Insulating the house (part 1)

A key aspect of the Passivhaus Standard and the Chilean Energy Rating for Houses (CEV) is thermal insulation. This is the first in a series of posts that will delve into this concept.

Since Rodrigo and I started dreaming of our house and since we committed ourselves to building with the highest energy efficiency standard possible, we have spoken A LOT about insulation. And it seems that everyone has an opinion on the subject and various people have told us that we are exaggerating with the amount of insulation we are using in the house.

But let me use a simple analogy to describe the importance of insulation:

I am sure everyone can relate to a situation in which children are playing outside in winter, and inevitably a mother comes out at some point and shouts “wrap up warm, it´s getting cold” and the children put a jersey on. Mothers don´t shout “heat yourself up, it´s getting cold” because we know that the best way to conserve body heat is putting on warmer clothes (or layers).  

Therefore, we should think in the same way when it comes to our homes, and not only focus on how we will heat the house once it is built, but rather pay far more attention from the very beginning to how we will “wrap up” the house in order to make the heating more effective, and without a doubt more economical.

I have heard so many people say that they installed underfloor heating in their homes and after the first winter when they realized how expensive it was to run the heating system, they quickly turned it off and reverted to other, less effective heating methods. The problem is not that underfloor heating is expensive, it is that the house was not built well enough to make the most of the heating system.

Thermal insulation is vital, but unfortunately current building standards in Chile (OGUC) only require 2,5cm of insulation in the walls and 7cm in the ceiling (these values are approximate for the central zone and change according to insulating material used and the geographical zone in the country). The standards don´t require insulation in the foundations or the floor of the house, which is in direct contact with the earth (and thus a key point for heat loss).

In our house, insulation is critical in all parts (foundations, floor, walls and ceiling) in order to reach the thermal transmittance values that will allow us to achieve the desired level of energy efficiency. For those of you like me, who are wondering what on earth “thermal transmittance” is, it is the rate of transfer of heat through one square metre of a structure divided by the difference in temperature across the structure. And this all starts in the foundations of the house. And if this still doesn´t make sense to you, think of it as heat loss between the inside and the outside of the house.  

Therefore, from the first week of building, we have had a mountain of insulation, waiting to be used in the foundations and slab of the house:  

Installing insulation in the foundations places our house within 0,8% of the entire construction industry in Chile. Nice to think of ourselves as pioneers…