complex societies, which lost the human scale of things. Without cultural records, mankind has no memory to learn from its successes and failures. Proven many times over, ignorance of history condemns us to repeat things. Is it not our common duty to safeguard the most valuable knowledge in the best way possible? An important responsibility we face that facilitates the realization of specially designed repositories, such as the library in the Sierra Nevada mountains. After all, a library still is the best way to preserve the important aspects of man ' s written information for a future made by hand. Not DVD ' s, hard disks, chips, or the Internet.
DESIGN
The underground repository was constructed to last for millennia. The library builders created a maximum of storage space, efficiency and durability, with a minimum of budget, labour and visual impact. The building consist of a 8m diameter dome shaped bunker, surrounded by 4 book vaults. Created to separately contain knowledge about art, science, spirituality and a seed collection. The building was designed to blend in an existing massive terrace, once created by the Moors centuries ago to produce green tea or silk( mulberry trees). The library was conceived not to be open for public use, not only because of its mere role as being a back-up, its remote location, but the presence of many good communal libraries in the area for the day-to-day access to books and information. Because of this specific approach, we could focus to optimize the environment for physical preservation that facilitates the most basic access.
The repository is designed to both borrow cold and keep cold. The structured borrowed cold by digging deep into the ground, where the temperature well below the frost level remains fairly constant 11,11 Celsius( 52 ° F). This works two ways. The deep-down earth library is slow to be affected by freezing high mountain surface temperatures in the winter, and protected by the hot Andalusian summer heat. The repository will maintain excellent storage temperatures between 0 ° & 13 ° Celsius( 32 ° & 55 ° F), comparable with the statistics of several underground root cellars in the region. An inbuilt proper ventilation system, creates a constant airflow to help reduce excessive humidity and thus preventing undesirable condensation. The underground complex has 2 hatches, one as a main entrance connected with the dome, a second directly with the seed vault, to be used in case the first would become blocked. The main entrance is located at the end of a dolmen-style cave, connecting the library with the outside world. We intentionally made the entrance narrow, making physical entering difficult to prevent the building to be used for other purposes than the long term store of small items. Protecting its content by design, from the use as a living unit or animal stables.
Based on the design principle to use the current technologies and construction possibilities, the library builders created a resistant structure that otherwise would be very difficult to realize in a possible energy descent future. The constructors applied the most innovative construction techniques and materials, such as a special concrete mix and replacing steel by a combination of glass fibres and composite rebar to reinforce the concrete structure. Steel is susceptible to oxidation( rust), leading overtime to cracking and deterioration of reinforced concrete. Composite rebar won ' t rust or corrode, so it ' s ideal for a long-term structure, making it extremely durable and maintenance free. Another advantage is that the tensile strength of fibre rebar is several times higher than steel, providing excellent fatigue