If you have ever stood in the sun on a cold day, you would have noticed that standing in the sunlight actually makes you warmer than if you were standing under cover.
If you happen to be wearing black, you would have also realized the sun actually made you feel warmer in a much faster period of time.
This article will explain why the color black is what works best to allow your window air heater to work more efficiently to generate free heat.
The basic concept of a solar air heater include capturing energy from sunlight to warm the air as it moves through the heat chamber.
When air begins to warm, it rises upward through the black space being exposed to the sun's energy and into your home.
The best color to use when building your heat chamber is the color black.
The reason black is preferred is the same reason you felt warmer on a cold day wearing black clothes.
The sunlight that falls onto the surface is absorbed more quickly and not reflected back toward the light source.
This light is then absorbed and converted to heat, which is the basic idea behind your heat chamber.
Air passing behind the black material begins to warm and rise through the chamber.
The chamber becomes a sort of heat engine that generates heat from cold air being fed into the system and the sunlight that comes from above.
Using these basic principles and a bit of carpentry, you can generate heat from thin air as long as you have a good source of sunlight and the correct color for your heat engine to make it more efficient.
That is why the color black is what you should be using for your solar furnace.