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Advanced Blower Door Techniques
North Carolina Energy Star Conference Friday November 16, 2007
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• Is that unconditioned attic connected to the conditioned basement?
Is that nasty crawl space inside or outside the house?
Is that air blasting through the register a leak to the outside or a disconnected duct in the basement?
Learn how to perform the pressure measurements, and more importantly, how to interpret them and understand the implications for air sealing or indoor air quality.
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Objectives• Learn to use your blower door more effectively
and to improve your air sealing work• Find out how to use pressure diagnostics to
locate thermal bypasses and building connections
• Discover multiple ways of determining air sealing potential, from using basic charts to using computer software and handheld calculators
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Use Your Blower Door to do more
– Where the air barrier (PRESSURE BOUNDARY) is so we can determine where to air seal
– If the Pressure Boundary and insulation (THERMAL BOUNDARY) line up
– Are zones with poor air quality such as Garages connected to the indoors
– Is warm moist air getting into the cold Attic
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Zone Testing
• “Pressure Diagnostics” = Zone Testing
• What are Zones?• Spaces that might be better connected to
Inside or Outside
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ZONE TYPEScan you tell what determines type?
Interior WallAttached Porch
Porch CeilingCrawlspace
SoffitsGarage
Floor Cavity b/w Floors Basement
CantileversAttic
Secondary ZonesPrimary Zones
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Zone Types• Primary Zones
– Are zones that have an opening in one of the surfaces• House to Zone or Zone to Outside• This is an advantage for testing
• Secondary Zones– Do not have an access in either surface
• Only Direct Pressure measurements can be taken
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Levels of Zone Testing
• Level 1 – Direct Pressure Measurement (Review)
• Level 2 – Charts and Graphs (Walk away able to do this )
• Level 3 – ZPD Calculators (Will do some examples)
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Level 1 Pressure Only
• Is the zone more indoors or more outdoors?
• Do Pressure and Thermal Boundaries line up?
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• The Pressure Boundary and Thermal Boundarymust be together and continuous.
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• If the boundaries are misaligned or If there are holes,voids or gaps this will make the building difficult to heat and cool.
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Outside Zones and Inside Zones Measured with Reference to House
We want Zones Outside the House(Unheated Areas) to be closer to 50
We want Zones Inside the House(Heated Areas) be closer to 0
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Examples of Outside & Inside Zones
Outside Zones(Unheated)
Attics
Garage
Porches
Crawlspace
Basement
Inside Zones(Heated)
Interior Walls
Floors Between Stories
Crawlspace
Basement
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WRT With Reference To• Zone WRT House = 40PA• Zone WRT Outside = ___PA
• Zone WRT House = 15PA• Zone WRT Outside = ___PA
• Zone WRT House = 25PA• Zone WRT Outside _______PA
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Let’s Do Some Level 1!
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Kneewall Attic
Unsealed/Uninsulated
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Interconnection• Depressurize house to 50 Pa
• Measure pressure to one zone
• Open a door to the other zone, readjust blower door to read 50 again
• If the zones are connected, the pressure in the first zone will change, If not, it won’t
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Pressures and LeakageAttic Zonal Reading of 25paMeans hole between Attic and House is Same size as Hole Between Attic and Outdoors
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Pressures and LeakageAttic Zonal Reading of 48paMeans hole between Attic and House is 1/8th size of Hole Between Attic and Outdoors
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Ratios of Pressures to LeakageZone Pressures Relative Size of Leaks
Zone-House Zone-Out Zone-House Zone-Out
12 38 2 1 25 25 1 1 37 13 ½ 1 41 9 1/3 1 45 5 ¼ 1 48 2 1/8 1 49 1 1/13 1
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Level 2 Charts and Graphs
– Zone with an opening
– Can calculate square inches leakage of both barriers
– Can calculate the leakage through the zone (available CFM50 reduction) Total Path Leakage
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Total Path Leakage
• The CFM50 that describes how much air will go through the two barriers
• Always less than the tightest barrier
• Identifies potential for reduction in house CFM50
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Add a Hole
• Depressurize house to 50 Pa, measure house-zone and zone-out
• Make a hole in one of the barriers• Adjust fan to keep 50 Pa, measure pressures• Use Chart or software to get CFM50 of either
barrier
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Open a Door (Flow Method)• Depressurize house to 50 Pa, measure house
CFM50, house-zone and/or zone-out
• Open a door with highest pressure difference across it (tightest air barrier)
• Measure new house CFM50– Verify house-zone is near 0 and or zone-out 50
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New Charts for In-Field
• Garage Chart – You can always open a DOOR H/G or G/O
(makes this easier)
• Attic Chart– You can only open the hatch that is there (a bit
more tricky)
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Let’s Do Some Level 2!
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Give the Charts a Try! (Hand them out!)
