Almost everything in the renovated Neue Nationalgalerie is new. It's not just the old Modernist Architecture from 1968 that still strikes us as radiantly new after fifty years — as a living icon of Modernism, just as we are always touched anew by the works of Modernist Art for which it was built as an exhibition venue at that time. In the course of the comprehensive basic renovation of the gallery building started in 2015, some of the things that had long since been lost, disappeared, forgotten and destroyed over the course of time were made “new again”.

Objects, surfaces, furnishings and materials were restored. This also included the upgrading and renewal of the new technical building achievements that made this Modernist building possible in the first place. Some completely new elements were also installed as a result of the renovation planning and measures, until the handover in April 2021 (1). New objects were developed in this process so that some "old" elements of the Neue Nationalgalerie would work better or could be preserved in their current state. Its status as a monument of radical Modernism is thus made more comprehensible and can be experienced (2) authentically (3). The "old" was preserved and new things were planned and installed to meet today's new requirements for use such as new exhibition standards, better building infrastructure installation and further necessary improvements.

New?: The facets of the meaning of this little adjective are varied and far-reaching. Does one mean new to be "of recent origin / different [being] from before, from before [or does it have the meaning of] not yet used / not worn out?” (4). When renovating a historical building — especially a Modernist one — it is inevitable to come across with such questions of time classification. The answer is based on a construction-analytical “investigation” which leads to a decision process about the “value” of the building and its components:

• Is it “authentic”, “reconstructed” or had some later additions?
• Is it a later “intervention”, a necessary addition in the course of “restoration” or “repair”, or were there “alterations” carried out on its original state?

The renewal of a building, the “conservation” (5) of its substance (6) or the addition of new elements requires a range of planning and action possibilities in “rehabilitation” (7). First of all, a thorough preliminary examination of the apparent “damage” (8), deficiencies in use and the “conditions” (9) of preservation found is essential. In buildings that date back as far as the 19th century, this increasingly includes the building services, infrastructural systems and installed machinery (10). In the case of Modern buildings — often in comparison to older monuments — the aesthetic bond to the seemingly achieved cultural "timelessness of architecture" is also an important factor of impression and poses new, different questions of evaluation, e.g., with regard to authenticity, ageing and existing traces of use in the case of renovation.

"Sticks and Stones" (2014) by David Chipperfield: installation of 143 hundred-year-old trees Sitka spruces (latin Picea sitchensis) mounted on granite floor slabs which dialectically thematizes the gravity of tectonic bearing and burdening in contrast to the Miesian construction of a light, balanced and transparent architectural conception
Foto/photo Klaus Brendle, 2014

Starting points for the basic refurbishment

After almost fifty years of use, structural changes, outdated functional standards, changed visitor expectations and exhibition-related deficiencies made the building stock deteriorated to such a state that required a "basic refurbishment” (11) of the Neue Nationalgalerie. In this process, it was also necessary to take a particular look at some of the technical problems that had always caused difficulties in the use of the building:

• Which building elements and usage patterns had to be preserved, reinserted or changed?
• What was to be done to preserve the Neue Nationalgalerie together with its internationally significant cultural use?

The Federal Office for Building and Regional Planning in Berlin — BBR, the State Museums Berlin — SMB of the Prussian Cultural Heritage Foundation — SPK, David Chipperfield Architects Berlin and the Department for the Preservation of Historical Monuments of Berlin — LDA (12), decided upon together on a pragmatic and non-dogmatic approach based on the principle of "invisible intervention" (13). However, the entire interventions on the Neue Nationalgalerie, from leaving it as it is to insertion of new parts, and the planned and implemented rehabilitation measures (14) includes: conservating — repairing — reintegrating — restoring — reconstructing — and, new-constructing.

The building was reduced to the state of a "carcass" by the dismantling work before restoration — basement floor with the concrete cassette coffered ceiling: on the far right, one of the eight solid concrete columns with capitals supporting the structural system of mushroom-type slabs
Foto/photo courtesy David Chipperfield Architects Berlin, 2015

Before investigation (15) and safety measures were initiated, an extensive structural consolidation (16) was required to verify its stability in order to avoid later interventions. Load tests of an experimental nature were carried out on selected ceiling sections in 2015-2016. This showed that the existing ceiling slabs had sufficient load-bearing capacity — despite their incorrect iron position — and thus the static stability could be experimentally proven. Further thoroughly structural interventions could be avoided, showing how essential and helpful, however costly, comprehensive preliminary investigations are in order to be able to determine appropriate measures for the monument or to avoid unnecessary procedures.

Preserving restoration — conservating and repairing

EN 15898 3.3.10. Restoration: "actions applied to a stable or stabilized object aimed at facilitating its appreciation, understanding and/or use, while respecting and/or revealing its significance” (17).

Conservating (18)

EN 15898 3.3.1. Conservation [...]: "measures and actions aimed at safeguarding cultural heritage while respecting its significance, including its accessibility to present and future generations. Note 1 to entry: Conservation includes 'preventive conservation', 'remedial conservation' and 'restoration'. [...] Note 3 to entry: All conservation actions are based on documentary and/or material evidence”.

