Online educational resource on achieving indoor environmental quality with radiant based HVAC systems
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Fundamentals of indoor environmental quality / thermal comfort and air quality solutions using radiant based HVAC

Figure 1. Good insulating practices for cold climate construction


Discussion

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 polystyrene insulation

  • 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

Discussion

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
 

Discussion

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.

 
 

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