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www.freyarchitekten.com 1

Project description

The Smart Green Tower

Building-‐Integrated PV energy supply in the megawatt-‐class with storage

technology as the core of "Smart Green District" concepts


1. Short description The so-‐called "Smart Green Tower" pertains to an approximately 51-‐meter-‐high residential and commercial tower, which on account of its planned size, architecture and environmental equipment, can evolve to become a flagship project in the area of innovative building-‐integrated energy systems. The most outstanding characteristic is a sophisticated energy supply concept for large objects with a high solar fraction, which a consortium of experts from the Fraunhofer Institute for Solar Energy Systems (ISE), the Siemens AG, the ads-‐tec, Frey Architekten as well as the FWTM and badenova want to realise. The energy concept is based mainly on the following aspects:

- own energy generation based on renewable energy sources, in a volume that temporarily exceeds own consumption and can thus be used by other buildings in the neighbourhood

- flexible internal energy storage in larger dimension, with the option to connect further energy producers in the district

- optimised handling of energy pursuant to the current offer, demand and from a cost perspective within the building

- provision of balanced energy loads from the building in conjunction with the adjoining district, to the Smart Grid over an intelligent connection

This concept will be realized with the latest technology. In particular, an intelligent energy management within and outside of the building will thereby enable an optimised regulation of all local energy flows (see below). 2. With FWTM, Freiburg geared to become a Smart Green City The Freiburg Economy Tourism and Exhibition Company (Freiburg Wirtschaft Touristik und Messe -‐ FWTM) is a management and marketing corporation. Next to economic development and strategic management, the tasks of the FWTM also include promoting innovation and technology, cluster development on the tourism marketing and exhibition, conference and event management. The Green City of Freiburg is an ecological model city and has often been honoured with prestigious environmental awards. This success at the same time constitutes a challenge for Freiburg and the FWTM, to promote and implement further ecological flagship projects. The Smart Green Tower Freiburg is like a new lighthouse for the Green City, a building of high symbolic value. The Smart Green Tower has been co-‐developed and advertised by FWTM. Thanks to FWTM, it is well-‐known amongst local politics, administration and in the public, thus supported the visibility and feasibility of this project. FWTM will proceed supporting this project by promoting the Smart Green Tower nationally and internationally.


The concept of the Smart Green Tower will be designed so that it can be extended. This means that the demonstration building should form a perspective standpoint constitute the core, for developments that extend beyond those of a single building. The Tower will be in conjunction with existing architecture and new objects, able to generate, store, use as needed as well as provision energy in an intelligent manner. Thus, the energy concept of the Smart Green Tower is fundamentally different from projects in which only single, self-‐contained buildings merely produce energy for own consumption or else feed the aforementioned into the grid. It is thus also consistent with the objectives of the Green City and will seamlessly be incorporated into Freiburg’s new energy-‐ and resource-‐optimised commercial area GIP – Green Industry Park, to which the northern industrial area planning to be remodelled. The vision: Such a network of several intelligent objects works optimally in an intelligent grid, and thus forms the basis for innovative district concepts, in which various Smart Green Buildings communicate in a meaningful way – the Smart Green District. This idea leads to the vision of a Smart Green City, in which the Smart Green neighbourhoods coalesce into an urban network. This concept in the Smart Green Tower will for the first time be implemented in Freiburg at the freight yard area in the north of the city. On account of the modern architecture that enables living and working in a building, the building itself stands for the pioneering integrative neighbourhood concept of the Freiburg freight yard area. It can however in principle be applied to all urban structures – a key objective of this demonstration project. Further Smart Green Tower projects have already been requested by other cities. 3. Cooperation project A consortium of experts from industry and academia has joined forces for the purpose of the realisation of this ambitious project, which has broad support within the city of Freiburg.

Partner Contact Address Phone E-‐Mail

Frey Architekten W. Frey

Bertha-‐von-‐Suttner-‐Str. 14 79111 Freiburg

(+49) 761 / 477415 11

info@architekten-‐frey.de

FWTM Dr. B. Dallmann Rathausgasse 33 79098 Freiburg

(+49) 761 / 388 111 01

[email protected]; franziska.pankow @fwtm.de

Fraunhofer ISE

Dr. M. Vetter

Heidenhofstr. 2, 79100 Freiburg

(+49) 761 / 458 856 00

[email protected]


