You might have read my blogs or heard me refer to installing a puit canadien and double flux as part of our extreme eco-renovation (other names include, mad crazy English people's renovation, what on earth are they doing now renovation...)
So What is a puit canadien or canadian well, sometimes referred to as a puit provencale?
Well it's a type of renewable energy which provides both heating cooling in conjunction with a Double Flux (mechanical heat recovery and ventilation system in the UK). The system we are going to be using is by Helios. The thermal study was conducted by Fiabitat. What we are installing is a ground to brine heat exchanger which increases the efficiency of the Double Flux.
So what is a Double Flux?
Well it is a ventilation system heat recovery with enthalpy - eh? Well it takes in fresh air and in Winter preheats it before dispensing it around the house. The stale humid air is taken out but the smart part is that the heat generated in the house is not lost straight out of the house, it goes through a heat exchanger and passes the heat energy to the new cold air coming in then the stale stuffy air is released outside. The result is you have clean fresh air into the house without losing up to 90% of the heat (through opening windows or simple ventilation systems which extract hot air out to the cold outside).
Why? The humdifying function helps to keep the rooms at a healthy and comfortable climate without the need for additional energy i.e. air conditioning, humidifier units etc.
As you can see below, the fresh air is piped into each living room/bedroom in the house and spoiled air from bathrooms, toilet and kitchen is taken each room and passed through the double flux to retain the heat calories before expelling the exhaust air.
The Puit canadien is an underground geothermal loop system which further supplements this and should save even more energy and money as it pre-heats the air before it comes in without any additional energy being required.
This system uses the fact that the temperature below ground is relatively constant throughout the year. Our pipes are laid at 2.5m deep and 1.2m below the ground level.
Firstly a huge hole the size of a swimming pool is dug and prepped:
Then the tube is laid in
They are covered with sand and geotextile (the blue mesh to warn you not to dig into the tubes by accident in the future)
then the earth was laid over and compacted
ready for the second layer.
and now this is what it looks like:
The pipes come through a long trough into what will be the new chaufferie:
This will eventually join up to the indoor kit:
and the Double Flux:
All this kit will sit in the new chaufferie, as well as the wood gasification boiler and AKVATerm tank for the solar thermal hot water. Its going to be interesting to see that lot going in as well as the many pipes which run all through the building taking the clean and stale air out again.
As I said it's an extreme eco-renovation. The plan is to spend the money on investing in the heating/cooling technology up front and then hopefully have little or almost no heating costs in the future.
What's the point of having all this in an old stone house? It wont work as old houses are leaky right? Well we are insulating the entire inside of our house in 8cm of chaux chanvre - lime and hemp wall insulation, building internal walls out of chanvribloc (hemp blocks) and we are fitting good quality windows and lots of roof insulation. This insulation is referred to as a thermic correction rather than making it completely air tight. The old building can still breathe (avoiding humidity problems) but it is well enough insulated not to lose precious energy.
This is just the start - the terrassement has been completed and now we move indoors. The new internal wall foundations were poured a couple of weeks ago and hopefully this is where we now start to see the house taking a new shape and a new life. Bring it on!
For anyone interested in this sort of thing...have a look at Fiabitat website - a mine of useful information, also I subscribe to 2 French magazines - been wonderful for improving my french and building knowledge - Natura & La Maison Ecologique http://www.lamaisonecologique.com/