• Attached garages– Quick– Easy– Important
• Attics– Sometimes Quick and Easy– Also Important
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Level 3 Software
– More Detailed calculations using Software or Handheld Calculator
– Test Can be automated with laptop computerand equipment
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Remeasure When You Think You’re Done
• Outside zones (attic, garage) should be much closer to 50 than when you started
• Inside zones (interior walls, chases, ducts) should be much closer to zero than when you started
• Zones that haven’t changed much in the right direction are opportunities for further improvement
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Limitations/Cautions
• Don’t attribute much meaning to measurements between 47 & 50– Small errors in measuring may generate large
errors in the result– Don’t assume attic is OK because pressure is 48– Can seal zone-exterior (attic vents) to get
numbers into a better range– Read small pressure
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Limitations/Cautions
• Re-check unusual measurements– “If a number is unbelievable, don’t believe it!”– Disconnected, misplaced or pinched hoses– Unknown fans– Mis-read gauges
• Its best to be able to get 50 Pascal before and after adding a hole
• Zone Connections can give exaggerated numbers in doing advanced on several zones, especially kneewalls
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Improving Accuracy• Take Baseline Measurements• Measure pressures directly; don’t subtract• Try to measure the smallest pressure
difference carefully• Do it again• For add-a-hole, try to add the hole to the
barrier with the largest pressure difference
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The End
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Are the zones where they are supposed to be??
If not we need to seal holes between inside and outside.
By sealing the holes we stop Air Leakage by making a PRESSURE BOUNDARY
Pressure Boundary (Air Block between Inside and Outside)
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Kitchen Soffit and Base Cabinetwere open to attic
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Soffit Open to Attic
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Kneewall Attic
Insulated/Air Sealed
Heated
Area
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Kneewall Attic
Insulated/Air Sealed
Unheated
Area
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Addition attic is open to Floor System between 1st
and 2nd Floors
(Can Look all the way through to Porch)
Unsheathed Kneewall where addition attic meets 2nd story
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Porch is Open to Upstairs and DownstairsExterior Walls
Porch is open to Floor System between 1st and 2nd
Floors
(Can Look all the way through to Attic above single story)
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Test Key AreasAttics, Side attics, Porch roofsGarages,Basements, CrawlspacesChases (plumb, elec, duct, chimney)Plumbing Access, Duct Location, Soffits
Keep It SimpleRecord basic pressure measurementsExplain bad pressure readings (ex 10 attic)Should take very little time (Bdoor is all ready up)
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Kneewall Attic
Unsealed/Uninsulated
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Kneewall Attic
Air Sealed/Uninsulated
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Kneewall Attic
Air Sealed/Insulated
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Snow melting because of bypasses in attic kneewall
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Interconnection• Depressurize house to 50 Pa
• Measure pressure to one zone
• Open a door to the other zone, readjust blower door to read 50 again
• If the zones are connected, the pressure in the first zone will change, If not, it won’t
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Ratios of Pressures to LeakageZone Pressures Relative Size of Leaks
Z o n e -H o u se Z o n e -O u t Z o n e -H o u se Z o n e -O u t
1 2 3 8 2 1 2 5 2 5 1 1 3 7 1 3 ½ 1 4 1 9 1 /3 1 4 5 5 ¼ 1 4 8 2 1 /8 1 4 9 1 1 /1 3 1
Bypasses
Ceiling Soffit
GableRoof
Attic Zone – Leakage paths and Surfaces
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ATTICS
• In Mild to Southern Climates (e.g. No Ice Damns) Direct Pressure is sufficient.
• Look at venting to help guide you. – 48PA WRT House and not a lot of venting = good,
but if 48 and lot of venting still should check– 15PA = there are some major holes that need to be
dealt with
58Garage Wall to House
Ceiling
Exterior Garage Walls
Attached Garage Zone
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Garage
• Advanced Zonal Pressure Diagnostics are recommended – Open Door Method (Manual or with TI-86)– Hybrid Method (with ZPD Utility, PC, PDA,TI-86)
• Ideal to get below 20sq inches of Leakage between Garage and House
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Basic Procedure
• Measure pressure between the house and a zone, with the house depressurized to 50 Pa– Can close attic vents to get better numbers– Make sure to take baseline pressures– Is this zone in or out? A little or a lot?
