Building Energy Management Systems and Their Role in the Energy Transition Results from Research Projects and Applications in Germany Severin Beucker, Simon Hinterholzer Borderstep Institute for Innovation and Sustainability Berlin, Germany beucker@borderstep.de, hinterholzer@borderstep.de Abstract - The building sector is responsible for a major share of Although efficiency measures (e.g., high-quality building the final energy consumption in the European Union. Most insulation, solar architecture) and decarbonization strategies attempts to improve this situation to date have focused on (e.g., using more renewable energies), are widely applied in the construction or retrofitting measures. In contrast, this article construction of new buildings,1 retrofitting the existing centers on the role of building energy management systems and its ability to improve energy efficiency as well as to increase the residential building stock is extremely challenging. High costs consumption rate of renewable energies in the building sector. and inadequate financing schemes [4] and [5], long life cycles of The authors present findings from two research projects in materials and appliances, as well as social constraints Germany that have analyzed applications of the technology for (increasing rents and housing prices) and cultural constraints reducing heating demand and electricity consumption in (preserving historic buildings and urban centers) delay the residential buildings and households. Particular attention was implementation of efficiency measures and the roll-out of paid to life-cycle-wide and rebound effects of the technology to renewables in the building sector. ensure that the applications achieve net savings. Another approach to increasing efficiency is through smart The results also illustrate that building energy management building technology, in other words, distributed, intelligent, and systems can facilitate the implementation of the next phase of the energy transition, which will require flexibility from the building networked hardware and software systems that can reduce and sector to adapt energy consumption to more volatile production shift energy consumption in buildings and households (see patterns from renewable energies. Open architectures, standards, Section II). Smart building technology is becoming more and interfaces play a crucial role in this process. important for the following reasons: • Networked information and communication technology Index Terms (ICT) in the energy sector: autonomous and ubiquitous Building energy management, energy transition, flexible energy sensors, smart measuring technologies (smart meters consumption, demand-side management and smart meter gateways), and open platforms and interfaces are sweeping the building sector, becoming I. THE ENERGY TRANSITION IN THE BUILDING SECTOR integral components of existing technologies and The building sector is of considerable importance for the products (heating, cooling, appliances, etc.) [6]. Energy transition and decarbonization of the energy system. Almost networks and infrastructure (transmission and 80% of total final energy consumption in the EU is used for distribution networks) are also being equipped with heating and hot water in residential and non-residential buildings smart technologies, gradually allowing communication [1]. Moreover, approximately half of the stock of residential across different levels of the energy system (see II.B). buildings in European countries was built before thermal • Demand for energy management in buildings: in regulations or building codes were introduced in the 1970s [2], addition to the objectives for energy efficiency, the resulting in poor insulation and high thermal losses. increasing share of fluctuating energy production from The EU has therefore agreed on two policy goals for 2030. renewable sources is creating a need for more demand- First, energy efficiency should be improved (in all sectors) by side flexibility in the energy system and the building 27% and greenhouse gas (GHG) emissions reduced by at least sector [1]. Smart building technologies provide 40%. Second, the share of renewable energies is to be increased solutions for managing energy consumption in buildings to 27% of the energy supply [3]. These policy goals present two and households, for coupling heating and electricity challenges to the building sector: an increase in efficiency and consumption, and for adapting energy consumption the integration of fluctuating renewable energy sources into a patterns to fluctuating energy production. system with a steady demand. • User and behavior orientation: finally, users are an important factor in the transition towards an efficient 1 These principles and strategies are integral parts of building codes and directives for energy performance (see, e.g., the Energy Performance of Buildings Directive (EPBD) and the Energy Efficiency Directive (EED)). and flexible energy system. Besides rapidly developing optimization vs selective optimization) and the number and technology and improved usability, behavior is crucial accuracy of the measured variables and values used for for mobilizing efficiency and flexibility potentials in the optimization [12]. While thermostat-based heating