Among the main factors that endanger the conservation of Nero’s palace, now underground after Trajan’s works, a crucial role for the frescoed surfaces is played by light.
Unfortunately, light may encourage the growth of microorganisms harmful to the paint layer if precise limits are not respected (emissions must be under 150 lux per room).
On the other hand, the need to constantly monitor the stability of the vaults and walls to ensure the safety of workers entailed a need to devise a lighting system suitable for the conservation of the monument’s decorative heritage but that also allowed for frequent and regular checks.
The project was managed by Prof. Fabio Aramini, director of the Photometry and Lighting Design Section of the Istituto Superiore per la Conservazione e il Restauro (ISCR). The Soprintendenza already implemented a first part in 2010; a second part is currently being defined and will be completed by October 2012.
We first set up a lighting system in rooms that had previously been dark and that for this reason had never been studied, some of which belong to the East Wing: rooms from no. 56 to no. 64, also including Cryptoporticus 19 on the north edge of the West Wing.
Subsequently, we adopted the type of lighting already successfully tested in all our open worksites.
We chose to use recent generation high efficiency white LED lights equipped with electronic components specially chosen for the rooms of the Domus Aurea, under conditions of extremely high humidity.
These LED lights offer greater guarantees for the conservation of plasterwork, frescoes and stucco work, since they emit a light equivalent to only 35 lux per room, thus lowering the potential for the development of algae, fungi and lichens (agents of bio-deterioration) by 80%; however, over time other advantages have also emerged:
- the high chromatic quality of the light,
- the absence of ultraviolet and infrared emissions
- the potential for a very low voltage electricity supply.
Low electricity consumption is also significant: when implementing the first intervention we estimated an energy saving of 60% and a very long lifetime of the light sources, between fifty and a hundred thousand hours.
Finally, additional optical devices able to further improve the uniformity of emissions were used on the lights in some of the rooms served by the new system and all the appliances in Cryptoporticus 19.