Friday, May 23, 2014

Super-Insulating a Basement?

We've just finished the foundation and basement of our little SuperGreen Laneway house.  This includes a "super-insulated" basement. 

Why do that you might ask?  

Additional perimeter R25 insulation on Insulated Concrete Form (ICF) basement ready for backfill.
We know from recent work by Mark Carver at NRCAN and Energy Solutions Centre on their cost optimization study that basement insulation has less bang-for-the-buck than above-grade wall insulation.  This makes sense because the temperature differential between inside versus cold winter air of the above grade wall is much higher than the basement to ground temperature differential.  Higher temperature differential means higher heat loss (which is why keeping your house cooler inside reduces heat loss).  

The challenge however with building a small SuperGreen home is the space.  Because of all the insulation, the walls get quite thick. This makes it hard to keep the home small and fit it on the property.  There are limitations to practically how much insulation you can install.  This leads you to find places that are convenient to stuff lots of insulation, but won't compromise the design of the building.  A common example of this is the ceiling.  When looking at where the heat loss in a house is, the ceiling/roof really is a small portion of the heat loss.
So why do we heap the insulation so high in the ceiling (i.e. R100 or more)?
Because it is a cheap and easy place to pile up a lot of insulation, even though its effectiveness is definitely on the upper end of the diminishing returns curve.
 
ICF Basement/foundation ready for concrete
In the SuperGreen homes we've built we've been using Insulated Concrete Forms, or ICF, foundation/basements.  This gives a very resilient concrete foundation below grade, but is relatively easy to build and and gives you and insulated concrete basement.  The standard ICF block we use have about 5.75" of expanded polystyrene insulation.  This gives about R26 (with no thermal bridging).  In our last building, we then used an interior stud wall with additional batt insulation to add another R22 (making the wall R48).


ICF Basement braced and ready for concrete.
The problem with insulating on the inside is it eats up floor space.  In small home, this is undesirable.  When designing our new SuperGreen Laneway home the light-bulb went on:  Why not insulate on the OUTSIDE of the basement.  A product called "Terrafoam HS-40" by Beaver Plastics (made in Alberta) is commonly being used now in the Yukon for below-grade insulation.  It is specifically designed for this perimeter insulation and sub-grade application. 

Eureka!  We found it - here is another place, much like ceilings, where we can stuff lots of insulation without taking up space.  Since this will all be buried outside of the building footprint, this this an easy place were we can put lots of insulation without affecting the design of the rest of the building.  Yes, it is an area on the upper-end of the diminishing returns curve.  But when you are pushing the energy-efficiency envelope, we need to find these low(er) hanging opportunities. 

So our design calls for 5" of HS-40 insulation outside of the ICF.  The manufacturer claims it is R-5 / inch at -10C.  (The weird thing they claim is its R-value goes up the colder it gets.  That's nice!)  So this gives an extra R25 ontop of the ICF's R26 for a total of R51 basement.  Not quite R60 of the walls above, but getting closer.

Once again pumping concrete OVER the "heritage" house to fill the ICF foundation.
Below is the footing detail that shows how the insulation is installed.  Note that the second 2" layer laps over the footing, insulating the footing too.  Now keen observers will note a thermal bridge in this design between the slab and the footing.  Yes, I know it is there, and for a variety of reasons (that I don't have the energy to describe), I designed it that way for this particular building.

Footing detail showing exterior EPS insulation around ICF basement.

 Below are a few additional pictures of the waterproofing and extra-insulation installation details.

Self-adhering waterproof membrane installed on ICF.  The membrane laps over footing and ties into the poly wrapping the footing as a capillary barrier.



1st and 2nd layers of exterior insulation being installed.  Note how second layer laps over the footing to insulate it. The little bits of Tuck Tape (red tape) are just there temporarily to hold the insulation in place.  Once it is backfilled against, the insulation won't be going anywhere.


Another view of the below-grade exterior insulation around the garage portion of the house, ready for backfill.  Note the interior PWF cripple wall to support the garage slab.  The stud-bays here too have been filled with 3.5" of EPS insulation. 

Monday, May 12, 2014

Where does the energy go in our next SuperGreen home?

In a previous post, I mentioned that we are trying to build the next Most Energy Efficient Home in the Yukon.  The construction of our little SuperGreen Laneway home is well underway with the basement being formed up today. 

In the planning of the project we do energy modelling to estimate building performance.  A program called HOT2000 is used, which a venerable, but well proven residential energy modelling software.  We know that the modelling is pretty close to actual performance, and in fact in the high-performance homes, we've documented that the modelling, if anything, OVER-estimates the amount of energy used.  

For the purposes of EnerGuide rating, a series of standardized assumptions are used (i.e. number of people in the homes, appliance and lights, amount of hot water used etc.)  These are like the standardized test conditions used for determining fuel economy in cars.  Although this may not represent how you use your home, how many people you have and how frugal you are with your showers, it does allow you to compare homes' performance apples-to-apples.

Based on these "standardized test conditions", our new SuperGreen Laneway house is predicted that it will use about $2,200/year in total energy (electricity) - this includes only $260/yr in heat!   And this is based on the latest (increased) electrical rates as of January 1st, 2014.



