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.

Outlines

00:00

🏠 Verifying Air Tightness with a Blower Door Test

The first paragraph introduces the purpose of the test being conducted: verifying the air tightness of a newly constructed house. The test, called a blower door test, is now mandatory under changing building codes. Sean from Positive Energy is here to perform the test, and they will walk through how it works and its importance in ensuring a home's airtight performance.

💨 How the Blower Door Test Works

Sean explains the basics of the blower door test. The device is essentially a fan with calibrated plates that measures airflow as the house is depressurized to 50 Pascals. A Pascal is described as a small pressure difference, simulating 20 mph winds pressing on all sides of the house. This helps measure how airtight the house is by blowing air out of the house.

📊 Measuring the Pressure and Airflow

Sean describes how the fan is used to measure the house's pressure difference. A hose measures pressure inside and outside the house, and once stabilized, they can read airflow through the fan. This airflow data is crucial in determining how much air is leaking from the house, measured in cubic feet per minute (CFM), and how it translates into the number of air changes per hour (ACH).

🔢 Interpreting the Test Results

The test results are discussed, showing that the house had 2,100 CFM at 50 Pascals. Sean explains how to convert this into a meaningful ACH number. By knowing the home's volume (63,000 cubic feet) and multiplying the airflow by 60 to get per-hour leakage, they calculate the air changes per hour (ACH). This is important as the ACH helps determine if the house meets energy conservation standards.

🏆 Achieving Better Than Code Standards

Matt shares the results, which show the house achieved a score of 1.9 ACH at 50 Pascals, significantly better than the national code requirement of 3 ACH based on the 2012 International Energy Conservation Code. Additionally, this score is 60% better than the local Austin standard of 5 ACH, even after making compromises for architectural reasons, such as larger windows facing scenic views.

🔍 Using the Blower Door Test as a Diagnostic Tool

Matt and Sean shift the conversation to how this test can be used diagnostically to spot mistakes during construction. One common issue is unsealed top plates where penetrations occur, leading to air leaks. Sean shares examples where tradespeople inadvertently leave access holes that cause significant air leakage, demonstrating how this test helps identify such problems.

🔨 Common Air Sealing Mistakes

Sean gives examples of frequent mistakes in air sealing, such as tradespeople cutting holes into insulation in the attic without sealing them, which can undermine the air barrier. These mistakes can lead to inefficiencies and make it harder to meet airtightness goals. Matt adds that repeated testing has helped him refine his process, aiming to achieve as close to 1 ACH 50 as possible.

📚 More Resources and Final Thoughts

Matt wraps up by thanking Sean for conducting the test and highlights resources for further information. He promotes Positive Energy’s website and podcast for more content about air sealing and HVAC systems. He also invites viewers to visit his blog and follow him on social media for updates and more insights on home building and energy efficiency.

Keywords

💡Air Tightness

Air tightness refers to how well a house is sealed against unwanted airflow between the inside and outside. In the video, air tightness is crucial because it helps maintain energy efficiency, indoor comfort, and prevents air leaks that can raise heating or cooling costs. The video focuses on testing the air tightness of a newly constructed home.

💡Blower Door Test

The blower door test is a method to measure the air tightness of a building. It involves using a fan to depressurize the house and then measuring how much air flows in or out. In the video, Sean uses a blower door test to verify how well-sealed the house is by creating a 50 Pascal pressure difference to simulate a 20 mph wind, helping identify areas where air leakage occurs.

💡Pascal

Pascal is a unit of pressure used to quantify force per unit area. In the context of the blower door test, Pascal measures the pressure difference between the inside and outside of the house. The video mentions that 50 Pascals of pressure difference simulate conditions where wind is blowing at 20 mph on all sides of the house, helping gauge the air tightness effectively.

💡CFM (Cubic Feet per Minute)

CFM is a measurement of airflow, indicating how many cubic feet of air pass through a space in one minute. In the blower door test, the CFM value is critical as it tells how much air is leaking from the house. The house in the video recorded 2,100 CFM at 50 Pascals, which helps determine how many air changes per hour occur.

💡ACH (Air Changes per Hour)

ACH stands for air changes per hour and measures how often the entire volume of air inside a building is replaced with outdoor air. The blower door test uses the house’s volume and airflow (CFM) to calculate ACH at 50 Pascals. In the video, the house achieved 1.9 ACH, which is better than both national and local building codes, indicating excellent air tightness.

💡Top Plates

Top plates are horizontal structural elements in a building's framework where walls meet the ceiling or roof. In the video, Sean highlights that improperly sealed penetrations in the top plates, such as holes for wiring, can lead to air leakage, compromising the building’s air tightness. Ensuring that top plates are well-sealed is important to avoid leaks that weaken the house’s energy efficiency.

💡Energy Codes

Energy codes are regulations that set minimum requirements for energy efficiency in buildings. In the video, Sean mentions the 2012 International Energy Conservation Code (IECC), which sets a standard of 3 ACH at 50 Pascals. The video emphasizes that meeting or exceeding these codes, such as achieving the 1.9 ACH result, ensures that the house is well-insulated and energy-efficient.

💡Depressurization

Depressurization involves lowering the air pressure inside a building relative to the outside. The blower door test in the video depressurizes the house by using a fan to remove air from the interior, creating a pressure difference that simulates windy conditions. This helps identify air leaks by observing how much outside air flows into the house to equalize the pressure.

💡Manometer

A manometer is a device used to measure pressure differences. In the video, Sean uses a manometer to gauge the pressure between the inside and outside of the house during the blower door test. The manometer’s readings help determine the level of depressurization and assess the amount of air leakage in the building.