control often building sector. Smart building technology and relies on one or a small number of measuring points, BEMS take applications can facilitate and incentivize a change in many measured values from individual rooms, user preferences, consumption patterns (e.g., through visualization and building characteristics, and the weather forecast into account. efficient feedback mechanisms) [8] and [9]. B. Evolution Toward Open Standards and Platforms Against this background, the objectives of the present paper are: (1) to summarize and demonstrate that state-of-the-art smart Smart building technology is undergoing a radical change. In building technology can contribute to significant (net) energy the past, BAS and BEMS were known for their proprietary savings, and (2) to describe how the technology can be applied approaches and communication protocols that often led to to use inherent flexibility2 and demand management potential in technological and financial dependencies [14]. Furthermore, the building sector for the energy transition. applications were often user-unfriendly, forcing customers to The findings presented in this paper were gained from two adapt to autonomous control systems and leaving very little research projects and selected pilot installations of smart room for interaction. This situation has changed significantly building technology in Germany. Although the German over the past decade. Many (although not all) systems are based objectives and strategies for a transition of the energy system on interoperable hierarchical architectures and (semi-)open result from national policies and a specific building stock, the standards and protocols (e.g., Connected Living,3 OpenTherm, findings can be transferred to other countries. Open Metering System).4 The energy sector itself is a strong driver for open architectures and interfaces with the objective of II. ROLE OF SMART BUILDING TECHNOLOGY FOR THE ENERGY creating integrated and networked smart energy systems and TRANSITION markets, integrating energy generation, distribution, and consumption (see e.g., USEF,5 VHPready,6 and EEBUS.7) A. Definition of Smart Building Technology and Building Finally, BEMS user interfaces and feedback mechanisms Energy Management Systems have improved significantly, benefiting from the general Smart building technology is based on building automation development of smart devices such as smartphones and tablets systems (BAS). A BAS is used to monitor and control [13]. Another advantage of BEMS open architectures for users mechanical devices, lighting, heating, ventilation, and air is that these allow the integration of additional services from conditioning (HVAC) systems, etc. in buildings [10]. BAS can other smart building domains such as facility and service generally be used in residential as well as commercial and public companies (e.g., assisted living or security services). buildings, and also in industrial sites, where microcontroller- based automation emerged back in the 1970s [11]. The following definition focuses solely on residential buildings and their role in the energy transition, which is different to industrial applications. Building energy management systems (BEMS) are a subcategory of BAS that are specifically used for energy management in buildings and households. BEMS consist of distributed sensors (temperature, humidity, motion, etc.) and actuators (pumps, radiator valves, vents, etc.) in rooms, apartments, and buildings that are hierarchically linked to control units (apartment manager and building manager, see Fig. 1). Their main function is to control and monitor heating demand in buildings [6] and to adapt the central heat generating unit (gas boiler, district heating station, combined heat and power (CHP) plant, etc.) according to the demand of the building and its Fig. 1 BEMS with sensors, actors, and control units and an open platform for residents. The difference between BEMS and simple thermostat- services (source/©: © Riedel Automatisierungstechnik GmbH) based heating control derives from the architecture (hierarchical 2 5 This preliminary definition of flexibility for the energy system was USEF is a foundation created by organizations active in the smart energy developed as part of the research project WindNODE (see Section VI). industry. Its goal is to develop a framework and market model for an integrated 3 Connected Living is an innovation center and association that aims at smart energy system (www.usef.energy, retrieved December 2018). 6 creating a network and platform for a cross-sector and cross-producer smart VHPready is an open industry standard for the control and integration of home platform (https://connected-living.org/en, retrieved December 2018). decentralized power and heat generation plants, consumers, and energy storage 4 A number of open standards have been established. OpenTherm is a systems into virtual power plants and smart grid applications standard communications protocol used in central heating systems (www.vhpready.de/en/home/, retrieved December 2018). 