SPIDER - Subtraction as a measure to Preserve and Insulate historic Developments by Electric Robots

Motivation and research question

The ambitious goals of climate protection (compare the Paris climate protection goals of 2015) must be reflected in changed approaches in many areas of life, including construction. In the meantime, upon completion of this project, these goals have been further sharpened. The EU taxonomy regulation takes climate targets into account when financing construction projects and the invasion of Russia makes the phase-out of natural gas, which this project was about at the time of the application, more urgent than ever.

At the same time, it is widely recognized that designing new buildings in an energy efficient manner is just a drop in the ocean given the low rates of new construction. The inventory must therefore be considered and treated as well. Here, too, there was a remarkable speech by Ursula van der Leyen in October 2020, who, as Commission President, wants to trigger a wave of European renovations. However, when it comes to thermal renovation of the architecturally significant building stock, limits are soon encountered in the application of conventional, i.e. additive principles (attachment of thermal insulation panels to the outer facade).

Against this background, it is significant that approx. 30% of the masonry depth of the historic solid brick masonry is not statically relevant.

Initial situation/status quo

Based on the dramatically poor heat transfer resistance of the outer walls of historical existing buildings and at the same time a high social and building culture need to preserve ornamented historical facades, the key to a huge energetic improvement seems to lie in the subtraction of material without destroying the exterior of these buildings that shape the cityscape. Modern methods of analyzing the course of force and the effects of noise on the one hand, modern and easily available possibilities of robotics and the now high efficiency of photovoltaics and battery technology on the other hand allow a concept to be explored that examines a fully automatic, purely solar-powered renovation.

Project content and objectives

The aim is to develop a renovation system for ornamented 19th century façades that is not only highly ecological and highly economical as a result, but also as early as the construction phase. At the same time, the formative cultural identity, which is given by the rich ornamentation of the historical buildings, should be respected.

Methodical approach

The question, or rather the project goal, is based on the 19th century building fabric and the justified assumption of a constructive redundancy of the partially load-bearing masonry. As a first step, thorough research into the construction method, materiality and building structure is therefore required. The next step is to investigate how the constructive redundancy of the masonry can be used to reduce the thermal conductivity of the masonry through porosification. This requires, on the one hand, studies of the technically possible drilling patterns and drilling directions, and, on the other hand, research into the actual thermal properties of historical masonry is a necessary starting point. On this basis, a large number of possible variants are thermally simulated and improvements in the thermal properties are determined in this way. In order to be able to assess the potential for improvement, i.e., the possible energy savings through the measures, on a large scale, the building data for all 19th century houses in Vienna are statistically recorded and mapped into an energy balance model so that the changes in thermal conductivity previously determined by simulation can be incorporated. After identifying suitable measures, the final step is to develop concepts and technologies for technical implementation.

Results and Conclusions

In the course of the project research, an assessment of the Gründerzeit building stock in terms of thermal performance and the effects of possible renovation measures could be made. It has been shown that climate-neutral operation of these buildings in terms of their heating requirements is possible as soon as these buildings also produce energy. In the course of developing ideas for possible renovation strategies based on porosification of the masonry, the possibility of heating the masonry using photovoltaic-powered rods was also examined. Such a procedure can be of interest for the renovation, as it also increases comfort and dries out the walls, in any case also reduces the heat losses of the room heating and thus makes these buildings ready for the use of alternative systems such as heat pumps. The winter sunshine would already provide sufficient power. On the other hand, the majority of this radiation output could be offset against the operation of the heat pumps, which makes a climate-neutral balance possible, especially since the roofs remain free for the production of household electricity and lighting energy.

Outlook

No matter how successful the European refurbishment wave is, the supply of heat and, increasingly, cooling will remain a necessary factor. In addition to district heating and biomass, the latter releasing emissions in the form of dust and exhaust gases, heat pumps remain the cleanest option for a heating system. Moreover, it can also be easily combined with cooling. As in mobility, electricity thus plays a crucial role. From the Gründerzeit energy certificate tool that we developed in the course of thus project we know that around 31 km2 of opaque facade areas lie fallow on the Gründerzeit houses. If a quarter of this can be activated for electricity production, with an average radiation of 750 kWh/m2a, the fifth share of electricity can be produced these buildings need after renovation to operate heat pumps. In this way, they would be CO2-neutral in terms of heating requirements.

The speed of remediation now also required by the political situation (independence from Russian natural gas) will make it necessary to support the previous, conventional construction activity with automated systems.

Project management

Univ.Ass. Dipl.-Ing. Arch. Bernhard Sommer
Universität für Angewandte Kunst, Abteilung Energie Design

Project or cooperation partners

• Mag.arch. Galo Moncayo, MFA; BFA - Universität für Angewandte Kunst, Abteilung Energie Design
• Dipl.-Ing. Malgorzata Sommer-Nawara - Universität für Angewandte Kunst, Abteilung Energie Design
• Univ. Prof. Dipl.-Ing. Peter Bauer - TU Wien, Institut für Architekturwissenschaften
• Univ. Prof. Dipl.-Ing. Dr. Ardeshir Mahdavi - TU Wien, Institut für Architekturwissenschaften
• Univ.Ass. Dipl.-Ing. Dr. - TU Wien, Institut für Architekturwissenschaften

Bernhard Sommer
Universität für Angewandte Kunst, Abteilung Energie Design
Oskar Kokoschka-Platz 2
A-1010 Vienna
Tel.: +43 (699) 195 69 794
E-mail: bernhard.sommer@uni-ak.ac.at
Web: www.dieangewandte.at