Air Sealing: A Critical Player in Energy Efficiency

When we talk about energy efficiency, air sealing can't be ignored. It's not the flashiest player, often overlooked in favor of more visible strategies like insulation or efficient appliances. Yet its impact on a home's energy use and comfort is immense.

Air sealing, in essence, is about stopping unintended air movement in and out of our homes. It's about finding and plugging the leaks, the little gaps and cracks that can let heated or cooled air escape and unwanted outside air to infiltrate. These leaks can be surprisingly common, found around windows and doors, in attics and basements, or wherever building materials join together. And while each individual leak may be small, their cumulative effect can be significant, akin to leaving a window open all year round.

Why does air sealing matter? Firstly, uncontrolled air leaks can waste a significant amount of energy. In the winter, heated indoor air can escape through leaks, while in the summer, hot outside air can infiltrate. This forces our heating and cooling systems to work harder to maintain comfortable indoor temperatures, leading to higher energy use and costs.

Secondly, air leaks can compromise comfort. They can create cold drafts in winter and hot spots in summer, leading to uneven temperatures throughout the home. They can also allow the entry of outdoor noise, allergens, and pollutants, affecting indoor air quality.

Thirdly, air leaks can contribute to moisture problems. Moist air entering through leaks can condense within building assemblies, leading to issues like mold growth and structural damage.

So how do we tackle air sealing? The process usually involves two steps: identifying the leaks and then sealing them.

Detecting air leaks can be done in several ways. Some leaks can be found through a simple visual inspection. Others might require more sophisticated methods like a blower door test, which depressurizes the home and makes leaks easier to identify, or infrared thermography, which uses thermal imaging to show where air leaks are causing temperature differences.

Once the leaks have been identified, the next step is to seal them. This can be done with a variety of materials and methods, depending on the size and location of the leaks. Caulk can be used for sealing gaps and cracks less than 1/4-inch wide, while spray foam can be used for larger gaps. Weatherstripping can be used to seal leaks around movable building components like doors and windows. For larger areas, like an attic floor, a combination of air-sealing materials and insulation can be most effective.

Air sealing, like other energy efficiency strategies, should be approached holistically. It should be integrated with other measures like insulation, moisture control, and ventilation. In particular, as we make our homes more airtight, it becomes increasingly important to ensure adequate ventilation to maintain good indoor air quality.

By reducing uncontrolled air movement, it can significantly reduce energy use, improve comfort, and contribute to a healthier indoor environment. It's a powerful testament to the fact that in building science, every act matters, and the seemingly small steps can lead to big improvements in our homes' performance.