Siemens AG N. Schmidt Habsburgerstr. 132 79104 Freiburg

(+49) 761 / 271 235 0

[email protected]

ads-‐tec T. Speidel Heinrich-‐Hertz-‐Str. 1, 72622 Nürtingen (+49) 7022 / 252 211 01 t.speidel@ads-‐tec.de

badenova AG & Co. KG P. Majer

Tullastr. 61 79108 Freiburg

(+49) 761 / 279 35 40

peter.majer @badenova.de

4. Use concept – time schedule – construction financing In the case of the planning of the Smart Green Tower the local architect’s office, Frey Architekten, purposely deviates from common standard architectural aesthetics and places its focus on a building, whose outward appearance enables the overall energy concept to be visible. Not only are photovoltaic modules installed on the roof, but the façade is also activated for energy generation and provided with circumferential PV modules -‐ on the one hand in order to harvest energy, where it is needed and the other hand also to protect the façade from overheating. Thus, an – for a residential building – unusually large amount of electricity can be produced (for more information see below). The whole complex will be realised on a 5,600 square metre plot and consists of a main building and two wings with a total gross floor area of approximately 15,000 square metres plus garage. The main building will be realised as a round 48-‐meter-‐high tower, which finds its completion by a solar hut on top, on account of which the main building will reach a total height of about 51 metres. On the upper floors of a total of 16 floors, approximately 70 one to four-‐room apartments with be realised with a gross floor area of about 4500 square metres. Pursuant to the current plan the apartments are intended to the most part to be rented. This is planned to be effected pursuant to a rental model with neighbourhood management – which has as usual been deployed by Frey Architekten– that entails a qualified social area model. Good experience has been demonstrated with the aforementioned in many other buildings that have been realised by Frey Architekten. Some of these buildings have as a consequence evolved to become role models of neighbourhood living. A further area of about 3200 square metres is envisaged as office space and as boarding accommodation – for instance, for the employees of the local research institutions and institutes. A restaurant will also be housed in the tower. The western wing will consist of five floors with a total height of 16 metres. The northern wing will be approximately 22.5 metres high and will consist of seven stories. Both wings have been planned as an office building. Furthermore, the entire complex will also be realised with a garage with about 250 parking spaces.


In order to do justice to the lighthouse character of this project, the highly efficient battery storage system as well as the overall energy management system should later also be set up in a showroom and made accessible to visitor groups. Furthermore, a seminar room is planned directly adjacent to the showroom, in order to organise "audience appeal" seminars, workshops, project meetings and the like. The seminar room can also be made available to visitors of the Green Industry Park Freiburg North as well as the Green City Freiburg. The Smart Green Tower pertains to a private investment project. The Green Tower GmbH thereby officially assumes the role of the project developer. The planning application maturity should be reached in winter 2014/2015. The construction period is planned from mid-‐2015 to mid 2017. Already in May 2014, the city of Freiburg will present the project to the public within the framework of a press conference. 5. Technology The following constitutes the basis for the innovative energy supply concept in the Smart Green Tower

- a highly efficient PV system on the roof combined with PV façade modules with a power output of about 400 kWp

- a highly efficient energy storage of about 0.5 MWh in the form of a lithium-‐ion battery, perspectively enhanced with additional battery systems, for example in the form of vanadium redox flow batteries

- an advanced building management system in the state of the art - the coupling of the building management system with PV systems, batteries and

selected consumer groups over a DC-‐intermediate circuit - the integration of a – currently in development – energy management system

for the meaningful use and distribution of energy which extends beyond the building, in order to also include the district

PV-‐system In the case of the Smart Green Tower, PV modules will deployed, which consist of high-‐performance cells. They produce a higher yield with optimal exposure and have an excellent low-‐light performance. Special glass / glass PV modules, which provide for a light transmittance in different scales, will hereby be originated. In order to realise an optimal integration in the façade design, an innovative interconnection system of the sockets will be developed for this purpose. Storage technology Advanced storage systems based on lithium-‐ion technology will be deployed in the project, whereby their operation will be controlled by the energy management system.


