Technology and Innovation - Solar Greenhouses
How long have we been hearing about the so-called "solar greenhouses"? But how many of you actually know how they work and the benefits they offer?
How long have we been hearing about the so-called "solar greenhouses"? But how many of you actually know how they work and the benefits they offer? With this brief article, we will try to satisfy your curiosity.
The solar greenhouse is a passive solar system used to capture solar radiation and help mitigate the climate of indoor environments. The operation of a greenhouse does not require any kind of system, but it is a system capable of guaranteeing certain performances thanks to the materials, architectural shape, and thermodynamic phenomena of heat transfer.
The design of a greenhouse must take into account specific technical aspects, as well as comply with local building regulations, which usually consider greenhouses as if they were technical rooms, and therefore do not include them in the calculation of the building's total volume. There are also maximum dimensions to be respected, which vary according to the various local regulations.
Every solar greenhouse must guarantee energy savings, which must be calculated and certified. The greenhouse accumulates heat during the day and must therefore be designed to capture the rays optimally, with the incidence possibly perpendicular to the shape of the windows during the hours of greatest solar gain, so as to transform them into heat by means of the so-called "greenhouse effect".
Greenhouses are useful in the winter seasons to heat rooms by accumulating heat during the day and minimizing heat loss to the outside during the cold night hours. In the warmer seasons, the opposite effect of the greenhouse must be avoided, which would excessively overheat the rooms, so appropriate solar shading must be provided.
When choosing the material for the frames, it is necessary to consider thermal transmittance, light transmittance, and the solar factor.
Based on the ways in which heat is transmitted, three different types of solar greenhouses can be identified:
- Direct gain greenhouse: Does not have separating walls between the interior and the greenhouse.
- Convective exchange greenhouse: Interior and greenhouse separated by an insulated dividing wall with vents or windows useful for convection exchange.
- Radiant exchange greenhouse: Interior and greenhouse separated by a dividing wall that must maximize radiant exchange, so the infill should not be insulated.
