A systematic method has been established to perform and analyse in detail the Energy Performance Certification of 21 faculty buildings located at the University of Zaragoza (Spain), according to the transposition of Directive 2010/31/EU. First of all, the problem background and a review of the state-of-the-art of the energy certification in buildings is outlined, regarding both the actual state of the Government regulations and the studies undertaken in several countries to assess the energy performance of different types of buildings, residential and non-residential. A summary of the causes found in other studies for the discrepancies between the estimated (by simulation) and actual energy consumption is shown which is afterwards tested and compared with the results found in the present study. Thereafter, the method followed to undertake the buildings' energy performance certification is explained, and the main results found together with the discussion are detailed, comparing

Energy poverty is a common issue in social housing all over Europe, with a harder impact in Southern European countries. Social housing buildings play an important role in energy poverty. They are usually owned and managed by public institutions and usually share common characteristics and issues. Behavioural changes and energy retrofitting are interesting paths forward but some solutions do not fit well in this type of housing due to socioeconomic reasons. This paper makes a thorough analysis of possible energy efficiency measures in social housing buildings, characterizing them by energy and economic savings and investment and proposing different methods of prioritization. A rational approach of behavioural and retrofitting solutions that best fit into this particular housing type is delivered, with the aim to increase the thermal comfort of the residents and mitigate the energy poverty issue. Results show that there is a wide range of domestic efficiency measures to be applied in this type of dwellings at none or low costs, bringing annual savings per average dwelling of about 510 €/year (55% of initial energy costs) including measures both at domestic level, and at building level with a final aggregated payback of the investments to be about 1.5 years.

In developed countries, a large part of the building stock in 2050 will consist of currently existing buildings. Consequently, in order to achieve the objectives in terms of energy efficiency in the building sector we must consider not only new infrastructures but also the old ones. A reduction in energy consumption for climate control of between 50 and 90% can be achieved by rehabilitation and the implementation of different energy efficiency measures. Currently, these measures to reduce energy consumption and associated CO2 emissions can be modelled using computer tools. However, high precision and detail of thermal behaviour models through simulations can mean a great computational cost for companies, which results in a blockage of servers and workers. In this paper, the Response Surface Methodology (RSM) is presented as an innovative methodology for the simplification of models for calculation of the energy savings associated with thermal comfort improvement in buildings. A single-family house model, located in three different climates, is presented as a case study in order to validate the proposed methodology. Different scenarios were simulated, addressing heating and cooling temperature set points and external wall insulation represented by the transmittance (U-value). Results obtained from energy simulation using Design Builder were contrasted against those estimated from the simplified model extracted from the RSM analysis. The results revealed a deviation lower than 3% when comparing both methods. Therefore, the simplified mathematical prediction models are demonstrated to be suitable for the study of the energy performance of buildings, saving computational time, costs and associated human resources.

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