No abstract

Architects and historians commonly claim that when designing the Palau Güell, Gaudí experimented with some architectural elements which would influence his later works, with the arches being prevalent in the building. But, to date, no mathematically thorough study has been conducted in order to determine the type of each of such arches. Furthermore, literature contains subjective and intuitive claims which create ambiguity and contradictions. Owing to the methods used by Gaudí, the arches in Palau Güell are best fit by conical curves (ellipse, parabola, hyperbola) or hyperbolic-cosine curves (catenary, Rankine). Using photogrammetrical and mathematical techniques, in this paper we will classify the arches of this building according to their types, we will eliminate the inconsistencies which currently exist in literature, and we will obtain the corresponding analytical equations, which may be helpful in future studies.

Introduction: Quadric surfaces are commonly used in buildings due to their geometric ability to distribute and focus sound waves. The Central Hall in Palau Güell — a UNESCO World Heritage Site — is topped by an ellipsoidal dome. Antoni Gaudí envisaged this room as a concert hall where the organ and the dome play a lead role. Methods: The two previously mentioned elements are the main subject of our paper, which serves two purposes: 1) determining the values of the acoustic parameters of the hall through onsite measurement and also through simulation, and 2) using the geometric parameters of the quadric surface, which best fits the dome, in order to check whether it is possible to improve the acoustics of the hall by placing a new emission source at the focus of the dome’s ellipsoid. Results and Discussion: Contrary to the authors’ expectations, due to the focal reflection properties of the quadric surface, some acoustic parameters on the listening plane do not improve significantly. Therefore, we conclude that Gaudí took the acoustical impact into account when designing this hall.

In this paper, the use of HVAC systems and non-HVAC control measures to reduce virus-laden bioaerosol exposure in a highly occupied indoor space is investigated. A simulation tool was used to model the fate and transport of bioaerosols in an indoor space in the hotel industry (bar or pub) with three types of HVAC system (central air handling system (CAHS), dedicated outdoor air system (DOAS), and wall unit system (WUS)). Non-HVAC control measures such as portable air cleaners (PAC) and local exhaust fans were considered. Occupant exposure was evaluated for 1 μm bioaerosols, which transport SARS-CoV-2, for 3 h/day of continuous source and exposure. The combined effects of ventilation (400 l/s of outdoor air), recirculated air filtration (90% efficacy), and a PAC with a capacity up to 900 m3/h mitigated the (normalized) integrated exposure of the occupant by 0.66 to 0.51 (CAHS) and 0.43 to 0.36 (DOAS). In the case of WUS, the normalized integrated exposure was reduced by up to 0.2 when the PAC with a capacity of up to 900 m3/h was used. The corresponding electricity consumed increased by 297.4 kWh/year (CAHS) and 482.7 kWh/year (DOAS), while for the WUS it increased by 197.1 kWh/year.

El Palau Güell de Antoni Gaudí está catalogado por la UNESCO como World Heritage. Es comúnmente afirmado por arquitectos e historiadores que la superficie del diseño de la cúpula que cubre el Salón Central del Palau Güell es un paraboloide. Mediante técnicas fotogramétricas y geométricas mostramos que tal afirmación no es cierta. Esta investigación determina cual es la superficie cuádrica que mejor ajusta a la cúpula. Además, damos una medida de ese ajuste, y mostramos cuáles son los parámetros geométricos que configuran esa superficie.