What Is a Blower Door Test? Energy Consulting Can Help You Pass

diagnostic tool used to measure how airtight or insulated a home is

As energy prices rise globally, the push for energy efficiency and conservation has never been greater. 

A major push by utility companies and the government is leading this trend to provide rebates and cash incentives for Energy Star equipment and retrofits that help conserve energy.  

Beyond this, many construction managers utilize numerous quality control and quality assurance measures to ensure that new homes are built sustainably and efficiently. 

One tool that’s become a popular part of new home inspections is the blower door test, which tells people how well-insulated their home is. 

The blower door test is also available for existing homes and commercial spaces to help individuals identify areas where they can save money with insulation. 

This guide will explain everything you need to know about the blower door test, how to interpret its results, and ways to improve your blower door scores. 

What Is a Blower Door Test?

A blower door test is a diagnostic tool used to measure how airtight or insulated a home is. The results can be used to determine how much air (i.e., cool air or heat) is leaking outside of your home and costing you money. 

The test is conducted by fitting a blower door to the frame of your front or back door. The blower door is equipped with a giant fan and motor in the middle, which sucks out air from your home and measures the difference in air pressure between the inside and outside of your home via digital gauges. 

The results are calculated by the amount of “air changes per hour” (ACH) or how often the fan recycles the air in your home over an hour-long period. 

In layman’s terms, the higher your ACH score–or the number of times air would be completely replaced in an hour-long period by outside air–the leakier your home is. ACH scores range from a value of 2-12 on average, with a lower number indicating a more insulated home. 

The test may also measure airflow in cubic feet per minute (CFM), which simply tells you how much air moved past the fan during the test. Generally, the higher the airflow in CFM, the leakier the home–although this is not always precise, which is why ACH is preferred. 

The Importance of the Blower Door Test

So, why should we care about air leakage in a home? 

Well, your home’s airtightness regulates several important factors that include:

  • How much heat will escape from your home in the winter
  • How much cool air will escape from your home in the summer
  • How many outdoor contaminants can enter your home via natural passages
  • How well can air condensate in your home

Understanding your home’s air tightness and insulation grade can help you choose the right heating and ventilation equipment to manage your home’s energy efficiency, humidity, and air quality. 

You can save money by improving your air tightness and enjoy cleaner air in your home. 

Understanding Blower Door Test Scores

There are two ways to interpret blower door test results, depending on your unit of measurement. 

Generally, we divide the following blower test scores by their ACH number to determine how leaky a home is:

  • 2-4 ACH: A tightly sealed home that would pass inspections in all 50 states. 
  • 5 ACH: A moderately sealed home., but still an ideal target for older homes that are harder to insulate. 
  • 6-9 ACH: A leaky home that generally needs improvements to pass an inspection in states with the requirement. 
  • 9-12 ACH or more: A very leaky home that requires extensive insulation work. 

On the other hand, if you use CFM to calculate your blower door test, the rule of thumb is to achieve a CFM below your square footage. So a 2000 sq. ft. home should generally aim for below 2000 CFM on their blower door test. 

Naturally, the lower your CFM, the better your air tightness.  

What States Require a Blower Door Test?

Blower door tests have become a popular tool for many states to help them meet individual energy initiatives and are required by some states in the post-construction phase to pass inspection. These states include:

  • New York
  • Michigan
  • Pennsylvania
  • Florida
  • Georgia 

Several other states actively encourage blower door testing and have contemplated measures to make them mandatory for new construction homes. 

Regardless, a blower door test is often a very effective tool to help promote energy efficiency for new or existing homes. It should be taken by all homeowners looking to save money on their energy bills. 

What Are the Biggest Sources of Air Leakage?

Many buildings fail or score high on their blower door test because there is a source of air leakage in their home, which is unsealed. 

Generally, the most common sources of air leakage in any home occur at or around:

  • Unsealed doorframes 
  • Old windows
  • Unsealed roofs
  • Fireplace inserts and open flues
  • Bath fans
  • Recessed light fixtures 
  • Vented heat appliances
  • Gaps between the foundation and wall framing

Sealing these sources of air leakage is the most surefire way to make your home more airtight and improve your blower door test to pass inspection. 

Ways an Energy Consultant Can Help You Improve Your Score 

Hiring an energy consultant during or after the construction process is a great idea for construction managers to proactively address any energy concerns and improve their blower door test.

An energy consultant will audit your HVAC equipment and airflow to determine any sources of leaks and where improvements can be made to existing equipment for savings. In some cases, switching from a vented water heater to an Energy Star electric pump could create tremendous savings.

An energy consultant can also offer a thermal inspection and provide ideas for additional insulation to prevent air leakages. 

The experts at Path Light Pro are equipped to handle any residential or commercial job and ensure your home or business is up to today’s energy standards. We provide energy audits that help you pass code-based inspections and ensure your home complies with all local and federal regulatory standards. 

Ultimately, we help you, and your customers save money and conserve more energy.