All dismantled elements of the facades, floors, building services and construction (approximately 40.000 reusable elements) were inventoried and stored. Unusable parts and building services installations were also dismantled and then disposed of. In the case of the remaining carcass, the concrete damage that had become visible had to be partially removed down to the steel reinforcement and then repaired. The particular way of dealing with the natural stone-clad concrete walls of the "Sculpture Garden" is described in section Reconstructing.

Structural damage — carbonation and insufficient concrete cover of the reinforcement of the concrete walls at the base of the building
Foto/photo courtesy GSE Ingenieurgesellschaft mbH, 2017

The steel components of the slab and roof supports were fully functional and were selectively unscrewed at the damaged points. After treatment, the analytically determined black colour of the initial version could be reapplied by hand with a visible brush stroke. The entire Mies van der Rohe / Lili Reich furniture was restored, cleaned and partially repaired.

The original furniture designed by Ludwig Mies van der Rohe and Lili Reich — handcrafted restoration of the original leather upholstery of the 1968 Barcelona Chair
Foto/photo R. Roßberg [Courtesy ProDenkmal, 2018]

The metal ventilation grilles were cleaned (19) as well as the wooden skirting boards (wall end profiles approximately 440 m) which were removed and then later reinstalled. After their removal, furnishings such as the veneer-covered wardrobe units, partition walls and doors were given a fresh colour and carefully conserved using a newly developed, reversible (20) wood veneer treatment and could be reinstalled in accordance.

The original 1968 medium voltage power distribution board remained in place as a historical relict; the new central electrical system and the control system were placed in the new technical rooms
Foto/photo courtesy David Chipperfield Architects Berlin, 2015

The original 1968 medium voltage power distribution board remained in place as a historical relict; the new central electrical system and the control system were placed in the new technical rooms
Foto/photo courtesy David Chipperfield Architects Berlin, 2015

All those conservation measures followed the principles of the Venice Charter (21), which asserts the preservation of the original substance as a main goal of monument conservation. Accordingly, in the case of certain types of damage, the objects (22) were repaired, original parts were left on the building as far as possible or carefully dismantled, treated if necessary or gently cleaned, stored and later reinstalled in the course of the construction work (see section Reassembling).

2.2. Repairing

EN 15898 3.5.10. “repair: action applied to an object or part of it to recover its functionality and/or its appearance. Note 1 to entry: Repair is a conservation action only if it respects significance and is based on evidence”.

a. Natural stone work

The procedures carried out in the restoration of the natural stones of the facades and the floor of the outdoor area included cleaning, removal of foreign materials and adhesions. Broken stone parts were needled, cracks were injected, missing parts were filled with stone replacement material and, in the worst case, the stone was completely replaced. As with the new original building, replacement material of Striegau granite could presumably be obtained from the same quarries in the vicinity of Strzegom / Poland (23). To avoid a too strong colour contrast between the new and the existing granite stones, a shade of grey approximating the patina colour was chosen after careful cleaning (24). The repairs made with the new stones, therefore, remain visible but without the domination of their original colour.

Repair work (not yet completed) to the original granite cladding of the external walls with the insertion of new lighter coloured stones which will be slightly darkened by careful post-treatment. However, they will still be legible to be distinguished from the original stones (EN 15898:2019 3.3.4. Legibility)
Foto/photo Betânia Brendle, 2021

b. Steel-glass façade

The difficult problems with the entire steel-glass façades, on the other hand, are conceptually a "defect", which requires extensive repairs. According to EN 15898, a "defect" is characterised by the “imperfection of an object due to its conception, its production or its construction process or to the nature of materials employed (25).” Three different problems must be distinguished in the case of glass façades:

• Forces due to weathering and thermal movements (1)
• Stability and traffic safety of the glazing (2)
• Condensation on the glass surfaces and steel profiles(3)

Deformation values determined from the dead load of the roof body and the loads of snow, rain, wind loads and temperature-related movements acting on the façade construction from above
Desenho/drawing courtesy David Chipperfield Architects Berlin, 2015

b.(1) Steel-glass façade and weather influences as well as additional loads

The wind forces acting on the overall façade on one side of the building are diverted to the roof slab by means of movable steel strips (by a so-called sword-sheath-construction) and to the floor concrete slab of the terrace. However, these wind shear forces at the building corners also have an effect on the respective right-angled adjoining longitudinal façades and load them from the lateral building corners. In addition, the upper structural steel strips jammed in the guide rails ("sheathings") on the steel roof due to dents that had occurred. The weather-related thermal effects also deformed the lengths of the façade steel construction (by several centimetres), and this did not have enough space to expand. Added to this were the loads from the steel cassette roof itself, from snow, rain, wind loads and temperature movements, which affected the façades from above because they could not move freely enough from the roof and floor slab. At that time, no expansion possibilities had been planned for these force effects and also for vertical movements. The interacting rigidity or insufficient mobility of the overall steel construction of the façade transferred its compressive load to the glass panes, which repeatedly broke under this load from the very beginning.

