CABIN 1.2: BLOWER DOOR TEST 01

Blower door installation at test - 11.21.12

The results of the first blower door are back.  We measured the porosity of a fine meshed sieve.  

So what does this mean?

The question I wanted to know is what does the test mean in terms of ultimate outcome, the meaning of terms (Pa), air changes, etc.

The 2012 IECC  (International Energy Conservation Code) tests the thermal performance of the building envelope (R402.4) looking for a test pressure of 50 Pascals at a pressure of .2 in w.g. resulting in 3 air changes per hour at this climate zone (6B).

The US Army Corps of Engineers has tested recent buildings and has found the average building studied achieves a result of .25 CFM / SF air leakage of exterior envelope at 75 Pascals at a pressure of .3 w.g.

A pascal is the SI unit for pressure and is independent of ambient temperature, local gravity and media density.  1 pascal = .0001450377 psi.  Per an online conversion table 50 pa of pressure is roughly equivalent to a 21 mph wind.

The results of this particular test (see image below) are that I could not get the blower door to register 50 pa with the fan at highest speed.  Maximum Pa I could get was 31.0.  The second number on the meter should be relatively close to the square footage of the space being tested.  In the case of this little structure it should be around 715 - 720.  The meter reading is 7913,  So I am about 10 times draftier than I should be, and I should be able to achieve at least a 50 Pa reading when the retrofit is complete.

The results are not unexpected.

This information is really good to start with.  Something we as architects should know about early in a design process as we deal both with the art of our profession and the science of our profession.  This is the science part.

This will help inform the technical decisions that are coming quickly. 

Air barrier v. no air barrier?

What happens to the existing building materials - that have been around for 70 years that are dry and in great shape - when the envelope gets tightened up and possibly subject to more moisture?

When insulating the building and tightening the envelope what materials are most appropriate and constitute legitimate air and vapor barriers?

What is the most efficient insulating material?

The performance of the new windows will be what?

So I go to the cabin this morning to continue the demolition, exposure of the structure and the "cleansing" process.

CABIN 1.2: BLOWER DOOR TEST 01

Blower door installation at test - 11.21.12

The results of the first blower door are back.  We measured the porosity of a fine meshed sieve.  

So what does this mean?

The question I wanted to know is what does the test mean in terms of ultimate outcome, the meaning of terms (Pa), air changes, etc.

The 2012 IECC  (International Energy Conservation Code) tests the thermal performance of the building envelope (R402.4) looking for a test pressure of 50 Pascals at a pressure of .2 in w.g. resulting in 3 air changes per hour at this climate zone (6B).

The US Army Corps of Engineers has tested recent buildings and has found the average building studied achieves a result of .25 CFM / SF air leakage of exterior envelope at 75 Pascals at a pressure of .3 w.g.

A pascal is the SI unit for pressure and is independent of ambient temperature, local gravity and media density.  1 pascal = .0001450377 psi.  Per an online conversion table 50 pa of pressure is roughly equivalent to a 21 mph wind.

The results of this particular test (see image below) are that I could not get the blower door to register 50 pa with the fan at highest speed.  Maximum Pa I could get was 31.0.  The second number on the meter should be relatively close to the square footage of the space being tested.  In the case of this little structure it should be around 715 - 720.  The meter reading is 7913,  So I am about 10 times draftier than I should be, and I should be able to achieve at least a 50 Pa reading when the retrofit is complete.

The results are not unexpected.

This information is really good to start with.  Something we as architects should know about early in a design process as we deal both with the art of our profession and the science of our profession.  This is the science part.

This will help inform the technical decisions that are coming quickly. 

Air barrier v. no air barrier?

What happens to the existing building materials - that have been around for 70 years that are dry and in great shape - when the envelope gets tightened up and possibly subject to more moisture?

When insulating the building and tightening the envelope what materials are most appropriate and constitute legitimate air and vapor barriers?

What is the most efficient insulating material?

The performance of the new windows will be what?

So I go to the cabin this morning to continue the demolition, exposure of the structure and the "cleansing" process.

CABIN 1.1: ENERGY ANALYSIS

So after some removal of materials to expose the structure I now have a pretty clear idea of where to take the cabin rehabilitation.

The little cabin has minimal wall insulation, no floor insulation at the main area.  I'll verify any insulation if it exists in the Northern portion when I get through the floor sheathing.  The ceiling in the main area had R-30 batts in the ceiling.  The ceiling in the North portion had R-11 at best.

So I have registered the project with Energy Smart Colorado.  This will allow us to qualify for rebates and low interest loans for the thermal upgrades that will be made.  We start with a blower door test.  This will be interesting...it is like testing a fine mesh strainer for air tightness. 

The good news:  I'll be able to demonstrate significant thermal improvement when complete!

A remodel like this - as all are - is the balance between cost, thermal improvement and design. Us architect folk walk that balance beam every day of our lives.  It's fun!

My strategy for thermal improvement is rigid insulation.  I believe, short of in-situ sprayed poly iso foam (expensive) - the rigid insulation strategy will offer the most efficient thermal performance.  Why?...I have 2 x 6 floor joists, 2 x 4 and 2 x 6 roof joists at 24" oc and  I don't want wall furring any greater than 2 x 4's for space reclamation and use.  At R-5 per inch I can get an R-27+ floor with 5-1/2" of rigid and the same for the roof without re-building the structure of either assembly.   Simple.

My initial thermal calculations - if they are correct - using conservative heating degree day numbers for this region (Eagle County Airport and NOAA weather data) indicate with the revised thermal envelope I should be able to heat the cabin with $50 worth of gas per year.  I'm going to verify the calculations.

