In future, buildings will interact much more closely with the electricity grid, whereby the boundaries between electricity producers and loads are set to become more fluid. For this reason, buildings shall become grid-supportive and cooperate with the public electricity grid, which will supply increasingly more renewably generated electricity. There will also be major changes in heating networks: In urban areas, individual buildings will be linked to form larger energy units, and an increasing amount of renewable energy will flow in the necessary heating networks. In addition, electricity and heating systems will become increasingly coupled, for example via electrically driven heat pumps and thermally activated component systems. Increasingly complex building and district energy concepts and networked energy systems are therefore being planned and built.
In view of this, the German Federal Ministry for Economic Affairs and Energy intends to use the new Energiewendebauen research initiative to more closely bundle research into buildings and districts. The newly formed initiative was presented for the first time at the 1st Energiewendebauen Congress, which was held on 30 and 31 January in Berlin. In the historic surroundings of the Schöneberg Gasometer, which has strong energy-related ties, around 350 participants from research institutes, universities, architecture and planning offices, politics, energy suppliers, cities and municipalities as well as the real estate industry discussed how the energy supply of buildings and districts can be shaped in future in a sustainable manner.
A report on the event by Uwe Friedrich and Johannes Lang.
The event took place in Schöneberg Gasometer. Built by the Berliner Gaswerke utility company one hundred years ago, it initially supplied Berlin’s street lighting and the rising number of residential gas stoves. Today it acts as a landmark for the EUREF campus, a CO2-neutral model district with a decentralised energy supply system that also houses research facilities and companies working on the energy transition.
The objective set by the German federal government to make the entire building stock climate-neutral by 2050 requires an 80 per cent reduction in the building sector’s energy consumption relative to today’s levels. During his welcome address to the conference participants, Dr. Frank Heidrich from the German Federal Ministry for Economic Affairs and Energy emphasised the enormous efforts that would be required to reach this goal. He said that the energy transition had already made some considerable progress, which was not least due to exemplary research projects. However, he also warned that considerable work still needs to be done in terms of the broad application of the concepts and technologies developed in research. “We need to increase our efforts,” he added. This is set to be achieved with the new ENERGIEWENDEBAUEN research initiative. It brings together the “Energy Optimised Building” (EnOB), “Energy-Efficient City” (EnEff: Stadt) and “Energy-Efficient Heating and Cooling Networks” (EnEff: Wärme) research initiatives and supplements these with the thermal energy storage systems and low-temperature solar thermal energy systems research areas. This is intended to facilitate the pooling of research and the networking of topics.
Keynotes: Energy transition from four perspectives
In four keynote presentations, the delegates were introduced to the challenges associated with the energy transition, and opportunities and trends were identified. For Kamel Ben Naceur, Director for Sustainability, Technology and Outlooks at the International Energy Agency (IEA), energy-efficient cities are the key to lowering greenhouse gas emissions, whereby the transition from internal combustion engines towards electrically driven transport systems was crucial. He added that cogeneration and urban heating networks make an equally important contribution to decarbonisation as renewables. On a global scale, Ben Naceur sees a dominant role for biomass if the two-degree target is to be achieved by 2050.
For Christian Stolte from the German Energy Agency (dena), the energy transition is actually an issue affecting society as a whole that has hitherto only been treated in a piecemeal manner in accordance with specific sectors and interests. From the point of view of the consumer, what matters are pragmatic approaches; for example it should be possible to carry out building renovations more easily.
Here, a specific dena project aims to implement an individual renovation roadmap for residential buildings. In addition, the training of consultants and trade specialists needs to be strengthened and the framework conditions improved by providing funding and reliable information.
To ensure a stable and secure power supply in future, the electricity grids need to be adapted to changes in the production structure. Grid expansion provides the key to successfully achieving the energy transition. And the expansion of the grid has always included overhead transmission lines, which however are being increasingly opposed by people due to their visually disruptive nature. However, the legislator has recently given the four transmission network operators greater possibilities for laying power lines underground. Florian Bokermann from the transmission network operator Tennet TSO reported on the expansion goals for the Südlink project. He views this HVDC transmission line, which will connect northern and southern Germany by 2025, as the main artery of the energy transition. However, such a massive grid expansion requires acceptance. According to Bokermann, the public participation model that is now being applied for grid expansion projects with web-based tools and on-site events is a success. An intensive dialogue culture is an important success factor in planning and implementing transmission line construction schemes. In the ensuing discussion, the demand for uniform network charges and thus a more equitable distribution of loads among the regions along the major electricity transmission corridors was addressed. This is because at the moment regions without points of receipt also have to pay charges. The good news: The German Federal Ministry for Economic Affairs and Energy is planning a gradual adjustment of the network charges.
