> I also think if you don't care about what your house looks like, you can either paint it black or wrap it in black plastic. Such heating will work during the

> I also think if you don't care about what your house looks like, you can either paint it black or wrap it in black plastic. Such heating will work during the day but transporting the energy from the heated plastic into the house is another matter. The hot surface also would radiate a lot of heat immediately away. And when the night comes you heat the sky with what you have stored up. The article is fascinating as it shows what can be achieved on a system engineering level. As an engineer however I would also like to see some performance measurements like air flow and temperature deltas going beyond the anecdotal story keeping the build warm in the northern US. Did not see anything on his homepage. There have been related posts on HN that showed advances on material science level where the absorption and radiation wavelengths of surfaces have been optimized. > Unfortunately there are big problems that I encountered that I couldn't solve cheaply. PV system cost these days is dominated by other costs than the solar cells. Engineering something that can withstand weather for a sustained period is both non-trival and not cheap. There may be some overlap in what PV systems require and what a passive heating system requires. Maybe the massive investments in the PV space make passive heating systems these days more practical?