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In 2008 the German Ministry of Economic Affairs and Energy launched an initiative for new or retrofitted energy-efficient school buildings as focus area within their research programme “EnOB” (Energy Optimised Buildings). The initiative (www.eneff-schule.de) comprises three different energy levels: • Best practice schools with energy-efficient renovations above the requirements in the energy-saving ordinance • Three-liter-house schools with energy needs for heating, hot water and auxiliary below 34 kWh/m2year • Plus energy schools that produce more energy than they use in the annual balance Currently three different plus energy school buildings have been planned, realized and monitored within the initiative, two of them being renovations (Stuttgart and Rostock), the last one being a new school building (Hohen Neuendorf). The three energy concepts include rather different technologies to generate heat and to reduce the energy consumption of ventilation and lighting systems. This is partly due to the research initiative approach of “EnEff:Schule” that asks for testing innovative technologies. There is however a general tendency to: • Low U-values of the building envelope with about 0.11–0.15 W/m2K at the walls and roof, 0.10 W/m2K for new base plates and 0.20–0.34 W/m2K for renovated ground slabs and basement ceilings and 0.80 W/m2K for windows • Large PV areas to compensate for the remaining energy use, sometimes in combination with other technologies or systems that generate electricity • Mechanical ventilation systems with high heat recovery rates but in combination with natural ventilation • User-dependent control strategies for ventilation and heating • Use of daylight at both the window/solar shading side and the electrical lighting control The paper compares the different technologies used at the building envelope, the heating, ventilation and lighting systems, the calculated and measured energy consumptions and the building costs.

Germany possesses a long tradition in energy-saving construction and has continuously tightened the energy performance requirements and extended the balancing scope in its energy-saving ordinance. In the last few years, several buildings with energy concepts that have the aim of generating more energy than the building needs (if compared in an annual balance) have been designed, realized and monitored - so-called plus energy buildings. This article presents selected examples of the plus energy approach for both residential and non-residential buildings along with their key technologies and available research initiatives dealing with the issue. It also discusses the different possibilities for defining the notion of plus energy and points to ongoing further developments for additional building types and settlements.

The aim of the “School of the Future” project ( www.school-of-the-future.eu [1]), which receives funding within the EU's 7th Framework Programme, is to design, demonstrate, evaluate and communicate shining examples of how to reach the future high- performance building level. School buildings and their primary users, namely pupils - the next generation - are in the focus of the project. Both, the energy and indoor environment performance of 4 demonstration buildings in 4 European countries and climates are being greatly improved due to holistic retrofit of the building envelope, the service systems, the integration of renewables and building management systems. The results and the accompanying research and dissemination efforts to support other actors dealing with building retrofits are leading to a multiplied impact on other schools and on the residential sector, since the pupils will act as communicators to their families. The user behaviour and the awareness of energy efficiency and indoor environment are being improved due to tailored training sessions. Nearly zero emission or nearly zero energy buildings are main goals in various country roadmaps for 2020. The demonstration buildings of this project may not completely reach this level, though, as the aim of the FP7 call is cost efficiency and multiplication potential. The retrofit concepts, however, result in buildings with far lower energy consumption than achieved by regular retrofits and focus on high indoor environment quality - thus leading the way towards zero emission. They can be considered as schools of the future. Results from national examples of zero emission schools complete the information used for developing the deliverables such as guidelines, information tools, publications and a community at the EU BUILD UP portal. The project is based on a close connection between demonstration, research and industry which is being represented by the “Design Advice and Evaluation Group”. This group of research and industry partners meets twice at every demonstration building site in order to give advice to the local planning group like informing them about suitable up-to-date technologies.