The highly flexible and dynamic control of the cells in the field of storage technology is unique and in combination with fast, highly volatile producers of renewable energy, in particular provides for an ideal platform for the research and development of intelligent building concepts. This applies to aspects of the optimisation of energy consumption in buildings as well as to the development of future, innovative management scenarios. The integration of a lithium-‐ion storage in the building as a link between decentralised renewable generation systems of photovoltaics and the distribution grid also improves the integration of renewable energies into the grid by smoothing their fluctuations. At the same time, an improved alignment of the generation and consumption at the local level is ensured. This contributes to the relief of the grid and to an improvement of the stability of the grid. The direct arrangement in the building and the proximity of the lithium-‐ion battery to the decentralised generation systems, as such already allows for a stabilisation of the grid at the feed point. Innovative lithium-‐ion storage systems can play an important role in the future overall energy consideration of complex building architectures with regard to the avoidance of grid expansion costs as well as contribute to the general stabilisation of Smart Grids, without having to concomitantly sacrifice the benefits of renewable energy. Lithium-‐ion storage systems, thus already provision in this project, a consistent contribution to the sustainable continuation of the energy transition. Modern Building Management A comprehensive building management system is intended to be realised in the project Smart Green Tower, which will be provisioned by Siemens. This will comprise of the following functions:

- energy management of cold, heat, electricity, - building automation, room automation and energy efficiency, in particular

energy-‐optimal operation without sacrificing the comfort of heating, ventilation, air conditioning and lighting,

- building security with intrusion detection and video surveillance as well as access control,

- technical fire protection (fire alarm and extinguisher system) and evacuation. Such a system renders it possible to control, monitor and optimise all the disciplines in the Smart Green Tower, and as such to save energy in a sustainable manner and reduce costs -‐ without sacrificing interior comfort. This is ensured by approved applications as well as energy saving and monitoring functions at all system levels.


Coupling of the building management system with power supply over a DC-‐intermediate circuit An innovation in the energy supply concept of the Smart Green Towers pertains to the intention, to couple the building management system with a direct current (DC) intermediate circuit. Background: On the consumer side, the number of DC loads is steadily increasing. Nevertheless the transmission and distribution of electrical energy – with a few exceptions –, is still effected over alternating current (AC). In the case of a predominant supply over an AC-‐coupled photovoltaic battery system, this means that the generated direct current of the PV generator is non-‐rectified, and subsequently in the case of an intermediate storage rectified again in the battery, then if necessary re-‐converted again in alternating current and distributed, in order to again be rectified in many devices – with correspondingly high efficiency losses. In contrast to this conventional power supply of buildings, the intention in this project is to couple the battery storage (see below) with the PV system over a DC link. In addition, the intention is also to directly connect specific consumer groups to the DC intermediate circuit, such as heating, ventilation, air conditioning, elevators and lighting. The DC intermediate circuit bus offers the advantage that various energy sources and sinks, with different characteristics can feed excess energy into the grid over a common grid inverter or else draw energy from the latter for the purpose of grid support. Energy management In the case of future electricity grids with a high share of renewable energy, it will be important to not only ensure that the generated electrical energy is efficiently utilised, but that is also only then consumed when it is plentiful and available at low cost. Conversely, it is intended in the event of a low supply of renewable energy to reduce the drawing of electricity by selectively switching off flexible consumers and possible drawing the residual demand from the battery storage. Load peaks of the Tower, such as at noon, can be smoothed over the battery storage. The Tower as such conducts itself intelligently and "grid-‐friendly", much in the same way as one should in future also expect from other buildings, which are connected with a high share of renewable energies to the grid. Siemens is currently developing an appropriate add-‐on module: an energy management system (PowerManager) that complements the building management system. Other pilot projects by Siemens have already provided experiences and useful data in this case. Depending on the progress of development, it is envisaged that this system will also be deployed in the Smart Green Tower project. It will provide for a targeted recording and control of the electrical energy producers, consumers and storage on the basis of specific operator strategies such as self-‐consumption optimisation, peak load reduction (peak shaving) or load shifting. The optimisation criteria, depending on the operator's strategy thereby pertain to increased energy efficiency and the reduction of energy supply costs or the CO2 emissions.


Some of the novelties in the project are the intelligent alignment of renewable electricity supply, energy demand and operator strategies -‐ for example, the optimisation of self-‐consumption, the optimisation of electricity procured from outside sources or peak load reduction. 6. Findings and objectives The consortium expects from the demonstration project Smart Green Tower, to among others acquire key findings about

- the interaction of renewable energy generation, a building management system with integrated power management as well as storage technology in large buildings, with the power grid

- the connection of key consumer groups such as heating, ventilation, air conditioning, lifts to a DC intermediate circuit

- the optimisation of operator strategies, such as self-‐consumption, load shifting or the optimisation of the supply of energy, particularly with the involvement of a battery storage

- options for the enhancement of individual intelligent building with existing architecture and new buildings to Smart Green Districts

