You'll find fewer drafts in modern homes than in older constructions. That’s because in 2016, Michigan introduced a significant code requirement that transformed the way we assess the airtightness of homes: the blower door test. This test has become a pivotal standard in the construction industry, ensuring homes meet specific airtightness standards for energy efficiency, comfort, and sustainability.

What is a Blower Door Test and Why is it Required?

In simple terms, a blower door test is required as part of the state code to measure the amount of air that leaks in and out of a building. This standardized assessment is crucial in understanding a home's energy efficiency and how it performs in terms of retaining heated or cooled air. Essentially, it's a way to measure how much energy your home might be losing due to drafts and leaks. 

How Does a Blower Door Test Work?

The test involves fitting a powerful fan into an exterior doorway. This fan depressurizes the house, drawing air out and lowering the indoor air pressure. This creates a pressure difference between the inside and outside. A technician then uses a manometer to measure this pressure difference in pascals. The test quantifies the amount of air leakage at a standard pressure difference, usually at 50 pascals, hence the term ACH50, which stands for Air Changes per Hour at 50 Pascals.

What Do the Results Mean?

The results of a blower door test are expressed as the ACH50 value, indicating how many times per hour the entire volume of air within a house is replaced at a pressure difference of 50 pascals. The lower the ACH50 number, the tighter the home. Building code in Michigan requires 4 or less air changes per hour. In all of our homes we build we aim to achieve a value of 2 or less air changes per hour. For reference, older homes tend to have higher than 4 ACH50 values, indicating higher air exchange rates due to natural drafts and leaks.

Why is Airtightness Important?

Airtightness is crucial for several reasons. Firstly, it significantly impacts energy efficiency. A tightly sealed home retains heating and cooling, reducing energy consumption and costs. Secondly, it enhances indoor comfort by minimizing drafts and temperature variations. Lastly, an airtight home contributes to sustainability by reducing the carbon footprint associated with excessive energy use.

In Michigan, the blower door test has become a cornerstone in constructing energy-efficient and comfortable homes. Understanding its significance in measuring airtightness and energy efficiency helps homeowners and builders make informed decisions toward creating more sustainable living spaces.