Blower Door Test

Summary

This video covers a blower door test used to verify the air tightness of a newly constructed home. Sean from Positive Energy explains how the test works by depressurizing the house and measuring air flow through a fan to determine air changes per hour (ACH). The home in question scored a 1.9 ACH, which is significantly better than the national and local codes. The video also discusses potential issues found during the test, like unsealed top plates and insulation barriers, and how the test can serve as a diagnostic tool to ensure proper construction practices.

Takeaways

• 🔧 The video discusses air tightness testing for homes using a blower door test.
• 💨 The blower door depressurizes the house to 50 Pascals to simulate 20 mph winds, assessing air leaks.
• 📊 A manometer is used to measure the pressure difference inside and outside the house during the test.
• 🏠 Air tightness is calculated using the home's volume and airflow, resulting in air changes per hour (ACH).
• 📏 National building codes require homes to meet an air tightness standard of 3 ACH at 50 Pascals.
• 🏆 The tested house achieved a score of 1.9 ACH, which is better than the national and local codes.
• 📉 Common areas of air leakage include unsealed penetrations in the top plates and holes cut into insulation.
• 🔎 The blower door test can diagnose air leaks caused by incomplete work from trades, improving energy efficiency.
• 👨‍🔧 Proper sealing and insulation are critical to reducing air changes per hour and enhancing a home's performance.
• 📚 Additional resources are available on Positive Energy’s website and the host’s blog for more details on air sealing and HVAC systems.

Q & A

What is the purpose of the blower door test?

The blower door test is used to verify the air tightness of a house. It helps determine if the house meets air tightness goals by measuring how much air is leaking through the building envelope.

How does the blower door test work?

The blower door test uses a fan to either pressurize or depressurize the house. In this case, the house is depressurized to simulate wind pressure, and the air flow through the fan is measured to determine air leakage.

What does 50 Pascal pressure difference simulate?

A 50 Pascal pressure difference simulates a 20 mile-per-hour wind pressing on all sides of the house, which helps measure how much air is leaking under those conditions.

What is the significance of the CFM measurement in the blower door test?

The CFM (cubic feet per minute) measurement shows the volume of air moving through the fan. It helps determine how much air is leaking through the house by measuring the air flow at 50 Pascals.

How is ACH (air changes per hour) calculated from the blower door test?

ACH is calculated by multiplying the CFM by 60 to get the air leakage per hour, and then dividing that by the volume of the home. This gives the number of times the air in the house is completely replaced per hour at 50 Pascals.

What is the national code for air changes per hour (ACH 50) according to the 2012 International Energy Conservation Code?

The national code for air changes per hour is 3 ACH 50, meaning the house should not exceed 3 air changes per hour at a 50 Pascal pressure difference.

What was the air tightness score of the house in this test?

The house scored 1.9 ACH 50, which is better than the national code requirement of 3 ACH 50 and the local Austin code of 5 ACH 50.

What compromises did the builder make that could have affected the air tightness score?

The builder used larger, more leaky windows and doors to take advantage of the lake views, which could have impacted the air tightness score. Despite this, the score of 1.9 ACH 50 was still very good.

How can a blower door test be used as a diagnostic tool?

A blower door test can help identify construction issues, such as improperly sealed penetrations or insulation gaps. It can show whether trades completed air sealing work correctly and help detect common mistakes like unsealed top plates or cut access holes.

What are some common mistakes found during blower door tests?

Common mistakes include unsealed penetrations in top plates and access holes cut into insulation without being properly sealed. These can significantly affect the air tightness of a house.