Architecture in the second half of the 20 th century: forms of expression and the “environmental issue”

Highlights Abstract Conservation and energy retrofit issues in the second half of the 20th century architectural heritage.Responsible approach based on the analysis of the relationship between architectural language and technology. Attention to detail, materials, and original construction techniques may lead to design proposals which attempt to respect the intentions of its authors, preserving the features which are holders of cultural values. Numerous architectural works from the second half of the 20 th century, having a recognized cultural value, turn out to be quite problematic when observed in the scope of today’s unavoidable principle of environmental responsibility. Though representing an energy “issue”, they are at the same time a “high-level witness” in the context of architecture, whose original form of expression, language, and perception must be preserved as intact as possible. This paper critically presents three interventions on architectures in Turin by Domenico Morelli that allow us to make a series of general observations concerning the relationship between preservation and adaptation of works from the second half of the 20 th century.


INTRODUCTION
If the "window" and "building envelope" topic should in our opinion become a prerogative in terms of inalterability -especially in the renewed use or rehabilitation of the architecture from the second half of the 20 th centuryand thus should be considered an unavoidable perceptive characteristic of the preservation action -as much as distribution, material, and construction procedure -then the choice to write this paper concerning some of the architectural works by Domenico Morelli -"an important witness within
Nevertheless, the good intentions of the new rehabilitation project was partially disregarded in the executive phase, due to a lack of continuity and coordination between design and construction management.
The third case study concerned the RAI headquarters in Turin, a work of established cultural value, considered one of the most important works by Aldo Morbelli and Domenico Morelli, currently abandoned but object of attentions for a possible rehabilitation intervention in the near future. The building currently has a similar appearance to its original form, and the building envelope is still unchanged. The matter of relationship between preservation and retrofitting of energy performance is currently open and not easily solvable.

SIP OFFICE BUILDING OF TURIN
"The use of warm and precious materials, the meticulous study of coloursoften elementary and bright -the affectionate and joyful care for every single technological detail -from the light sources to the air conditioning system and the acoustic system -humanize this interior, they make it lived-in. At this level, technology ceases to be the topic of an engineering manual, and rises to the status of expression medium" [1]. The monobloc designed for the SIP (hydroelectric company of Piedmont) offices in Via Avogadro formalizes an advancement in the architectural production by Domenico Morelli, and in this specific case even in the positively established relationship with the existing former headquarters, 500 metres away, designed by Carlo Angelo Ceresa, marking an almost unique contrast and result in Post-war Turin.
In fact, the plan -as well as guaranteeing good sunlight exposure to both façades -allowed the creation of a rupture on the front facing the Turin Citadel, distinguishing the new construction from the existing elements.
Morelli distributed the wing of offices across a rectangular plot of land along the main north-south axis, leaving the central section for the industrial area, but also introducing an innovative exposed load-bearing structure (designed by Eng. A. Antoldi), a metal skeleton with "the walls made of light, vertically undulating metal alloy, with the exception of the two stair blocks and the services coated with clinker, of a cold yet harmonic blue-green colour" [2]. The façade is distinguished by an extruded steel load-bearing structure, protected only on the sides on the ground floor with stone slabs, with a serizzo granite base between each load-bearing element for an improved resistance to wear. At the top floors the walls have insulating panels clad with anodized aluminium, which "[…] represent the most relevant decorative element of the entire work; perhaps it is due to the profile pureness of these parallel ringswith a light and shadow effect that is the result of the trapezoid contour of the slabs composing them -that is the cause of the aerial structure effect", as we can read in the design report of 1957 [3]. In the staircase block, the structure is a metal skeleton integrated in the walls, whilst the external envelope is made of enamelled blue-green klinker.
The building offers very interesting and particularly innovative solutions (standardization of the construction system, component modularity, dry assembling of the building envelope panels), with special attention to construction details that reduce most of the recurring technical issues related to buildings of this kind, such as thermal bridges and condensation.
"The 1.63 m window module has been installed in relation to the dimensions of the room as a whole or to the possible combinations following different uses, given the purposely designed movable walls.
[…] Therefore, the factors accurately controlled were the rationality of workspaces, the frequency of motion along the horizontal and vertical plane, the elimination of causes of disturbing noises, the uniformity and adjustment of natural and artificial light, temperature adjustment, the hygrometric layer, and the air recirculation within the environment over the different seasons" (Project report, 1957) [3].
In December 1951 Morelli wrote to Gio Ponti to have direct information concerning the Sculponia pivoting wooden window, with the Venetian blind interposed between the double glass [3]. The type of window the architect would choose was very similar, but the final material used for it would be anticorodal [4], a special type of aluminium, silicon, magnesium, and manganese alloy that increases corrosion resistance, manufactured by the company L.L.L.
(Lavorazione Leghe Leggere), with a particular colour recalling the white hue of silver and the shininess of chrome and nickel: "The broad glass surface of the façade was made of anodized anticorodal windows that needed to respond to high aesthetic demands as well as functional requirements, such as a high thermal and sound insulation capacity, as well as the insertion of Venetian blinds for protection from sun rays" [5].
(Lavorazione Leghe Leggere), con una particolare colorazione che ricorda il bianco dell'argento e la lucentezza del cromo e del nichel: «L'ampia superficie vetrata della facciata è stata realizzata con un tipo di serramento in anticorodal anodizzato che alle elevate esigenze di carattere estetico doveva soddisfare anche esigenze funzionali, quali un elevato potere di isolamento termico ed acustico e permettere l'inserimento di tende alla veneziana per la protezione dai raggi solari» [5]. Dalla relazione di progetto del 1957 [3]  In the rehabilitation interventions carried out on the architecture of the second half of the 20 th century the use of new windows complying to new standards turned out to be in most cases distortive of the expressive traits and choices of their designers (Fig. 3).
In the case of the former SIP offices the construction details adopted by Morelli, due to their thickness, would have allowed an eventual windows replacement with adequate performaces, safeguarding the distinguishing features of the work.

