How Many Blower Door Fans Does It Take to Test a 26 Story Tower?

How Many Blower Door Fans Does It Take to Test a 26 Story Tower?

Passive House Certification of The House at Cornell Tech

Blower door test being completed on June 3, 2017

Ten? Nine? Eight? Seven? Six? Five? Four? Three? Two?

If it's the Certified Passive House at Cornell Tech? Just one.

This astonishing fact is one of the many aspects of Passive House that challenge the fundamentals of how we think about construction. Many images of blower door testing in big buildings include a veritable wall of fans and gnashing of teeth over complexity and cost - as if it's a mission to Mars. But with a successfully completed Passive House building - the blower door test need not be a NASA test flight.

In a Passive House, it's not the horsepower, it's the planning and execution.

certified passive house plaque

Admittedly, the blower door test of The House at Cornell Tech was quietly completed on June 3rd, 2017 by the project's Passive House consultants Steven Winter Associates, with Terry Brennan of Camroden Associates. Not only was just one fan needed to complete the task but while the airtightness required is a stringent 0.6 ACH50 - the testing resulted in an airtightness measured at just 0.13 ACH50 - more than four times less than the maximum limit allowed.

And with the final blower door successfully completed - the project was on a clear glide path to occupancy and final certification.

On October 17th, 2017 the Passive House Institute issued the official certification for the building. Called The House at Cornell Tech it has 352 units of housing for students and faculty and is fully occupied this fall semester.

Congratulations Cornell Tech team!

More congratulations are in order because, as this overview Designing and Building the World's Largest & Tallest Passive House Building by Handel Architects notes, the building was completed ahead of schedule and under budget!

Installing air and smart vapor control at Cornell Tech
Installing air and smart vapor control at Cornell Tech

475 is proud to have played a role - working with the architects, Passive House consultants, Monadnock Construction, Kevin Brennan of Brennan Brennan and all the other team members - in making a resilient and complete air barrier system with smart vapor control.

This system today, is now formulated with the INTELLO X membrane, and sealed with TESCON Vana, TESCON Profil and CONTEGA SOLIDO SL connecting tapes manufactured by Pro Clima.

From the foundation to the rooftop parapet, 26 stories above, absolute continuity was the objective. By avoiding common mistakes and with painstaking attention to all the details the effort was assured to pay off.


Passive House Certification of The House at Cornell Tech was the culmination of a journey that started with the 2012 RFP, developed in partnership between Hudson Companies and Related Companies.

The House at Cornell Tech continues to be the inspiration to corporations, institutions, and governments for the potential of deep energy efficiency that provides a better building for occupants, and moves us toward the post-carbon society we all so urgently need.