Energy-saving building envelope: constituents of the building envelope and what are the requisites to talk about energy efficiency.
L'building envelopeit is, by definition, one or more layers of material that separate the internal environment from the external environment of a building. L'building envelopeit has the function of protecting the internal environment from external agents such as cold, heat, humidity, rain, hail, snow, wind, light, sources of noise pollution and, based on the criticality of the place, air and / or electromagnetic pollution .
When it comes toenergy-saving building envelopethe location in which the building is located cannot be ignored. Abuilding envelopeable to guaranteeenergy savingin areas with a mild climate, it will probably not be able to guarantee the same thermal performance in areas with a rigid or tropical climate.
What the building envelope is made of
Abuilding envelopeit is made of one or more layers that determine its shape, appearance and properties. Based on the constituent materials, abuilding envelopeit can guarantee lower or higher energy efficiency.
Regardless of the materials used and the technologies used, thebuilding envelopesconsist of 4 standard functional structures, these are:
- 1. Horizontal structures where thecasingseparates the internal environment from the ground or from the outside.
- 2. Perimeter vertical structures that come into contact with unheated (external) environments; in this context we also speak oftransparent building envelopeor opaque.
- 3. Flat or sloping roofs (butterfly roof, non-ventilated insulated roof, ventilated roof to cope with the problems of humidity, mold and summer overheating).
- 4. Transparent closures. They represent the weak link ofenergy-saving building envelope.
Based on the techno-functional properties of the chosen constituents, we will have a more or less efficient building envelope.
Energy-saving building envelope
L'building envelopemust meet severalenergy standardsin order to ensure living comfort and guarantee a resource saving in meeting the energy needs of HVAC systems.
Green building loves acronyms: HVAC stands forHeating, Ventilation and Air Conditioning and contains all those devices that deal with cooling, heating or ventilating the rooms. Abuilding envelopewell insulated must take into account the thermal transmittance of each structure.
The four functional structures of aenergy-saving building envelopethey will have to:
- Prevent condensation phenomena.
- Thermally insulate the building by maximizing theenergy savinglinked to heating in winter and cooling in summer.
- Minimize thermal bridges.
- Waterproof from water and rising damp.
- Avoid any direct contact with the ground.
- Conveying and managing rainwater, even better if with a recovery system integrated into the roof.
- Isolate the interior from noise pollution.
- Maximize natural ventilation.
- Maximize natural lighting.
- Maximize the breathability of the shell.
- Integrate photovoltaic systems capable of guaranteeing an energy supply such as, for example, the photovoltaic butterfly roof.
The photovoltaic integrated into the building envelope it is a well established reality. The construction sector is not lacking in photovoltaic tiles, photovoltaic walkable roofs, photovoltaic tiles and even photovoltaic transparent facades.
Another innovation ofsustainable building envelopeexploits the reactions of photocatalysis with the diffusion of photocatalytic coatings. In this context, the photocatalytic activity of certain metals is exploited to eliminate smog and dirt present in the area adjacent to thebuilding envelope. This solution is recommended in city centers where the levels offine dust PM 10(for further information:what is PM 10) far exceeds the maximum limits imposed by the European Union.
If thebuilding envelopetraditional, for energy saving proposed "only" thermo-insulating plasters, panels and products for thermal insulation (thermal coat, special blocks ...) and nanotechnological paints, thegreen buildingpoints tosustainable envelopeswith ventilated walls, ventilated roofs, green roofs, green walls and other innovations that do not exclude thetransparent building envelopes. The transparent closures of thebuilding envelope affect living comfort both because they allow greater control of solar radiation and natural lighting, and for the aesthetic impact, however, the structurestransparentmust be managed with greater attention to address the problem ofthermal bridgesand thermal transmittance. L'glazed building envelopeit must be well optimized both for the transparent materials used, and for the thicknesses, the fixtures and the frames.
To deepen the theme ofenergy-saving building envelopewe refer you to the article dedicated toenergy performance of the building envelope and that dedicated to the building envelope
Credits Opening picture: © ATIproject - all rights reserved.