The four newly created façade sections on each side — each one has lower expansion values due to their individual division (red arrows). Three “expansion posts" with integrated movement joints are used to absorb the temperature expansion of the façades. Further shear forces at the façade corners are absorbed by stiffly bonded, special steel-glass composite surfaces
Desenho/drawing courtesy David Chipperfield Architects Berlin, 2015

Horizontal section of the new "expansion posts" — the horizontal movements (red arrows) of the steel-glass façade are absorbed almost invisibly within the new posts by small spacer buffers per façade individual section. These special post replicas have th
Desenho/drawing courtesy David Chipperfield Architects Berlin, 2015

Horizontal section of the new "expansion posts" — the horizontal movements (red arrows) of the steel-glass façade are absorbed almost invisibly within the new posts by small spacer buffers per façade individual section. These special post replicas have the same dimensions as the original posts and can only be read on the screws as a modified copy (EN 15898:2019 3.3.4. Readability); the building interior is at the bottom
Desenho/drawing courtesy David Chipperfield Architects Berlin, 2015

With the new, improved construction solution, the maximum temperature deformation per façade section could be reduced to approximately three times 1.5-2.0 cm each by dividing the façade into four (invisible) structural individual sections on each side. For this purpose, three new special “expansion posts” were detailed in each case, which can accommodate this reduced expansion / shrinkage per section. They are also composed of solid profiles like the originals, but have certain movement possibilities by means of screw connections and internal distances. The effects of the movements of the roof body on the four façades are ensured by reduced, adapted connection plates and by new vertical movement possibilities. Another measure for stabilising and absorbing the lateral shear forces is the formation of “shear-stiff corner elements", which was achieved by a special static bonding of the glass panes there with the steel profile frames.

b.(2) Steel-glass façade and glass stability

The built-in single glazing with dimensions up to 5.37 x 3.46m could only be produced with cast glass (d = 12.5 mm) at the time of construction. It was produced in France by the Boussois Company, contained little iron, arsenic and fluorine and had a similar colouring to today's white glass. It is no longer produced and can no longer be installed because of the hazards of possible glass breakage. Instead, a laminated glass (compound safety glass made of 2 x 12 mm heat strengthened glass) was selected consisting of two bonded glass panes with a tear-resistant film in between, which has a high bending tensile strength and stability. At the time of the renovation work, there was only one manufacturer in the world, in China, who could produce laminated glass in the required maximum dimensions. The re-installation of single glazing meant that condensation on the inside of the glass panes could not be ruled out in the future.

Neue Nationalgalerie, air flow at the glass wall, sketch for analysis of insufficient and inconstant airflow
Desenho original/original drawing courtesy David Chipperfield Architects Berlin

b.(3) Steel-glass façade and condensation formation

In addition to the instability of the façade due to the very thin glass and the safety risks in case of breakage, there was a clear formation of condensation water inside the glazing and the steel construction, since its construction, at certain external temperatures in winter (below 5˚C), as both are not thermally separated. As a result, some of the steel parts were clearly corroded and, due to insufficient drainage of the condensate water, there were moisture problems at the base of the façade despite retrofitting with U-gutters. To avoid or reduce the formation of condensation, warm air was blown in close to the façade at the bottom and extracted at the top. The functionally necessary curtain has been an integral part of the design since 1966 and was also intended to better control the warm airflow and create a dampening microclimate just near behind the façade. However, the vertical flow of warm air remained unstable, and it was not possible to guarantee a secure, uniform indoor climate in the exhibition hall. The planning and installation solutions at the time were not sufficient for this from a building physics point of view. In addition, the curtain mounted on three sides of the façade, which was replaced by a darker curtain in the 1970-1980s, was completely dismantled in 1998, regardless of its climatic necessity. (For more details on the planned curtain, see section Reintegrating).

In accordance with the restoration aims, it was decided to reinstall the original, thermally non-separated façades with the narrow, profiled steel profiles. Their surface treatment with the preservation of the original colours through cleaning and with selective repairs is explained in section Conservating. By preserving the original parts and with the replaced new "expansion posts" of the same colour, which were necessary from the point of view of building physics, it was possible to preserve the transparent effect of the façades. However, the air-conditioning and heating system had to be completely redeveloped (26) in order to better regulate the local building-physical conditions on the façades. In relation to the technology of the HVAC (27) system of the construction period, this should be seen as a destruction of original parts of the monument, but from the prevailing point of view as a hall for art exhibition, an absolutely necessary "repair" of the indoor climate parameters.

Steel-glass façade and microclimate — 1:1 test setups of the simulation model in the laboratory for redesigning the inside climate control system along the glass façade (h = 8,4 m), opened on the left and with a curtain segment on the right
Foto/photo Tobias Smolla SLT
Courtesy Schanze Lufttechnik Lingen, 2018

In elaborate laboratory tests, the airflows along the 8.4 m high glass façade were investigated and optimized in order to minimize the problem of strong condensate formation over the entire inner façade height by means of a continuous flow of warm air. The newly designed central air-conditioning system generates a specially prepared heat and air quality for the glass façade with the required flow-relevant values, so that the air-conditioning system can better buffer the effects of the weather on all four façades. Nevertheless, (minor) condensation formation cannot be completely ruled out.

The drainage of the condensate was optimized by some precise measures, e.g. in the steel profiles themselves and by a better drainage by means of an enlarged gutter form at the base of the façade, so that the condensation water no longer flows into the into the adjacent supply air grating.

