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AeroBarrier Case Study: Multi-family Renovation without Mechanical Ventilation

Preparation of living room for Aerobarrier installation showing the nozzle set-up. Courtesy photo.

Nate Gusakov

This is the fifth article in this series highlighting our experiences installing AeroBarrier around New England. Here’s a quick refresher on the technology.

AeroBarrier is a patented building envelope sealing technology that simultaneously measures and seals building envelope air leaks. In a nutshell, the system involves pressurizing the building (to +100 Pascals) with a blower door, setting up a series of tripods with spray nozzles on them (similar to mini snowmaking guns) and introducing a fine mist of aerosolized water-based acrylic sealant. From there, the pressure drives the sealant to all the small cracks in the building and seals them up. During installation, we monitor the air leakage on our computer and watch as the various holes and cracks throughout the house are sealed. When we reach our leakage target, we turn off the machine, clear the air with a few fans and open windows and clean up. The space can be worked in again within about thirty minutes, and once cured, the sealant is a non-toxic, low-VOC substance that is GreenGuard Gold certified for use in schools and hospitals.

In this article we share our experiences air-sealing three connected units in Bristol, VT. The units were being completely renovated to serve as low-income housing, and the scope of the project included weatherization to maximize comfort and minimize heating and cooling utility bills. An interesting challenge for the project team was that because mechanical ventilation had not been specified for the renovations to the units, there was a risk of sealing them too tight—this would potentially have left the occupants without adequate fresh air, and also might have risked excessive humidity buildup during winter months when all the windows would be shut tight for the season. After performing ASHRAE calculations for required fresh air and factoring in some passive air inlets that were being installed, the team called for the units to be sealed to an airtightness measurement of 2.0 ACH50 – no more, no less. Because we are monitoring air leakage in real-time as we install, we were able to guarantee that we could bring the units to that target, without surpassing it and over-tightening the building envelopes.

Zone 6 onsite at Hunt Farm for Aerobarrier installation. Courtesy photo.

When installation time came for AeroBarrier, another challenge presented to us was that the units had been finished and carpeted ahead of schedule; this meant we would have to do an exacting and thorough job of covering horizontal finished surfaces to protect them from accumulating a thin film of AeroBarrier sealant. (The sealant leaves no lasting damage, but if that thin film cures on finished surfaces, it takes a fair amount of elbow grease to get them clean again.) Our crew took care to protect each unit thoroughly; wrapping appliances, laying adhesive carpet protection or rosin paper on finished floors, and covering fixtures. Once preparation was done, we set up and began our install. After one day of sealing, we had brought the three units to airtightness measurements of 1.95, 1.91, and 1.96 ACH50 respectively. Our ability to monitor leakage in real-time as we install enabled us to stop installation right at the target, ensuring maximum possible air-tightness for the units without over-sealing them.

Nate Gusakov is a Lead Installer for Zone 6 Energy. Zone 6 Energy is a home-grown Vermont company specializing in air leakage diagnostics and consulting. They offer commercial and residential blower-door testing, home energy audits, and AeroBarrier installations throughout New England and upstate New York. www.zone6energy.com

 

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