A study of the comfort, energy- and cost-efficiency of different measures to achieve an nZEB renovation in Spain

• Almudena Espinosa ^[1] ; Marta Monzón ^[1] ; Belinda López ^[1]
  1. [1] Universidad de Zaragoza

     Universidad de Zaragoza

     Zaragoza, España

     
• Localización: Disruption: 11º Congreso Europeo sobre Eficiencia Energética y Sostenibilidad en Arquitectura y Urbanismo – 4º Congreso Internacional de Construcción Avanzada: On line 1-2 Diciembre 2020 / Rufino Javier Hernández Minguillón (ed. lit.), 2020, ISBN 978-84-1319-308-3, págs. 91-106
• Idioma: inglés
• Títulos paralelos:
  • Estudio sobre confort, eficiencia energética y costo efectividad de diferentes medidas adoptadas para lograr la rehabitación nZEB en España
• Enlaces
  • Texto Completo Libro
• Resumen

  • The European Commission defined in 2010 the concept of Nearly Zero Energy Buildings (nZEB) as those characterised by a very low energy demand and a high on-site renewable energy production. This concept relies on a careful design of passive and low-energy strategies, on-site or near renewable energy sources and high efficiency facilities and equipment. The definition of nZEB offers flexibility to the Member States to specify their own demands, adapted to the local construction practices and national climatic conditions. Different technical specifications and procedures are being defined by Member States to ensure the construction of newly built nZEBs by the end of 2020 and to boost the retrofit of existing constructions. In Spain, the modification of the so-called Energy Saving Basic Document (Documento Básico DB-HE de «Ahorro de Energía», in Spanish, and DB-HE in short) approved by Real Decreto 732/2019, of December 20 (BOE 27-diciembre-2019) updates the definition of Nearly Zero Energy Buildings, as a building, new or existing, that meets the regulatory requirements regarding the limitation of energy consumption established for newly built buildings. According to the National Institute of Statistics of Spain (INE), 87,7% of the buildings in which we will live in 2050 are already built. In addition, 44% of these buildings were built before 1979 and did not have to comply with any regulations that limited the energy demand or consumption. The built environment in Spain is old and inefficient. It represents an opportunity to reduce CO2 emissions and energy efficiency towards the ambitious aim to reduce up to 80% the EU carbon emissions of the building stock by 2050. It accounts for more than 40% of the overall energy consumption and 36% of the overall CO2 emissions in Europe. The reduction of the energy use in the building sector has its own policy development. Strategies are being defined to drive governments towards the retrofit of the existing building stock. In this paper, a residential building located in Zaragoza (Northern Spain) is studied with the aim to evaluate what implies its transformation into an nZEB according to the Spanish energy efficiency regulations. The paper studies four retrofit scenarios that could be implemented for the existing building, which consider the improvement of the envelope insulation, windows, and heat generation. The building energy performance is simulated with DesignBuilder (the most established and advanced user interface to EnergyPlus) and HULC (the official tool in Spain for energy certification). The simulated models are used for evaluation of the building’s non-renewable and total primary energy consumption and thermal comfort performance (according to ASHRAE adaptive standards) after the proposed retrofit scenarios. The results obtained are compared with the normative limit values for nZEB buildings. The paper also analyses the investment costs, in order to identify the most cost-effective solutions. The results show that the insulating externally the whole façade approach is the best strategy in regard to the studied aspects, achieving a 68,7% reduction of CO2 emissions and 77,7% of heating use, and the only one capable of transforming these buildings into nZEBs.