- recommendations for action with regard to follow-‐up projects Specific findings from the perspective of the energy supplier From the perspective of the local grid operator, the Smart Green Tower offers the opportunity to demonstrate how appropriately equipped buildings or building ensembles can conduct themselves system conform as consumers (who do not care about the grid loads) on account of the intelligent integration of the energy production in the building itself and the regulation of the energy consumption. From the perspective of an energy distribution, the building or else ensemble is regarded as a consumer and storage system that can participate in energy markets as a whole better than its parts. Since the volume of the energy that has to be exchanged with the market – bundled over the PowerManager of the Tower – is at the grid connection point greater than the energy volumes of many small production plants with many feed points. This raises issues, such as the internal settlement in a local grid in the case of own consumption, which have hitherto not been in the focus of a public energy distribution, but are increasing often being posed and can as such be tested in the Tower and the included buildings. The building is from a technical perspective also interesting, since a new technology (DC) is intended to be deployed, which could also be deployed in other technical applications, if it were sufficiently tested. Finally, the project supports the efforts of badenova in the association KlimaSchutzPartner Oberrhein (Climate protection partners of the Upper Rhine), with the realisation of a modern research and testing infrastructure


around the industrial area north of Freiburg, which provides for the deployment of new components of the energy supply in an urban area. 7. Scientific monitoring In order to achieve the above objectives and to generate relevant findings, the consortium aspires to realise an accompanying scientific research in connection with the planned Smart Green Tower project, under the leading role of the Fraunhofer ISE. The partners are of the conviction that this offers important insights for the future, since one can currently only draw on a few experience values with grid-‐connected PV-‐battery systems. Although the first systems have been installed both for the enhancement of the self-‐consumption rate in single-‐family houses and in very isolated cases (like commercial environments), significant results with systems in the order of the planned Smart Green Tower as well as their performance and behaviour under real operating conditions, hitherto hardly exist. It is therefore intended that the very detailed monitoring with comprehensive scientific analysis, which is planned within the framework of this project, should therefore shed light on the behaviour of the deployed components, their interactions with each other as well as the behaviour of the overall system. On this basis, optimisation potentials and informed recommendations for action for subsequent projects can be derived. The initial aim is to generate a sound simulation-‐based design of the PV-‐battery system for the Smart Green Tower. It is intended with the help of the models that are available at the Fraunhofer ISE, supported by data from the laboratory of the Fraunhofer ISE, to set up a system simulation, which makes it possible to optimise both the system dimensioning as well as the operational management strategies. Through the subsequent detailed monitoring during the operation, the data will then be determined, which can be used to verify the simulation results and based on which the optimisation potential can be identified. The generated results can then be used for subsequent projects. An important aspect of this project is characterised by the fact that the planned Smart Green Tower is intended to serve as a nucleus for the purpose of establishing a so-‐called Smart Green District. Therefore, the energy concept should be designed so that it can be easily extended to other producers and storage capacities. This should be taken into account in this project at the outset, and also in the case of the simulation-‐based system planning. The planned publications are intended to provide for wide access to the generated results and should thereby ensure that the lessons learned from this demonstration project can be profitably used in similar construction projects.


Overview of the project phases and work packages Planning AP 1 Concept for the electrical energy supply of the building and

simulation-‐based system design AP 2 Selection of the components of the electrical energy supply and

requirements for the system integration AP 3 Monitoring concept Demonstration operation AP 4 Installation and commissioning of the measuring equipment AP 5 Data acquisition, analysis and evaluation Optimisation potentials and recommendations for action for subsequent projects AP 6 Determination of the optimisation potential at components and

system level AP 7 Options for the enhancement to a Smart Green District

Integration of existing buildings with their own generating capacity such as the New trade fair with MW PV plant Integration of new building with own generating capacity and possibly own storage capacities such as the FWTM new building

Description of the individual work packages in detail AP 1: Concept for the electrical energy supply of the building and simulation-‐based system design In the case of the building complex of the Smart Green Tower, a split of the loads, which can be supplied over the conventional AC-‐rail and the loads that should be directly connected to the DC intermediate circuit of the PV-‐battery system will first be effected. A specification will be prepared for these DC-‐loads. In the next step the determination of the load profiles will be based on the available information. In the case of the PV-‐battery system the operating scenarios will be tested and the associated management strategies will be specified. This includes the supply of the building complex itself and the possible provision of grid services. On the basis of the determined load profiles, optimised system configurations for the individual operating scenarios within the framework of the simulation studies will be determined. For this purpose, the models to be deployed for the components will be adapted and validated with available measurement data and the associated management strategies implemented in the simulation environment. Based on these results, a specification for the system components will be prepared on the part of the producer and on the part of the storage.


