Why Airtight Building Envelopes are the Key to Future Home Construction

AeroBarrier Canada ?is a Silver Sponsor Member of?CHBA’s Net Zero Council . The Council and its sponsors share a commitment to innovation and high‐performance housing solutions, and sponsors bring significant knowledge or capabilities to the Council in specialized areas important to the advancement of Net Zero Energy housing.

Air leakage in the envelope of a home (exterior walls, below grade walls, slab, ceiling, and windows/doors) can be a major source of heat loss and other problems. According to Natural Resources Canada , air leakage represents about 20-30% of heat lost in older homes. This uncontrolled airflow leads to drafty homes that don’t maintain consistent comfort from room to room (such as uneven temperatures and humidity) and use more energy to heat and cool than needed. Moisture, which can lead to mould, allergens such as pollen and dust, pests, smells, and sounds also find their way into a home through these cracks and holes, negatively impacting occupant comfort, indoor air quality, and durability of the home.

Sealing these air leaks is one of the more complicated aspects of building or renovating a home, leading to inconsistent airtightness, longer build/renovation times, and higher costs for the builder/renovator – which ultimately get passed on to the home buyer/owner.

Net Zero and Net Zero Ready Homes are designed for energy efficiency first - meaning the building envelope insulation and airtightness reduces the size of the mechanicals and how often they need to run. These highly efficient mechanical systems will use a very modest amount of energy, which means you need fewer PV panels.

As the residential construction industry continues to move toward higher performance homes, including the CHBA Net Zero Home Labelling Program with both Net Zero and Net Zero Ready levels of energy performance, improving the building envelope yields the greatest benefits – with airtightness being the biggest hurdle to achieving that goal. An airtightness of 1.5 ACH50 or less is needed for detached and 2.0 ACH50 for attached Net Zero and Net Zero Ready Homes, which can be challenging for some builders and renovators to achieve.

Why can it be challenging for some builders and renovators to reach these levels of airtightness in their homes?

With multiple subcontractors who complete various aspects of air sealing (plumbers, electricians, drywall, framing, and insulation – and considering the turnover of these crews), and multiple materials as well as the various construction methods used, the leaks are hard to find. It’s time consuming, and air sealing requires a lot of “attention to detail” that’s easy to miss when manual air sealing is done, leading to inconsistent results. Additional time and effort, and therefore cost, is needed to be able to consistently achieve 1.5 ACH or better.

AeroBarrier is a simpler, more effective building envelope air sealing solution that is automated, done in a single step by one subcontractor, and guarantees that a home will meet its air tightness goal. Consistently tighter building envelopes are achieved, verified and documented air sealing results are provided, and no construction schedule or sequence changes are needed. In fact, it greatly reduces the time needed for air sealing, yielding shorter build times. Costs are reduced since less materials and labour are needed.

The AeroBarrier system operates on the very simple principal that air at higher pressure naturally moves towards lower pressure. AeroBarrier sealing stations are placed at a few locations inside the home, the interior is then pressurized using a blower door, an atomized sealant is then sprayed into the interior from the sealing stations in a mist, and the sealant simply follows the air moving towards lower pressure outside of the home through leaks in the building envelope and seals those leaks as it passes through them. Air leaks as small as the thickness of a human hair up to ?” in size are sealed, many of which can’t even be seen.

The entire process is controlled from a laptop computer, into which the airtightness goal is input. Progress toward the goal is reported every 60 seconds. Very little to no manual air sealing is needed, and the whole process takes approximately 90 minutes. 30 minutes later work by other trades can resume. When the air sealing is complete, an Envelope Sealing Report is generated, verifying that the air tightness goal has been achieved.

AeroBarrier has been adopted by leading builders across Canada and the USA for both their single family and multi-family projects. For more insight on how builders can meet home buyers’ expectations by providing a path to Net Zero and Net Zero Ready on a production scale without compromising construction schedules or increasing costs, CHBA members can view the Net Zero webinar “Shifting to Net Zero and Net Zero Ready at Scale,” presented by Brian Cooke, Sales and Marketing Manager of AeroBarrier Canada .

The webinar recording and slide deck can be found at?chba.ca/nzwebinars .