The boiler
What you see in that picture is an Okofen condensing wood pellet boiler 16kW. It will heat Amore North.
Boiler choice is non-trivial.
First of all, what energy source are you going to use?
- Gas or oil?
- A heat pump? Air or ground.
- Biomass?
Each of these has different economic, environmental and even geopolitical dimensions to it.
Gas or oil: Fuel boilers are relatively cheap, about euro6K for 16kW. But they burn fossil fuel, the prices of which fluctuate depending on the nature of global geopolitics.
The alpine valleys have bad air pollution, to which fuel boilers contribute.
A Heat Pump? Heat pump water heaters use electricity to move heat from one place to another. They can take heat from the air outside or from holes bored about a hundred feet into the ground to take advantage of the temperature of the earth. The holes cost about €10,000 each to bore, and you would probably need two for a house the size of Amore North. They don’t generate heat directly, but make the performance of electric generation much better. They can be two to three times more energy efficient than conventional electric water heaters.
France loves electricity and it is relatively cheap compared to other countries because it is generated by the country’s 59 nuclear power stations. France is the world’s second most nuclear nation, behind the United States. Even when using modern technology like heat pumps, the source is nuclear.
So if you believe that nuclear energy is not an acceptable option for the generations who may have to clean up a nuclear future, it is difficult to choose electricity.
So on an environmental basis it is biomass. Carbon swallowing trees are grown, chipped into pellets, and shipped via carbon emitting trucks to the house twice a year. But the carbon emitted along the supply chain is recycled within one human lifetime by the forests. France has the biggest forest reserves in europe. Sustainable management of forests is a whole different topic but we are learning.
Why the Okofen biomass boiler?
The Austrians are undeniably the best at making pellet boilers. Okofen was the first company to bring out a pellet boiler decades ago and have been at the lead in product development since then. The Okofen PEK condensing boiler is a new design with a breakthrough in efficiency giving a theoretically impossible 107% yield of heat from wood.
This can be done by using a low temp heating system (underfloor heat) and the return flow to the boiler is used to extract the heat out of condensing vapor in the chimney fumes bringing the heat back into the boiler. In short it is a boiler with cool exhaust, extracting more energy than was previously thought possible.
Heat Exchanger
The apartments in Amore North are air tight. Unless you open a window or a door, nothing gets in or out except via the vents which are connected to the ventilation system. The system takes the stale air out through vents, and downstairs to the boiler room and runs it through a heat exchanger. This device does’t look like much, just a box really:
But it takes the old stale air from the house, which comes down to the basement at about 20 degrees, and runs it through a series of leaves, transferring heat to much colder, fresh air that has been pumped in from outside. So the stale air, when it is sent outside, is already much cooler and has less energy to waste.
The pellets
A couple of times a year pellets get delivered on a truck that is just like a petrol tanker. It comes down the drive and unfurls a 20 metre long tube which gets attached to a tube on the side of the house. Pellets are pumped into a big bladder in the baseement. The biggest downside of all this is that you need space to store the pellets — about 10 cubic metres for a hopper big enough to hold enough pellets to keep the house warm and supply hot water for one winter, more or less. It costs €900 to fill the hopper.
All this equipment cost a lot to install, but once its installed, Amore North is good for efficient energy consumption for the next 20 years!
