Civic centre Cristalleries Planell 1015

This public facility houses an adult education centre, a language standardization consortium, and a space for entities on a triangular plot in the Parliament district. Two of the three sides of the site are defined by the heritage-listed frontage of the former Planell glass factory, built on Calle Anglesola in 1913.

The building makes use of the entire plot, acting as an intrinsic part of the urban landscape, although the triangular shape and the classified façades prevent it from occupying the entire site. The programme is distributed across four levels which are set back from the south-facing heritage facade. The resulting atrium reconciles construction and heritage, improves the natural lighting for the classrooms and provides a heat and sound barrier. This long, narrow courtyard is reproduced at the northern vertex, which exhausts the geometry but acts as a relational system between the administrative uses of the building and the exterior.

The building section shows how it controls and manages the air under natural conditions. In winter, it is necessary to control heat loss due to air renewal, redeem the heavy internal load built up due to the inertia of the wall structure, and draw fresh air in from the atrium, which thus acts as a natural air recycle. In summer, the heat has to be dissipated by moving the largest possible volume of air and fresh air must be strictly natural, based on solar chimneys and caps that apply the Venturi effect. Cross-ventilation between the courtyards is ruled out by the programme and the need to avoid conflicting noises. The building therefore gives each strip of usage space a long structural break where the air circulates vertically, ‘pulled upwards’ in the chimneys by the power of the sun, which also give the building a silhouette and a distinctive, transparent materiality.

The resulting volume is an answer to the strict triangular geometry of the plot, for its power and urban behaviour. The ceramic materiality aims to exalt the heritage façade by integrating and not singularizing it, to use and not sacralise it. The new and the old are set with similar materials and techniques. This puts them practically on the same level, but in both cases the building demands are attended: the closing, the reception, the ventilation of the chambers and patios. The materiality is composed by structural meanings. The block of solid glass has been introduced as part of the wall enclosure that allows light to enter the north patio and capture the south patio. This improves the light conditions of the courtyards and provides the façade with a material linked to the memory of Cristalleries Planell.

The main strategy of energy efficiency of the building is the reduction of demand through the optimization of natural light, natural ventilation, and inertia. However, to achieve the normative comfort levels it is necessary to assume the use of highly efficient heat and cold production systems (geothermal). This minimum energy consumption (the building has a maximum consumption of 30 KW, one third of the consumption of a reference building) must be balanced with a percentage of production to assume the responsibility of the municipal facilities to reach “nearly zero”.

The facility generates electrical energy with flexible solar panels integrated into the solar chimneys. The absorbent layer of the solar chimney is a black sheet that must acquire high temperatures in order to produce the movement of the air. Tests were carried out during construction to confirm that the photovoltaic plates maintained the required temperature in the simulations of the absorbent layer, therefore, in the most optimum orientations of the chimneys, 12 m2 of plates (3 KWp) were installed so that, without reducing the chimney’s power, they produce self-consumption electricity.

The two basic tools of the building’s climate comfort are the use and activation of the inertia (bearing structure) and the movement of air. There is no artificial conditioning of the air, but it is necessary to move it in a controlled and intentional manner. In winter, it has to move little to reduce the high internal charges due to the use of teaching (based on CO2 sensors). In summer it must be moved by temperature difference and in quantity enough to remove the internal charge and avoid overheating.

The device that moves this air is a natural engine that acts as a cover of the building too. It consists of four solar fireplaces that generate, thanks to its matter and geometry, three natural systems of ventilation: the chimney effect produced by the difference in height with the interior spaces, the venturi effect produced by the top hats that guarantee ventilation at night, and finally, the greenhouse effect produced by the superposition of a transparent surface (etfe) on a black surface. The temperatures reached by the system are much higher in summer (necessary to move 16,000 m3/h) than in winter. The pyramidal geometry of the chimneys responds to the movement of the sun throughout the day during summertime.