Pioneering building integrated photovoltaic solutions to support the energy transition in historical cities

15 Oct 2021 — A study carried out in the historical center of Évora shows building-integrated photovoltaic solutions that will reduce the energy consumption of historical buildings while respecting their aesthetic features

Over the past decades, energy consumption demands have increased due to global population growth and rapid economic development. Cities can play an important role in inverting this trend as the buildings and buildings construction sectors combined are responsible for over one-third of global final energy consumption. To do so, cities need to follow stable and long-term strategies for the transformation of their buildings and districts into Positive Energy Buildings (PEBs) and Positive Energy Districts (PEDs), respectively. These are buildings or urban areas that produce more on-site energy from renewable sources than they consume.

But when it comes to historical buildings, that are typically low energy performance, the retrofitting procedure gets more complicated. In fact, not every retrofit technology can be installed in historical sites due to architectonic, conservative, and cultural barriers, along with each country’s existing regulations. Thus, alternative methods and solutions must be considered to improve the energy consumption of these edifices. Building-Integrated Photovoltaics (BIPV) are photovoltaic materials that are used to replace conventional building materials in parts of the building envelope such as the roof, skylights, or façade. BIPV represent a solution to make historical and protected buildings more sustainable while respecting their aesthetic features.

A recent paper presents the study that has been carried out for the implementation of BIPV solutions in the Historic Centre of Évora, UNESCO heritage site. Évora’s well-preserved historical city center is one of the richest monuments in Portugal and is also one of the PEB (Positive Energy Block) pilot sites of the European funded project POCITYF.  The area presents very restrictive laws for the protection of cultural heritage, which constitute an obstacle in the implementation of business-as-usual solutions for renewable generation (e.g. photovoltaic panels). Eight municipal buildings will be provided with renewable generation capacity. Consequently, to overcome the constraints, five different BIPV solutions were designed by two entities of the consortium, that comply with the specifications and guidelines imposed by the Regional Culture Administration of Alentejo: ONYX – a Spanish company specialised in BIPV solutions – and Tegola – an Italian company specialised in aesthetic photovoltaic roofing.

The proposed solutions aim at fulfilling all the guidelines for preserving the historic center and achieving the positivity metrics agreed with the European Commission on the challenging and indispensable path to the decarbonisation of European cities.

Read the full paper here.


Authors: Georgios Tsoumanis,João Formiga, Nuno Bilo, Panagiotis Tsarchopoulos, Dimosthenis Ioannidis and Dimitrios Tzovaras

Academic Editors: Marc A. Rosen and Charalampos Dimoulas

Sustainability 202113(16), 9358;

Received: 30 June 2021 / Revised: 30 July 2021 / Accepted: 13 August 2021 / Published: 20 August 2021

(This article belongs to the Special Issue Cultural Heritage Storytelling, Engagement and Management in the Era of Big Data and the Semantic Web)


Photo credit: photovoltaic skylight Malaga Port Authority – ONYX Solar