7 (www.opentherm.eu, retrieved December 2018), and the Open Metering System EEBUS is an initiative that seeks to introduce a global language for devices is a standard for manufacturers and utilities for communication between different in the energy sector to communicate with one another (www.eebus.org/en/ utility meters (www.oms-group.org, retrieved December 2018). vision/language-for-energy/, retrieved December 2018). C. Building Energy Management Systems: Interoperable management, storage technologies, and dynamic pricing Platforms for Flexibility schemes [18] and [19]. The evolution of BEMS toward open and interoperable BEMS provide interfaces to receive signals for external systems and platforms has unlocked new areas of application. incentives for flexibility (see Fig. 3). The signals might be either While in the past systems often focused on the optimization of control, price, or other incentives that ensure that an economic energy efficiency in single apartments and the behavior of optimum is achieved at the local level. The system is able to react individual residents [15], [16], and [17], new interoperable (best flexibly to external events such as surpluses from wind energy available) technology takes into account the optimization of or bottlenecks in the electricity grid. Signals can either be used whole buildings and neighborhoods8 as well as the supply to stimulate adaptive behavior or for autonomous optimization system with increasing shares of renewable energies, a more with BEMS. Signals can be emitted by market participants (e.g., decentralized energy production (e.g., integration of solar aggregators10) that collect smaller flexibilities and trade these panels, heat pumps, or CHP) and consumption (e.g., storage in either via virtual power plants11 (VPP) or directly on energy batteries, electric mobility) (see Fig. 2) [21]. markets. New flexibility markets and models of the above- mentioned aggregators are described for example in “The Framework explained” by Universal Smart Energy Framework (USEF) [19]. III. RESULTS FROM THE DEVELOPMENT AND APPLICATION OF BEMS IN A GERMAN NEIGHBORHOOD The results presented in the following section were derived from two joint research projects funded by the German Federal Ministry for Economic Affairs and Energy (see Section VI). The objective of the projects was to integrate an existing BEMS into an open smart building platform and to further develop its optimization functions. The improved technology was implemented in two different neighborhoods in Germany and the effects of the energy management were monitored over a period of several years. A. Integration of BEMS into an Open Smart Building Platform In a first step, an existing BEMS for the optimization of the energy consumption (heat and electricity) in households and buildings was integrated into an open smart home platform.12 This allows the system to communicate and interact with standardized bus systems and interfaces from the home automation sector (IP-Bus, EnOcean, wireless M-Bus, etc.). A Smart Home Internet Protocol (SHIP) connects proprietary with open standards (see Fig. 3). During integration and further development, particular attention was paid to the usability of the BEMS. A newly designed graphical user interface and feedback mechanisms for single room temperature control were implemented. Fig. 2 The role of energy management in buildings against the background of a changing energy system (source: according to [7]) Integration of BEMS into interoperable platforms is a prerequisite for the fast-developing demand for flexibility and BEMS can be used to optimize complex systems and energy management in a future smart grid (see Section IV). The facilitate and allocate flexibility.9 Flexibility is becoming more main driver for this is the increasing share of fluctuating important with the increasing share of fluctuating renewable renewable energies (solar and wind) in the grid [18]. energies (solar, wind, etc.) in the grid. Alternative strategies for dealing with a fluctuating energy supply are demand response 8 11 A neighborhood is defined in this paper as an aggregation of several A virtual power plant is an approach to connecting decentralized energy (multistory) residential buildings. systems to capitalize them in a combined form and it appears on the market like 9 Flexibility is understood as the capability of elements in the energy system a traditional power plant. 12 to actively react with adapted performance to an external signal that reflects the The existing BEMS of the German company Riedel variability in electricity production and consumption. (This preliminary Automatisierungstechnik GmbH was integrated into the open smart home definition of flexibility for the energy system was developed in the research platform concept of the German Connected Living Association (see project WindNODE, see Section VI). www.connected-living.org/en). 