Energy renovation of the built heritage housing based on the living building challenge certification. Case study in Bresca (Spain)

In light of increasing sustainability requirements, one of the challenges related to the heritage building stock consists in finding a balance between preserving the existing architectural character and improving energy efficiency. The project presented in this article has been carried out through a collaborative design process, involving experts from different disciplines (e.g. construction, energy, low-carbon materials, etc.), through a simulation-driven approach integrating both architectural and energy-performance evaluation aspects from the early-design phases of the project. In order to go as far as possible in terms of sustainability, the Living Building Challenge (LBC) label has been taken as a guide, providing a design framework to create regenerative spaces where people connect to daylighting, air, food, nature and community. It aims to obtain self-sufficient buildings from a holistic point of view (e.g. positive-energy building approach, treatment of the used-water onsite, prioritizing low-impact materials to obtain healthy living spaces). The project consists of the complete renovation of a rural home located in the medieval urban fabric of a small village called Bresca in the north of Spain. The initial construction date is unknown, but the house underwent a first basic renovation in 2007. The building consists of a typical farmhouse, well oriented regarding solar exposure, with poorly insulated massive walls and no heating system. The renovation project includes both passive and active strategies, improving thermal insulation of the building envelope and integrating a sunspace that helps to reduce heating and lighting demand, in addition to a photovoltaics (PV) installation with storage system that feeds a high-performance heat pump. This paper focuses on the energy aspects, comparing design results and post-occupancy evaluation in terms of energy consumption/production (energy performance gap). We highlight the high energy performance achieved while surmounting the architectural challenges related to the heritage constraints of the existing building. Results show that between February and March 2019, the house produced 858 and consumed 508 kWh, demonstrating that it is possible to achieve high levels of annual PV coverage ratio while respecting and valuing traditional architecture.

Active renovation strategies with building-integrated photovoltaics (BIPV). Application on an early 20th century multi-family building

Sergi Aguacil Moreno

Tomorrow's cities are already largely built, as much of the existing building stock – with a low level of energy performance – will still be standing in 2050. Urban renewal processes therefore play an essential role towards the sustainable transition of European cities. In this context, building-integrated photovoltaic (BIPV) systems can potentially provide a crucial response to achieve current energy and mid- to long-term carbon targets. Functioning both as envelope material and electricity generator, BIPV systems can simultaneously reduce the use of fossil fuels and greenhouse gas (GHG) emissions, while providing savings in materials and electricity costs. These are precisely the objectives of most European energy directives, from zero- to positive-energy buildings. However, despite continuous technological progress and increasingly favourable economic conditions, the significant assets of BIPV remain broadly undervalued in the current practice. Focusing on the architectural design, this paper presents the results of a multi-criteria evaluation in terms of Life-Cycle Assessment (LCA) and Cost (LCC) of different renovation and energy-use scenarios, showing which strategies can allow to achieve the ambitious targets for the 2050 horizon by integrating into the design process: (1) Passive strategies, to improve the envelope through low-embodied energy materials and construction systems; (2) BIPV strategies, using innovative photovoltaic products as a new construction material for façades and roofs, and by selecting the BIPV surfaces in order to synchronize on-site generation with the building consumption profile; (3) Active strategies, adapting the HVAC system to improve its efficiency and maximize PV self-consumption, thus reducing the dependence on feed-in-tariffs to ensure the profitability of investments. The research methodology, presented in this paper through the comparison of different renovation scenarios applied on a 1900’s archetype building in Neuchâtel (Switzerland), proposes a new way to address rehabilitation projects of existing buildings in urban environments towards Low Carbon Buildings. The main outcome provides - to architects and engineers - advanced BIPV renovation strategies depending on the building typology, the architectural design goals, and the level of intervention.