• Quantify the leakage– Add a hole– Open a door– Estimate venting
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Add a Hole
• Depressurize house to 50 Pa, measure house-zone and zone-out
• Make a hole in one of the barriers• Adjust fan to keep 50 Pa, measure pressures• Use chart or software (TI-86) WX Ware) to get
CFM50 of either barrier
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Take initial direct pressure Reading
Follow up to Line 1 and over to left to find target Pressure
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Measure Size of Hole made in Square Inches
Open hole to zone enough to reach target pressure
while keeping Blower Door at 50PA
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Available CFM Reduction
Take initial direct pressure Reading
Follow up to Line 2 and over to right
Sq” size of Hole times Multiplier = available CFM50 Reduction
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Open a Door• Depressurize house to 50 Pa, measure house
CFM50, house-zone and/or zone-out
• Open a door with highest pressure difference across it (tightest air barrier)
• Measure new house CFM50– Verify house-zone is near 0 and or zone-out 50
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1
Saturn Resource Management
1
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Estimate Roof Venting
• With house at 50 Pa, measure house-zone and zone-out
• Estimate net free area of roof venting by visual inspection
• Use chart or software to get house-zone CFM50
• Usually the least accurate method, because difficult to estimate net free area
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Add a Hole, Low-Tech Version
• With house at 50, measure house-zone• Open a hole (attic hatch) just big enough to cut
the house-zone pressure in half– Keep house at 50
• The hole you added is roughly equal to the existing leakage
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Remeasure When You Think You’re Done
• Outside zones (attic, garage) should be much closer to 50 than when you started
• Inside zones (interior walls, chases, ducts) should be much closer to zero than when you started
• Zones that haven’t changed much in the right direction are opportunities for further improvement
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Limitations/Cautions
• Don’t attribute much meaning to measurements between 47 & 50– Small errors in measuring may generate large
errors in the result– Don’t assume attic is OK because pressure is 48– Can seal zone-exterior (attic vents) to get
numbers into a better range– Read small pressure
73
Limitations/Cautions
• Re-check unusual measurements– “If a number is unbelievable, don’t believe it!”– Disconnected, misplaced or pinched hoses– Unknown fans– Mis-read gauges
• Its best to be able to get 50 Pascal before and after adding a hole
• Zone Connections can give exaggerated numbers in doing advanced on several zones, especially kneewalls
74
Improving Accuracy• Measure pressures directly; don’t subtract• Try to measure the smallest pressure
difference carefully• Do it again• For add-a-hole, try to add the hole to the
barrier with the largest pressure difference
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New Zone Pressure Diagnostics • Study Completed by Center for Energy and
Environment, Michael Blasnik & Assoc. and the Energy Conservatory
• To test out how accurate the current tests are and when to use them
• Actually ended up creating a Hybrid method by combining Add a hole and Flow Method. To crosscheck and increase repeatability
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When to Do Advanced Zonal Pressure Diagnostic Testing
• Important to access amount of leakage for
– IAQ issues (How much Leakage between Garage, or Moldy crawlspace and house)
– Durability Issues (How much leakage of moist house air leaking into attic of cold climate house)
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New Zone Diagnostics
• Previously had programmed new hybrid method into a spreadsheet, and has now develop into a stand alone windows program, and currently developing for palm by The Energy Conservatory
• Rick Karg has added this to the TI-86 Calculator (Ziptest Pro2)
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ZPD Utility for PC• Available at
www.energyconservatory.com• Select Products link then click
on Software• Scroll to bottom of page to
download installation file
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• ZPD Study Available at Energy Center of Wisconsin website www.ecw.org
• To get directly to download page visit
http://www.ecw.org/ecw/productdetail.jsp?productId=384
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Reference Articles • Home Energy Magazine May/June 2002
– Zone Pressure Diagnostics
• Home Energy Magazine Sept/Oct 1994– User Friendly Pressure Diagnostics
– BOTH OF THESE ARE AVAILABLE AT www.homeenergy.org
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TECTITE & ZPD Utility• The ZPD Utility can be used with a handheld
manometer or by using TECTITE.• I use a form to collect data from TECTITE • Then am able quickly input data into ZPD Utility • TECTITE zone pressure info can be collected at
same time as multi-point blower door test.
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Summary of Work Flow (1)
• Find Primary Zones and Thermal Boundaries
• Infrared scan before Blower Door
• Initial Blower Door Reading
• Use Infrared Camera with Blower Door to locate air leakage paths
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Summary of Work Flow (2)• Direct ZPD for all Primary Zones
• Can use Pressure Ratio Chart to determine relative leakiness by estimating Net Free Area of Hole through one surface
• Direct Measurement on suspicious areas– Cantilevers, Soffits, Chases, Floor Cavities, Porches
• Check for Interconnections between zones
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Summary of Work Flow (3)
• Advanced ZPD for all Attached Garages and Crawlspaces with moisture/mold issues.
• Advanced ZPD for Attics in cold climate areas, especially for tight houses with high moisture
• Use Visual Clues and Smoke Puffer from inside zone to help locate leaks in Pressure Boundary
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Summary of Work Flow (4)• Where is Pressure Boundary,
– Is the Zone Inside or Outside
• Does it line up with Thermal Boundary
• Where should the Zone be and how will it be accomplished (Strategies for Air Sealing and Insulating)
• Explain recommendations to client (Mechanical, Air sealing, and Insulation)
– (e.g. leaving enclosed porch outside and insulating wall betweenthe house and the porch)
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Summary of Work Flow (5)
Do Intermediate Blower Door Test• Did Zone Pressures move toward right
direction– Exterior Zone closer to 50PA WRT House– Interior Zone closer to 0PA WRT House– Pressure Pans in outside zone less than
1.0PA
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Summary of Work Flow (6)
• Advanced ZPD to Measure remaining leakage to primary zones that were measured during the assessment
• Final Infrared Scan
• Take Final Blower Door Reading
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