10 An aggregator is a generic market role combining electrical appliances to make their energy and flexibility more valuable on the market. buildings to times with lower grid loads or by actively feeding energy (electricity from CHP plant) into the grid. In the above-mentioned case of the neighborhood in Berlin, it was done by using the thermal building mass. Simulations of the buildings have demonstrated that up to 16% of the yearly heating demand in the multistory buildings can be shifted by the temporary adaption of average room temperatures by ±1 °C in apartments [21]. This thermal storage capacity of the building’s mass can be made accessible through BEMS, as the system allows precise predictions of heating demand. Combined with technologies such as CHP, heat pumps or electric heating, this thermal flexibility can be made available to adapt the dynamic electricity consumption/production profiles Fig. 3 Open architecture of BEMS (source/©: Riedel Automatisierungstechnik of these systems [24]. Furthermore, the technology enables the GmbH) efficient allocation and coordination of small price-incentivized flexibilities. B. Reduction of Energy Demand in Residential Buildings The simulation was verified in the buildings with short trials of adapted operation modes of the CHP plant. This result is of In a second step, the BEMS was installed in a neighborhood interest for various reasons. First, it indicates that the inherent consisting of six multistory residential buildings with 224 building mass can be used to reduce and shift energy apartments in Berlin, Germany. These buildings, owned by a consumption in households and buildings. Second, it provides cooperative, were built in the 1950s/1960s and partially inexpensive flexibility that can be used and increased with refurbished in the 1990s (with new windows and moderate manageable additional measures (see Section IV). insultation on walls and attic). The buildings are supplied with locally produced heat and electricity from a CHP plant (34 kWel/ D. BEMS and User Acceptance 78 kWth), operated by a contractor, and additional boilers. The introduction of BEMS in the selected residential Subsequently, the energy consumption of the individual tenants buildings was accompanied by an intense and continuous and apartments for heating and warm water in the complex was discussion with the residents of the apartments. The residents monitored from 2015 to 2018. learned to operate the BEMS and to adapt the standard operating The introduction of the BEMS in the neighborhood led to an scheme of the single room temperature control to their individual average reduction of heat demand of 24% (80.8 kWh/m2a to 61.4 needs. To avoid a rejection and malfunction of the system, the kWh/m2a). Residents’ operating costs were cut by 17% [21]. following steps were taken: Although the heating energy savings depend on the • High priority during the development of the BEMS was characteristics of the building (size, building material and given to a user-friendly design and the user interface of physical properties, structure of residents, behavior, etc.), similar the control system (apartment manager) with simple savings (approximately 20%) have been documented in feedback mechanisms. comparable projects and types of buildings in Germany [21], • The cooperative (owner of the buildings) asked the [22], and [23]. The results also show that efficiency gains are residents ahead of implementation to endorse higher in multistory buildings with multiple apartments and introducing the efficiency measures and achieved an distinct heating demands than in individual or semidetached approval rating of over 75%. houses with simple heating patterns [22]. • The residents were trained to use the systems. Their In the same neighborhood, the BEMS was used (in concerns regarding comfort and costs were respected combination with smart meters) to visualize electricity and they learned how to change the settings if so desired. consumption of the residents in the apartments. Although Two years after implementation, a survey with all residents transparency of electricity consumption can lead to individual was conducted. Acceptance of the system was unchanged and savings (e.g., through exchange of appliances with high energy reduced operating costs, energy efficiency, and comfort were consumption and behavior change of residents) [8], there are discussed with representatives of the residents.13 currently no incentives for residents in Germany (e.g., dynamic prices) that would encourage an adapted consumption to a E. Assessment of Environmental Effects of BEMS fluctuating energy supply. Finally, assessment of the life-cycle-wide energy and C. Mobilizing Thermal Storage Capacity of Buildings resource consumption of BEMS is of interest in order to judge whether the technology can contribute to net savings. Research In a third step, the objective was to prove that BEMS can be by the authors has proven that: used to mobilize flexibility in the building sector. This can be done either by shifting energy consumption in households and • Potential net emissions savings through the application of BEMS strongly depend on the heat energy saved 13 The results of the survey have not been published. The data are the property of the building cooperative. (functional unit: 1 kWh saved), and can vary from • How can smaller flexibilities from buildings be approximately 0.4 kg CO2 equivalent (for natural gas complemented with other approaches or technologies to heating avoided) to over 1 kg CO2 equivalent (for form bundles that are technologically and commercially electric heating avoided in regions with GHG-intensive useful? electricity generation). At present, BEMS typically • What are use cases, value chains, and business models avoid at least 40 times as many GHG emissions as they that allow the aggregation of smaller flexibilities from produce over their entire life cycle if they are used in buildings and how can they be realized? regions with moderate to cold climates [12]. The following sections will describe how these questions are • A comparison of building insulation and BEMS in being pursued in ongoing research of the authors, using the Germany showed that CO2 abatement costs for building technology and neighborhood described in Section III above. insulation (approximately. €100/tCO2) are at least three times higher than the costs for BEMS (approx. 