ASHRAE 170 for Contractors: What to Check in Submittals

ASHRAE 170 sets the minimum ventilation requirements for hospitals and other health care facilities: air changes, outdoor air, filtration, relative humidity, temperature, and pressure relationships, defined room by room. 

For a GC project engineer, each of those requirements lands on a specific characteristic in a specific mechanical submittal, whether that's the AHU, the filters, the terminal units, the humidifier, the exhaust fans, or the controls sequence. Some of them can be confirmed on paper. Others can only be proven once the HVAC systems are running.

Take the operating room row in the standard. It holds six separate requirements, and none of them appears word for word on any single submittal. Knowing where each one hides is what separates a real review from a stamp.

Which edition of the ANSI/ASHRAE/ASHE Standard 170 applies to your project?

The current edition is ANSI/ASHRAE/ASHE Standard 170-2025, but your specs and your authority having jurisdiction decide which edition governs. The American Society for Health Care Engineering notes that AHJs have adopted and enforce different editions, so a 2021 reference in Division 23 is still the contract requirement. Check the reference standards article in the spec before you check a single one of the hospital ventilation requirements against a submittal.

ASHE, part of the American Hospital Association, develops the standard, formally titled Ventilation of Health Care Facilities, with ASHRAE. It is revised on a four-year cycle alongside the documents from the Facility Guidelines Institute, with addenda published between editions. FGI's 2026 edition now publishes as the FGI Codes for Planning and Design, and the new 2025 space types were added to line up with it.

What changed in ASHRAE/ASHE Standard 170-2025

Most 2025 changes touch design, but several show up in submittals:

• Outdoor air at the systems level. Systems serving both Standard 170 and Standard 62.1 spaces now calculate total outdoor air across the system, which changes the minimum OA value on mixed-use AHUs.

• Filtration testing. Equivalent alternative test methods were added for easier international use, so a filter may arrive rated to a different test standard than your spec names.

• Plant capacity. Updated cooling and heating reserve capacity and fuel on-site requirements affect chiller, boiler, and fuel storage submittals.

• Exhaust. Separation distances and stack discharge heights based on complex situations were clarified, which matters on exhaust fan submittals.

The edition also added the optional use of natural ventilation, an additional function of space types for behavioral health, and imaging and nuclear medicine updates. It clarified bronchoscopy requirements and unoccupied turndown requirements in outpatient spaces, and aligned similar space types across the different tables.

The 2021 edition before it brought a revised scope with improved guidance on thermal comfort and extensive modifications to the outpatient and residential sections, including a new outpatient ventilation table. It added expanded guidance on separation distance requirements for varied intake and exhaust arrangements, coordinated with related data in Standard 62.1, plus new columns to prescribe filtration requirement values and designate unoccupied turndown.

How to read ASHRAE 170 Table 7.1 as a submittal checklist for health care facilities

ASHRAE 170 Table 7.1 lists design parameters for inpatient spaces, from operating rooms and patient rooms to airborne infection isolation rooms. Table 8.1 covers outpatient facilities, and the residential sections have their own table. The ventilation tables share the same columns, which is what makes them usable as a review tool for the ventilation systems behind each space, including where recirculated air is allowed.

Each column maps to a characteristic you can find, or can't find, in a submittal:

"Partial" means the submittal proves the equipment can deliver the requirement, but the room only proves it at testing and balancing. That distinction drives how you write comments back to the sub.

Reviewing a hospital AHU package this week? Upload it to BuildSync and see every ASHRAE 170 characteristic checked against your specs. Book a demo.

Operating room air changes per hour: what a submittal can and can't prove

ASHRAE 170 requires operating rooms to receive a minimum of 20 total air changes per hour, with at least four of those from outdoor air, under positive pressure. A submittal can prove the equipment is sized to deliver that airflow. It can't prove the room achieves it.

Converting air change rates into CFM you can check

No cut sheet lists air changes per hour, because air change is a room property. To check it, convert: room volume in cubic feet times 20, divided by 60, gives the minimum supply CFM. Compare that number against the mechanical schedule, then against the terminal unit's scheduled maximum CFM for that room's tag.

From there, check the AHU. The supply fan has to hit its total CFM at design static pressure with filters loaded, so confirm the fan curve uses the final filter pressure drop. On a VAV submittal covering 20 tags, every tag needs its own check against its own schedule row.

When asked which ASHRAE 170 characteristic BuildSync flags as failing most often on hospital AHU submittals, and why it often gets past manual review, Tom Port, the co-founder of BuildSync, says:

"One of the areas where BuildSync adds the most value is identifying discrepancies in airflow requirements between the mechanical schedules, specifications, and submitted equipment data. On hospital projects, where ventilation requirements are particularly stringent, even small discrepancies can have significant consequences.

We find that these issues often get missed during manual reviews because engineers are working through hundreds of pages of technical documentation, cross-referencing multiple sources."