AP 2: Selection of the components of the electrical energy supply and requirements for the system integration Based on the results of work package 1, a selection of market-‐available system components with which the developed specification can possibly be optimally implemented, will be effected. This includes the selection of the PV generator on the roof of the Smart Green Tower and of the PV façade system, of the lithium-‐ion battery storage and of the power electronics that will be deployed. Envisaged as an energy management system is the deployment of a new prototype from Siemens. In the case of these system components, the requirements for the system integration will be identified and the necessary adaptation measures for a safe, reliable and efficient operation will be defined. This includes the communication interfaces between the individual system components. AP 3: Monitoring concept In the case of the electric power system of the Smart Green Tower, a detailed monitoring concept will be developed that includes the energy flows of the generating capacities, the battery storage, loads (on DC and AC side), as well as the energy flows into and from the connected distribution grid. Furthermore, the irradiation at different points of the PV roof system and PV façade system should be recorded, in order to verify the functioning and yields. Based on the prepared concept, appropriate counters will be selected, which will be connected to a locally installed computer (desktop or industrial PC) that allows remote access to the data. AP 4: Installation and commissioning of the measuring equipment The measuring equipment will be procured and installed parallel to the installation of the PV-‐battery system and taken into operation, pursuant to the Monitoring Plan developed in work package 3. Furthermore, an automated data transfer from the locally installed computer to the Fraunhofer ISE will be established. AP 5: Data acquisition, analysis and evaluation Over an initial period of two years, the recorded data of the Smart Green Tower will be precisely -‐ processed, analyzed and evaluated – on a daily basis – in ¼ hour intervals – by the Fraunhofer ISE. After the end of a calendar month, summary reports will in each case be prepared that entail the precise daily evaluations, and made available to the project partners.


AP 6: Determination of the optimisation potential at components and system level The data that is collected and analysed by the detailed monitoring, will be utilised to identify optimisation potentials at both component and system level. This will on the one hand be based on a structured analysis of the actual status of the system and a recommendation for action derived therefrom for the further development of the individual components. On the other hand, the collected data will however be also used to quantify the benefits of each measure that can be achieved with the help of the system simulation set up in work package 1. AP 7: Options for the enhancement to a Smart Green District The realised Smart Green Tower is intended to serve as the nucleus of a so-‐called Smart Green District, which can be accomplished by connecting existing buildings and new buildings, in each case with own producers and possibly also own storage capacities. An important goal is to thereby design an optimised local energy supply at the district level from an energy and economic point of view and to also to implement it in subsequent projects. Time schedule

Work packages

1. Year 2. Year 3. Year Q1

Q2

Q3

Q4

Q1

Q2

Q3

Q4

Q1

Q2

Q3

Q4

AP 1: Concept for the electrical energy supply of the building and simulation-‐based system design AP 2: Selection of the components of the electrical energy supply (Battery, power electronics, EMS etc.) and requirements for the system integration AP 3: Monitoring concept AP 4: Installation and commissioning of the measuring equipment AP 5: Data acquisition, analysis and evaluation AP 6: Determination of the optimisation potential at components and system level AP 7: Options for the enhancement to a Smart Green District


8. Necessary funding In the case of the Smart Green Tower, this pertains to an ambitious research project with direct reference to practice that can generate interesting insights for future projects and applications. The project is characterised by a high degree of innovation on the part of the system concept for objects in the order of the Smart Green Tower within the district. It shows also an exceptionally high level of commitment and pioneering spirit of the partners involved. The research and development work that is planned within the framework of the construction project Smart Green Tower goes far beyond that of conventional construction projects and their costs. In particular, the generation of the appropriate data for the development and detection of the necessary control algorithms, in order to systematically set up, to monitor and constantly continue to further develop the energy management system, requires enormous scientific effort. This is a prerequisite for the subsequent usefulness of the findings from the practical operation, especially in view of future construction projects. However, a project of this dimension on account of its high innovative character naturally also harbours risks that likewise also significantly exceed those of conventional construction projects. There is to this end an urgent funding requirement, in order to support the research and development work on the one hand and in order to mitigate the risks associated with the project on the other hand.

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