Initiated by the commitment of the mayor and public participation within the municipality Hohenkirchen-Siegertsbrunn in the South-East of Munich, the need for generating new child care facilities led to the realization of an energy-surplus day care center. This building illustrates how ecological and economic sustainability can go along with innovative techniques and architectural design, achieving high comfort and energy efficiency, simultaneously providing a child-oriented and enjoyable surrounding. This lighthouse project aims at increasing awareness and interest within the community and beyond for the issue of energy efficiency. Ensuring the successful implementation of this demanding task, a feasibility study was developed by the Fraunhofer Institute for Building Physics to define crucial key parameters for the design stage. In collaboration with the researchers a qualified team of architects and installation engineers closely worked together from the very beginning of the design process up to the end of execution, joining forces and knowledge. The project was awarded a prize by an expert committee and is supported by the Ger- man Federal Ministry of Economics and Technology within the funding program “Research for energy-optimized construction” (EnOB). This includes scientific guidance in planning, construction and start-up as well as a two-year monitoring phase. The energy concept, which is based on minimizing the energy need, includes a variety of features, partially influencing each other. Amongst others, these include a high level of thermal insulation, an optimized and demand-controlled ventilation system using preheated air and heat recovery in winter, a solar chimney for passive cooling and ventilation in summer, intelligent control systems and the use of renewable energy sources by highly efficient thermal heat pumps, solar thermal panels for hot water generation and photovoltaic panels. This solar electric system is designed to provide more electricity throughout the year than required for running the building with all its need. As electricity is the only energy carrier, both types of energy balances, primary and delivered, will result in a surplus.

Die wissenschaftlich-technischen Arbeitsziele dieses vom Bundesministerium fur Wirtschaft (BMWi) geforderten Projektes wurden in funf Teilen erarbeitet. Die einzelnen Themen resultieren aus aktuellen Fragestellungen; sie haben dennoch einen allgemein anwendbaren Charakter. Das Konsortium hat die folgenden Teilprojekte bearbeitet: (1) Aufbau einer Messtechnik zur Bestimmung energetischer und lichttechnischer Kennzahlen von Tageslichtbauteilen mit einem round robin test, an dem drei Institute beteiligt waren. (2) Realisierung eines detaillierten Bewertungs- und Nachweisverfahrens fur die Tageslichtversorgung von Innenraumen in unterschiedlichen Klimazonen. (3) Fur die Beleuchtungskontrolle privater Lebensraume wurde ein “Powerline Carrier Communication“-System evaluiert und die Vorteile gegenuber einem Funkubertragungssystem herausgearbeitet. (4) In einem Pflegeheim wurden quantitative Untersuchungen zum Wohlbefinden, zur Erfullung von Sehaufgaben und zur Eignung zur Melatoninsuppression bei verschiedenen Szenarien der Allgemeinbeleuchtung mit zwei unterschiedlichen Farbtemperaturen der eingesetzten Lampen (“warmweises Licht“ mit TCP = 3000 K und “kaltweises Tageslicht“ mit TCP = 6500 K) und vertikalen Beleuchtungsstarken an den Augen der Probanden zwischen 100 lx und 700 lx durchgefuhrt. (5) Fur zwei Schulgebaude in Berlin wurde der Endenergiebedarf der Bestandsanlage, des Referenzgebaudes sowie der Neuplanung ermittelt. Dabei wurde in beiden Beispielen deutlich, dass die Bestandsanlage im Bereich der Beleuchtung den zulassigen Wert nach EnEV 2009 mitunter weit uberschreitet. Eine gute Neuplanung hingegen kann den maximal zulassigen Wert deutlich unterschreiten. Diese Untersuchungen wurden von einem einjahrigen Monitoring des Energieumsatzes begleitet. Eine Querschnittsanalyse uber 48 Schulen mit insgesamt 86 Gebauden zeigt unter anderem einen erheblichen Sanierungsbedarf bei Schulgebauden, die vor 1990 errichtet wurden. Energy optimised lighting in buildings with simultaneous improvement of quality of life by daylight utilisation and innovative lamps and ballast techniques. The scientific and technical goals of this project were developed in five parts. The individual topics arising from current issues, they still have a generally applicable nature. The consortium has worked on the following subprojects: (1) Development of a measurement technique to determine energy and photometric key figures of daylight components with a round robin test with three institutes. (2) Implementation of a detailed evaluation and documentation process for daylighting of interior spaces in different climate zones. (3) For lighting control in private living areas a “Power Line Carrier Communication” system has been evaluated and the advantages of a wireless transmission system were identified. (4) In a home for elderly quantitative studies on the well-being, for the fulfillment of visual tasks and the capability of melatonin suppression at different scenarios of general lighting with two different color temperatures of lamps (“warm white” with TCP = 3000 K and “cold white daylight” with TCP = 6500 K) and vertical illuminance at the eyes of the subjects between 100 lx and 700 lx were performed. (5) For two school buildings in Berlin, the final energy consumption of the existing lighting system, the reference building and a re-planning were determined. It became clear in both examples that the existing lighting system exceeds the permitted value (EnEV 2009) by far. A good redesign, however, can be significantly less than the maximum allowed value. These studies were accompanied by a one-year monitoring of energy consumption. A cross-sectional analysis of 48 schools with a total of 86 buildings shows a substantial need for renovation of school buildings that were built before 1990.