2020

Influence of energy-use scenarios in Life-Cycle Analysis of renovation projects with Building-Integrated Photovoltaics – Investigation through two case studies in Neuchâtel (Switzerland)

Sergi Aguacil Moreno, Sophie Lufkin

Since tomorrow’s cities are already largely built, and as many of their buildings – with a low level of energy performance – will still be standing in 2050, urban renewal processes play an essential role towards the sustainable development of European cities. In this context, Building-Integrated Photovoltaic (BIPV) systems can potentially provide a crucial response for achieving long-term carbon targets. Functioning both as envelope material and on-site electricity generator, they can simultaneously reduce the use of fossil fuels and greenhouse gas emissions. Focusing on the architectural design, this paper presents the results of a multi-criteria evaluation in terms of Life-Cycle Assessment (LCA) and Cost (LCC) of different renovation and energy-use scenarios. The goal is to identify which strategies can allow to achieve the ambitious targets for the 2050 horizon by integrating into the design process: 1) Passive strategies, to improve the envelope through low-embodied energy materials and construction systems; 2) BIPV strategies, using innovative photovoltaic products as a new material for façades and roofs; and 3) Active strategies, adapting HVAC systems to improve the efficiency of the BIPV installation and reducing the dependence on the feed-in-tariffs to ensure the profitability of investments. An emphasis is placed on testing the impact of a proposed selection process of BIPV surfaces in order to maximise self-consumption and self-sufficiency, evaluating the effect of electricity storage systems with and without the possibility of injecting the overproduction into the grid. Our methodology and results are presented through the comparison of two real case studies in Neuchâtel (Switzerland). Proposing a new approach to address renovation projects of existing buildings in the urban context towards Low Carbon Buildings, the outcomes provide architects and engineers with advanced BIPV renovation strategies depending on the building typology, the architectural design goals and the level of intervention.

H. Elsharkawy, S. Zahiri, J. Clough2017

Velux Lab: innovation between art and science

Arianna Brambilla

Veluxlab is the first Italian Nearly Zero Energy Building. It is placed in Bovisa Campus of Politecnico di Milano and it represents a study case of high energy efficiency building, integrating in the future scenario required by the European Directive 2010/31/UE. VELUXlab was born as a Mediterranean Model Home for VELUX, called Atika, designed by J.A. Cantalejo and R.A.Ronda from ACXT/IDOM studio. It personified the prototype of energy efficiency building for the Mediterranean Region and it is the result of an important architectural and performance retrofit. The renovation was led by Atelier2 with the supervision of Professor Imperadori and Professor Motta from Politecnico di Milano.The collaboration between Politecnico di Milano and VELUX Italia gave the opportunity of create a new lab, a sort of test building, where it is possible to develop the experimental research on going in the University. In this way VELUXlab became itself matter of research on the energy efficiency and sustainability in the building sector. The use of innovative solutions and materials for the envelope coupled with an advanced technological system, makes representing the first Italian nearly Zero Energy Building in a University Campus. Furthermore, thanks to its energetic performance and to the integration of renewable source, it is the first built Active House in Italy (www.activehouse.info). VELUXlab is, therefore, an example of smart and sustainable re-use of an existing structure as well as a model of energy efficient building and a prototype for the new generation home, bringing forward future experimentations and implementation in the sector. It is the profitable collaboration between Politecnico and construction companies that allows to innovate, test and research sustainability and efficiency. The west wing of the building and the conditioning system are equipped with a revolutionary wireless sensors network (WSN), designed by the DEI Department of Politecnico di Milano (Prof. Cugola, Ing. Sivieri), that allows a constantly monitoring of the real performance of the envelope - indoor comfort system. The real time results are broadcasted on the University intranet, elaborated by a remote server and then made available on-line. Thanks to this streaming it is possible to understand the real performance of VELUXlab in the first year of measurement. This data portray the ordinary operational situation, including the internal strains given by the users; it is easy to understand that the building itself is a prototype, conceived as an active and dynamic laboratory. In order to make easier the data interpretation and management, the Design Department (Prof. Bordegoni), is been studying an innovative and more intuitive way to visualize the sensors data, with the implementation of the graphic interface in an augmented reality platform. It is easy to understand that VELUXlab offers continuously incentives and opportunities for testing and experimenting innovative solutions and ideas, giving the chance to continue research and studies.

2013