Steel-glass façade — "Vertical section of façade posts" — base point original scale M 1:5, detail from plan no. 3601 "Steel and glass façade of exhibition hall, standard details ground floor, as at 14.08.2015", with condensation gutter (see green arrow, author's montage)
Desenho/drawing courtesy David Chipperfield Architects Berlin, 2015

Interior view of the base of the facade — on the right the original granite floor edge, then the steel grille after dismantling and cleaning for the hot/cold air supply required to minimise condensation on the glazing. Further on the right, the new drainage gutter collecting the remaining condensation. On the far right, the cleaned and/or repaired lower steel frame, with the new modified (bolted) steel frame for mounting the glazing, and with the new thicker laminated glass panel (d = 25 mm)
Foto/photo Betânia Brendle, 2021

c. General climatic parameters of the building interior, especially in the hall

The inadequacies of the original building envelope, as described above, had a direct effect on the climatic conditions inside the Neue Nationalgalerie. In addition, when the sun shone in summer, the large glass surfaces heated up the building considerably. The consequences of these material and functional defects (28) in the building led to constant changes (29) that threatened the integrity (30) of the structure for nearly fifty years of use. The instability of the indoor climate in the hall affected its general use as an international exhibition venue. In addition, the climatic and safety requirements for room conditions in the international art lending business have become considerably more stringent since 1968.

Detail of the building's original service infrastructure system before dismantling
Foto/photo courtesy David Chipperfield Architects Berlin, 2015

A precise, reliable and constant regulation of the climatic conditions in the exhibition rooms — especially in the glass hall — was essential for the continued use as an exhibition building. In this respect, considerably higher indoor climate requirements had to be met during the rehabilitation. The other air-related requirements for visitors, staff, the depot and the technical rooms also had to be taken in account. The "repair" of the room climate therefore included a new heating, ventilation and air conditioning engineering (HVAC system), which allows a differentiated fine control of the entire system for eight different "climate zones" in the building. The heating or cooling is adapted to the respective spatial requirements via the air supply and quality, supported by the completely renewed underfloor heating in the hall. If necessary, this can now also be used for cooling against overheating of the glass-enclosed interior in summer. Thanks to the new layout and differentiated control of the HVAC system, the heated air is better extracted directly from the inside of the façade. Nevertheless, sensitive works of art can still not be placed near them.

3.0. Adaptive restoration (31) — reintegrating and reconstructing

Venice Charter, Article 9: "Restoration is a measure which should retain an exceptional character. Its aim is to preserve and make accessible the aesthetic and historical values of the monument”.

3.1. Reintegrating

EN 15898:2019 3.5.7 “reintegration: action of restoration which consists of adding material for the reconstruction of appearance. — Examples: Retouching, insertion, in-painting, infilling etc”.

The curtain

An essential visual and use-relevant "missing-place supplement" (in EN 15898, 3.5.7. e.g. “infilling”) in the image and use of the Neue Nationalgalerie is the original curtain planned to run around three sides of the façade. Its function is not only limited to supporting the microclimate on the glass façade (32), but it also regulates the light level in the exhibition rooms to some extent and prevents glare, irradiation and reflections. Problems arose due to the fabric panels sticking to the wet glass panes and also due to the excessive exposure to light for conservation reasons, also along the glass façade in the basement. In the 1970-1980s, the hall original curtain was replaced by a darker fabric one, being dismantled in 1998 and never reinstalled again. This mutilation happened about three years after the Neue Nationalgalerie was listed as a monument.

The semi-transparent curtains of the large hall on the ground floor (in red), their original arrangement on three sides, the marking of their storage locations and the pulling directions. The curtains are moved electrically with the upgraded original motors
Desenho/drawing courtesy David Chipperfield Architects Berlin, 2015 

Drawing reconstruction of the original curtain of the large hall on the ground floor — ground plan, cross-section and detail
Desenho/drawing courtesy David Chipperfield Architects Berlin, 2015

In accordance with the architectural values and concepts of the time, the intended spatial design effect should not be underestimated. Mies was intensively concerned with the material parameters of the curtain and saw in it an essential design element: a semi-transparent, soft and wavy-flowing textile fabric complementing the clear, austere and precise nature of the steel. Indoor-outdoor visual references were also important, both in terms of the urban space and for viewing the outside sculptures. Accordingly — and following the available project documents handed down at the time — various fabric samples were examined and finally the manufacturer, Knoll International, was again commissioned to reweave the curtain model "Saphir", colour "grey tinted no. 3". The electromotive curtain mechanism was upgraded as a technical monument.

Samples of the semi-transparent curtains for the great hall on the ground floor — originally reconstructed on the left, modified with a slightly more darkened transparency, on the right
Foto/photo courtesy David Chipperfield Architects Berlin, 2019

The reconstructive addition to the curtain was, however, technically modified in the suspension construction in order to be able to carry out spatial and/or exhibition-related adjustments more easily. The fastening is easier to dismantle, other materials can be mounted and, by means of an additional truss construction, partial shielding can now also be carried out flexibly at different heights, e.g. from half the height of the room. The temporary storage of the large fabric packages was also taken into consideration. The curtains for the basement glass wall were made more light-tight for conservation reasons and can be shaded by additional blackouts.

