Is "R-value" all you need to look at in order to get a high efficient house or a passive house?

The biggest trend in construction right now is designing and building highly efficient homes or even a "Passive House" to reduce our ecological footprint.  Most people understand a highly efficient home to simply have the highest R-value materials for insulation.  This is not really true.

As an example, a "Passive House" (considered the gold standard of high efficiency) does not require specific R-values. Instead it looks more at how much energy is used per square meter in a year for operating, heating and cooling the house. In order to achieve this standard a lot of other aspects need to be considered, such as passive solar design and landscape, window technology, airtightness, ventilation, space heating, lighting fixtures,  electrical appliances and insulation.
In other words, achieving this "Gold Standard" is not as simple as only looking at R-values.

The Canadian building code mainly considers R-values for insulation, which doesn't really tell you the whole truth about how efficient a building is.  Research has proven that a well built log home which only has an R-value of between 6 - 9 will have the same heating and cooling costs as a conventional 2"x6" stick framed and insulated building with an R-value of 22.  In fact, the Canadian building code will accept the R-value of a log house build with a 150 millimeter wide log or bigger.

How can a simple log with such a low R-value be as efficient as a 2"x6" insulated wall?
The answer is "Thermal mass"
In short, "Thermal mass" is the concept of "inertia" against temperature fluctuations.
For example, when outside temperatures are fluctuating throughout the day, a large thermal mass within the insulated portion of a house can serve to "flatten out" the daily temperature fluctuations, since the thermal mass will absorb thermal energy when the surroundings are higher in temperature than the mass, and give thermal energy back when the surroundings are cooler, without reaching thermal equilibrium. (this statement is from Wikipedia)

If we look at the Trappeur Homes wall design with the Bondu dovetail logs, we do have a very good thermal mass value due to the logs alone.  Further, we add 1.5 inches of wood fiber board inside the Bondu Logs which offers an additional high thermal mass value.  This 100% recycled wood-fibre board also provides additional insulation, acts as a wind breaker and becomes a complete thermal break (to avoid thermal bridging) between the log wall and inside framed wall.

Our standard wall system uses a 2"X4" inside framed wall and is rated at R-26 which is a bit more then a conventional 2"X6" stick framed and insulated wall at R-22.  With a 2"X6" inside framed wall our Trappeur Homes wall assembly is rated at R-34 (for those who want more).

Considering R-Values alone it appears there is not a big difference between our R-26 wall and a stick framed R-22 wall, but have a look at the diagram to the left showing the outside and inside surface temperature changes during the day.  The inside surface temperature stays very stable due to a very high heat protection value of 22.3 from the thermal mass giving us a temperature phase shift of 15.2 hours.

A similar chart on the right shows a conventional 2"X6" stick framed and insulated wall (R-22). The heat protection value is only 3.0 which gives  a temperature phase shift of only 5.5 hours leading to fast and significant inside surface temperature changes.  You can see the inside surface temperature is not very stable compared to the above diagram showing the Trappeur Homes wall system (Blue Line).
This explains how the thermal mass in a Trappeur Home helps it stay way cooler in the summer and makes it much more efficient than a conventional stick framed building.

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Research reference:
According to our interpretations of information from the Canadian Construction Materials Center and the Model National Energy Code (1997), a 150mm milled log wall need not comply with effective thermal resistance requirements, as trade off calculations for this type of log structure are permitted.

For purposes of trade off calculations, a 150mm milled log wall shall be taken as RSI = 1.3. Round Scribed log walls shall be taken as RSI = 2. SPF, (spruce, pine, fir) as the wood species.

For more complete information, please consult the:

Technical guide for Milled-log Buildings, report 13142 , Milled Log Houses report 13140 (5.2.1) and Model National Energy Code of Canada for Houses (1997) (3.3.1.2)
Canadian Construction Materials Center
Ottawa (Ontario)
Canada K1A 0R6

Other studies conducted in some northern states of the USA showed that R-values may be increased substantially to account for the thermal mass storage and thermal lag of solid wood walls.

In 1991, the NAHB (National Association of Home Builders) Research Center conducted a study for the LHC (Log Homes Council). This study showed that“ the thermal mass of log walls significantly reduces energy use for heating in cold climates. The study compared the actual energy use by eight log homes and eight well insulated foam houses during one winter. The houses were evenly divided between upstate New-York and Montana. The study also compared the home’s actual energy consumption. The results led to the conclusion that log homes are as energy efficient as frame houses, even though the average R-value of the log walls was 44 percent lower than the R-value of the frame walls.
More complete information is available in the:
Research Report on Energy Efficiency of Log Buildings published by the
Log Homes Council National Association of Home Builders
15th & M. Streets, N.W.
Washington, D.C. 20005
USA 

What does "Green" mean to you?

We have return home from the 2013 Green Building Conference which was held in Kimberley, BC.  This was a 2 day conference/expo with some very interesting workshops and exhibitors.

