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Abstract:The current European energy policies have an influence on the need to rehabilitate the housing stock in order to meet the objectives of the European Union. Most of this housing stock was built without any type of energy regulation in adverse technical and economic conditions and thus is now energetically obsolete. The major rehabilitation effort required must be approached through actions based on previous quantitative energy knowledge of the existing buildings in order to guarantee the efficiency of energy-retrofitted solutions. This assessment can be carried out through monitoring dwellings conditioned by use patterns; through simulation programs, which do not usually offer faithful representations of energy conditions; or by using test cells, which allow us to evaluate a controlled indoor environment without the influence of users. The objective of this paper is to present the design and performance of test cells as an experimental method for vertical facade analysis in order to tackle the problem of retrofitting residential buildings in a Mediterranean climate, taking into account energy and environment. With this equipment, efficiency and energy savings, as well as illumination and interior air quality, can be simultaneously and comprehensively evaluated.

According to the IPCC Climate Change projections by 2050 temperatures in southern Spain will have increased noticeably during the summer. Housing-in its current form-will not be able to provide a suitable response to this new climate scenario, and will in turn prompt an increase in cooling energy consumption and a series of problems relating to health and comfort. The Design Builder simulation tool was used to quantify the impact of this future climate scenario on energy demand, as well as its effect under free-running conditions on indoor temperature. Different passive conditioning strategies were evaluated to establish their influence on the indoor comfort conditions. The case study examined a theoretical single-family residential unit model in order to establish guidelines for the pre-selection of the most suitable passive solutions. The results show that passive conditioning strategies analysed (envelope treatment, solar gain protection and night-time natural ventilation) reduce energy demand and indoor temperatures, thus increasing energy efficiency and improving indoor comfort conditions. Therefore, these passive conditioning strategies reduce the cooling energy consumption.

Current energy efficiency policies in buildings foster the promotion of energy retrofitting of the existing stock. In southern Spain, the most extensive public sector is that of educational buildings, which is especially subject to significant internal loads due to high occupancy. A large fraction of the energy retrofit strategies conducted to date have focused on energy aspects and indoor thermal comfort, repeatedly disregarding indoor air quality criteria. This research assesses indoor air quality in a school located in the Mediterranean area, with the objective of promoting different ventilation scenarios, based on occupancy patterns and carbon dioxide levels monitored on site. Results show that manual ventilation cannot guarantee minimum indoor quality levels following current standards. A constant ventilation based on CO2 levels allows 15% more thermal comfort hours a year to be reached, compared to CO2-based optimized demand-controlled ventilation. Nevertheless, the latter ensures 35% annual energy savings, compared to a constant CO2-based ventilation, and 37% more annual energy savings over that of a constant ventilation rate of outdoor air per person.