Find out about Seismic Risk

In France, there is a useful database that you can search to find out about the level of seismic risk for your commune.

First choose your region(click the map or select from the list) and then drill down to find your commune.

This is the info that comes up for our commune:

There are some FAQs on and also a bunch of other info there related to construction – though of course no detail!

There is some more general info about seismic and other environmental risks on this

Green Energy Suppliers in France

One of the requirements of RT2012 is that all new builds must include a solar-power element. This can mean investing in micro-generation system for your own land or property, choosing a low-carbon, low-energy heat source as your main form or energy. But there is also a third option, which is great for those of us who are on tight budgets. That option is to commit to using an energy supplier that obtains at least 50% of their energy from green sources (solar, wind, water, etc.)

So how to find these? 

There’s quite a list in this article here but also this recent article which gives an overview of Greenpeace’s assessment of the main suppliers in France. Looking at the two lists I would think that you could pass RT2012 by signing up for EDF’s green tariff but according to Greenpeace you’re probably being greenwashed and unlikely to be actually buying energy generated from renewable and non-polluting sources.

One of the companies I lik the look of is There’s also, which also has non-capitalist credentials. Enercoop has a similar feel to Green Energy, which is the company we used in the UK and is also a cooperative. 

You might be thinking well, how green is it really to be buying energy from a company, but this recent article from the Centre for Alternative Technology suggests that connecting to the grid is a better solution than going off grid. It’s worth remembering that all technology has an environmental cost. Also, if you are generating energy that you are contributing to the total amount of green energy that is available for sale to others who perhaps don’t have the means to invest in solutions themselves. If green electricity is flowing in, the demand that needs to be met by dirty energy (and in that I include nuclear) is reduced. Which also feeds into this article about how being green has become something we do (and get to feel smug about) on an individual level when really collective action is needed.

There’s more info on packages with suppliers for auto-consommation (self-generation) here

Ilek seem to have a comprehensive calculator on their site, giving info on expected payback times and also taking government grants into account.

RT2012 Recommended Boilers (Thermo Dynamic)

For RT2012 one of the ways around having to have expensive solar solutions is to fit a thermodynamic boiler.

This one on Mano Mano is 1.5k euros and may be what we need. 

According to one green energy site they reduce the annual cost of heating water from 350 to 80 euros for a 4-person house.

This comes on the list under ventilation…

This might be one?
2035 euro

How thermodynamic water heaters work

Messages Sent

24/10/18 – Message sent to via their contact form.

I am planning a GREB house and considering how do to the foundations. I am interested in the method you chose and also the products you used. What is the make of the polystyrene blocks? I have tried to find them using the internet but no luck. Do you find the floor is well insulated?

A Simple Woodburner or a Boiler Stove?

Someone in a self-build group suggested a boiler stove instead of just a burner requiring separate water heating. The oone they linked to had a heat output of 2kW with 8kW going to the water. That seems low given we’ve been told we need a 10kW stove for m2.

Cost wise they’re not much difference though. Something to consider?

This one, the Stratford EBW12, has a total output for 24kW, of which 6kW goes into the room and 11.8kW into the water.

It has a direct air supply (required by RT2012).


Stratford EBW12 wood boiler stove

Trying to find out why you’d choose a water heating stove and the Centre for Alternative Technology have an article suggesting that it’s not worth it unless you have a super-duper stove such as the Broseley eVolution 26 boiler. With this you get 10kW for heating and 15.8kW for hot water heating. I can’t find a price for it though!

Choosing the Right Type of Foundation

Slab vs. vide sanitaire? Discussion here along with info on how to layer with the moisture barrier and insulation.

Some other useful articles here:

Tips from these pages:

  • Dig out the earth and then pack it tightly before pouring any concrete.
  • You can – if you’re crazy enough – do this without using any rebar (as if!)
  • You can literally make it up as you go along. These guys used rockwool under the slab and EPS under the footings. How does that not compress when under concrete and with the weight of the house on it. 
  • It IS important to use a Radon/vapour barrier before pour cement.
  • Remember to put the rebar over the vapour barrier!
  • Polished concrete is a good idea – but who is capable of doing this here in France?

Reaching Out

I got a message back from someone else about an hours drive away building a GREB house with a similar budget to us. They have a new baby so are pretty busy right now but are happy to be in touch so I will email him back asap.

He recommended getting in touch with the free architect, CAUE, and also with Ariege Conseil Energies Renouvenables ( I’ve seen that site before and now I have a recommendation I’ll follow up with them. I’d sent an email to the CAUE in Carca back on 10/10 so have sent a chaser message to them. 

Questions for Stan


  • Which is best? Slab on grade or vide santaire?
  • What’s the best way to insulate slab on grade?
  • How do we ensure the slab of concrete is level? 
  • If we decide to use form boards instead of breeze blocks, how do we make sure the blocks are level?

Window Specs

The plan is to spec double-glazing for the RT2012 survey but budget for triple glazing on the basis that it’s much nicer to have triple but to meet the spec we need to under-promise and over-deliver! Here are the window specs and prices from (German made :-))

Triple Glazing

For all these triple-glazed uPVC windows and doors, Uw = 0,87.

1800 x 1200 mm Triple-Glazed 3 Vantaux Window
  • Matière: PVC
  • Profilé: IDEAL 5000 (5 chambres avec 3 joints)  18,70 €
  • Couleurs: Blanc
  • Type de fenêtre: 3 vantaux – modèle de base
  • Sens d’ouverture: 3 vantaux – gauche fixe, centre OB-DIN droit, droit fixe
  • Largeur totale: 1800 mm
  • Hauteur totale: 1200 mm
  • Répartition Hauteur 1: 1200
  • Répartition Largeur 1: 500
  • Répartition Largeur 2: 800
  • Répartition Largeur 3: 500
  • Ferrures: Sécurité de base
  • Vitrage
  • Vitrage: Double vitrage Ug 1,1 selon DIN EN 673
1600 x 2100 mm Triple-Glazed French Door
  • Matière: PVC
  • Profilé: IDEAL 5000 (5 chambres avec 3 joints)  23,50 €
  • Couleurs: Blanc
  • Type de porte-fenêtre: 2 vantaux – modèle de base
  • Porte-fenêtres à deux vantaux: 2 vantaux – oscillo battant gauche, oscillo battant droit avec meneau central
  • Largeur totale: 1600 mm
  • Hauteur totale: 2100 mm
  • Répartition Hauteur 1: 2100
  • Répartition Largeur 1: 800
  • Répartition Largeur 2: 800
  • Seuil bas pour porte balcon: Non
  • Ferrures: Sécurité de base
  • Vitrage: Triple vitrage Ug 0,6 selon DIN EN 673 92,78 €

Double Glazing

For all these double-glazed uPVC windows and doors, Uw = 0,91.

Hardly any difference in price, which is surprising.

1800 x 1200 mm Double-Glazed 3 Vantaux Window
  • Matière: PVC
  • Profilé: IDEAL 4000 (5 chambres avec 2 joints)
  • Couleurs: Blanc
  • Type de fenêtre: 3 vantaux – modèle de base
  • Sens d’ouverture: 3 vantaux – gauche fixe, centre OB-DIN gauche, droit fixe
  • Largeur totale: 1800 mm
  • Hauteur totale: 1200 mm
  • Répartition Hauteur 1: 1200
  • Répartition Largeur 1: 400
  • Répartition Largeur 2: 1000
  • Répartition Largeur 3: 400
  • Ferrures: Sécurité de base

  • Vitrage: Double vitrage Ug 1,1 selon DIN EN 673