Dr. Fiona Williams from the mobile communications supplier Ericsson said the next generation of mobile communication in the form of 5G was already in the starting blocks. This technology is also very interesting for networked applications in the energy technology and transport sectors. This is because in just a few years 5G would permit extremely high transmission rates (factor of 1,000), with far lower energy consumption (factor of 10), improved coverage and building penetration (20 dB) and extremely low latencies for real-time applications (<5 ms). The new mobile communication standard could therefore provide the technological foundation for smart grids and future buildings and districts as smart, networked energy units.
Model projects from research
Several model research projects were presented during the further course of the event: several energy-plus and grid-supportive buildings, different decentralised energy supply concepts for urban districts, new approaches to heating and cooling networks, as well as methods and tools for the simulation and integral planning of buildings, districts and cities.
Assessing grid-supportive buildings
Prof. Antonello Monti from the Institute for Automation of Complex Power Systems (ACS) at RWTH Aachen University focussed on grid-responsive buildings and their energy efficiency-based assessment. The grid revolution allows buildings to play a new role – they are becoming grid-supportive and thus part of the overall energy system. Buildings that increasingly interact with the electricity grid and can provide thermal storage capacity for the electricity grid as required need to be assessed with regard to the overall energy-based system. Here it needs to be investigated how the electricity generated and consumed in buildings impacts on the grid. The dynamic mode of operation, which is due to the occasional interaction with the electricity grid, needs to be taken into account here. To this end, Monti presented a valuation method that he sees as an initial step towards holistic assessment.
New-build scheme for Freiburg Town Hall: Grid-supportive net zero energy office building?
As part of the first construction phase for the new administration centre in Freiburg’s Stühlinger district, the city is constructing one of the largest buildings in Europe aimed at achieving “energy-plus” status. With the new building, 16 different offices will now be concentrated in one location. 840 employees will move into the building in March 2017. The other two buildings (construction phases 2 and 3) are set to be completed by 2018. Dr. Peter Engelmann from the Fraunhofer Institute for Solar Energy Systems (ISE) explained the building’s energy concept and the planned building monitoring. The energy concept is characterised by innovative and at the same time streamlined building technology with high demands on user comfort.
The scientific evaluation based on extensive data collection will start from July 2017, whereby the question needs to be clarified as to whether and how the new administration centre can be operated in a grid-supportive manner. Nevertheless, it has already been determined by simulation that 100% of the generated photovoltaic electricity can be used in the building.
Energy-plus – a question of balance boundaries
Whether the new scheme will really be an energy-plus building depends on the balance boundaries. In this case, the energy demand for heating, ventilation, lighting and cooling in accordance with the German Energy Saving Ordinance (EnEV) is taken into account for the primary energy balance. Usage-dependent requirements, such as for work equipment, IT and the canteen, are not included. The challenge facing larger buildings in achieving a levelled primary energy balance by generating energy on and in the buildings is that the usable area, and thus the energy demand, is generally proportionately greater than the available areas for energy production such as roofs and facades.
To compensate for the energy input, almost the entire building envelope of the new administration centre is used to generate energy. Photovoltaics is mainly used, combined with photovoltaic-thermal hybrid collectors and a biogas boiler. The low-temperature thermal supply is based on groundwater-coupled heat pumps, heating and cooling is provided via radiant surface systems (concrete core activation in combination with edge strip elements), so that the building is heated with low temperatures. The building is almost completely cooled with environmental energy from groundwater wells. The building’s mullion and transom facade has high thermal insulation with passive house elements, including windows with triple glazing and mechanical ventilation with heat recovery. The heating and cooling loads are low owing to the very good thermal insulation.
