Sealing the house (part 1)

Apart from “wrapping up” the house (see here for more on this concept), another fundamental element of an energy efficient building is how well sealed it is. Airtightness is one of the key concepts we have become rather obsessed with since we began designing our house. This refers to the uncontrolled flow of air through unwanted “openings” (gaps) in the building envelope. This leakage has an important impact on the energy performance of the house.

So how do you measure the impact of air movement through these often miniscule and invisible gaps?

The concept used is called “air renovations/hour” which measures the number of times the air in the building changes in the space of one hour. The average in Chile for this indicator is 12,9 renovations/hour across all types of houses (concrete, bricks, bricks and timber, timber). And if we zoom in on the specific building type that we are using (timber), the rate is 24,6 renovations/hour.

This means that in winter, while you are heating the air in the house with gas, paraffin or electricity, you have to heat “new air” approximately 13 or 25 times in one hour to maintain the warmth.

Conclusion: we are constantly losing the air we have spent money on to heat.

To give you a comparison, the Passivhaus Standard permits a value of 0,6 renovations/hour to be able to certify the building, no matter what material is used. That is 96% less than the Chilean average and 98% less than a wooden house in Chile. To date, and according to our knowledge, no house in Chile has reached this incredibly demanding number. The closest a house has come in Chile is 1,1 renovations/hour.

Current Chilean building regulations do not have a specific requirement relating to air infiltration, although the CEV standard incorporates the concept in its calculation and recommends reducing the infiltration level as much as possible.

So what is the solution to the airtightness challenge? Make sure the house is well sealed.

How? Achieving airtightness depends on the material used to build the house. In the case of a house made of wooden panels it is particularly important to seal the tiny cracks that are inevitable between panels. In a “business as usual” wooden house, these tiny cracks are hidden by the exterior siding and interior wall coverings, but this does not mean that the cracks are sealed and air filtration still occurs. To seal these gaps we investigated a number of options and finally decided on an adhesive membrane that is applied to the exterior of the house. We imported this membrane from a company, Proctor in Scotland.

It is like applying wallpaper, but to the outside of the house
Our bright red house from the air (Photo credit: Roberto Oliva)

We will write more on the properties of this membrane and the airtightness concept in future posts when we apply more insulation to the exterior and the final siding and when we do the blower door test to determine the number of infiltrations/hour.

6 thoughts on “Sealing the house (part 1)”

  1. Hello Ingrid,
    Amazing reading your latest news about your house insulation! It is absolute the same way than we do it here in Germany! This blower door test will be done for each new build houses and apartments as we live here. We live here in a house with 10 families, each apartment has this result document!
    Our heating system is working with pellets and we have floor heating. I like that very much, because we can walk without shoes the hole year, it’s fabulous!!
    I don’t know how much we have to pay monthly, but the insulation is so well, it’s not a huge amount!
    I wish you a quick progress that you can receive your mom very soon 🐞🤗!
    Best wishes Ursula

    Liked by 1 person

    1. Thank you so much for all your support. Building this type of house in a country like Chile is a challenge, but we are very happy with how it is turning out. We are anxious and excited about the blower door test and will definitely write a post about it in a few weeks time.


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