We started setting up our display earlier then anyone else due the simple fact of the size of our display wall.  We feel it is definitely worth investing this time as people really appreciate seeing how the "open wall" concept is put together and of course love touching the beautiful dovetails.  This time we finished much faster then we thought and then had the opportunity to attend the offered workshops on Friday afternoon.

Aaron attended "Air Leakage Testing and the Air Barrier System" to learn more about the importance of a well implemented air barrier and it's function in our "breathable or open wall" system.  Max was at Tang Lee's workshop "Innovations for Present and Future Green Buildings" and was very impressed by how simply and cheaply "Solar thermal" can be applied to any new or existing building.  We will create a post about this in more detail in the days to come.

As already stated, we had an excellent turnout, learned a lot, met a lot of new and exciting people and had a lot of tire/wall kickers.  (George Nickel from Innotech Windows even climbed our wall)

The focus of the "Green Building Conference" seemed to mostly be on high efficiency.  Highly efficient products and methods are great as over time a lot less energy has to go into heating or cooling the building.  We agree this is important but feel this is only one part of building green.  There seems to be this large push towards high efficiency without regard to the recyclability or biodegradability of these "green" products.  Is it more important to be efficient than recyclable?  We strongly feel that both are important.  Our landfills and oceans are overflowing with products that aren't recyclable or biodegradable.  We think that "Green Building" should stress highly efficient products and methods that are natural and/or recycled/recyclable and incorporate the sun's free and plentiful energy wherever possible.

The main lessons we learned from the conference and the key note speech is that there is a trend in the building industry to:

• improve the building envelope to be more efficient in order to cut down on burning fossil fuel
• create a healthier, more comfortable living environment (avoid mould growth within assembly)
• implement simple solar technologies to take advantage of the free energy from the sun

From the "Green Building Conference" standpoint, our TrappeurHomes.com wall system and Bondu Log Homes fit perfectly into the above mentioned building trends.  Stay tuned for our ideas of how some simple solar solutions can be added to our Trappeur Homes system.

TrappeurHomes and Bondu Log Homes are:

• Highly "Green" with only natural, recycled and biodegradable products used
• Very "Healthy" open or breathable wall concept (detailed post will follow) 
• Super "Efficient" Log wall assembly with high R-values and a very high heat protection value of 22.3 which gives us a temperature phase shift of 15.2 hours (more detail on this will follow)

Stay tuned to read more about what we have researched and how we are implementing this into today's construction.

TrappeurHomes.com at the Calgary Buildex with Bondu Log Homes

We just got back from the Buildex Calgary show.
Thank you to everybody visiting and presenting at the show. Aaron and I had a blast and this show was defiantly a big success for us. The Buildex is mostly for all professionals involved in Design, Build or Management of all types of buildings, which allowed us to introduce our new developed "Green", "Healthy" and supper efficient log wall system.
What really excited us the most is that we got confirmed that our wall system is right on the leading edge of what the new building code and regulations like to see for the future.
More details about the Buildex Calgary is at www.BuildexCalgary.com 

Our next show to present our demo wall is at the 2013 Green Building Conference in Kimberly Nov 8 & 9 2013 

Bondu Log Home as a cost efficient kit

After showing off all the benefits of the Bondu dovetail log wall system, the next question is how much all this will cost.  In short, if you compare apples to apples, our wall system (bear in mind that walls are only a small percentage of the whole construction) will cost about 15% - 20% more then a stick framed wall.

The main benefits are:

• Unique design and eye-catching look 
• Very fast assembly 
• R-26 with 2"x4" interior wall and  R-34 with 2"x6" interior wall
• No settling maintenance as the log wall virtually does not shrink
• Healthy living with "Breathable" or "Open Wall" TrappeurHomes.com concept and natural materials
• No maintenance on exterior finishes if you use Lifetime Preservative (Valhalla Wood Stain - click here for more details)
• Run electrical and mechanical in the 2"x4" or 2"x6" liner wall used for insulation
• Choose any interior finish from log finish to drywall or paneling. 

To get down to the money, we offer complete materials kits which will be delivered direct to your construction site ready to be assembled on your awaiting foundation or sub-floor. The square foot of living space will cost an average of about $60 - $65 and includes all the outside and inside walls and insulation, timber, trusses and roofing, windows and doors, 2nd floor and stairs, porch, decking and railings.
Please follow the link to see our Bondu Model Log Homes and contact us for detailed prices.

Offering kits does not mean we are restricted to our model homes.

Please feel free to contact us with your ideas and plans and we would be happy to price a custom package for you.

Aaron & Max

Open Wall or "Breathable" wall system

What is an "Open or Breathable" Wall System?

Breathing Walls offers practical alternatives to conventional modern building practices that keep homes airtight.  Walls built today are energy-efficient but cannot handle the inevitable intrusion of moisture, resulting in mold, ill health for occupants and structural damage.  Instead of "build tight, ventilate right," we say make your envelope "waterproof but vapor permeable."
We work with, not against, the forces of nature.

from www.BreathingWalls.com

"Build tight, ventilate right," is what we do today, but what if moisture gets into the wall due to water leakage, improperly sealed electrical outlets, holes in the wall from hanging pictures etc?  What happens to that moisture?  In a typical wall assembly any moisture that infiltrates the wall will become trapped by the poly and the building wrap.  The drying cycle can be very long and before the wall cavity can dry, mould and mildew have started to form in the insulation and on the wood studs.  Mould and mildew in walls is obviously not good for you or the structure of the building.

