Energy certification of existing office buildings: Analysis of two case studies and qualitative reflection

Energy efficiency in buildings is of particular importance in the pursuit of international objectives in the area of climate and energy, as it is a sector that represents approximately 40% of the total primary energy demand in the world, with expected strong growth. In Portugal, the current Building Energy Certification and Indoor Air Quality System (known as SCE) is intended to be an important step in the promotion of energy efficiency and reduction of greenhouse gas emissions. This work presents the application of the SCE system to two large office buildings in the Lisbon area: an historical building (the Lisbon City Hall, built in the late XIX century) and a contemporary office building. In the context of the SCE energy audits to these two buildings, a cost-benefit analysis of different energy optimization scenarios was performed based on calibrated building thermal simulation models. The two case studies, being very different between themselves, represent opposite contexts in which the SCE can be applied to existing buildings and thus the results constitute a suitable basis to examine the principles and energy indicators used in this and other certification schemes, resulting in a qualitative reflection on the limitations of the SCE and opportunities for its improvement.