Figure 1. Good insulating practices for cold
Most people considering the renovation or building of a
new home are unaware that
Building Codes are minimum requirements created to
reduce the probability that someone would be injured or
become ill while occupying the dwelling. However, for
those living in Canada, the Federal Government along
with its Provincial partners have started to enforce the
National Energy Code of Canada for Buildings 2015 (NECB)
which address some of the inadequacies of the
National Building Code of Canada. This can affect
new construction starting after the fall of 2016
depending on your jurisdiction. To provide guidance for
new designs we recommended the following insulation
values below. The consequence of using less than these
values can be a life time penalty in thermal and
electrical energy to mitigate the frequent complaints of
thermal discomfort experienced in Code built buildings
with Code minimum HVAC systems.
The illustration above is considered good
practice - not "best practice" and not "bad practice"
but "good practice". The NECB may require more
insulation in some cases. Going less moves you towards bad,
adding more moves you towards best. Keep in mind the
more wood and windows you add to the wall the lower the
net R-value. Translation: an R-20 wall constructed with
20% wood is more like an R-12 wall. That R-12 wall
quickly becomes an R-6 or R-8 wall (or lower) if it is mostly
windows. For mostly window walls see below. For more on this topic see our discussion on
thermal bridging and mean radiant temperatures.
So what type of enclosure insulation do we like?
For under slabs: Type 3 or 4 extruded
For walls cavities: cellulose or
blown in blanket
For exterior wall surfaces: stone
wool / rockwool
For attics: cellulose
Cantilevered and joist headers: high
density spray foam
Here's a window
specification if you have lots of glass exposed to sun
without exterior shading such as roll down solar blinds.
Figure 2. Window specification for lots
of glass in cold climates.
See building orientation.
Here's how triple pane low-e 366 windows perform
Figure 3. Keeping the bad stuff out and
the good stuff in when you want the million dollar view
but don't want to overheat (as much as possible). Image
credit: Cardinal Glass
Let's draw your attention to the bottom
axis and make note of the term "UV", "Visible" and "NIR
Light". UV is ultra violet radiation and causes
degradation of materials of construction including
fading, particulate generation and off gassing from such
things as interior finishes. Visible is light radiation
you sense with your eyes in the form of colours. NIR
Light is near infrared radiation sensed as heat. The
Low-e 366 glass keeps some of the bad UV light out, most
of the visible light in and most of the heat generating
radiation out. If you live in a cold climate and have
low window to wall ratio's (WWR <20%) and flexible or
adaptable exterior solar shading you may want to
consider a glass with a higher solar heat gain
coefficient - but if you have lots of glass (>30% WWR)
then to prevent summertime overheating you'll want to
keep the heat out.
Learn more about radiation.
The consequences of
ignoring glass specifications: Discomfort
Figure 4. Window Pain (pun intended) -
are you prepared to suffer? Image credit: Cardinal Glass
Cardinal Glass have a energy calculator
and modeller for hours of discomfort based on window
performance. Now it comes with some caveats but you get
the picture...using our window specification in Figure 2
and comparing it to three other cases you can see it it
has the highest probability of creating a space which
results in the lowest amount of hours of discomfort.
Final remarks: this is the type of stuff
we do to help you build the best home you can
afford...but you need to
work with us before you hire your architect or have
given your plans to your builders and their sub-trades.
Once its in their hands and everything is on order
there's not much we can do to help you.