Concentration of CO2 in the Atmosphere

AeroBarrier Case Study: Lower Level of Brick Church, ca 1869

Nate Gusakov

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

The lower level of this former Methodist church is being used for offices. Air leakage was reduced by 87% using AeroBarrier. Courtesy photo.

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 (just like mini snowmaking guns) and the introduction of a fine mist of aerosolized, water-based acrylic sealant. From there, much like a balloon with pin holes in it, 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 the needle drop 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 the lower level of the new home of Paragon Digital, a digital marketing firm in Keene, NH. Originally built in 1869, the building was a Methodist church and remains a striking landmark.

This phase of the project involves partial renovation of the lower level of the church (approximately 3800 sq. ft.). The space will be used for offices, so the required ventilation (per ASHRAE 62.1 standards) is only 350 CFM (~0.62 ACH50). After discussions with the owner, we established an air-leakage target of 1 ACH50 (~670 CFM). Previous to our arrival, dense-pack cellulose insulation was added to the floor below and ceiling above and care was taken to ensure as complete a separation as possible between the lower level and the cathedral space above. (In order for AeroBarrier installation to be efficient and cost-effective, there must be no gaps larger than ½-inch across in the building envelope to be sealed). Knowing this beforehand, the owner was able to pay attention to the detailing as the new space was defined.

After covering the hardwood floor with red rosin paper (it is made of 100% recycled paper—it’s a great easy-down, easy-up floor protection) and protecting the few fixtures and appliances that remained in the space, we installed a blower door and depressurized the lower level while checking for large leaks with our theatrical fog machine. This guided diagnosis revealed a couple of large leakage pathways. One was through an interior wall separating the space from a mechanical shed (somewhat unexpected), and one through the ceiling into the space under the altar above, where it had been much harder to install the cellulose insulation (as predicted by the owner). We were able to address the mechanical shed wall manually; the space under the altar between floors was for AeroBarrier to deal with.

The lower-level building envelope measured 7.94 ACH50 (5478 CFM50) when we started installing AeroBarrier, and a little less than four hours later we achieved our target. Final testing measured the air-leakage at 709 CFM50 (1.03 ACH50). We had achieved an 87% reduction in air leakage, and the owner was ready to continue with the renovations the next day!

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.


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