A good open wall concept is all about what materials you use in your wall assembly.  In short, it is about the vapour permeability of those materials, the amount of humidity that can be stored (temporarily) in them and insuring that how they are arranged does not create a dew-point within your wall assembly.

The dew-point is the temperature that will cause vapour in the air to condense into water droplets.  It's very important in any wall assembly to ensure that the temperature within the wall never reaches the dew-point not allowing condensation to occur.
The Glaser Diagram (opposite & in German) shows the dew-point (Taupunkt, in blue) is not even close to the actual temperature (in black) within the TrappeurHomes wall assembly.

Here is how we create our "open or breathable" wall:
(from left to right)

• 1”x12” white pine interior finishing or drywall
• ProClima Intello - Intelligent High-Performance Vapor Retarder 
• 2”x4” framed wall for Roxul batt insulation 
• 1.5” inch 100% recycled Wood Fiberboard Panel 
• 5” x 10” white pine Bondu dovetail logs (bearing wall)

The wood fibreboard and the pine log walls are natural materials that have a high moisture storage capacity and high vapour permeance.  If there is a bulk intrusion of vapour into the wall assembly, these materials can safely absorb it and allow it to escape to the outside.

In our opinion, the "open or breathable" wall assembly is a key component in designing and constructing today's healthy buildings.

How is the Bondu dovetail log wall insulated

How is the Bondu dovetail log wall insulated

The Bondu Logs are air dried for a minimum of two years before they are milled.  This creates two huge benefits.  First any bad checks, pitch or other defects can be graded out of the logs before final milling.  Secondly and the key to our whole wall system is dry logs don't shrink or settle like normal green logs.  The most settling we ever see is approx. 1/4" over a 9 foot high wall.  With virtually no shrinkage we can add an insulation layer to the inside of the wall without needing the typical complicated and labour intensive systems that normal log walls are "famous" for.

The Bondu Log Wall Assembly (from left to right)

• 5” x 10” white pine logs (bearing wall) with dovetail corners
• 1.5” T&G Recycled Wood Fiberboard Panelling (air barrier & complete thermal break)
• 2”x4” stud framed wall filled with batt insulation (non-load bearing = minimal framing materials)
• Vapor membrane
• 1”x12” white pine interior finishing or drywall

R-value 34
with 2”x6” interior wall (12.5” total wall width)

R-value 26
with 2'x4" interior wall (10.5" total wall width) 

The spaces between the logs are filled with batt insulation. We generally supply mineral wool batts as we like it's fire resistant qualities and natural raw materials.  We do not recommend to spray foam as we like to keep the wall assembly breathable which will avoid any chance of condensation and mildew. If you live in a very wet area and are concerned about rain water penetrating from the outside, we can supply a rain-guard membrane which gets applied to the inside of the log wall. It is important to keep the wall breathable to allow any moisture within the wall (for what ever reason) to be able to dry out and not get trapped.  After many years of experience and thoughtful research and with the backup from our engineering reports we highly recommend this insulation regime however if you prefer a different system we are open to discussing other options available to you.

How is a Bondu dovetail log wall put together

How is a Bondu dovetail log wall put together?

This is a very fun and exciting part of the overall construction. The precision milling helps the walls go together very quickly and accurately with most projects requiring less than a day to assemble all of the log walls.

The Bondu Logs get assembled like a Lego house with each log stacked on the previous log only resting on the dovetail at the corners and on keyway blocks along their length.  The design of the dovetails creates a 1 1/2" space between each row of logs.  This space is filled with batt insulation which is then covered by a trim board (slat).

This space really works in our favour in several ways.  It creates a look which accentuates the dovetail and allows the opportunity to use different stains or colours on the logs, the slats and the ends of the dovetails.  This makes a wide variety of style options available to our customers.  Another important benefit of this space is to act as a buffer for any movement that occurs in the logs over time.  If a log twists a little bit, the batt insulation simply expands or compresses slightly to compensate instead of a new gap opening up as is common with logs that are stacked tight together.  The third benefit is an increase in vapour permeability which makes it even easier for vapour trapped within the wall to escape to the outside.  Finally, the space means 15% less wood is needed for the log wall which reduces the cost.

The dovetail joint is very strong and as each row is added the logs beneath are locked in place by the geometry of the joint.  At all door and window openings, a dovetail keyway is machined into the ends of the logs and a dovetailed spline is driven vertically into the keyway locking all of the logs together.  This makes for a bullet proof wall assembly.  Our display wall is so solid that you can stand on top without it moving even a millimetre.  All of this is achieved with no nails or glue.  Awesome.