Renovation of Detmold Vocational College to become an energy-plus school
Three school buildings and a sports hall have undergone major renovation on the campus of the Vocational College in Detmold. The amenity value and indoor comfort have been significantly improved. Harald Semke from the architectural office “pape oder semke” explained the ambitious goals behind the project: The intention was to reduce the energy demand by about 75 per cent and the heating demand by as much as 94 per cent. The buildings can achieve the plus-energy level by utilising solar power generation and district heating from predominantly biomass and combined heat and power generation.
New approaches have also been adopted in terms of the construction: For the purposes of providing thermal insulation, prefabricated modules filled with cellulose and built using a timber panel structure were mounted on the outer walls. This has enabled the construction time to be significantly reduced. The photovoltaic modules on the gently sloping roofs are visually integrated into the roof level. The buildings are still connected to the municipal district heating system, which will have a positive effect on the primary energy balance. The building is now being scientifically evaluated in operation.
More details on this building renovation are available at...
SWIVT housing estate components for existing residential districts
This project is concerned with developing an interdisciplinary planning strategy for integrating existing buildings into a smart grid. For this purpose, innovative energy technologies shall be networked at the housing estate level. The researchers at TU Darmstadt, the University of Stuttgart and AKASOL GmbH want to generate and store electricity and heat with innovative technologies based on renewable energies and also control the entire residential district in energy efficiency terms by means of a smart energy management system. They believe that this concept will enable them to improve the energy balance of the Postsiedlung housing estate in Darmstadt by at least 30 per cent compared with conventional renovation, whereby the renovation interventions will remain moderate in scale.
Smart control of energy flows
Until now, energy-related renovation has often focussed on improving the building envelope and integrating innovative individual components into the respective energy system. Power storage technologies are seldom considered and the storage of heat is usually restricted to small system solutions. Energy concepts with a coupled electricity-heat network and correspondingly integrated energy storage systems have not yet been implemented at the district level.
The SWIVT research project is focussing not only on high-quality living space and a hybrid storage system but also on the smart control of energy flows. This creates synergies and leverages further energy savings potential. The reduced need for renovation work on the building envelope avoids planning and construction work and saves time and resources. And with the flexible operation of the energy technology, the districts themselves can provide system services for the end-users on the ground as well as for network operators or the electricity trade. The researchers designed three energy supply scenarios with the aim of finding an optimal operating strategy. They are module-like in design and therefore enable the product-neutral, demand-dependent and flexible integration of innovative components such as, for example, hybrid storage systems for electricity and heat. The concept can therefore be applied to different districts.
Networked districts for the “Zukunftsraum Wolfsburg” project
In Wolfsburg, research is being conducted into implementing energy-efficient neighbourhood concepts in systemically networked districts. For the necessary conversion of urban and technical infrastructures, scientists from the Technical University of Braunschweig, together with the city of Wolfsburg, want to take into account relevant technologies regarding energy efficiency, renewable energy generation and networking in integral planning processes. In doing so, they are evaluating which technical components and interfaces are required as building blocks for a smart grid at different scale levels (buildings, blocks, districts). In order to promote the implementation of sustainable district concepts, the project brings together various players concerned with urban development, planning and the design of technical infrastructure, including local authorities, municipal utilities, Volkswagen, housing developers and researchers from various disciplines. The aim is to transfer the individual projects at an early stage into ongoing urban planning processes.
Systematically networking three new residential districts
In view of the scarce housing supply, the city of Wolfsburg plans to create at least 6,000 residential units in phases within the city’s current boundaries with its “Living & Building 2020” master plan. The master plan sees the greatest development potential in the eastern part of the city. Three new residential districts are envisaged as part of the city’s expansion: Hellwinkel Ost, Steimker Gärten and Nordsteimke-Hehlingen. Various concept variants are being developed for these districts by the Technical University of Braunschweig. These are essentially aimed at evaluating which technical components and interfaces are required as building blocks for a smart grid at different scale levels (buildings, blocks, districts). These district concepts are aligned with the objectives of the higher-level energy concept, optimised in terms of their implementation according to cost-benefit aspects and integrated into the ongoing planning processes conducted by the city of Wolfsburg. In addition to the monitoring concepts, it is intended to develop a tool for the operational energy and quality management as part of the project-accompanying evaluation.