3.2. Reconstructing (33)

EN 15898 3.5.6 “reconstruction: re-establishment of an object to an inferred earlier form using existing and/or replacement material. Note 1 to entry: Reconstruction respects the significance of the object and is based on evidence. Note 2 to entry: reconstruction can be either physical or virtual."

a. Reassembling

EN 15989 3.5.5 “reassembly: putting dismembered parts of an object back together".

About 40,000 components and "objects" were necessarily dismantled and stored at the beginning of the renovation work in order to be able to strengthen the underlying building carcass (see above section Conservating). After their refurbishment, they could — where possible and planned — be reassembled in exactly the same places in the final refurbishment phase thanks to the component coding and the dismantling plans.

The original skirting boards (at all approximately 440 m) prepared for reassembly in the basement, and on the right, a veneered wall panel — all coded for reassembly in the original locations
Foto/photo Betânia Brendle, 2021

b. Destructing and reconstructing

The walls of the "Sculpture Garden" had been causing structural problems for a long time, which became apparent in the form of cracks and broken granite slabs. The cause was the changing solar radiation with its partial heating of the clad concrete walls, which brought uneven stress loads due to temperature-related movements and the lack of expansion joints to counteract this. There were three structural engineering options for action: 1. cutting in sufficient movement joints with the result of visible vertical joints in the previously homogeneous natural stone cladding; 2. to leave the weather-related effects (34) in a controlled manner, resulting in further progressive deterioration (35) (decay), which can also be interpreted or accepted as ageing (36); and 3. the total demolition of the structural concrete walls and their reconstruction with sufficiently steel reinforcement to prevent the stresses and movements. Contrary to Georg Dehio's principle — "Conservating instead of reconstructing” (37) — the decision was made for the third — a complete new structural solution. The original concrete wall was demolished and the enclosing walls of the sculpture garden were reconstructed with the modified, stronger reinforcement. To the viewer, it is not this intervention that is visually perceptible, but only the garden walls clad with the original or replaced granite slabs.

4.0. New-constructing

EN 15898 3.2.4. "alteration: Change in condition, beneficial or not, intentional or not".

EN 15898 3.5.8. "rehabilitation: Intervention on an immovable object in order [...] to adapt it to [...] standards of comfort, safety and access".

4.1. " Wo gehobelt wird, fallen Späne...“ (38)

New construction in existing buildings always involves the loss of previously existing or added technical components and functional objects. In the Neue Nationalgalerie the removals were mainly limited to "invisible" technical components and to the replacement of worn-out parts or parts with outdated and planned "congenital defects” (39). During the long project and restoration period (2012 to 2021), some of the monument's preservation objectives had to be adapted or even revised (40). Despite the many goals achieved in the conservation measures of the Neue Nationalgalerie, there was a lack of concern regarding some building elements and accessories that were not considered as heritage losses and therefore replaced instead restored. These included the original marbled-like floor coverings, unusable glazing, the original Sculpture Garden, old coffee machines, historic lighting installations or new non-reversible fitting details such as expansion joints, among others. It is important to note that all these decisions were part of a conservation restoration process (41) to preserve the Modernist building and make it fit for further use. The fact that the fathers of the Venice Charter were not thinking of switchboards, copper cables, ventilation ducts and water pipes, glass material, pollutants and fire protection materials and so on, when they formulated their principles and guidelines, should be stressed. Time has come to reflect on the importance of preserving the technical installations, among other aspects and elements that constitute the tectonic and architectural substance of monuments, in particular those of the Modern architectural heritage. Lifts, light switches, machinery, services and building infrastructure are connective technical components without which no "monument of Modernity" could be conceivable and built. Otherwise, nothing would have been learned from Reyner Banham (42), who opened our eyes to the important technological advances that made the 20th-century architecture possible, also that of Mies.

4.2. New accessibility (43)

Effective information and guidance systems for people with limited mobility do not start at the building to be accessed, but are understood as overall urban systems. Building or a public space where people stay and move around thus becomes part of a comprehensive and uniformly regulated urban orientation structure for foreign visitors as well as citizens of one's own city, which helps mobility-impaired people to move to and around the place without outside help as far as possible. The city of Berlin has set up an information and support centre (44), where information material can be requested in advance of visits as needed, and among other services, a specialised tourist escort can be booked. For certain popular buildings and places, such as the Neue Nationalgalerie, access tips, orientation plans (also on the internet) and information about the institution are available on demand. The disabled-friendly provisions of the Neue Nationalgalerie dock directly onto this urban information system, e.g. with the specially designated parking spaces at the north-east corner of the site or with the bus stop directly in front of the building.

Ground floor and terrace area between the bus stop and the staircase (Treppe B) — section from the planning of accessibility
Desenho/drawing courtesy David Chipperfield Architects Berlin, 2015

Information steles at the stairways display the barrier-free access details. Starting from the bus stop, the south-eastern staircase and ramp (in the plan Treppe B) is reached directly, which was equipped with two ramps before, but they were too steep. Here, along the terrace wall, a new, longer ramp made of natural stone with a 3% gradient was installed, which is more comfortable than the standards stipulate and for which handrails could be dispensed with. Provided with prior information — from the preparations or from a local information stele — the path of the visually impaired leads over the stairs and by means of the floor indicators further to the steel-glass façade. With knowledge of the previous instructions, the path leads tactilely along the facades to the doors and revolving doors of the eastern main entrance there or to the left along the facade to the wider double doors to the west. These entrances can be entered autonomously without ringing a bell. People with wheelchairs, walking aids and prams reach the terrace via the newly constructed ramp and can access the hall barrier-free.

