When wildfire smoke reaches Sacramento, building operators face an unusual problem.
Under normal conditions, commercial HVAC systems intentionally bring outdoor air into buildings.
During a smoke event, the outdoor air itself can become the pollutant source.
The solution is not as simple as “turn off the outside air.”
Buildings still have ventilation, pressure, temperature and occupancy requirements. HVAC systems differ dramatically. Some buildings can adjust outdoor-air settings easily; others cannot.
That is why the best time to figure out how your building should operate during smoke is before the smoke arrives.
EPA recommends that commercial, public and multi-unit residential buildings create building-specific smoke-ready plans.
Understand the problem: PM2.5
Fine particulate matter is one of the primary health concerns in wildfire smoke.
Wildfire smoke can enter commercial buildings, and prolonged smoke events can affect indoor air quality even when people remain indoors.
Commercial properties therefore need to think about both sides of the building envelope:
How smoke gets in, and how particles that do get in are removed.
Step 1: Understand how your building breathes
Before creating a smoke plan, determine how outside air normally enters the building.
This may involve dedicated outside-air equipment, rooftop units, air-handling units, economizers, exhaust systems and natural leakage.
Potential smoke-infiltration points include doors, windows, loading docks, HVAC intakes, vents and gaps in the building envelope.
Walk the property with the HVAC contractor or building engineer. If the property does not have an established vendor, compare commercial HVAC companies serving Sacramento and verify controls, filtration and rooftop-unit experience directly.
Document the major outdoor-air intakes and areas where uncontrolled infiltration is likely.
Step 2: Ask your HVAC contractor to define “smoke mode”
Do not invent this procedure during an air-quality emergency.
Have a qualified professional determine what operational changes make sense for the actual HVAC system.
Building managers should learn how to modify HVAC run-time and outdoor-air settings where appropriate and practice transitioning between normal and smoke-ready operation before an event.
The final procedure should be written clearly enough that another qualified operator can implement it.
Step 3: Evaluate filtration before smoke season
Higher-efficiency filtration can reduce airborne particles, but a filter that creates excessive pressure drop for the HVAC equipment can cause other problems.
The answer is not simply to install the highest-numbered filter available.
Have the HVAC professional determine what the equipment can accommodate and whether fan performance or other modifications need to be considered.
Order appropriate replacement filters before smoke is already covering the region.
Step 4: Pay attention to doors and loading docks
A sophisticated filtration strategy can be undermined if exterior doors remain open continuously.
During smoke events, review delivery procedures, loading docks and frequently used entrances.
This may require operational coordination rather than construction.
Step 5: Know the building's pressure strategy
Commercial buildings are often operated to maintain pressure relationships between indoors and outdoors or between different spaces.
Changing exhaust or outside-air operation can alter those relationships.
This is another reason building-specific professional guidance matters.
Step 6: Monitor outdoor conditions
Sacramento-area property managers have access to regional air-quality information through the Sacramento Metropolitan Air Quality Management District and regional monitoring networks.
Decide in advance what source your team will use.
If every person on the operations team checks a different phone app, you may get different readings and inconsistent decisions.
Step 7: Consider indoor monitoring
Outdoor AQI does not automatically tell you what is happening inside a particular building.
Indoor/outdoor air monitoring can be one tool building managers use when developing smoke-response strategies.
If indoor monitoring is appropriate for the property, decide how readings will be interpreted before the event.
A sensor without an operating policy is mostly a display.
Step 8: Reduce avoidable indoor particle sources
During a severe smoke event, building management should not add unnecessary indoor pollution while simultaneously trying to filter outdoor smoke.
Review activities such as construction, dust-producing maintenance or other work that could worsen indoor particulate levels.
Step 9: Communicate with tenants
Tenants do not need a mechanical engineering lecture.
They do need to know what the building is doing.
A useful communication might explain that outdoor air quality is being monitored, the HVAC system has been placed into its planned smoke-response mode, doors should not be propped open and building management should be notified of unusual odors, visible smoke or comfort problems.
Communication also reduces the chance of well-intentioned occupants undermining building operations.
Step 10: Plan the recovery
A smoke event eventually ends.
Your plan should describe how the HVAC system returns to normal operation.
Inspect or replace filters as appropriate. Restore normal outdoor-air settings. Review indoor conditions and document any problems that occurred.
Then update the plan while the experience is fresh.
Build the plan before you need it
A smoke-ready commercial building is not necessarily one with the most expensive filtration system.
It is one where ownership, management and the HVAC team understand the equipment and have already decided what to do.
For Sacramento property managers, wildfire-smoke planning should increasingly be treated as part of normal building operations rather than an improvised response.
Official references
- U.S. EPA wildfire smoke and commercial building guidance
- Sacramento Metropolitan Air Quality Management District wildfire smoke and air-quality resources
Sources and official resources
These links are provided for reference and do not imply an endorsement.