💡Diagnostic Tool

A diagnostic tool helps identify problems or weaknesses in a system. In the video, the blower door test is used as a diagnostic tool to locate air leaks in the house, such as unsealed top plates or accidental penetrations in insulation. By pinpointing these issues, builders can improve the home’s air tightness and overall energy efficiency.

Highlights

Blower door test is used to measure the air tightness of a newly built home.

The blower door is a fan with calibrated plates to measure airflow when pressurizing or depressurizing the house.

The house is depressurized to 50 Pascals, simulating 20 mph winds on all sides of the house.

The CFM (cubic feet per minute) is measured to determine air leakage during the blower door test.

The airflow data, combined with the volume of the home, is used to calculate air changes per hour (ACH) at 50 Pascals.

The national code for air tightness based on the 2012 International Energy Conservation Code is 3 ACH at 50 Pascals.

In this test, the home achieved an air tightness of 1.9 ACH, which is 30% better than the national code and over 60% better than local codes.

Despite architectural compromises, such as larger windows and doors, the house achieved an impressive air tightness score.

Blower door tests can help identify construction mistakes, such as unsealed top plates or attic access holes in insulation.

One common issue found during testing is unsealed penetrations in the top plates, which can result in significant air leakage.

The blower door test can reveal both major and minor air leakage issues that could impact long-term energy efficiency.

Tradespeople sometimes leave unsealed openings in the insulation, such as cutting access holes into attics without resealing them.

Achieving air tightness close to 1 ACH at 50 Pascals is a high standard for energy-efficient homes.

Positive Energy offers resources, such as a podcast, to learn more about air sealing and HVAC systems.

The test provides a valuable diagnostic tool for homeowners and builders to ensure construction quality and energy efficiency.

Transcripts

it's test day we're verifying the air

tightness of his new home

we're talking air tightness today and

how to verify if the house you've just

completed actually met the air tightness

goals you know this test is called a

blower door test and it's become a lot

more important in recent years as the

codes have changed and required this

test here was Sean from positive-energy

Sean you're here to test and find out

how well this house did walk us through

the basics of what you're doing today

thanks Matt so this is a blower door

it's basically a fan that has these

calibrated plates on it so I know how

much air flow is moving through the fan

I then depressurize the house you can

pressurize or depressurize but I

depressurize the house and 250 Pascal's

and a Pascal is a very very small

pressure difference think like a PSI on

a car tire it's a fraction of that

gotcha

so that basically simulates 20 mile an

hour winds on all sides of the house at

once so in other words we're deep

pressurizing the house we're gonna be

blowing out of this door this is

actually the door to the carport on this

house and so we're gonna blow out and

depressurize the house correct correct

and then tell me about how you can find

out how leaky the house is based on

those fans measurements once I get to

the 50 Pascal measurement the pressure

measurement I I know that because I've

got a hose that's going to the outside

that's measuring the pressure outside

versus the pressure inside okay and once

that is stabilized I can then look at my

reading here which I entered this

manometer with the ring size and it

tells me how much air flow is moving

through the fan and that airflow number

I can then use that and the volume of

the home to determine how many air

changes per hour happen got it so this

fan is going to tell you a CFM number at

50 Pascal's of difference between the

inside and out and then how do you

translate that CFM number so we actually

ran the test a minute ago and we ended

up about 20 100 CFM at 50 Pascal's how

does that translate back to a number

that we can use based on code for ACH 50

yeah so I take the volume of the home

which in this case was about 63,000

cubic feet of air in this home okay and

I then look at the number of CFM that

actually is coming out of the home this

is CFM so it's cubic feet of air per

minute and the ACH number is an hourly

number so I need to multiply the CFM by

60 to get the

flipper our that goes out of the house

once I get that number I then divide

that into the volume of the home to

determine the air changes per hour at

the 50 Pascal test pressure got it so

code nationally right now based on the

2012 International Energy Conservation

code is three air changes per hour at 50

Pascal's how do we do on this out John

what was my test Mathieu actually scored

a one point nine one point nine that's

good so just to remind you code

nationally is three ACH fifty on the

current 2012 codes and here in Austin I

need to make a five ACH fifty so I'm

about thirty percent better than

national code over sixty percent better

than the local codes you know I had to

make a couple of compromises on this

house Sean based on the architecture and

the location we're in a spot facing the

lake we have some giant gorgeous views

we've got a couple of windows and doors

that are a little more leaky than I

would typically like to use but you know

I think a 1.94 is a really good score

considering some of the compromises we

made and that's of course much better

than is required in this area let's

change gears a little bit and say if we

would have had a higher score than code

what could that tell us about this house

and how could we use this as a

diagnostic tool the number one thing

that I'm looking for is making sure that

the trades did what they what you wanted

them to do one of the things I see

that's often missed are the top plates

where the all the penetrations go

through your top plate those things are

not sealed and that can you know death

by a thousand cuts that can lead to a

lot of issues later on tell me what

you've seen in terms of bigger mistakes

and houses that you've tested yeah Matt

sometimes I see where some trades needed

to get into a part of an attic and so

they just go ahead and cut an access

hole into the insulation and don't tell

anybody and now there's this four foot

by four foot hole in your air barrier

your insulation barrier everything yeah

that's that's a really good point Sean

and I think that this test can help you

find not only the big mistakes but as

you run this test for many years like I

have it's allowed me to really hone it

down I'm really looking to get as close

to one ACH 50 s I can on my houses and I

really appreciate you testing this house

and all my houses Sean for more

information visit positive energies

website they've got a great podcast

where they talk about air sealing and

HVAC systems all kinds of things when it

comes to

thing you can also visit my blog at

mattress here calm and of course I'd

love to have you follow me on Instagram

or Twitter we'll see you next time on

the build ship