Flexible cooling saves primary energy
Berlin-Adlershof is one of the largest research and development sites in Germany. More than 1,000 companies and scientific institutions are based here across an area of more than 4.2 km2 – about 21,000 people are currently working, researching and studying on the campus. An energy concept has been developed for the Adlershof site as part of the “High Tech – Low Ex: Energy Efficiency Berlin-Adlershof 2020” project, which is now being implemented in phases. The aim is to reduce the primary energy demand in Adlershof by 30% by 2020. The joint “Berlin Adlershof Energy Network” project makes an important contribution to achieving this goal and provides the planning basis for the efficient energy supply of urban districts. Selected energy-based concepts and measures from the “HighTech – Low Ex” energy concept shall be implemented on a pilot basis.
Taking part are the Technical University of Berlin (TUB), Siemens AG and Berlin University of Applied Sciences (HTW). Prof. Dr. Kai Strunz from the TU Berlin described how the key focus is on networking at real estate and district levels. Individual measures encompass the networking of energy flows, a Smart Grid Alliance and the associated energy planning guidelines.
Smart grid for electricity, heating and cooling
In the “Berlin-Adlershof 2020” project, the “Networking of energy flows” measure includes the hydraulic optimisation of the existing cooling network at the Centre for Photonics and Optics (ZPO), geothermal cooling with the help of an aquifer and the installation of a brine network.
On the campus, the researchers are also testing a smart grid that is exemplary for the energy transition and which encompasses electricity, heating and cooling. The focus is on developing an operating model that improves the energy-efficient networking of the cooling generators. The goal is to operate the cooling generators with maximum efficiency and avoid unfavourable partial load states. In addition, the development of the aquifer will ensure the year-round cooling of suitable loads based on free cooling. This will reduce the need for machine-generated cooling.
The “Smart Grid Alliance Adlershof” interest pool is intended to contribute decisively to its implementation. It encompasses properties which, in terms of their load shifting potential and savings possibilities, are suitable for participating in the construction of the smart grid. The establishment of the Smart Grid Alliance requires the comprehensive integration of different players.
In order to coordinate the research results with the ongoing district development, the new energy management planning tool shall be applied for the first time in the urban context of Berlin-Adlershof. It is aimed at energy-efficiently meeting future energy requirements as part of the urban development. Thanks to its high level of detail, it provides an interface between energy usage planning and specific project planning. In doing so, it combines energy supply systems (supply) with the traditional land use and/or development planning (demand) provided by the municipalities. In Berlin Adlershof, exemplary usage and functional variants are being developed that take into account existing and newly planned energy networks. The energy management planning was originally developed in Bavaria for smaller residential areas (Ismaning).
Renewable heat for district heating
Until now, there have been no examples in Germany where decentralised solar thermal heat is fed into a large district heating network. To demonstrate its feasibility, the SWD.SOL research project is developing a prototype for combining a solar thermal system and a district heating substation with the ability to feed heat back into the network. The particular challenge is to adapt the heat input to the changing technical conditions of the network with regard to the pressure and temperature. If these technical prerequisites are met, the effects of decentralised solar production on the entire system shall be examined with central cogeneration plants, peak load boilers, district heating networks and connected customer systems. This raises the following fundamental questions: What heating potential could be tapped? How can solar district heating supplement cogeneration production in such a way that a maximum of primary energy savings and energy efficiency is achieved? What would be the economic benefits for the district heating system operator and the solar system operator based on various possible business models?
In the SWD.SOL project, various feed-in concepts and innovative components will be tested in a model housing estate belonging to the Rheinwohnungsbau housing association in Düsseldorf, which is earmarked as an expansion area for extending the district heating system belonging to the Stadtwerke Düsseldorf municipal utility company. This is also concerned with opening up the utility company’s networks to third parties so that, for example, industrial waste heat or solar thermal heat can be fed into it.
Denmark as a model
Renewable energies are increasingly replacing (summer-time) electricity production. As a result, the existing district heating systems, which are generally operated using the waste heat from combined heat and power plants, are losing their heat source. However, depending on the technical and economic conditions, it has been shown that the use of heating networks in combination with large-volume heat storage systems and large-scale solar thermal systems can already be feasible and economical. In Denmark, for example, 18 large-scale solar thermal systems with a total nominal output of 120 megawatts were thermally integrated into district heating systems between 2010 and 2012.
