Sunday, 29 December 2013

Popsicle Stick House!

If only it was this easy!  A student builds a wonderful design from nothing but Popsicle sticks.

Building Popsicle Mansion Time Lapse HD

The interesting part is that he took the same amount of time to build the 1/24 scale model as I am budgeting for my build - 18 months

Should I be nervous?

Thursday, 19 December 2013

FPInnovations - Guide for Designing Energy-Efficient Building Enclosures

Whether you are designing single or multi-family dwellings, this Wood-Frame Multi-Unit Residential design guide  from FPInnovations is packed with valuable design information and the relevant science behind each design.

Sponsored in part by the Homeowner Protection Office and prepared by RDH Building Engineering, the 244 Page guide contains information on building energy efficient assemblies in various configurations including split insulation, double stud, mass timber, and wood frame infill.

While I chose to not build to any of these specific assemblies in my dwelling, my design still relies on the fundamental principles expressed and recommended in this guide.  I have also had the privilege of attending many of the lead author's (Graham Finch - RDH) building science courses and seminars over the last 3 years.  His knowledge and ability to disseminate the information in an understandable manner has helped me immensely in my ability to absorb and understand the key building science principles discussed throughout this guide, including the importance of assemblies that can perspire, as well as the importance and impact of reducing thermal bridging.

Whether building a code minimum house or going to the other extreme and building a Passive House, this guide has got something for you and should be part of your reference library.

I give it two thumps up!

Sunday, 15 December 2013

Corn Based Ethanol - Why?

Like the author of an article I just reviewed, I too question the logic of creating 'fuel' from food crops.  Why would we create an industry that takes food out of our mouths while at the same time most likely consumes more energy than it produces.

Alex Wilson of wrote in his article 'Ethanol Under Fire'

"Depending on whose study you believe, it either takes a little more or a little less energy to produce corn-based ethanol than that end-product contains. That EROI ratio ranges from 0.8:1 to 1.5:1, depending on the study."  "Any time the EROI is less than 1:1, it takes more energy to produce the fuel than the fuel contains. Even giving the ethanol industry the benefit of the doubt by assuming the actual EROI is 1.5:1, that means to produce a gallon of the fuel takes two-thirds of a gallon (equivalent) of fuel — diesel for tractors and combines on the farm, natural gas to produce nitrogen fertilizer, natural gas and electricity at the ethanol plant, and energy to ship that fuel around the country." "By comparison, the ethanol produced from sugar cane in Brazil has an EROI closer to 8:1 — for every gallon (equivalent) invested you get about eight gallons back out.
No matter whose numbers you believe, from an energy standpoint turning corn into ethanol to fuel our cars makes little sense."

Giving the politicians the benefit of the doubt (I know - extremely generous), they want to do the right thing! 

But we have to start focusing our resources and research in more intelligent ways, at least for the immediate future while we deal with the emergency on hand - Global Warming.  How much public funds has been misdirected and abused by research and subsidies on schema that will never result in a significant reduction in the burning of fuels that cause global warming (look at the hydrogen fuel cell as another great example)?  At this critical time, we need to concentrate on options that at least on paper have a significant chance of a healthy EROI. 

How much time have we lost going down these dead-end roads.  After all, time is of the essence if we have any chance of effecting the outcome!

Monday, 9 December 2013

It's All About The Air Barrier!

Building Science Corporation has just released their report (available here ) that confirms that if you give insulation a chance by air sealing the assembly, all insulation will perform the same from a thermal transfer stand point.

The report highlights the increasing level of importance attributed to getting the details right as you increase the performance of an assembly by adding more insulation. Loosing 10% of your nominal value when you have a R15 assembly is a lot less critical than when you have a R50 assembly.

In order to complete this study, BSC had to design and build a hot box that significantly improved upon past designs.  

Key improvements include the ability to: 
  • test higher R value enclosure assemblies (which have lower heat fluxes),
  • expose enclosure wall samples to realistic temperature differences while maintaining the interior temperature at normal room temperatures, and
  • measure the impact of imposed airflow at a given pressure difference across the specimen in both directions
This new and improved hot box was able to measure and confirm the effects of thermal bridging, the performance of insulation at various temperature gradients (for instance some polyisocyanurate insulations used in the TM Research Project exhibited a sharp increase in thermal conductivity - and decrease in Rvalue/in. - as temperatures approach and go below freezing), and the effects of air movement through part or all of the assemblies.

An interesting outcome of the air leakage measurements:

"Air leakage always increases the total heat flow through the building enclosure. However, air interacts with the materials in an assembly as it travels through. This interaction changes the temperature field in the assembly and through an assembly. The Thermal Metric wall test results provide strong evidence of the interaction between conductive and convective heat flows. This interaction results in heat exchange between the air and the materials inside the wall assembly and the total measured heat flow will be less than predicted by the commonly used discrete air leakage model"

Also of interest was the observation that "All of the reference test wall assemblies were subjected to significant temperature differences: up to 50°C or 90°F in the winter tests and up to 40°C or 72°F in the summer tests. Natural convective looping was not noted in any of the wall assemblies."

One of the most important confirmations for me was that "All wall assemblies experienced a loss in thermal performance due to air movement through the assembly. This is true for all of the assemblies tested regardless of the type of insulation material used (e.g. cellulose, fiberglass, ocSPF, ccSPF, XPS)".  With the failure of an effective air barrier that I typically see on spray foam jobs, this research helps to confirm that without an effective AB, even the might spray foam has diminishing thermal resistance. The report also confirmed "spray foam insulation only seal areas where the spray foam is installed; significant leakage paths often remain at wood to wood connections"  This confirms my conviction that spray foam is highly over rated.  If it does not guarantee an air tight assembly (see 3.6.4 on pg 102 of the report to see air barrier failures that occurred even in these lab conditions), why use it when there are cheaper products of lower environmental impact available?  I see attempting to use insulation as an air barrier as being just as foolish as attempting to use a poly vapour barrier to double as an air barrier.  Both products are hard pressed to represent an effective and durable air barrier.

Finally, it was interesting to note that they were able to measure the various resistance to air flow that different insulation represent. In 1.1 the report confirms that wet sprayed cellulose has more resistance to air movement over various fibreglass bat products.  It is too bad that they did not test mineral wool as it would be interesting to see how it compares to WPC.  Maybe next time!