Solar greenhouse: what it is and how it works

What is a solar greenhouse? This term refers to a structure - made of insulating materials and glass - that captures solar energy and gives a house great aesthetic value and improved energy efficiency.

A solar or bioclimatic greenhouse can be built on a veranda/balcony or on the roof of a building. It is usually characterised by a futuristic appearance, since it refers to an open space, although it is closed by transparent material and finishes that almost always appear discreet, minimal and in some ways essential.

Function or purpose of a solar greenhouse

What is the main function of a solar greenhouse? The main purpose of a solar greenhouse is to provide the environment with a cool climate in summer and a warm climate in winter, without the need for machinery or air conditioning. The great strength and sustainability of a solar greenhouse lies in its ability to regulate itself and make an important contribution to energy and environmental sustainability. In order to achieve its purpose, a solar greenhouse must be built with special materials and specific construction techniques. For this reason, bioclimatic greenhouses are very special structures, and for this reason they are subject to legislative measures. Let's take a look at the main characteristics of these structures.

Characteristics and features of a solar greenhouse

The solar greenhouse is a pioneering structure in terms of energy efficiency. Its characteristics are expressed in technical requirements and strict protocols.

A solar greenhouse should always be oriented to the south in order to maintain a good ratio of light and shade. A bioclimatic greenhouse should always be exposed so that it can enjoy the warmth of the sun's rays throughout the day - from sunrise to sunset.

A bioclimatic greenhouse should always be exposed so that it can enjoy the warmth of the sun's rays throughout the day - from sunrise to sunset. The only non-glazed side of the structure is the side that faces the house. The roof of a solar greenhouse should also be made of glass. Combined materials should also be used in the production of these structures, alternating high standards of insulation with high heat absorption capacities. The greenhouse should also be equipped with mobile shading systems: the shading should never be fixed, but mobile, in order to prevent the environment from overheating, which can often occur during the summer season.

As far as volume is concerned, a solar greenhouse must never increase the volume of the house - at least officially. In any case, the structure must not exceed a certain size: it must not exceed 15% of the house - the percentage increases to 30% if a building permit is applied for and obtained.

What a solar greenhouse should look like

A solar greenhouse is not an investment for everyone. It is a complex project that has to meet specific requirements. The price is not the only limitation for this type of installation: in some cases the decision to build a solar greenhouse is a winning move, while in others it is unnecessary and has no positive impact.

Here are the cases in which the decision to build a solar greenhouse is more than appropriate:

• Wanting to give your home a higher value than it currently has. By constructing a solar greenhouse, the energy class of the building improves, and not just a little, which increases the value of the house;
• The desire to give your home a particular style or aesthetic taste. Solar greenhouses are characterised by a typical, particularly futuristic and modernist design. The style of a greenhouse is definitely more minimalist than classical: this element should not be underestimated;
• The house is located in a climatically uncomfortable area. If you live in an area with a mild climate and not particularly cold winters and hot but not torrid summers, building a solar greenhouse may not be worth the effort;
• If you live in a mild area with a mild climate and not particularly cold winters and warm but not hot summers, building a solar greenhouse may not be worth it. It is necessary to carry out an architectural project, as well as a bioclimatic project and a DIA. If the size of the structure exceeds 30% of the size of the house, it will be necessary to apply for and obtain a building permit.

How much does it cost to build a solar greenhouse?

Finally, we come to another sore point: we are obviously talking about the price of designing and building a solar greenhouse. Generally speaking, the costs are not very high: a solar greenhouse can in fact be likened to a common high energy window application. The only difference is that the windows occupy a limited space, whereas greenhouses surround the space on three sides.

Here is a basic indication of the prices for the design and construction of a solar greenhouse.

• Solar greenhouse made of glass and aluminium - high energy efficiency - + paperwork costs: 400 to 600 euros per square metre;
• Solar greenhouse made of glass and PVC - very high energy efficiency - + paperwork costs: €600 to €700 per square metre.

Labour costs of between 50 and 100 euros per square metre must be added.