The aim of the SWD.SOL research project is to demonstrate the technical and economic possibilities with which solar thermal heat can be fed into urban district heating systems. Using the example of the district heating network belonging to Stadtwerke Düsseldorf, it is also intended to identify development opportunities for the entire German district heating sector. Together with the utility company and Rheinwohnungsbau Düsseldorf, the researchers from Solites and AGFW are therefore testing new feed-in concepts, including for example the pure feed-in of solar heat. In addition, they are testing and measuring innovative single components, mainly pilot transfer stations. A measurement programme for optimising the operation and evaluating the work is also planned. In the event of success, namely with proven efficiency and profitability, business models could be created for district heating system operators and solar plant operators.
Local heating and cooling energy from waste water
Sewage stinks and is filthy – but it is nevertheless suitable for supplying heating and cooling to buildings. In Stuttgart’s new Neckarpark urban district, the energy in the municipal waste water is extracted by means of a trough heat exchanger in the sewage channel and utilised via a low-temperature local heating network. This provides the basis of the energy concept for the new district, which is being created on a brownfield site belonging to the former Bad Cannstatt railway freight depot. There, the city of Stuttgart is developing a new urban district with a highly energy-efficient construction scheme (KfW Efficiency House 55) comprising approximately 450 apartments, a primary school with a children’s day care centre, a sports swimming pool, hotels, service and commercial enterprises. The combination of nearly-net zero energy buildings and waste water heat is aimed at achieving an optimised overall system for supplying heat to the buildings.
As an alternative heat source for saving fossil fuels, waste water heat provides a particularly interesting option for municipalities because they have the sole right to utilise the waste water that accumulates in their area. The city of Stuttgart therefore commissioned a study to enable it to assess the possibilities for using waste water for heating and cooling. The analysis of the temperature in the aeration tank at Stuttgart’s main sewage treatment plant showed that the temperature is at least 12 C even in periods of cold weather. The waste water, which flows with a speed of at least 1,300 litres per second into Stuttgart’s main sewage treatment plant, can potentially provide nearly 11 megawatts of heat output and around 17 gigawatt hours of heat each year.
In summer it makes sense to utilise the cooling potential of waste water. For economic operation, the loads should lie within 300 metres of the sewage channel. Based on these criteria, a waste water heat potential map for Stuttgart has been created. This shows that seven per cent of the sewers in Stuttgart are suitable for utilising heating and cooling energy.
The Neckarpark energy concept
Realising the Neckarpark as a low-energy development would enable the supply temperatures of the planned heating network to be lowered to 30 C or less. This in turn would enable the large-scale use of waste water heat. Various heat exchanger systems are capable of doing this, both as channel-integrated and as bypass systems. In 2015, the city of Stuttgart opted to use a trough heat exchanger, i.e. a heat exchanger in the sewage channel with an extraction capacity of 2,100 kW. The operating requirement: The flow rate of the waste water must be sufficient enough to prevent or rinse away deposits. This requires a gradient of at least 0.1%. The energy in the waste water shall be withdrawn by the trough heat exchanger and fed into a low-temperature local heating network. The heat for heating domestic hot water shall be generated in a heating centre using a CHP plant. The heating network is designed as a 4-line network: a supply/return for low-temperature space heating and a supply/return for the hot water for domestic hot water heating. Such an optimised overall “heat supply/building” system, with the additional integration of renewable energies, could also be used for the extensive expansion of district and local heating in areas with low thermal densities. The waste water heat utilisation will provide the first buildings with heat from 2019.
District heating network as a “heating hub”
In Hennigsdorf in Brandenburg they are aiming to increase the renewable proportion of heat in the municipal district heating network from currently about 50% to more than 80% within five years by utilising industrial and commercial waste heat, large-scale solar thermal systems and by optimising existing fossil fuel-operated CHP systems. This will be achieved by deploying a multifunctional heat storage system and consistently leveraging all optimisation potential in the load systems and in the district heating network itself. To this end, among others a flexible control system is being developed for the existing and new-build heat storage systems in the district heating network.