30 A. Increasing the Flexibility Potentials from Buildings €/tCO2) [25]. It follows from this that BEMS can be With residential buildings, there are several options to efficiently used to quickly reduce energy consumption increase flexibility potentials. Although BEMS were primarily in the building sector, even when cost restrictions for developed to control and optimize heating systems and refurbishments or strict conservation codes for buildings electricity consumption in buildings, thanks to their open apply. architecture and interfaces, they can also integrate (existing and Finally, as with other technologies, BEMS can have rebound additional) sources for flexibility, such as cooling, air effects [26]. Direct or primary rebound effects deriving from conditioning, heat pumps, electric mobility, etc. BEMS can be eliminated with a high degree of certainty due to One option that can easily be realized in residential buildings the high efficiency achieved by the technology. Indirect or is power-to-heat (PtH) elements in existing warm water buffer macroeconomic effects are more difficult to assess. At this point, systems. These can be retrofitted in existing hot water storage it can only be assumed that these effects are not dominant tanks and local district heating networks and they provide because of rising operating costs (heating and electricity) for inexpensive solutions for flexibility by converting excessive residents in the German housing and rental market. renewable energies (e.g., PV or wind) into heat14. PtH elements are therefore simple solutions for coupling the electricity sector IV. FUTURE APPLICATIONS OF BEMS FOR THE ENERGY to the heat sector. TRANSITION The neighborhood in Berlin, Germany described in Section The results presented in the preceding section indicate that III.B was equipped with such PtH elements (6 x kW = 48 kW) BEMS can successfully be used to manage complex buildings in existing warm water buffer tanks. The PtH elements were and neighborhoods with multiple power generating units (e.g., integrated in the BEMS (see Fig. 1) and are now, together with boilers, CHP plants). In these applications, BEMS serve as a the CHP plant (36 kW), part of the flexibility potentials of the platform for complex controlling and optimization processes. buildings. The flexibility can be used to: They minimize costs (e.g., residents’ operating costs) and • consume electricity from the grid by turning off the CHP environmental effects (e.g., GHG emissions) and translate this plant and charging the warm water storage tanks into specific objective functions of the BEMS, using priority (negative balancing power in times of high grid loads) circuits for CHP plants (to prevent wear and tear)) [6]. Hence, or by BEMS can also be used to facilitate and allocate flexibility or • feeding electricity into the grid from CHP plant and grid-reactive behavior of buildings by using inherent storage. slightly overriding the present temperatures in the Thus, buildings can provide affordable alternatives in complex by max 1°C and using the buildings as inherent comparison with other storage solutions (batteries, power-to-x, thermal storage (see Section III.C) (positive balancing etc.) [18]. power in times of low grid loads). A key insight from research projects to date is that, although Control via the BEMS ensures that costs are minimized and technically possible, the mobilization of flexibilities from the changes made due to flexibility options will be in line with the building sector is highly dependent on (financial) incentives. temperatures preset by the residents with minor alterations. These incentives could be, for instance, dynamic pricing schemes that take into account availability of renewable B. Analyzing Value Chains for Energy Flexibility of energies, storage options, and grid capacity. Dynamic pricing Residential Buildings would be a strong driver for the allocation of (relatively For the commercialization of flexibility of the building speaking, compared to other sectors such as industry) smaller sector, it is important to understand the flexibility needs in the flexibilities from residential buildings. Such smaller flexibilities energy market and to identify approaches or instruments that can could then be allocated to dimension in the GW range with serve these market needs. Although demand for flexibility is significance for the energy system. Further research by the subject to national (in this case, German) regulations, some authors therefore focuses on two questions: general rules apply. First, flexibility is needed to balance upcoming supply and demand on the market (day-ahead and 14 The installation of PtH elements in warm water