Confessions of a sinful architect

Embodied Energy

Confessions of a sinful architect

I am going to confess, here, publicly, my biggest environmental sin (so far).

I have to warn you: if you keep reading, whether out of curiosity, morbidity or with mere informative intent, you may find that you yourself have committed some sins as well.

And precisely, that is why you should keep reading.

I had decided to become independent and start doing work on my own, as my first job on a larger scale, I got the project of a terrace for some acquaintances; I would be in charge of the entire project, but also of the execution and construction. Basically all the decisions would fall to me. Without giving it much thought, I decided to follow the trend and propose a structure with steel profiles to support a 9mm glass cutting; they loved it and so we continued the project.

So far it does not seem that any crime has been committed, I imagine that many of you will even feel identified with this story, but I promise you that, if you let me explain, you will understand why it seems such a great sin to me and perhaps I will be able to convince you, it is for you too; It's a matter of very basic math.

I'm going to focus only on the steel structure, if we count the glass and others, this story would be even sadder. Let us begin:

The structure that I designed in steel (verified by a professional engineer) had a weight of 736 kg; For the manufacture of a kilogram of steel, approximately 0.012 MWh (Megawatt hours) are needed, do not be scared, it is only a way of measuring energy. Simple math tells us that this structure used 8.82 MWh to create. But what is 8.82 MWh?

Well, for starters, it's the energy a standard car would use to go from Mexico City to New York, 4.5 times. The same amount that this same car would spend to go around the earth, along the equator, 1.5 times. 18,869 km. 1,572 liters of gasoline. Do you start to see it?

Now, let's make it worse; according to the notice issued by the Mexican Ministry of the Environment: this year our energy system generates 0.494 tCo2e/MWh, yes, almost 0.5 TONS of CO2 for each MWh we use (there are countries with less polluting Energy Systems, this depends on the percentage of renewable energy they use). From here the mathematics becomes simpler, but also more alarming; if we multiply the 8.82 MWh of energy by the 0.494 tCo2e/MWh, we would know that the manufacture of the steel structure emitted 4.35 tons of CO2.

I know it sounds like a lot, but such large numbers are difficult to understand if they are not put in context, let me make it clearer:

The amount of CO2 that was emitted (or that I directly or indirectly emitted) for the manufacture of the simple structure of a 25m2 terrace is the equivalent of what a pine tree (already mature) will absorb in 36 years... Yes, 36 years! Does it now sound like a sin to you too?

I haven't even lived 36 years and the environmental impact of this decision was already taking its toll on me. (and note that I am only talking about energy consumption and, therefore, CO2 emissions, it would be necessary to take waste into account, but we leave that for another day).

So… I needed to plant a pine tree, which would grow enough to reach its mature age and then 36 years would pass before I could close the cycle of that material and I had not even thought about it.

Don't get me wrong; I have nothing against steel, in fact, it seems to me a necessary and very useful material (the Home Insurance Building in Chicago can tell us), all I'm saying is that we have options.

My sin was in having all the possibilities to choose and to do it without asking myself more; decide for fashion, for comfort, for habit. My sin was not having the slightest idea of ​​the costs of my decisions (environmental, of course) not only because of ignorance, but also because of laziness or perhaps the cowardice of not wanting to know, because once you know, you can't go back. Ignorance is comfortable, it is easy, but it is still that, ignorance.

I believe that it is valid to choose the best material for each situation and requirement, what is not valid is doing it without sufficient information, doing it without responsibility and awareness, doing it with one eye closed so as not to see what is not convenient.

This article does not intend to tell you what materials you should or should not use, I will have to leave that to your discretion, what I am looking for here is to open your eyes, give you enough information so that you cannot close them again; if I made a breakdown of my mathematical process, it is so that you also have sufficient data and methodology to replicate it, to know the energy contained in each of the materials you choose and, above all, in the environmental impacts they have.

With the growing environmental crisis in which we live, we cannot afford to decide in ignorance.

*For a better understanding of this article, I homogenized all the units used. In this table the energy content of the materials appears in MJ/kg; to convert it to MWh/kg, it is only necessary to convert from MJ to MWh. *1 MJ=0.000278 MWh
Very important note to the reader: a material with a lower embodied energy is not necessarily a more suitable material in terms of sustainability. The conversion that we must look for here is: MJ/functional unit, that is; which is the material that requires less energy due to the same function (in this case, structural, but it could be any other).


Rodriguez, G. “El impacto de la enseñanza de la sostenibilidad en la arquitectura y el urbanismo”. Universidad Austral de Chile. 2006