The Hennigsdorf heating hub’s concept presupposes that all renewable heat generators are available during the summer’s low-load period – waste heat from a steel mill, the existing biomass heating plant and the heat generated by solar thermal energy, which was determined using a simulation model for the Hennigsdorf district heating network. This resulted in a possible collector area of 20,000 m² as well as the need to integrate a multifunctional heat storage system with a 22,000 m3 water volume. It secures the flexible supply of renewable energies, absorbs the waste heat, stores it seasonally and quickly compensates for power peaks in the network. The preparatory studies will be finalised shortly. It is planned to implement the “Heating Hub” project between 2017 and 2020.
Network optimisation ensures waste heat utilisation
The Stadtwerke Hennigsdorf municipal utility company operates the district heating network in the town with seven heating plants and 50 km of pipe systems. Heat is supplied to 9,500 residential units in apartment buildings that were mainly renovated in the 1990s. Also included are about 90 commercial and industrial enterprises, including major industries for metal production and processing as well as communal facilities. These structures determine the supply temperatures of the district heating network – in summer there is an 85 °C supply temperature and 60 °C return temperature, and in winter there is a varying supply temperature of up to 108 °C. These temperatures are significantly higher than in solar-assisted local heating systems such as can be found, for example, in Denmark and in German pilot projects such as in Neckarsulm or Crailsheim. On the other hand, it provides a typical example of a larger district heating system as used in medium-sized towns – and is therefore worth imitating.
Using dynamic and thermo-hydraulic simulations of the entire supply network and individual network meshes, weak points have been identified and optimisation targets derived. Among other things, it is planned to optimally utilise the storage potential of the network for short load peaks in the heat supply. For this purpose, the network operation needs to be made more flexible to enable decentralised, customer-side heat inputs – by means of automatic network switching and flow reversal as well as by load management of the heat storage systems in the network. The simulations confirmed that it is possible to reduce the supply temperature for the winter case to a maximum of 95 °C. However, this still needs to be demonstrated in practical network operation.
An analysis of the waste heat potential provided by the steel mill has shown that, although considerable heat potential is available, this occurs at a low temperature level and is subject to considerable temporal fluctuations. Researchers and the municipal utility company therefore favour the use of waste heat from the walking beam furnace via an exhaust gas heat exchanger for direct coupling into the district heating system.
Geographical heat information and simulation system in Hamburg
Strategic heat planning and urban development need to be interlinked so that the climate protection potential can be exploited and resources used with high cost-effectiveness. The development of a heat information and simulation system for Hamburg serves this purpose. Prof. Wolfgang Renz from HAW Hamburg explained how this would take urban development into account and thus support the municipalities’ strategic thermal planning.
The GEWISS research project is aiming to develop a heat information and simulation system for Hamburg based on a geo-information system. With the help of the simulation system and information tool, the aim is to support strategic heat planning that also takes into account urban developments such as densification, conversion, demolition and the renovation of buildings. Local political developments, external framework conditions and socio-demographic aspects shall also be investigated in terms of their impact on the heat supply system. Here the researchers will show ways of using heat as efficiently as possible and compare different efficiency measures. Also covered is the integration of renewable energies for heat generation and measures for coupling heat and power generation.
Forecast of the heat demand development until 2050
Currently, the GEWISS planning tool is being developed as a prototype. For this purpose, the researchers are calculating the precise heat consumption for individual buildings for the entire existing building stock as a first step. Two different approaches have been selected for residential and non-residential buildings:
The calculation of heat consumption for residential buildings is based on the SimStadt planning tool, which was developed as part of the “SimStadt energy simulation of urban districts” project for the planning, operational optimisation and scenario calculation of innovative energy and building concepts with grid expansion strategies. Within the scope of GEWISS, the extensive functionalities of SimStadt are being used for calculating the heat requirements (according to DIN 18599) for residential buildings and, if necessary, modified for application to Hamburg – for example through the import of Hamburg climate data.
For non-residential buildings, a typology for the heat consumption characteristic values is being used with 15 non-residential building types that are typical in Hamburg. In addition to determining the consumption characteristic values, industry-specific characteristic values for the process heat demand and waste heat potential are also being generated. In order to depict the future development of the heat demand until 2050, the planning tool is being developed on the basis of two renovation steps.
