Blower Door Test
Summary
TLDRThis 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
- ๐ง The video discusses air tightness testing for homes using a blower door test.
- ๐จ The blower door depressurizes the house to 50 Pascals to simulate 20 mph winds, assessing air leaks.
- ๐ A manometer is used to measure the pressure difference inside and outside the house during the test.
- ๐ Air tightness is calculated using the home's volume and airflow, resulting in air changes per hour (ACH).
- ๐ National building codes require homes to meet an air tightness standard of 3 ACH at 50 Pascals.
- ๐ The tested house achieved a score of 1.9 ACH, which is better than the national and local codes.
- ๐ Common areas of air leakage include unsealed penetrations in the top plates and holes cut into insulation.
- ๐ The blower door test can diagnose air leaks caused by incomplete work from trades, improving energy efficiency.
- ๐จโ๐ง Proper sealing and insulation are critical to reducing air changes per hour and enhancing a home's performance.
- ๐ Additional resources are available on Positive Energyโs website and the hostโs 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
๐ 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.
๐จ 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.
๐ 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).
๐ข 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.
๐ 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.
๐ 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.
๐จ 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.
๐ More Resources and Final Thoughts
Matt wraps up by thanking Sean for conducting the test and highlights resources for further information. He promotes Positive Energyโs 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.
Mindmap
Keywords
๐กAir Tightness
๐กBlower Door Test
๐กPascal
๐กCFM (Cubic Feet per Minute)
๐กACH (Air Changes per Hour)
๐กTop Plates
๐กEnergy Codes
๐กDepressurization
๐กManometer
๐กDiagnostic Tool
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
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