The medieval village of Montieri (pop 1250) is located in the southern flank of the Larderello Geothermal District, about 15 kms SSE from the city of Larderello in Tuscany. The GEOCOM activities involve the whole community delivering three distinct actions: 1) Building a brand new and highly efficient district heating system to utilize high enthalpy geothermal steam from the Montieri-4 well (courtesy by ENEL) 2) Retrofitting a number of selected public buildings and 3) deploying 8.5 kW solar PV as part of the system integration scheme. The sheer volume and complexity of these investments alone would render the Montieri demonstration site to be the flagship component of the GEOCOM initiative. In addition to this the allocated budget further reinforces its special status among the project demo sites. The total budget of our project is just over 11.5 million Euro of which more than 8 million Euro comes from the Regional Government of Tuscany exclusively to support the activities in Montieri.

Retrofitting and RES integration

The retrofitting component –similarly to the other two demonstration sites – was also a mandatory element of the project activities here, too. The medieval building stock under architectural heritage protection presented a major challenge for the architects to deliver feasible energy efficiency solutions for these very old structures. Upon the start of the project most parties were convinced that the proposed 40% reduction of energy needs for the buildings coupled with a 100% fossil fuel free status while meeting all the requirements of the cultural/architectural heritage status is actually a viable scheme. In such an architectural heritage site, the potential for intervention at the building envelope is quite limited. However some other measures can be taken in order to reduce energy needs, to improve thermal comfort, air quality, natural lighting, all meeting the regulations and are suitable for these building types. Read more

In addition, Montieri represents a challenging site for defining and testing a qualitative architectural integration of standard renewable energy technologies (such as PV and solar thermal systems) again due to their visual impact on the protected estates. The 425 residential dwellings which were selected to be linked to the district heating system were the primary subjects of the proposed innovative retrofitting measures such as: opening of skylights to increase the natural ventilation, selective covering of the massive walls from inside in order to optimize the comfort conditions and the thermal inertia of the building and solar photovoltaic technologies integrated into roofing and glazing just to name a few.

The initially proposed measures for retrofitting the building stock in Montieri had been challenged by various factors over the course of the project. Once it was clear that the original plans cannot be delivered a detailed assessment of the key issues were collected and a mitigation plan was drafted listing a set of viable interventions which have been updated and tailored in order to meet the targets set by the proposal while not confronting any currently effective legislation. The building stock in Montieri is largely characterized by thick stone masonry walls and floor and roof systems made of wooden load bearing structures. Local urban and architectural heritage regulations restrict any intervention on these buildings’ facades and roofs in order to preserve and maintain the current profiles and dimensions of such buildings (including the wooden window frames) for the sake of keeping the cultural character of the historic town. Despite all the research efforts carried out so far (even a full PhD thesis had been delivered on the subject), and in spite of all the proposed solutions aiming at the improvement of the energy performance of all these historic buildings, it had to be concluded that this task has a whole lot more angle than originally  anticipated.

At this stage of the project, the main objective is to decide about whether the initially set thermal requirements for these structures could be achieved on the affected building stock with the currently available energy retrofit technologies, which also suit the owners, or not. Research has shown that certain technologies could deliver the desired thermal specifications while meeting the standards set by the cultural heritage protection authority, but they are way too expensive solutions for most of the inhabitants in Montieri. Since the retrofitting component was meant to be co-funded by those home owners whose properties were affected, the project cannot impose on the dwellers any costs which they are not willing to pay. In short, the local population is no longer interested in energy efficiency measures on their homes simply because the cost of their heating will have been dropped by 90% once the district heating system will be turned on and the rate of return on any of the proposed retrofitting measures are considered to be way too long. In order to tackle some of these issues and to maximize building energy performance, the initial plans were not only extended to local public buildings, but a series of technical guidelines were drafted too, setting minimum thermal insulation requirements, which on one hand were less ambitious than the ones in the original concept, and on the other hand could potentially be suited for Montieri and other local historic towns as well as for Italian and European ones. Results of the monitoring activity (as part of this initiative) are expected to prove energy savings and improvement of indoor comfort as a direct outcome of the installation of the updated retrofit measures.