Building information models for planning, design and operational optimisation
Prof. Petra von Both from KIT in Karlsruhe argues that simulation and evaluation tools must be used with a view to the entire lifecycle of buildings in order to develop energy-optimised planning concepts as well as to ensure good performance during operation. However, for planners and building experts there have been considerable obstacles preventing the continuous use of such instruments. Both believes that this is caused by the complexity of the software tools available for architects and urban planners, the enormous effort required for the data acquisition as well as a lack of interoperability between the various software tools owing to inadequate technical interfaces.
With the joint EnEff-BIM research project, standardised information technology methods for planning, designing and optimising the operation of energy-efficient new and existing buildings are being developed, tested and made accessible to specialist planners. In addition to KIT, two institutes from RWTH Aachen University and the Berlin University of the Arts as well as the IBP and ISE Fraunhofer Institutes are involved in the project. The modelling, simulation and operational optimisation are being carried out here on the basis of open building information models (BIM) with the aim of achieving a continuous exchange of data in the technical planning based on a digital, semantic 3D design model. Here the intention is to make consistent use of future-proof modelling and interface standards.
Uniform digital format for exchanging data
In contrast to singular or proprietary software solutions, the work in the EnEff-BIM project shall be based on the open-sourced, object-oriented modelling approach used by Modelica. The national research project is participating in the IEA EBC Annex 60 initiative in order to consolidate the standardisation and dissemination of this approach from the mechanical engineering sector in the construction sector and also promote the formalised use of Modelica internationally.
In order to make better use of Modelica models over various planning phases and application areas, existing model libraries from the partners were matched, adapted, exchanged and generalised in the project in terms of their reusability. Based on this, EnEff-BIM investigated the possibilities for instantiating the Modelica simulation models with source data from the international lifecycle-oriented IFC (Industry Foundation Classes) BIM standard. For this purpose, a uniform digital format for exchanging data for building and plant simulation was developed.
Extensions to the existing IFC scheme for describing the simulation-relevant elements were made. These scheme extensions were carried out in cooperation with buildingSMART and normative bodies from VDI and DIN in order to ensure the highest possible practical relevance. The core element was therefore the development of an open, product-neutral interface between IFC and Modelica sub-models as well as the integration of established simulation tools using the Functional Mockup Interface (FMI) standard.
International tool development for advanced energy performance simulations
Prof. Dirk Saelens from KU Leuven explained why the new requirements for buildings and cities regarding energy efficiency and quality of life must also have consequences for the simulation programs used for product development, design and operation. The IEA-EBC Annex 60 is aimed at developing and demonstrating a new generation of freely available, documented, validated and verified calculation methods for urban energy systems such as district heating networks, buildings and districts with low energy requirements. The researchers and organisations involved in Annex 60 shall coordinate the research, development and validation of appropriate simulation methods.
The software development will be based on the freely available Modelica modelling language and the Functional Mockup Interface (FMI) specification.
Discussion shows fields of action for research and application
The following findings and areas of action emerged during the presentations and discussions at the 1st Energiewendebauen Congress:
- In the future, building renovation will particularly focus on cost-effective and minimally invasive refurbishment concepts. This is the only way to render the entire building stock effectively climate-neutral.
- The networking of buildings and districts to form grid-supportive units that cooperate with electricity and heating networks is a new step in qualitative terms that still requires some research and development effort. Further accompanying technological developments are required to enable buildings to interact flexibly (depending on demand) with networks and carry out energy generation, storage and distribution functions in the energy supply system.
- At the district level, locally adapted, decentralised heating supply solutions need to be developed and the integration of renewable heat tested — in technical, organisational and economic terms.
- When designing and operating networked buildings and districts, new planning methods, tools and participation processes are required to enable the efficiency potential to be actually leveraged in a quality assured manner.
- Reliable, less complicated and harmonised framework conditions are required in many areas in order to make new concepts both economical and practical, for example in relation to construction legislation or network tariffs for the provision of decentralised grid services.
- Research is indispensable in developing and testing new ideas as far as market readiness. Ultimately, and all participants agreed on this, it is concerned with the broad application of energy efficiency and renewable energies. New concepts and technologies would therefore have to be made available, as Professor Norbert Fisch from TU Braunschweig emphasised in his presentation of “Zukunftsraum Wolfsburg” as an energy-efficiently networked district of the future.