storage/buffer tanks is inexpensive and can be performed by plumbers in a few working hours. intraday). Second, there is a need for flexibility to stabilize the 1) Grid Services for a DSO/TSO Flexibility Platform transmission grid (frequency control) and to avoid network The first model aims at offering flexibility to the electricity bottlenecks (congestion management). Third, electricity grid. It combines the functions of a TSO16/DSO17 operational suppliers (the balance responsible party) have to supply their online platform (acquiring flexibility from plant operators) and electricity to customers continuously and precisely as required. a coordination platform (optimization between TSO and DSO, They need to be flexible for short-term adaptation to in this case, a project specific platform, see Fig. 3) according to unforeseeable fluctuations in electricity generation and USEF [28]. consumption [27]. Finally, flexibility can be used to achieve a high self-sufficiency rate. For prosumers, this means that their own production is able to meet their needs most of the time, so that they rarely have to buy energy from suppliers. These needs have a strong impact on the technological options for flexible energy supply of buildings. At present, market demand for flexibility is almost exclusively met by bigger power plants (multiple MW each). Market access for smaller (individual) plants, for example, from the building sector, is therefore difficult to realize. For this reason, instruments that might help operators of smaller plants or units to achieve flexible energy supply are Fig. 4. Flexibility of buildings through TSO flexibility platform (source: own) being examined. Digital platforms and virtual power plants are one approach for overcoming the existing barriers for smaller Offers for flexibility can be submitted both a day ahead and flexibility providers. They can efficiently pool flexibilities by intraday for individual quarters of an hour (96 values per day). streamlining processes and minimizing costs that arise, for The call for flexibility can be both day-ahead and intraday. instance, through registration and trading. Flexible systems can be registered and offers submitted Marketing via VPP can also allow producers to offer either manually via a browser interface18 or automatically via flexibility to more than one market at the same time (“multi- transfer of an xml file. An automated process fundamentally use”). Based on precise predictions, it is possible to sell reduces the specific registration/transaction costs per kilowatt. electricity (e.g., from CHP) on the market 24 hours a day and This is of importance for small flexible devices/systems wishing simultaneously hold back negative balancing power for to compete with larger ones in the future. frequency control. Therefore, CHP units are usually operated at 2) Market Flexibility via Virtual Power Plant full power. If, for example, high loads occur in the grid (e.g., due The second model aims at integrating flexibility into the to surplus feed-in from wind generators), the output power of a market through a virtual power plant (VPP). VPP operators CHP unit can be reduced at short notice to support grid usually control various plants for the generation and balancing. consumption of electricity in order to be able to react flexibly to C. Identifying Use Cases and Market Incentives for Digitally demand on the energy market and to generate optimum results Enabled Flexibility Services Provided by the Building across their entire portfolio. Sector To explore options for flexible or grid-reactive behavior of buildings and to align them with market demand, research on the current electricity system/market was conducted together with relevant stakeholders. Potential models were drafted from a local consortium consisting of a BEMS supplier, a CHP operator, a housing company, and two research organizations. These drafts were presented and discussed at a stakeholder workshop in Berlin in 2017.15 On the basis of these workshops, potential models for flexibility services of local neighborhoods were developed. Two models that fit the current framework of the electricity system best are presented below: Fig. 5. Flexibility of buildings through VPP (source: own) This case allows VPP operators to react to predictable fluctuations of electricity production in advance by optimizing 15 17 Participants in the stakeholder workshop were: housing companies, CHP DSO: distribution system operator, the party responsible for operating the operators, BEMS suppliers, TSOs, DSOs, energy legal experts, energy distribution grid (sometimes called DNO, distribution network operator). 18 consulting companies, energy suppliers, and research organizations. See www.flexplattform.de (retrieved December 2018). 