Aeroseal Global Patrick Rouleau & David Hardy – April 01 2019

A leaky duct network can lead to lots of headaches, the consequences of which can have an impact on occupants’ well-being, as well as energy costs, the environment, and equipment durability. To reach the desired balance within a building, it’s essential that ventilation ducts be airtight. The Aeroseal sealing process is as essential for property managers, engineers and architects as it is for building professionals who want to save money, improve their systems’ energy efficiency, and provide their buildings’ occupants with greater comfort.

The Big Deal with Tiny Holes

To better understand the scope of the issues that can be caused by leaky ducts, it’s important to be aware that very small holes—even those as little as 5/8 of an inch in size—can effectively add up to one huge hole. When this occurs, it can represent a huge risk of pressure imbalances and can lead to a variety of other problems, especially uneven temperatures; humidity issues; excessive energy use; the introduction of cold, dry air through the return air vent; and much more.

These leaks can also cause dust, allergens, mould, and bacteria to be introduced into the ducts. This phenomenon, known as the Venturi effect, is caused when a large volume of air moves from the bigger ducts—often those located closest to the HVAC system—toward narrower ducts, like those that distribute the air into individual rooms. The speed with which the air is projected into the narrower ducts increases naturally. When ducts are leaky, air outside of them is drawn into them by the movement of the air. This is the Venturi effect. As a result, every type of undesirable substance or particle can end up in the ducts, only to get distributed out to every room.

A Local Problem

In most Quebec homes and some buildings, supply ducts and the return air vent (which isn’t ducted) share the same wall cavity spaces that are comprised of structural components or floor joints. When those supply ducts are leaky, the heated and conditioned air first gets drawn in by the return-air wall cavities and is then sent back to the air handler; this process is called short cycling. The rest of the leaked air inside the wall cavities then simply doesn’t make its way back into the occupied spaces and instead gets extracted to the outside of the building envelope.

As a result, the thermostat isn’t even impacted by the energy that was expended, causing the HVAC equipment to work harder to reach the desired temperature. The closer a leak is to the central distribution device, the more of an impact it will have because of the high static pressure coming from the air handler. As a result, approximately 20% to 30% of treated or conditioned air never reaches its destination.

A Local Problem

In most Quebec homes and some buildings, supply ducts and the return air vent (which isn’t ducted) share the same wall cavity spaces that are comprised of structural components or floor joints. When those supply ducts are leaky, the heated and conditioned air first gets drawn in by the return-air wall cavities and is then sent back to the air handler; this process is called short cycling. The rest of the leaked air inside the wall cavities then simply doesn’t make its way back into the occupied spaces and instead gets extracted to the outside of the building envelope.

As a result, the thermostat isn’t even impacted by the energy that was expended, causing the HVAC equipment to work harder to reach the desired temperature. The closer a leak is to the central distribution device, the more of an impact it will have because of the high static pressure coming from the air handler. As a result, approximately 20% to 30% of treated or conditioned air never reaches its destination.

Significant Losses

From a financial perspective, this issue can represent $0.20 to $0.30 of each dollar on a cool/heating bill. That’s far too much! And those numbers don’t factor in the added burden this situation places on the HVAC system, which consequently has to increase production. The result: The system gets prematurely worn out. You might think that the energy that escapes stays inside because it’s still within the building envelope—but that’s not the case, because it never reaches the areas where it’s supposed to improve occupant comfort. According to a study conducted by the Center for Energy and Environment in Minneapolis, various types of buildings can derive considerable benefits from duct airtightness. The results indicate that Aeroseal allows for an average airtightness of 86%.

Collaboration between Aeroseal and the OHRN: Extremely Conclusive Results!

Aeroseal Global recently had the opportunity to demonstrate its innovative process as part of a joint project with the Office d’Habitation de Rimouski-Neigette (OHRN). Its mandate involved sealing ventilation ducts in four residential buildings in the municipalities of Saint-Fabien (15 dwellings), Saint-Anaclet (20 dwellings), Sainte-Blandine (20 dwellings) and Saint-Narcisse (13 dwellings)—the buildings in the latter two of which had recently had their systems redone. The OHRN noticed major issues, both in terms of air loss and delivery, as well as a major leak rate—which reached up to 63% in Saint-Narcisse! A variety of solutions had initially been envisioned: manual sealing of the accessible ducts and installation of new insulation, rebuilding of the entire network, and increases to the system’s heating capabilities. However, none of those options offered all the advantages that the Aeroseal process can.

Last August, a team of Aeroseal Global technicians visited the site to work on each of these buildings’ central ventilation systems. First, the ducts were inspected to detect major leaks and eliminate built-up dust and debris. The ventilation equipment was then insulated, the distribution grilles (for fresh air) and exhaust grilles (that expel

the stale air) were blocked, and the occupied areas were protected. Aeroseal sealant—a stable, non-toxic, non-flammable emulsion of water and vinyl acetate polymers—was sprayed throughout the duct system. The particles then gathered around leaks and formed a durable, resistant, airtight seal.

“This method is much less costly and time-consuming than the solutions that were initially considered, and is remarkably simple and effective,” explains Patrick Rouleau, Sales and Marketing Director at Aeroseal Global. In fact, the results speak for themselves: ductwork airtightness of between 75.7% and 88.9% was achieved for the distribution grilles (for fresh air), and between 74.4% to 97.5% for exhaust grilles (that expel the stale air)! In addition, the longest of the sealing operations took only just over an hour. “In the end, we were able to reach optimized ventilation, making the investments on renovations recoupable,” added Patrick Rouleau. How much did the operation cost? From $1.50 to $2.50 per CFM of ventilation-supply/return capacity (if ducted). The results of this process should also have a major impact on energy bills and comfort during the coldest months of the year.

By 2030, Quebec aims to lower its carbon footprint by becoming a leader in energy efficiency. That’s why the province has adopted an ambitious transition plan to meet this goal. A total of $501 million has already been announced to promote energy-efficient solutions. Recently Énergir recognized the Aeroseal process as part of its program encouraging the adoption of energy-efficient measures. In this context, Aeroseal Global is the perfect partner to help you seal your ducts and meet increasingly strict standards.

This article was written by David Hardy with the help & guidance of Patrick Rouleau. David Hardy is an up and coming writer that specializes in energy efficiency solutions for building mechanics. His drive is his passion to promote green construction techniques.

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