While the building science behind Passive House construction can get complex, the core principles behind the methodology are relatively simple. There are five: continuous insulation, thermal-bridging-free detailing, superior windows, mechanical ventilation with heat recovery, and airtight construction. When all five are in place, the result is a quiet, efficient, comfortable, healthy, and durable building.
In this blog post, we’ll focus on the importance of airtightness:
We’ll also learn about Partel’s new line of airtight grommets, many of which have been phA certified.
The Role of Airtightness
Within the world of construction, airtightness refers to the barrier separating the outside from the conditioned (i.e., heated or cooled) interior. A building that is not airtight will have a barrier with holes, cracks, and gaps. Airtight construction methods strive to eliminate or at the very least minimize these openings. Consequently, within an airtight home conditioned air stays inside and unconditioned air remains outside of it.
While airtightness may not be flashy, it is the unsung hero of high-performance building and energy efficiency. Conversely, when a building is leaky because it has not been properly sealed, it leads to significant energy waste. In fact, air leaks are estimated to be responsible for almost 25% of final energy use by buildings in the United States.
You can learn more about airtightness here.
Airtightness in Passive House Construction
With Passive House construction, buildings are so airtight and well insulated that they remain comfortable with limited active heating or cooling measures. This translates into dramatically lower utility bills, even when outdoor temperatures are at their most extreme. Additionally, a combination of airtight construction and mechanical ventilation makes sure all the air that is allowed into the building first passes through a filtration system that keeps out allergens and dust, as well as bugs.
Airtight construction also contributes to the building’s indoor air quality and durability by providing moisture control, ensuring that wall assemblies remain free of mold, protected from the elements, and operating at peak performance.
Where Does Air Leakage Occur?
Virtually all modern homes are built with an airtight layer or barrier to minimize air leakage. When these airtight layers converge, they need to be sealed to ensure that the barrier is continuous. Unfortunately, conventional construction methods do not always prioritize sealing these junctions, resulting in leaks. Some of the most common junctions that are not properly sealed are where the walls and windows meet, where the walls and floors meet, and where the walls and roof meet.
