Gray energy of a new house: 50 to 100 years of heating!

[Christophe]

I've been looking for it for a long time and you read that right and this figure is simply amazing!

(...) the materials for an average house built in a conventional manner required around 700.000 to one million kWh. This gray energy represents around 50 to 100 years of heating and hot water and its impact is therefore very significant.

Found on http://www.citemaison.fr/scripts/biblio ... eriaux.php paragraph Definition -> gray energy!

What do you think? I thought it was important but not at this point ... Do the "new house" DPE and RT2005 take this embodied energy into account? Would the renovation therefore be much cleaner than a new house (even green) ...?

[Chatham]

I've been looking for it for a long time and you read that right and this figure is simply amazing!

In my opinion there is an error or the house concerned is that of Johnny Halliday ...

[Christophe]

Well ... that's what I thought too but we could check on the shell with the gray energies given on the same page right?

It would therefore be necessary to state the number of m3 or tons of materials necessary to make an "average" house. Not being from the building I am unable to make such an inventory (just for the foundations for example) ...

Maloche maybe it is in your strings?

If we obtain 1/10 of this value it is because there is a problem ... if we obtain approximately or more than 50% it is what is realistic: there would remain the finishes and equipment (sanitary, heating .. .) ...

[Remundo]

This may well be true for cement houses / concrete blocks ... everyone knows that the cement industries are extremely energy-intensive, in construction and also in demolition (removal of spoil, recycling by crushing ...).

Under these conditions, it is better to renovate / insulate / equip an old house, for example with a heat pump combined with a few PV panels ... or a wood boiler with all the small (and big !!) wood that gets lost on the edge paths ... Make rock wool / wood counter-walls against the walls, especially exposed to the north ... Caulk the roof too.

@+

[stone-ernest]

The reference cited by Christophe makes it possible to determine an average gray energy of 500 kWh for all the materials used in a house.
A rough calculation allows to estimate all the materials of an average house (1 floor, 120 m2 on the ground) at 500 m3
This makes 250 kWh.
Or another 9 10 ^ 11 joules or else: 21,5 tonnes of oil equivalent (or domestic fuel oil). Or still about 5 years of heating !!!

Another myth that takes on water.

[Christophe]

Mouais Pierre that is discussed. I know nothing about architecture, but your reasoning stands ... it's just at the level of the foundations that I have a doubt ...

Although 5000L of fuel per year is enormous for a house of 120m² ca 420 kWh / m2.year !!

Finally even if it is 3 times less, 15 years is not 50 to 100 ... but 120m² is small ... so all in one (low consumption house and larger surface) we can arrive soon enough at 50 ...

[Flytox]

Bonjour à tous

(...) the materials for an average house built in a conventional manner required around 700.000 to one million kWh. This gray energy represents around 50 to 100 years of heating and hot water and its impact is therefore very significant.

Found on http://www.citemaison.fr/scripts/biblio ... eriaux.php

The gray energy calculations given by this link seem rather curious to me:

Concrete block 275 Kw / m3
Concrete earth Straw 18 Kw / m3
Plywood 4000 Kw / m3
Chipboard panel 2220 Kw / m3
Straw 0 Kw / m3
etc ...

The calculation method should not be standardized and comes from disparate sources (comparison impossible !?). As such, it looks like a disinformation site run by people who have commercial interests in certain building materials.
A+

[I Citro]

Pierre Ernest, I did not understand your equivalent in joules ...

Regarding your presentation in oil equivalent, it seems to me to be wrong:
If you consider 10 kWh per liter (domestic fuel) and a mass of fuel at 845 kg / m3, your 21.5 tonnes represent more than 25000 liters of fuel.
or as Christophe just wrote, 5000 liters per year is enormous!
A Gironde house of more than 200m² in stone built on a marsh with capillary lifts, humidity and poor insulation consumes less than 2500 liters / year ...
So your numbers mean 15 to 20 years rather than the 5 years you are announcing. Not enough to dispel the myth.

Concrete, concrete blocks and even bricks are very energy-intensive in their manufacturing process as well as in their transport and at no time are these materials carbon sinks ...

Straw and raw wood are carbon sinks, but displaying 0kwh / m3 also seems excessive to me because they are no longer worked, harvested, transported by animal traction as in the last century ...
They are nevertheless the best materials (unbeatable) in carbon footprint with Adobe if we use local resources ...

[stone-ernest]

Mouais Pierre that is discussed. I know nothing about architecture, but your reasoning stands ... it's just at the level of the foundations that I have a doubt ...

Although 5000L of fuel per year is enormous for a house of 120m² ca 420 kWh / m2.year !!

Finally even if it is 3 times less, 15 years is not 50 to 100 ... but 120m² is small ... so all in one (low consumption house and larger surface) we can arrive soon enough at 50 ...

I counted 120 m2 on the ground. With 1 floor, it's 240 m2.

[Christophe]

The calculation method should not be standardized and comes from disparate sources (comparison impossible !?). As such, it looks like a disinformation site run by people who have commercial interests in certain building materials.
A+

Rah frankly no! I do not believe...

But it is true that the significant gray energy of all "wood" material had intrigued me ... there must be a rational explanation somewhere ... The "hash"? Glue?