Tactile floor for the visually impaired located between the accessible staircase and/or ramp and the south facade of the Neue Nationalgalerie. The new granite slabs are still being darkened. For reasons of monument preservation, the floor indicators are not contrasting as is usually the case
Foto/photo Betânia Brendle, 2021

A newly installed lift, housed in the former cleaning room of the hall, leads to the basement, where there is a service counter for wheelchair users that can be accessed from underneath. There, hearing-impaired people also receive supportive audio equipment for visiting the facility independently. The two staircases have also been equipped helpfully for the visually impaired, e.g., with discreet step markings on the first and last steps and information in Braille on the handrail.

Information on the tactile handrail and step markings on the staircase
Foto/photo courtesy David Chipperfield Architects Berlin

In the basement, all public entrances are either automatically open (45) or can be opened with a door-open button. Disabled WC facilities are of course available, also for disabled staff. All in all, due to the unique character of the monument, the markings and structural aids were kept moderate and reduced in the planning discussions in order to respect the pure simplicity of Mies' design as the basic mood. This in turn offers the supporting, necessary measures and indications a calm background against which they can stand out more legibly. With these new installations, systematic information provision and the devices that can be automated, it is now possible to visit an exhibition without outside help.

Service desk in the stair hall (Treppenhalle) of the basement with a wheelchair-accessible information place for people with limited mobility
Foto/photo courtesy cortesia David Chipperfield Architects Berlin, 2021

4.3. New fittings and new-constructed additions

Providing a café, appropriate new cloakrooms and a new museum shop in more suitable rooms demanded the relocation of further original service rooms. A functional consequence was the construction of a new underground eastern annex underneath the front podium of the building which provided areas for the sculpture and painting storage areas as well as for the additional technical back-of-house spaces according to today's international standards. The newly designed technical building installations (HVAC) (46) were also relocated to the new building addition. The only "legible signs" of the use of the formerly non-public spaces, resulting from the relocations carried out until 2021, are the raw concrete ceilings and walls left in place for the new cloakroom and new museum shop (47).

New underground additions and extensions in red (section of the building and below, the basement floor plan), including the new granite floor surfaces of the new cloakroom and new museum shop; to the right, the new storeroom (about 600 sqm) and adjoining technical areas (300 sqm). The green arrow above indicates the proposed underground access to the neighbouring museum — Museum of 20th Century Art, designed by Herzog & de Meuron
Desenho/drawings courtesy David Chipperfield Architects Berlin, 2015

Further spatial intervention in the Neue Nationalgalerie relates to the new “invisible” underground access to or from the planned neighbouring "Museum of 20th Century Art" (by Herzog & de Meuron) provided for in the basement (see above green arrow). This strongly affects the unique and singular spatial dramaturgy of the approach to the Modern "temple of art", the Neue Nationalgalerie. The experience of walking up to the terrace and entering the raised glass hall, then descending to the smaller more "introspective" collection spaces, from where one can "contemplatively" conclude the visit in the "intimate" area of the "Sculpture Garden" — will be eliminated by the planned new underground access which will destroy this striking spatial sequence and degrades the Neue Nationalgalerie to a mere appendix. The future "museum neighbour" damages the conceptual spirit of this architectural monument, which to this day preserves the art-viewing and art-perception of the 50s/60s provided by this icon of Modernism, the last built work of Mies van der Rohe.

notes

NA — Special thanks to Martin Reichert (Director and Partner, David Chipperfield Architects Berlin) for his great support and the valuable project information. And also, to the architects Rubens Luiz Santos and Fábio Araújo.

1
Due to the Covid-19 pandemic, the Neue Nationalgalerie was officially opened in April 2021 with a small group of authorities present. The opening for the general public took place on 22 September with an exhibition by Alexander Calder. The work Distance (1928) by the Brazilian artist Tarsila do Amaral was specially brought from the Museu de Arte Moderna de São Paulo — Masp, for the exhibition Die Kunst der Gesellschaft 1900-1945. Tipps und Termine Wohin am Wochenende? Monopol. Magazin für Kunst und Leben, 20 ago. 2021 <https://bit.ly/35xUgZD>.

2
The project description and evaluation of the intervention in the Neue Nationalgalerie as well as all used definitions is based on the current standard (european norm) EN 15898:19 of 2019 entitled: Conservation of Cultural Heritage — Main general terms and definitions. This norm standardizes all the used common heritage conservation terms and measures and will help for a more precise professional understanding. The EN 15898:19 was carried out by the CEN/TC 346 (Comité Européen de Normalisation / Technical Commitee 346) “Conservation of Cultural Heritage”, the Secretariat of which is held by UNI (Italian National Unification Body). In Portugal, the current standard (norma portuguesa) NP EN 15898:2021 was introduced on 10.01.2020 by the Comissão Técnica de Normalização CT 174 "Fotografia", whose coordination is ensured by the Organismo de Normalização Setorial, (Associação Portuguesa dos Profissionais da Imagem) (ONS/APPImagem). — In this article, most quotations are addressed as sources only by the outline numbers and subtitles of the current EN 15898:2019 (which is similar to the numbers of the NP EN 15898:2021).