So the technical evaluation of the envelope begins.  I am modeling the performance using hand calculations and will attempt to translate those calculations into a zEPI (Zero Energy Performance Index) number soon.

CABIN 1.1: ENERGY ANALYSIS

So after some removal of materials to expose the structure I now have a pretty clear idea of where to take the cabin rehabilitation.

The little cabin has minimal wall insulation, no floor insulation at the main area.  I'll verify any insulation if it exists in the Northern portion when I get through the floor sheathing.  The ceiling in the main area had R-30 batts in the ceiling.  The ceiling in the North portion had R-11 at best.

So I have registered the project with Energy Smart Colorado.  This will allow us to qualify for rebates and low interest loans for the thermal upgrades that will be made.  We start with a blower door test.  This will be interesting...it is like testing a fine mesh strainer for air tightness. 

The good news:  I'll be able to demonstrate significant thermal improvement when complete!

A remodel like this - as all are - is the balance between cost, thermal improvement and design. Us architect folk walk that balance beam every day of our lives.  It's fun!

My strategy for thermal improvement is rigid insulation.  I believe, short of in-situ sprayed poly iso foam (expensive) - the rigid insulation strategy will offer the most efficient thermal performance.  Why?...I have 2 x 6 floor joists, 2 x 4 and 2 x 6 roof joists at 24" oc and  I don't want wall furring any greater than 2 x 4's for space reclamation and use.  At R-5 per inch I can get an R-27+ floor with 5-1/2" of rigid and the same for the roof without re-building the structure of either assembly.   Simple.

My initial thermal calculations - if they are correct - using conservative heating degree day numbers for this region (Eagle County Airport and NOAA weather data) indicate with the revised thermal envelope I should be able to heat the cabin with $50 worth of gas per year.  I'm going to verify the calculations.

So the technical evaluation of the envelope begins.  I am modeling the performance using hand calculations and will attempt to translate those calculations into a zEPI (Zero Energy Performance Index) number soon.

CABIN 1.0: CABINISM

CABINISM:  An architectural style I defined years ago when working on a cabin owned by my wife's family on Priest Lake, Idaho.  Generally used to describe a style of construction that was functional, resourceful and funky.  The construction techniques were forged out of practicality not necessarily high design or highly engineered and used materials that were readily available and sometimes cut directly from the forest. 

 We see and experience these styles a lot and sometimes describe them as cozy or quaint.  ...And, they seem to last a long time in spite of our critical code and construction knowledge.

So we start on the cabin.  This is a little toy of a structure - 750 + square feet in area.  It is fun.

Removed the drywall on the ceilings in the living room and bedroom this weekend.  In so doing revealed the original construction of the bedroom addition (date of addition unknown) - photo above.  It went right over the top of the existing roof - cabinism.

The roof at the bedroom requires some remedial work.  2 x 4's at 24" on center (o.c.) will not handle the snow loads we have here in Eagle.  Someone, apparently, realized this after the fact and installed a solitary 2 x 12 to assist the roof.  We'll fix that.

The removal of the drywall is intentional.  When I first walked in the space I knew the ceiling would be gabled - a quality of space issue.  This is too small a space to have flat ceilings.

As I remove the drywall I now go to figuring out the final revised framing strategies which includes final floor plans in order to determine the first phase of framing revisions and which are the most critical.  The revised framing in the bedroom is top on my list which will include extending a wall to the ceiling and a new beam on the other side.

And, as the framing and plan design goes on so does the technical evaluation of the envelope revisions to determine appropriate insulation, air barrier, and dew point calculations to get the building to perform well when complete.  The goal here is to consume as few resources in heating and cooling as possible.

One step at a time in the unheated, cold, drafty cabin.  Winter work...but good work.   

CABIN 1.0: CABINISM

CABINISM:  An architectural style I defined years ago when working on a cabin owned by my wife's family on Priest Lake, Idaho.  Generally used to describe a style of construction that was functional, resourceful and funky.  The construction techniques were forged out of practicality not necessarily high design or highly engineered and used materials that were readily available and sometimes cut directly from the forest. 

 We see and experience these styles a lot and sometimes describe them as cozy or quaint.  ...And, they seem to last a long time in spite of our critical code and construction knowledge.

So we start on the cabin.  This is a little toy of a structure - 750 + square feet in area.  It is fun.

Removed the drywall on the ceilings in the living room and bedroom this weekend.  In so doing revealed the original construction of the bedroom addition (date of addition unknown) - photo above.  It went right over the top of the existing roof - cabinism.

The roof at the bedroom requires some remedial work.  2 x 4's at 24" on center (o.c.) will not handle the snow loads we have here in Eagle.  Someone, apparently, realized this after the fact and installed a solitary 2 x 12 to assist the roof.  We'll fix that.

The removal of the drywall is intentional.  When I first walked in the space I knew the ceiling would be gabled - a quality of space issue.  This is too small a space to have flat ceilings.

As I remove the drywall I now go to figuring out the final revised framing strategies which includes final floor plans in order to determine the first phase of framing revisions and which are the most critical.  The revised framing in the bedroom is top on my list which will include extending a wall to the ceiling and a new beam on the other side.

And, as the framing and plan design goes on so does the technical evaluation of the envelope revisions to determine appropriate insulation, air barrier, and dew point calculations to get the building to perform well when complete.  The goal here is to consume as few resources in heating and cooling as possible.

One step at a time in the unheated, cold, drafty cabin.  Winter work...but good work.