Educational buildings such as kindergartens, schools and universities display many similar design, operation and maintenance features in most countries. The two most noteworthy similarities amongst these building types are the high energy consumption and the necessity for retrofitting many buildings within this sector. However, studies have shown that during retrofit, energy saving measures are only rarely applied, because the decision-makers lack knowledge of investments and the efficiency of potential energy saving measures. The main goal of the International Energy Agency ECBCS Annex 36 is to provide the educational building decision-makers with sufficient data, information and tools to improve their learning and teaching environments by improving the energy efficiency of their buildings. This is the background for the development of an Energy Concept Adviser (ECA) for energy and financial retrofit measures that is useful during the planning and concept development phases for educational buildings. On the one hand to help the owner to find the most efficient energy saving measures and on the other hand to prevent that exaggerated expectations are raised. The ECA should be applicable during the entire retrofitting phase to ensure that both the calculated energy savings and financial success will be achieved after retrofitting. This paper describes a tool that assists educational building decision-makers while the construction project is still in the design phase. This tool will improve new or existing buildings through the identification and calculation of potential energy savings. The ECA includes suggestions of energy systems to use and potential design concepts to be considered during the design phase. During the past 6 years, data have been gathered from all the 10 participating countries of the Annex 36. This electronic Internet-based tool incorporates an interactive source book of information, which includes design concepts, design advise, design and decision programs, and case studies. The tool has been translated into several languages.

The project BESTFACADE, sponsored by the Energy Intelligent Europe programme of the European Union, and led by MCE-Anlagenbau, Austria, accumulated the state of the art of double skin facades (DSFs) in seven European countries (Austria, Belgium, France, Germany, Greece, Portugal and Sweden). Twenty-eight facades of different buildings in all partner countries of BESTFACADE have been analysed for the aspects, types of facade in different countries, DSFs in different climatic regions of Europe, existing simulations and measurements, thermal behaviour, indoor air quality, comfort, user acceptance, energy demand and consumptions, control strategies, integrated building technology, cost (investment, maintenance and operation), resource conservation, environmental impact, comparison to conventional glass facades (CGFs), integration of renewable energy sources into DSFs, as well as non-energy related issues, such as, acoustics, aesthetics, fire protection, moisture, corrosion, durability, maintenance an...

