TRANSFORMATION OF RESIDENTIAL HOUSINGS FROM THE REAL ESTATE BUBBLE INTO NEARLY-ZERO-ENERGY BUILDINGS: CASE STUDIES

Abstract

Spanish residential buildings built during the real estate bubble (200-2009) complied with the Spanish Basic Building Standard on building thermal conditions NBE-CT-79. In 2006, the Basic Energy Saving Document of the Spanish Technical Building Code (CTE-DB-HE) came into effect. This code developed the Spanish Organic Law on Buildings 38/1999 and it was also much more restrictive. Recently, this regulatory framework has been updated by the Spanish Royal Decree 732/2019 on energy efficiency. This Royal Decree transposes European Directives 2010/31/EU, 2012/27/EU and 2018/844/EU on nearly-zero-energy consumption buildings (NZEB). In this paper, the energy, emissions and economic impact caused by this legislation change on a standard semi-detached house in the 153 cities of Andalusia is analyzed. In each location, the household’s original thermal behavior with the compliant with current legislation is compared. The calculations are performed with HULC energy simulation tool and the European PVGIS climate data, considering the most adverse orientations. The house adaptation involves a partial modification of the envelope, the inclusion of solar-thermal energy for the domestic hot water supply (DHW) and photovoltaic energy to reduce electricity consumption. Results show that European objectives are largely exceeded. Energy savings vary between 81% and 146%, emissions improve between 71% and 128% and the electricity and natural gas bill is reduced between 67% and 123%. Keywords: Spanish real estate bubble, energy efficiency, nearly-zero-energy building, thermal envelope, thermal insulation, solar-thermal energy, photovoltaic energy, technical building code, housing rehabilitation, Andalusia.