season list.

• Automatic transfer switch – Exercise the ATS, a generator that runs but never picks up the load is no better than one that won’t start.
• Refuel plan – Line up a priority fuel contract before the season; after a regional event, everyone is calling the same suppliers.

Conduct the load test, not an idle test, as all failures become apparent under load.

According to NFPA 110, at least thirty-minute-long exercise at no less than 30% of the nameplate rating is to be performed monthly. If the monthly run cannot achieve that level of load, an annual load-bank test is needed.

A run at light load only will lead to cylinder glazing and “wet stacking”, i.e., accumulation of the unburnt fuel on the cylinders of a diesel. Therefore, the load test not only helps to prevent but also to prove the generator. A generator which starts smoothly at no load may fail under building load.

Next, determine the four most frequent reasons why the generator may not start under load during the storm.

• Battery failure is the most frequent cause of the no-start.Perform a test on the battery, clean and tighten the connections, and make sure that the charger breaker is turned on, as it is often turned off after service.
• Fill up the tank and determine the runtime under load. According to NFPA 110, generators are classified by available on-site fuel.Thus, for instance, a “Class 48” generator provides forty-eight hours of on-site fuel. High humidity and presence of ethanol cause condensation and microbial growth in the stored diesel and thus clog filters mid-storm.

  Therefore, the fuel polishing needs to be included in the list of pre-season activities.

• Examine the ATS, as the generator running but not picking up the load is of no use compared to the generator which fails to start.
• Obtain a priority fuel contract prior to the season as regional events always generate a very high demand for it.

What has to stay on emergency power?

Find out explicitly rather than assuming; that is, that is the step which most buildings ignore.

The life safety code requires the operation of the fire pump, fire alarm, egress and exit lighting, and elevator recall on emergency power. However, loads which keep the building operational and habitable after the storm are usually operated on optional standby and may not even be included on the generator.

In the tower, it is the domestic water booster pump (that keeps the pressure in water on upper floors). There is to be at least one elevator for the building access, sump and lift station pumps and sufficient cooling/dehumidification preventing mold growth.

Florida regulates that sector at the vulnerable end of the market: following twelve heat-related deaths in a nursing home after Hurricane Irma in 2017, the state started requiring nursing homes and assisted-living facilities to maintain interior temperatures at or below 81°F for 96 hours on emergency power.

The multifamily housing is not regulated yet but the standard is moving in that direction due to the same considerations. Map the emergency distribution and make sure that the generator still covers all of today’s dependent loads.

What HVAC steps matter before hurricane season?

Anchorage of units, clearance of the condensate paths, and fast humidity control restoration plan are to be developed. Make sure that all rooftop and outdoor units are securely fastened to their engineered tie downs and curbs, verify surge protection and grounding before lightning season and clear all condensate paths.

After the shutdown, humidity control should be restored first, as a sealed building in Zone 1A without dehumidification gets mold within days after the outage.

What is on the water-side and drainage checklist?

Roof drains, scuppers, sump and lift station pumps and below-grade areas protected by these measures need to be addressed.

Clogged primary roof drain turns rainfall into the unexpected structural load on the roof, while a non-operating lift station turns the building into the one that back-sewers.

At below grade level, it is to be confirmed that the sump pumps operate and are on emergency power, and that elevator pits and parking areas drain properly as flooded elevator pit makes the elevator inoperative for an extended period of time.

For any ground-floor or below-grade electrical and mechanical rooms which may be exposed to potential flooding, flood barriers and door dams should be staged prior to the season. Verify backflow preventers.

The storm itself does not cause failure; it only reveals maintenance which was neglected in the spring.

When should you shut MEP systems down as a storm approaches?

As the winds grow, the air-side equipment is to be de-energized and isolated.

The operator uses 40-50 mph as the threshold, however, the actual threshold is provided by the equipment manufacturer and the owner’s wind-speed policy, as some kinds of equipment tolerate higher values of wind speed (e.g., elevators and cooling towers compared to outdoor-air units). Debris ingestion and voltage fluctuations above that threshold can damage the compressors.

Remember to recall elevators and park them above the flood levels, not in the pits. Prepare a shutdown sequence in advance, i.e., which systems should be powered off and in what order and which ones remain energized for life safety, drainage and communications.

A shutdown sequence existing only in one engineer’s mind carries the risk of failure in case he/she is unavailable.

How do you safely restart MEP systems after the storm?

Restart the systems gradually, never energize the wet equipment.

According to NEMA recommendations, the equipment exposed to water during the storm needs to be evaluated by a qualified specialist as, due to corrosion and contamination invisible to the naked eye, the equipment may need to be reconditioned or replaced. Energizing of water-exposed equipment leads to fire and life-safety risks.

Check and test the equipment before power restoration, and perform insulation resistance (megger) test as a standard test of the water-exposed equipment. Then energize systems in sequence rather than all at once, starting with humidity control as the first comfort system to prevent mold.

Document all affected equipment, as the record will be needed by the insurance companies and the property resilience assessment.

The recommendation. Prepare a building-specific pre-season checklist and implement it in June: load test and fuel polish the generator, service the battery, exercise the ATS, check which loads are on emergency power, clear the condensate and roof and below-grade drainage and stage flood barriers. Obtain priority fuel and service contracts prior to the season, not during it.

Prepare a shutdown sequence and restart sequence to ensure that responses do not depend on the availability of the particular individual on site.

We can help prepare building-specific pre-season checklists and shutdown-and-restart sequences under our Resilience & Sustainability service. Facilities teams can use them so the response does not depend on who is on site that day. If you want one for your building before June, contact us.

Sources: NFPA 110 — generator exercise and load-bank testing · Generator no-start — battery is the leading cause · Florida emergency-power rule for nursing homes/ALFs (81°F/96 hrs) · NEMA — handling water-damaged electrical equipment · Commercial hurricane prep — shutdown & checklist · ASHRAE climate zone 1A