3
“Authenticity: extent of alignment between an object and the identity attributed to it”. Definition of term taken from “3.1.8. authenticity” in the european norm — EN 15898 Conservation of cultural heritage — Main general terms and definitions as amended in 2019.

4
Etymologisches Wörterbuch des Deutschen [Etymological Dictionary of German], compiled under the direction of PFEIFER, Wolfgang. Licensed edition. Koblenz, Akademie Verlag, 2012, p. 920-921. See also the 18 meanings of "new" (in English), in Collins English Dictionary. Third edition. Glasgow, Harper Collins Publishers, 1991, p. 1050.

5
All these before in the text mentioned terms and notes are defined in the EN 15898:2019 as follows: “3.6.3. investigation: obtaining and gathering the information necessary for a conservation decision-making process. Note 1 to entry: This should include both qualitative and quantitative information [...] / 3.1.6. value: aspect of importance that individuals, communities or society assign(s) to an object, ensemble or collection in a particular context. Note 1 to entry: Values can be of different types, for example: artistic, symbolic, historical, social, economic, scientific, educational, technological, functional etc. / 3.1.8. authenticity:” loc. cit. and "Note 1 to entry: The concept of ’authenticity’ should not be confused with the concept of ’originality’. / 3.5.6. reconstruction: re-establishment of an object to an inferred earlier form using existing and/or replacement material. [...] / 3.5.1. treatment: direct intervention to achieve stated conservation aims. Note 1 to entry: The least invasive treatment consistent with achieving the stated conservation aims is often referred to as minimum intervention. / 3.5.7. reintegration: action of restoration which consists of adding material for the reconstruction of appearance. Examples: Retouching, insertion, in-painting, infilling etc. / 3.3.10. restoration: actions applied to a stable or stabilized object aimed at facilitating its appreciation, understanding and/or use, while respecting and/or revealing its significance and the materials and techniques used. Note 1 to entry: In some professional communities, especially in the field of immovable cultural heritage, the term restoration traditionally covers the whole field of conservation. Note 2 to entry: Remedial conservation is often carried out at the same time as restoration. / 3.5.10. repair: actions applied to an object or part of it to recover its functionality and/or its appearance. Note 1 to entry: Repair is a conservation action only if it respects significance and is based on evidence. / 3.2.4. alteration: change in condition, beneficial or not, intentional or not. / 3.3.1. conservation / conservation-restoration: measures and actions aimed at safeguarding cultural heritage while respecting its significance, including its accessibility to present and future generations. Note 1 to entry: Conservation includes ’preventive conservation’, ’remedial conservation’ and ’restoration’”. See also notes 2-3 to entry.

6
Wolfgang OBEREISENBUCHNER im Gespräch mit David KASPAREK, Erhalt als Sinnfrage. Dinge sammeln und Werte vermitteln. [Preservation as a question of significance. Collecting things and conveying values]. In „der architekt”, n. 3, Berlin, 2018, p. 67-69. Note: all translations from German in this text by the author.

7
„rehabilitation: interventions on an immovable object in order to recover an inferred earlier functionality, to adapt it to a different function or to standards of comfort, safety and access”. In EN 15898, 3.5.8., see also notes 1-2 to entry.

8
„damage: non-beneficial alteration. Note 1 to entry: Although damage is non-beneficial to the object, it may sometimes be considered as broadening significance, e.g. traces of war on an object [...]”. In EN 15898, 3.2.7.

9
„conditions: physical state of an object at a particular time”. In EN 15898, 3.2.1.

10
BANHAM, Reyner. The Architecture of the Well-Tempered Environment. Chicago, The Architectural Press, London, The University of Chicago Press, 1969; „Verdrängte Substanz. Zum Denkmalwert häuslicher Infrastrukturen. [thematic booklet]. In „der architekt“, n. 3, Berlin, 2018, p. 14-57.

11
REICHERT, Martin. Der unsichtbare Architekt — die Grundinstandsetzung der Neuen Nationalgalerie Berlin als Zielkonflikt-Moderation [The invisible architect — basic refurbishment as a moderation of conflicts of objectives]. In BRANDT, Sigrid, HASPEL, Jörg (ed.) Denkmal — Bau — Kultur: Konservatoren und Architekten im Dialog. Kolloquium anlässlich des 50jährigen Jubiläums von Icomos Deutschland, „Icomos — Hefte des Deutschen Nationalkomitees”, LXIII, Berlin, 1st ed., 2017, p. 51-61.

12
Bundesamt für Bauwesen und Raumordnung — BBR in Berlin, Staatliche Museen Berlin (smb)in the Stiftung Preußischer Kulturbesitz — SPK, David Chipperfield Architects Berlin and the Landesdenkmalamt Berlin — LDA.

13
For Chipperfield's intervention concept and its theoretical principles towards the conservation and critical restoration of the Neue Nationalgalerie, see BRENDLE, Betânia, The Invisible Intervention. The Restoration of Mies van der Rohe's Neue Nationalgalerie in Berlin.