Addendum y changes how air changes get turned down

Addendum y to Standard 170-2025, approved in September 2026, keeps the 20 ACH design value for operating rooms. It adds a requirement that a risk assessment be completed before any operational adjustment to space ventilation, documented in a ventilation management plan.

The committee's rationale came from testing and balancing data on 521 operating rooms across 45 hospitals, which found higher ventilation did not reduce surgical site infections. For contractors, the practical impact sits in the controls submittal: if the sequence includes unoccupied turndown, ask whether the owner's risk assessment and plan exist before approving it.

Air filtration, humidity, and temperature on AHU submittals

Filtration and humidity are the most checkable ASHRAE 170 requirements, because they appear directly on filter and humidifier data. They are also where small mismatches slip through.

Air filtration ratings that deliver cleaner air

For operating rooms, Table 7.1 sets a minimum filter efficiency of MERV-16. Minimum efficiency reporting value is a test result that describes removal efficiency across particle size ranges, so check the rating against the test standard your spec names, especially now that the 2025 edition accepts equivalent international methods.

Many designs carry high-efficiency particulate air (HEPA) final filters in surgical suites. Confirm the filter bank location matches the spec, frame and gasket details prevent bypass, and the final filter is rated for the scheduled face velocity. Cleaner air depends on the whole assembly: media, frame, and seal.

Relative humidity, temperature, and indoor air quality

Operating rooms carry a design range of 20% to 60% relative humidity and 68°F to 75°F. On humidifier submittals, check capacity at the winter design condition, steam source, and type (adiabatic humidifiers have been accepted since the 2017 edition). On coils, confirm latent capacity holds humidity levels under the upper limit in summer.

Airborne infection isolation rooms and pressure relationships: why "unknown" is often correct

Pressure relationships between a room and its adjacent spaces can't be verified from equipment data alone, so an honest review often returns "unknown." Airborne infection isolation rooms, for example, run at negative pressure with all exhaust air sent directly outdoors, which depends on duct leakage, door undercuts, and balancing as much as on any fan.

What the submittal can show: the exhaust fan serving isolation rooms is dedicated and sized correctly, terminal unit offsets match the schedule, and the room pressure monitor carries the specified range and alarm. Positive pressure rooms work the same way in reverse. The 2017 edition also clarified that controls to change pressure relationships between spaces are prohibited, so flag any sequence that switches a room between positive and negative.

Proving the system is functioning correctly

These rooms protect patients and health care workers from airborne contaminants, the core concern behind federal disease control guidance for healthcare facilities. Room pressure gets proven at TAB and commissioning, when facility managers confirm the system is functioning correctly.

When asked what a PE should send back to the subcontractor when BuildSync flags room pressure or air changes as unknown, and which items should be left for testing, adjusting, and balancing (TAB), Tom Port, the co-founder of BuildSync, says:

"BuildSync flags an ‘Unknown’ when information is missing, design requirements conflict, or there isn’t enough detail to confirm compliance. The PE should take a look at these findings and, where needed, go back to the Sub for clarification or additional documentation.

Some things, like actual room pressure and air change rates, can only be confirmed once the system is up and running. Those should be left for TAB."

When manual cross-referencing isn't enough on a hospital job

A single hospital AHU can carry dozens of characteristics, each tied to a spec paragraph, a schedule row, or a Table 7.1 value. Checking them by hand on a fast-track renovation is where reviews get rushed.

Monteith Construction faced that on the UNC 7th Floor hospital renovation, a fast-schedule job with a heavy load of MEP submittals. Project Manager Daniel Recktenwald ran product data submittals through BuildSync inside Procore and reports spending 70% less time reviewing them, as described in the Blueprints to Bedside case study. On a grilles and diffusers submittal, BuildSync flagged fins oriented the wrong direction, a detail he doubted anyone else would have caught.

That's the job BuildSync does on an ASHRAE 170 submittal. It breaks the package down by tag, extracts each technical characteristic, and checks it against plans and specs. When the schedule and spec disagree, both values are flagged with the more stringent one noted, which gives you the basis for an RFI. Every determination links to the source pages, so you can verify before you trust. BuildSync reviews product data submittals; it doesn't review shop drawings.

Skepticism about AI on hospital work is reasonable when a missed value can cost a commissioning failure, and every rejected submittal already averages $805. The fair test is your own hardest package.

When asked how healthcare GCs use BuildSync differently on fast-track hospital renovations compared with office or school projects, Tom Port, the co-founder of BuildSync, says:

"It's critical that submittals are correct on all projects, but especially in healthcare, where even small discrepancies can have serious consequences.

Compared to an office or school project, healthcare facilities have much stricter requirements around ventilation, filtration, and air pressure, which makes the review process more complex. We pride ourselves on making sure these niche details aren't overlooked."

For more context, see how mechanical subs put together an HVAC submittal package, the BuildSync guide to hospital submittal review, and how Division 23 HVAC spec sections are organized.

Try BuildSync free on your most complex hospital mechanical submittal, or book a demo to see it working inside your Procore workflow.