Understanding ASHRAE Standard 90.1-2019

Retrofit projects that meet building codes with vestibule exceptions.

Choose a commercial air curtain as a space-saving alternative to an expensive vestibule.

ASHRAE Standard 90.1-2019 has good news for building owners, retail store managers, and some engineers.
As everyone is aware, this standard includes the exception for a vestibule, with the inclusion of an AMCA-certified air curtain.

As most know, air curtains create a seal used to prevent contaminants, insects, and even air from moving from one space to another. These units are in proximity to the door; either just above, recessed into the ceiling, or even mounted vertically on the sides.

This seems like a no-brainer when considering the price of an air curtain compared to the vestibules, which need the extra set of doors, glass, framing support, etc. And not to forget the install-labor difference between the two.

The Air Movement and Control Association (AMCA) has conducted extensive research into the differences between single doors and vestibules. and doors with air curtains.

By setting up a methodology of airflow characteristics; net zero, infiltration, and exfiltration, they have further evaluated the effects of critical pressures, entrance orientation for different climates zones, and frequency of door use for the energy analysis.

As surprising as the results were, obviously in benefit of the installing air curtains – and the large amounts of energy saved, the data does allow us to see a bit into the future.

Once the building is commissioned and the HVAC system balanced, we tend to think that we can walk away and not have to worry about it – typically, until something breaks down.

But in today’s world, with a climate that could rapidly change from day to day, week to week, or even fluctuating building load capacity due to workplaces adopting hybrid schedules, balancing has gotten a bit more complicated.

The data supports that air curtains contribute even more in energy savings for unbalanced buildings.
Newer air curtains with smart temperature control and ‘ramp-up speed with varying traffic settings’ work well in this realm while still maintaining equipment performance.

End users should have peace of mind knowing that the data and experience are available when substituting vestibules for an air curtain in terms of ROI and performance.

The AMCA-certified units are tested. This ensures the manufacturer’s data has been double-checked and keeps all on a ‘leveled playing field’ when doing a comparison.



Schwank North America

Schwank is renowned for its high-efficiency products and cutting-edge technology; we are dedicated to our customers and creating an exceptional experience. As an industry leader, Schwank is in a prime position to expand into the HVAC market’s cooling and air movement side to offer smart climate comfort solutions to endure varying demanding conditions.

We stand by our claim to deliver products and services of the highest quality, performance, and efficiency, with ease of installation always top of mind. With Schwank, you rely on a premium, trusted manufacturer.

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