14
In this article only a few practical examples of restoration procedures and postures were described. For more information and details with extensive photographic documentation on the various stages of restoration and renovation (between 2015-2021) see the German blog (March 2021), Staatliche Museen zu Berlin (March 2021). MARLIN, Constanze von; SCHMEDDING, Anne <https://bit.ly/3Hp5gWA>.

15
„investigation: obtaining and gathering the information necessary for a conservation decision-making process. Note 1 to entry: This should include both qualitative and quantitative information”. In EN 15898, 3.6.3.

16
„consolidation: improvement of internal cohesion or mechanical stability, usually involving the addition of material. Note 1 to entry: When only mechanical stability is considered, the term ’strengthening’ is also used”. In EN 15898, 3.5.4.

17
Further in EN 15898 3.3.10.: “Note 1 to entry: In some professional communities, especially in the field of immovable cultural heritage, the term restoration traditionally covers the whole field of conservation”.

18
„conservation / conservation-restoration”: see definition in the following quote of EN 15898, 3.3.1. in the text. — See also the entire section 3.5. in EN 15898: „Remedial conservation and restoration terms”.

19
“Cleaning: removal of unwanted material from an object. Note to entry: The criteria for something “unwanted” always have to be stated, e.g. potentially damaging, obscuring detail, un-aesthetic, etc. and should acknowledge the time and context in which the decision was made.” In EN 15898 3.5.3.

20
„reversibility: extent to which the outcome of an intervention can be undone without damage to the object”. In EN 15898, 3.3.5.

21
International Charter for the Conservation and Restoration of Monuments and Sites. — Basic document adopted in 1965 by Icomos (a non-governmental international organisation dedicated to the conservation of the world's monuments and sites). The Venice Charter resulted from the II International Congress of Architects and Technicians of Historic Monuments, held in Venice from 25 to 31 May 1964.

22
„object: single manifestation of tangible cultural heritage. Note 1 to entry: The term ’object’ is used in this standard for cultural heritage, both immovable and movable. In specific professional contexts, other terms are used: e.g. ’artefact’, ’cultural property’, ’item’, 'site’, ’building’, ’monument’, ’specimen’, ’structure’, ’cultural landscape’, ’document’”. In EN 15898, 3.1.3.

23
City of Striegau in German territory before the Second World War, then was incorporated into Poland and named Strzegom.

24
“cleaning”. In EN 15898 3.5.3.

25
“defect”. In EN 15898, 3.2.5.

26
See section General climatic parameters of the building interior, especially in the hall.

27
HVAC system: Heating, Ventilation and Air-Conditioning plants.

28
See 3.2.5. „defect”, loc. cit.

29
See 3.2.4. „alteration“, loc. cit.

30
„integrity: extend of physical or conceptual wholeness of an object”. In EN 15898, 3.2.3.

31
See 3.3.10. „restoration”, loc. cit.

32
See also above section 2.2.b.(3) Glass façade and condensation formation.

33
„reconstruction”: see definition in the following quote of EN 15898, 3.5.6. in the text.

34
„weathering: alteration due to exposure to outdoor environment”. In EN 15898, 3.2.11.

35
„deterioration: unintentional alteration that reduces significance and/or stability. [...]” In EN 15898, 3.2.8.

36
„ageing: natural alteration over time. Note 1 to entry: The results of ageing can also be artificial”. In EN 15898, 3.2.6.

37
DEHIO, Georg, Denkmalschutz und Denkmalpflege im 19. Jahrhundert. Festrede an der Kaiser-Wilhelms-Universität in Straßburg am 27. Januar 1905. In DEHIO, Georg, Kunsthistorische Aufsätze, München/Berlin, R. Oldenbourg, 1914, pp. 275 / or currently new formulated by Hartwig SCHMIDT [1998].„ Rehabilitating instead of reconstructing!”

38
The English version and translation of this proverb does not have the appropriate architectural meaning / sense like in German. Directly translated, the idiom means: "If you plane wood, this gives wood chips". It shows the inevitable consequences of working with material.

39
„The steel-glass façade [...] has two birth defects: broken glass and heavy condensation". In REICHERT, Martin. Op. cit., 2015, p. 56.

40
„[About] [...] the goal of maximum preservation of the original substance of the building [...]. In the middle of the implementation planning, we now have to take stock of the fact that we can only meet this own claim with limitations”. In REICHERT, Martin. Op. cit., p. 55.

41
„conservation process / conservation process: process of decision-making, planning and implementing conservation”. In EN 15898, 3.3.2.

42
BANHAM, Reyner. Op. cit.

43
„accessibility: opportunity to engage with an object, physically and/or intellectually”. In EN 15898, 3.1.11.

44
See accessBerlin App. The accessible app for Berlin. Visit Berlim <https://bit.ly/35zaKRy>.

45
In the event of a fire, fire protection doors now close automatically; some original swing doors therefore had to be converted to revolving doors; due to new fire compartments, some existing glass doors had to be given new fire protection glazing (G30).

46
See section General climatic parameters of the building interior, especially in the hall.

47
See BRENDLE, Betânia, 2021. Op. cit.

about the author

Klaus Brendle is architect and urban planner, with Studies in Social Sciences (including Architectural Psychology). Architecture Office k.brendle planungsbuero a&a, Lübeck and Lecturer at the Technische Hochschule Lübeck, Germany.