Going fossil free, putting my money where my mouth is

(for my friend Luis)

Shouting for change, angry blogs about political institutions unwilling to act and so on, you know me by now. But in order to have some credibility I need to show that going Fossil Free in order to save our planet is not just a tree huggers dream but a realistic option.

So when the time came that I had to buy a new house I decided to put my money where my mouth had been: I was going to go Fossil Free.

I will disappoint my greatest critics emidiatly : I still buy bread in a plastic bag (although that goes into the plastic recycle bin). I still have a car (although I cycle, train and walk whenever possible) and type this blog on an iPad that heavily relies on international supply chains and energy intensive we services (although this blog is hosted on my personal server running on my own electricity half the day).

Right, the lines are drawn : my household is going carbon free and energy neutral.

I bought a house that had floor heating as main heating, good roofs for PV, seemed well insulated and had room for plans.

This typical Dutch house has roofs on West (photo) and East, a garage and a garden of 8×15 meters. It was heated with gas (exhaust pipes on the roof). This modern house has a “heat recycling” system where it sucks the used air from the house, passes it over fresh outside air in a heat exchanger and blows the warmed clean air back into the house. The used air is dumped back out.

I sat down in the price negotiation phase to make energy transition plans:

Plans included PV, heatpipes for hot water and heating, moving the heat-exchange pipes to clear the roof. I thought this was all feasible, so I was really happy when I negotiated a good price. Now waiting started for the notary moment, time to go shopping for stuf and deals.


I bought an induction stove to replace the gas stove. I started investigating energy suppliers for my renewable energy, I started investigating heat pipes, boilers and PV systems. Than I got hit by a streak of serendipity I guess.

Solar panels 

Being startup Crowdfunder I came across ZelfStroom, a startup offering “Solar Panels for rent”, where you pay the rent with the energy you create. Brilliant idea. I invested in the company, and got a nice discount as investor on another service they sold : full service installation with nice support for PV-equipment, moving service in case you move elsewhere and more. I ordered panels for my west roof.


That took care of my electricity. Now it was time for hot water. The side wall faces south and I thought heatpipes where a no-brainer. Then a tweep got into a discussion with me, and asked me: what do you do with your heatpipes when the boiler is hot? That’s right, absolutely nothing. You can have a bigger boiler, or multiple ones but it increases complexity and they don’t heat your house on cloudy winter days. He suggested to install an air-water CO2-heatpump, capable of making 65 degree salmonella free hot water, AND run the floor heating at high COP’s. Using the CO2-heatpump I could go to “all electric”. That makes a lot of sense, because if the heatpump is ready making hot water (at the same moment heatpipes would be most efficient) it shuts down and the PV-panels go on making fossil free energy. That made so much sense that I ordered a Sanden AquaEco2

It sucks outside air, steals the heat from it (it even harvests heat from air of -20C) and blows out the cooled down air. A bonus in my case: the exhaust air from the heat exchange unit still contains some heat that I capture with the heatpump, improving efficiency 4%. (The aluminum pipe).

So when I got the key of my house the 31st of March I had all plans ready to go fossil free:

– induction cooking

– PV 

– CO2 heatpump 

The induction was installed on day 1, so I never used gas for cooking.

First weeks of April were cold and I used the opportunity to get a feeling for how well the house was insulated. Nights were around freezing, and the house only cooled down from 20 to 18 degrees, without heating. The sun warms the house via the large windows. So I was confident that low temperature floor heating would be sufficient (heat capacity is only 4kW for the heatpump).

Second week of April the heatpump was installed. It went like a breeze and I showered fossil free! Last step was the PV.

15 300 Watt  panels were placed. It works flawlessly, much better than expected, at 8:30 the system (facing west) already produces 300 Watts, the base load of my house. It goes on till 21:00. Can’t wait till another 3 panels get placed facing east, that will give me full day carbon free electricity. 

Now it’s waiting for Elons Energy Wall (looking for a sponsor) to get to a 24×7 self sufficient system.

One last picture of my fossil free energy neutral house (delivering 12kWh energy into the net today, on top of what I used myself, the system made 18 kWh of carbon free energy)

PS. The 20% efficiënt Autarco panels perform amazingly: this cloudy morning the west facing (so afternoon sun) 4.5kWp delivers 900 Watts at 9 o’clock already! With the 3 panels facing east coming next week my house should be energy positive almost all daytime hours. Looking for a sponsor for Elon’s energy wall  


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