In 2019, in Europe, 63.6% of the house's energy consumption was related to space heating, 24.2% was covered with non-renewable natural gas and 17.7% from renewable and wastes, meaning resources burning (wood / waste)
In parallel to this fact, today most heating solutions rely on the physical principle of convection which occurs when heat is carried away from the heated element via moving air.
However, convection is not the most efficient solution for space heating, the phenomenon of heat stratification in the air induces energy over-consumption without managing to homogeneously heat the space, which brings a bad thermal comfort.
Temperatures on °Celcius
Space not homogenously heated. T on °Celcius
Space homogenously heated. T on °Celcius
Heating and energy:
Whatever the solution, heating is an energy-intensive activity.
As showed earlier, most of the heating energy source comes from combustion (gas, wood, waste) because they produce an important amount of energy which can be directly used for heating, but at the same time they release greenhouse gases.
We’ve also seen that today’s most energy-efficient electricity-based heating solution (low carbon or not depending on electricity production) are the radiation heaters.
However, this solution is still energy-intensive relatively to other uses of electricity in a household. To get the magnitude of the energy required to heat a space we can rely on the recommended power (Watts/m²) for heating:
The sun reflecting parabol is a very common, DIY plan available solution, widely known mainly as a sun-cooking solution.
Today, it’s easy to find on the market mirror-adhesive films presenting a high efficiency-reflecting rate > 90% for parabol’s construction.
Using a parabol as a collector solution presents the advantage of concentrating, the sun radiation power on a small point, making it easier to transport elsewhere (inside the house in our case).
The system consists of a:
One main parabol: for collecting the sun radiation and sending it to its focal point
One secondary parabol: placed at the main’s parabol focus point it sends the main parabol collected radiation back to the main’s parabol summit where the transport system is located.
Such solution presents the interest of placing the concentrated radiation at a very simple collecting point AND having radiation rays arriving with an important incidence angle (close to 180°) to the transport system. This will be necessary for transportation which will rely on the principle of total reflection.
SunHeater parabol. 1: sun radiation, 2: sun radiation reflected, 3: sun radiation reflected back to the main’s parabol summit for transport
The energy transportation
The first solution to be imagined was a unique straight reflecting pipe from the parabol’s summit to the in-house distribution conducing to the following design:
However, the rigidity of such system brings a constraint, the roof space availability at the very top of the in-house space to heat.
A more polyvalent solution would be to use a flexible cable transporting the radiation relying on the principal of internal total reflection. In other words, the optical fiber technology approach.
The materials allowing such total reflection for sunlight minimizing attenuation (absorption by the materials) is still to be determined and will be done during the prototype phase.
The good news is, taking into consideration the parabol design, the incidence angle is as high as possible, close to 180°, giving the maximum flexibility for the choice of the materials.