title: A microclimate study on hypogea environments of ancient roman building.
abstract: Roman hypogea, vernacular settlements or crypts, are underground places characterised by specific and unique challenges (RH<90% and almost constant temperature throughout the whole year) related to their relative isolation from the outdoor environment. These sites often require adequate monitoring tools providing complete environmental information in order to carry out appropriate strategies for scheduling routine maintenance and designing suitable layouts for their preservation. In this work we present the results of a carefully planned thermo-hygrometric monitoring campaign conducted in a peculiar Roman building (130CE), the "Casa di Diana" Mithraeum, sited in Ostia Antica (archaeological site, Rome-Italy), with the aim of characterising the indoor environment as the structure suffers of several conservation problems (biocolonisation, efflorescences, evaporating and condensing cycle for wall-building materials). The campaign involving multipoint continuous measurement was carefully planned to better describe this micro-clime. In addition to underground environmental data available in literature, we have also performed, as a checkpoint control, a thermo-hygrometric monitoring campaign in the "Terme di Mitra" Hypogeum, a few meters from the "Casa di Diana". The recorded data was analysed by multivariate statistical and chemometric analyses. The results brought to light the presence of different microclimates (three areas) within a single Mithraeum: a room (pre-Mithraeum) and an area (Mithraeum: 2-4m) present a thermo-hygrometric environmental behaviour in accordance with a semi-confined environment, another area (Mithraeum: 1-2m) behaves accordingly with underground environments (although it cannot be described as such), and the last area (Mithraeum: 0-1m) where was recording RH values close to saturation (96-99%), associated with non-ventilated areas where the rising damp is "held" and not dispersed, describing an own micro-clime, comparable to a "small greenhouse". This study has allowed to identify some critical areas in view of planning future conservation solutions, without exporting the artefacts kept inside.
authors.affiliation: Department of Earth Science, University of Rome "La Sapienza", Piazzale Aldo Moro 5, 00185 Rome, Italy. Electronic address: claudia.scatigno@uniroma1.it.
authors.forename: C
authors.initials: C
authors.lastname: Scatigno
authors.affiliation: INAF/IAPS, Via Fosso del Cavaliere 100, 00133 Rome, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Gaudenzi
authors.affiliation: Department of Chemistry, University of Rome "La Sapienza", Piazzale Aldo Moro 5, 00185 Rome, Italy.
authors.forename: M P
authors.initials: MP
authors.lastname: Sammartino
authors.affiliation: Department of Chemistry, University of Rome "La Sapienza", Piazzale Aldo Moro 5, 00185 Rome, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Visco
keywords: Hypogeum; Indoor monitoring; Mithraeum; Multivariate statistic and chemometric analyses; Preventive conservation; Thermo-hygrometric parameters