Jesica Fernández-Agüera, Rafael Suárez, Per Heiselberg
Bibliographic info:
33rd AIVC Conference " Optimising Ventilative Cooling and Airtightness for [Nearly] Zero-Energy Buildings, IAQ and Comfort", Copenhagen, Denmark, 10-11 October 2012

In Spain, the residential sector is the third principal source of energy consumption; many of these dwellings are obsolete and do not have optimal conditions of comfort. For this reason, their energy retrofitting means an enormous step towards the energy efficiency. Under the general intervention strategies, the study and analysis of the air-tightness of the building envelope (as measured by the degree of infiltration) is a fundamental factor, because of its impact on energy efficiency, thermal comfort of occupants and indoor air quality. For this purpose, it has become a regular research field in other European countries and the USA. However, there is a lack of studies with adequate roominess to allow a proper analysis and interpretation of what happens in our regional climate and construction typology.

The aims of this paper is presenting a case study for the energy retrofit of 68 social multi-dwelling units in Cordoba (Southern Spain) evaluating their global energy demand and analysing the importance of air-tightness.

An in-situ air-tightness measurement campaign was carried out in these multi-dwelling units, before and after retrofitting, using Blower Door equipment. The best method for obtaining these parameters is pressurization/depressurization tests. It has been effectuated some modifications on façades and windows in order to obtain a better air-tightness.

The energy consumption was evaluated for the different levels of air-tightness by some tests which have allowed models to be generated. These models have been analyzed using Design Builder Energy Simulation software program, based on the DOE 2.2 calculation engine, obtaining predictive energy consumption, before and after retrofitting, including only air tightness changes and other retrofitting improvements (insulation, solar protection, U-transmittance in windows and facades) for the dwelling-units during a typical year.