energy for free | battery from nature that looks like luxury  Read about the thermal mass first. The whole thing is pretty simple. I will explain in a minute and you’ll understand it. 1) Build a house with a big south facing glazing and insulate it very well. 2) Put thermal mass inside.

Let the greenhouse effect do its job. Additional Arduino and raspberry phi sensors, electronics and shutters on the glazing are required for high-end performance. That’s for managing the heat and energy transfers from one place to another, when needed.

The sun shines through the acrylic sheets on the concrete or granite walls of the inside. The free energy will accumulate within the house. The same energy will be reused in the evening. Distribution of the heat can be done with hidden water tubes. Just look at the picture below.

We have huge granite / concrete walls in the core of the building. Within the walls there is a huge water tank. In this example we position a few “chimneys” and pipes in the water. If we burn wood (or gas) then the hot air will heat the water. In most cases the Sun will be enough to heat up the granite, water or the underground lake.

An additional thing instead of the auxiliary wooden/gas heating : Solar panels are quite cheap in China (google, alibaba.com) and water heaters are also cheap. The only problem is storing electricity. However when the sun shines you can heat up the water quite fast. Use cheap electrical heaters.

You will get plenty of hot water in the house and in the walipini, in the form of hot air, hot water or hot granite walls. You can transfer the heat with some cheap pumps and vents with an Arduino based systems. Then you can transfer the extra energy within a tesla battery

You can transfer the excess used hot air to the walipini. You can use cheap air pumps to push the air underwater. Air bubbles will oxygenate the water for the crabs and fish. The heat will transfer faster into the battery (water). The heat will accumulate on the upper surface of the underground lake. That is why the plants are positioned here. Because is and so they grow faster as if they would be planted in the ground. The Co2 from the air will be cleaned by the plants. You can pump it back into the house.

This way you don’t pump -10C of air in the house (outside air). You’ll pump a 17-22C pre heated clean air full of oxygen.The underground lake has it’s own greenhouse effect. If the upper part of the air in the underground lake overheats in the winter  then you can pump the hot air in the water. This way even exotic fish, crabs, flowers, vegetables, fruits will excel and grow fast, even in cold climates. You will have plenty of first quality organic food.

In the summer | underground lake. You can push the extra heat to the outside trough the vents or let the wind blow out the hot air (naturally) on the lateral openings. A thin layer of shading on the upper part (on the acrylic sheet) will help a lot. Two, free layers of plants one above another will do the shading.

In the winter | underground lake. Just pick 1-2 layers of plants instead of 2-3 that you would in the summer…this way the sun could heat up the water and the granite rocks. The water and the smashed granite will store up the energy for the evening. In the arctic or real cold climates you can use an insulated shutter above the underground lake. Arduino based systems can close these shutters at night to prevent further heat loss.

Lots of cheap solar panels (obviously from China): ex alibaba.com) and specialized leds could  prolong the sunshine hours in the winter. In case you live in Iceland and you have a “blizzard month” you could easily shut the insulated shutters above the glazing . Use the solar panels to light up the leds underneath.  Or you might use electricity stored in the tesla battery.

Position your solar panels a few meters above the ground. Even after heavy snowfalls you’ll have plenty of electricity to keep warm the “underground lake”(hyperlink).  You’ll be able to light up the ecosystem and you’ll be able to melt the snow. In really cold climates I would insulate the lake as well. I would put a thick insulation below the rocks used in the aquaponics system  and below the lake itself as well.1-2 meters of snow and insulation, if it makes sense.

Usually these leds are red and violet because that’s the color range that helps growth. Basically that’s the formula 1 space technology of agriculture. It cost less and less, making it quite affordable now. I won’t say that you should go all pitch black and that you should ignore the sun. All I am saying is that if you have tons of organic food inside and you have extreme weather for weeks, it won’t affect your food supply. Basically you’ll lower the risk factor.

The excess hot water could be used to heat up the water Jacuzzi or it would provide hot water in the kitchen or bathroom. Or it might be stored in the lake so that in wintertime you might be able to swim in it in a 5mm wetsuit. By circulating the water in the granite walls (use cheap thin tubes instead of thin pipes) you will be able distribute the temperature even and fast.

Use insulated shutters to block the big southern facades to overheat the house. Basically you don’t need the insulation in the summer but it helps a lot in the winter. You might consider mineral wool here. The only place in the project where you should consider using it. It’s not that good as these materials but it is lightweight and in some projects it would be a perfect fit.

4 layers of acrylic sheet  and 20-cm of mineral wool combined with the chimney effect would be enough. It’s all project dependent: winds, positioning, climate, shape, workmanship sun are extremely important to make a final verdict. While you’re not at home (the hottest hours) the shutter might be closed to generate a chimney effect. Additionally you might plant big trees in front of the windows to block out the summer light.

The same trees after they lose the leafs in the autumn they could let the sun heat up the building. (greenhouse effect). As an extra thing you could : circulate water in tubes to cool the granite walls and the store water within the house.