By comparison, the following graph is of an "average" existing Yukon home of equivalent size.  As you can see, the average home costs more than 3 times as much in energy costs.  What is even more astounding is the SuperGreen home costs using 95% LESS per year to heat!   Many will be shocked by how much it costs to heat the "average" home.  By average, this is the average heating requirement based on energy audits compiled by Yukon Housing Corp on 1703 homes.  So, a pretty comprehensive cross section of Yukon homes.

 

Note that the above graph does not represent a new house build in the City of Whitehorse (where the City's Green Building Standards apply)  or a home built to the current edition of the National Building Code of Canada.  For these new homes, the heating requirement would be about half of the average home shown above - or about $2,500 per year for a house of this size. 

Wednesday, May 7, 2014

Beginning construction of our new SuperGreen Home starts with destruction

Last week we started construction on our new SuperGreen laneway house.  But before we could start, we needed to remove the old "suite" that was occupying the back half of the lot.  The property (704 Wood St.) consists of the registered heritage "Hulland House" on the front of the lot, with an old, dilapidated garden suite in the back.  I think it was originally a tool shed that, in a very ad-hoc fashion, got made into a dwelling unit.  It was pretty rough. 




We'd been renting the garden suite out for a number of years at very modest rent because it was so small and "primitive".  What was interesting is almost all of our renters were very happy having a modest place to live.  That taught me that there is a need for modest, basic accommodation for folks, especially at various stages of their life (e.g. if they are young, moving around, on adventures, have had some bad luck, etc.).  But the place was VERY poorly built right from the start and it just got to the point where we were no longer comfortable renting it out.

Although I was proud to provide low cost, modest housing to my friends and community, I just didn't want it to get to the point where I was a slumlord.  Hence, we commenced this project to replace the shoddy garden suite with a modest but dignified, new laneway house.

Having a focus on sustainability, we sought to salvage as much as we could practically from this building.  I invited my extend (and thrifty) family over for a salvage weekend.  It's amazing how over 2hrs on a Saturday morning a house can be rendered totally non-livable.  It was like a band of Vikings razed the house.  Unfortunately, because the place was so shoddily constructed and built of scrap and misc. salvage originally, there was very little of value in the building.  I have quite a bit of project experience and knowledge with "architectural" salvage (residential or industrial)--what I know is that salvage/demolition diversion is a VERY hard thing to make viable & reasonable, especially in a small community like Whitehorse.

Note that as part of our LEED Canada for Homes project, we do not get any credit for salvaging the old building.  We did this just because we think it's the right thing to do. 


Here is what we DID manage to salvage/recycle.

  • All windows - not suitable for a new home, but would be used for a shed.
  • Front door - again, too bad condition for a new home, but taken for use as as shed.
  • Greenhouse glazing - again, not usable for new, but tenant hopes to use them for a new greenhouse.
  • Click flooring - for my parents cabin.
  • Stove - in rough shape, but picked up by a guy from Skagway for summer worker housing.
  • Fridge - again in rough shape, but donated to the local gaming club to make a "kegerator."
  • Kitchen sink - rough, but salvaged to be cleaned up for use in the new home's guest suite.
  • Toilet - was fairly new and High- Efficiency Toilet (HET) rated - can be used in new home.
  • Upper kitchen cabinets - again rough, but can be nailed to the wall in the new home's basement.
  • A bit of misc. hardware including towel bars, some screws, murets, rope, etc.
  • A bit of wood trim and some misc. dimensional lumber and relatively new plywood for backyard projects.
  • Exterior 2" XPS foam - will be incorporated as deep footing insulation as part of backfill in new home (better than landfilling it at the dump.)
  • Electric wall-mounted heater (donated to electrician in exchange for work.)
  • Electrical service mast, service wire and electrical panel - again old, but not too old and creative electrician felt he could use them for remote/temporary camps.
  •  About $7 in copper and brass.  The brass wasn't worth much.
  • About $5 in aluminum from the eavestrough and some of the flashing - check that stuff, some might be aluminum!
So overall, what did we salvage?  Maybe 10% by volume?


Not salvageable/ recyclable

  • Lower kitchen cabinets - crappy particle board, low quality and falling apart
  • Vanity & tub - dated, poor condition, nobody wanted it.
  • Not much copper - house had been plumbed with plastic
  • Wood siding - hoped to use if for kids playhouse, but it was all short salvaged pieces doubled nailed with BIG nails.  It all split and splintered when removed.  Probably fir.  Useless.
  • Dimensional lumber - again, no value.
  • The rest of the house.
When demolition time came, it was maybe four end-dump trailer-type loads went to the landfill.  It is amazing how fast it came down.  By noon the old garden suite was gone, but that was very slow because the work had to be done very carefully due to the low overhead electrical service at the back of the property.  It was quite interesting to watch (for all of 2 or 3 minutes) how carefully the excavator operator had to work to move each bucket load under the wire, then up, and into the dump truck.

My son and his cousin took the morning off school to watch the house smashing. How cool is that!  My brother took a timelaps video of the start of the demolition, but they started off doing a bit of site grubbing.  Although the real action only starts at the end, his video is only 50 seconds long.



video

My brother's cinematic commentary on this film:

"here is some time-laps footage of the little yellow house going down (and also a stump being pulled at the start). sadly the batteries in my camera were not fully charged this morning and it turned off mid demolition.  The dump trucks pulled up shortly after and blocked the view anyways. "