"PALAZZO NUOVO"
In • the complete refurbishment of the main façade, which were dismounted and substituted with prefabricated panels with high performance windows and integrated shading system (Figs. 5-6); • the application of an insulation coating on the opaque portions of the building envelopes for both blocks; • ventilated façades were built on the ends of the two main blocks; • solar thermal, PV, and rainwater collection systems were integrated.  Fig. 3). Tuttavia nel caso degli ex Uffici della SIP la soluzione costruttiva adottata da Morelli avrebbe consentito l'eventuale sostituzione dei serramenti originali (già di elevato spessore) con altri con prestazioni adeguate, nella salvaguardia dei caratteri identitari dell'opera.  fabbrica principale (Fig.5) con l'installazione di una facciata continua a pannelli prefabbricati (Fig. 6)  The improvement of energy performance has been -as in many other cases -the main reason for renovation work on the building. The building has subsequently undergone expansion work (construction of the library on an underground floor of the inner courtyard) and functional upgrade (i.e. the fire escape stairs, removal of asbestos), but it would have mostly required a planned and efficient maintenance and, perhaps, an all-encompassing recovery design, able to integrate the "energy" issues with cultural, functional, and layout issues. The recent intervention and the task given to the designers, on the other hand, was limited to a building envelope and to the energy saving objectives, avoiding the possibility to design an overall refurbishment.

"PALAZZO NUOVO"
Compared to the original condition, in this case the exposed metal structurethat recalls the innovative SIP office solution -turns out to be less protruding.
Moreover, the new façade is glossy and reflective, offering the image of the Mole Antonelliana monument in front of it (Fig. 3). The remaining opaque portions of the building have been insulated using rendered EPS panels that, increasing the façade's thickness.

RAI HEADQUARTERS SKYSCRAPER IN TORINO
The RAI (national public broadcasting company of Italy) headquarters skyscraper (Fig. 7),

GRATTACIELO PER UFFICI RAI A TORINO
La sede RAI di via Cernaia (Fig.  7)  operations of removal of asbestos, and the eventual reuse is more oriented towards the preservation of the building envelope respecting fully the compositional characteristics of the complex would be desirable.
The conservation of the current building envelope, however, would probably prove to be incompatible with the performance levels required by the current energy saving and efficiency regulations, unless the new requirements are met by a new internal "envelope". In this way the external alterations would be minimal and it would not even be necessary to verify the impact of the intervention with respect to the context. Finding solutions, even within the complex and not too clear legislation on energy retrofitting, which allows to preserve the building envelope even without responding effectively to environmental issues, may not, however, prove to be the correct path from a point of view not only ethical but also economic, given the high maintenance and management costs required to maintain adequate levels of internal comfort. The considerable investment necessary for the rehabilitation and retrofitting the architectural complex would probably lead to exploring solutions that would allow to limit not only intervention costs but also management costs.   Perhaps other intermediate ways between the two scenarios outlined could be viable but always with particular attention and in-depth analysis during the phases of knowledge and project and, above all, with the recognition of the value of the building.
The easiest way, that of the intervention of replacement of the envelope, regardless of the existing architecture and its context, almost as a new building (as in the case of the former SIP Offices), denying the original architectural features of historical and cultural values, is absolutely to be avoided.

CONCLUSIONS
The recent rehabilitation and retrofitting work on modern architecture of an On the other hand, it would be necessary to also work towards adjusting often "indistinct" standards, perhaps effective for ordinary construction work, but that may turn out to be unsuitable for architecture recognized as cultural heritage.