16 TSO: transmission system operator, the party responsible for the electricity transport grid. schedules. In an ideal market, only facilities that produce the with dynamic pricing, decentralized production (e.g., CHP or smallest specific emissions at the lowest cost, just enough to PV) and power-to-heat technologies, BEMS can serve as an cover the load (see Fig. 4), will operate. optimization platform for coupling the electricity and the heat A control box (gateway) is installed in one or more buildings sector. to connect the neighborhood to the VPP operator. The box Although the individual flexibility from buildings and interacts with the BEMS which determines the local flexibility neighborhoods appears small (below 100 kW), the total for this options and optimizes their operation. sector in Germany amounts to gigawatts [29]. Thus, the building sector with its inherent flexibility potential can be made D. Testing of Use Cases accessible for a renewable energy supply. The two cases developed for the building sector (DSO/TSO flexibility as well as market flexibility for VPP) will be C. The Role of ICT Open Architectures, Standards, and implemented and verified with tests in the neighborhood in Interfaces Berlin, Germany (see Section III.C). Time-limited trials (24-48 ICT and autonomous algorithms that optimize energy hours each) under changing conditions (different seasons) are management on different levels of the system (building, planned. A major challenge is the requirement to not interfere neighborhood, local (distribution) grid, and transmission grid) with the need for continuous supply of heat and electricity for are prerequisites for the efficient organization of a future energy the residents. system. Not only does the technology make it possible to balance The trials will encompass the processing of external signals energy production and storage, but it also allows the integration for flexibility (e.g., signal from platform or VPP operator) via of decentralized flexibilities of buildings and private households interfaces of the open BEMS architecture (including interfaces (including appliances such as refrigerators, air conditioners, between the BEMS and the plant/units for flexibility), as well as etc.), which can serve as additional reserves for demand-side the ability of the buildings to react to the signals. flexibility. It is expected that the flexibility potential will depend on Although open standards and interfaces in the home various factors such as building physics (building construction, automation and energy sector are currently developing, we are materials, etc.), utilization of the building, and types of heating still a long way from having open, interoperable, and (inter-) and hot water systems. nationally accepted architectures that cover different sectors of It is also expected that, due to the current market and pricing the energy transition (energy production and distribution, scheme (fixed prices for electricity, no incentive for flexibility, industrial production, buildings and mobility). etc.), options for commercialization of the flexibility will be D. Economic Incentives for the Energy Transition limited (see Section B), but that with dynamic prices in the future (due to higher shares of renewable energies) new business Finally, it can be concluded that financial incentives play an models will develop. important role in the energy transition. Initial assessments indicate that under today’s regulatory and pricing scheme (in V. CONCLUSIONS Germany), only small revenues can be obtained from these Results from the research, development, and trials with decentralized flexibilities in the building sector. However, it is BEMS allow the following conclusions. also assumed that automated handling of flexibilities from the building sector with BEMS, platforms, and marketplaces will A. BEMS and their Contribution to Energy Efficiency in the significantly lower the costs of aggregation. Building Sector Thus, it is likely that handling and trading of smaller The building sector plays an important role in the transition flexibilities will become more efficient. Together with of the energy system and BEMS can help to make the building incentives for flexibility (e.g., dynamic pricing schemes for grid- sector accessible for this development. The technology can reactive behavior, a flexible grid fee or tax) the development of improve energy efficiency in buildings and households by viable business models will be possible in the near future. significantly reducing heating demand. If state-of-the art knowledge and technology is applied, 20% of heat energy can VI. ACKNOWLEDGMENTS be saved in partially refurbished residential buildings in The authors would like to thank the reviewers for their moderate to cold climates. This can be done in an economically valuable comments and suggestions that helped to improve the reasonable way, without interfering with the autonomy and quality of this work. comfort of the residents, and with net energy savings over the The results presented in this article are based on two research life cycle. projects funded by the German Federal Ministry for Economic Affairs and Energy (WindNODE (www.windnode.de), funding B. BEMS Foster the Integration of Renewable Energies into reference number FKZ 03SIN504, and ProSHAPE the Grid (www.borderstep.de/projekte/proshapeconnected-energy/), In addition, BEMS can act as a key technology to balance funding reference number FKZ 01MG3002A). fluctuating electricity production from renewable sources with the need for a steady energy supply in households and buildings. The technology (together with smart meters) can be used to increase transparency on energy consumption. 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