Das Bundesministerium fur Verkehr, Bau und Stadtentwicklung (BMVBS) hat in Berlin ein Modellgebaude als Pilotobjekt fur die neue Forderinitiative “Effizienzhaus Plus“ errichten lassen. Mit diesem Modellhaus sollen die Leistungsfahigkeit der verschiedenen Konzeptkomponenten erprobt und Erfahrungen fur die Breitenanwendung gesammelt werden. Im Rahmen eines Monitoringprogramms wird das Gebaude vom Fraunhofer-Institut fur Bauphysik im bewohnten Zustand zwei Jahre lang messtechnisch erfasst und energetisch bewertet. Dieser Bericht beschreibt die ersten Zwischenergebnisse nach Ablauf einer 12-monatigen Messperiode. Die Messungen zeigen, dass trotz ungunstiger meteorologischer Randbedingungen die Ertrage aus den fassadenintegrierten Photovoltaikanlagen hoher ausfielen als die Gebaudetechnik und die Nutzer im Laufe der Messperiode fur den Gebaudebetrieb benotigten. Mit der uberschussigen Energie konnten etwa 25 % des Energiebedarfs der Elektromobile abgedeckt werden. Unter “normalen“ meteorologischen Bedingungen hatte das Haus den kompletten Bedarf der Elektromobile abdecken konnen und noch Uberschusse ins Netz eingespeist. Die meteorologischen Randbedingungen in der Messperiode Marz 2012 bis Februar 2013 fuhrten zu etwa 20 % (3.320 kWh) geringeren Solarstromertragen aufgrund der real aufgetretenen ca. 40 % geringeren Sonnenscheinstunden als im Jahresmittel der letzten zehn Jahre. Die Energieverbrauche im Gebaude lagen im Messzeitraum etwa 75 % hoher als vorherberechnet. Dies lag im Wesentlichen an Ineffizienzen im Bereich der Heizanlage aufgrund deutlich hoherer Systemtemperaturen als geplant, an der nicht bedarfsgeregelten Ausenluftmenge der Luftungsanlage und an hoheren Stromverbrauchen als angenommen im Haushaltsbereich. Die Ergebnisse des ersten Betriebsjahres zeigen, dass bei hocheffizienten Hausern eine Monitoring- und Einregulierungsphase zwingend eingeplant werden muss, um die planerisch ermittelten Kennwerte auch im praktischen Betrieb realisieren zu konnen. Validation measurements of the BMVBS Efficiency House Plus in Berlin – Survey period from March 2012 to February 2013. In Berlin, the German Federal Ministry of Transport, Building and Urban Development (BMVBS) had a model building erected to pilot the new funding initiative ‘Efficiency House Plus’. This model is also intended to test and prove the performance of various components of the concept and to provide experience for a wider application. During a 2-year monitoring programme conducted by Fraunhofer IBP, data of the occupied building will be measured and analysed with regard to its energy performance. This report presents the first preliminary results obtained from a 12-month survey period. Measurements found that – despite unfavourable meteorological boundary conditions – the power yields from facade-integrated PV systems still exceeded the energy needs of building services and building users during the survey period. The resultant surplus energy was used to cover about 25 % of the energy demand for electro-mobility. Under ‘regular’ weather conditions the House would have been able to completely cover the energy demand of the electric vehicles, and still there would have been energy left to be fed into the public grid. The meteorological boundary conditions that were prevailing in the measurement period from March 2012 through February 2013 caused a 20 % drop (3,320 kWh) in the solar power yield due to an actual reduction of the sunshine hours, which were about 40 % less than the annual average of the last ten years. In the survey period, the energy consumption in the building was about 75 % higher than predicted. This discrepancy was mainly due to the inefficient performance of the heating system (caused by substantially higher system temperatures than assumed). It was further due to the uncontrolled amount of outdoor air in the mechanical ventilation system and last but not least it was also due to the fact that the electricity consumption of household appliances was higher than expected. The results of the first year of operation suggest that in the case of high-performance buildings it is absolutely required to include a planned monitoring and regulation/control phase, to be capable of realising the design parameters in practice.

A current topic is the possibility of raising the thermal protection offered by multiple glazing by using layers of foil between the panes.Measurements, both predictive and practical, carried out at the Fraunhofer Institute of Building Physics, Stuttgart, are reported here. The concept is feasible, it is slated, and improvements can be achieved, but much existing data is over-optimistic. In practice it would seem that the air spaces must be at least 20 mm, and further attention must be given to the durability and ageing behaviour of such techniques.

The energy efficient renovation of the Solitude-Gymnasium in Stuttgart is one of the 4 demonstration buildings within the EU 7FP project “School of the Future”. The secondary school with about 710 pupils consists of a typical configuration with a main building, a building of scientific classes, a big pavilion, a small pavilion and a gym, built between 1966 and 1975. The main building and the gym include flats for the caretakers. The total heated floor area of the buildings amounts to 8,924 m 2 . The exterior walls of the buildings are made of exposed concrete or brick. All buildings have flat concrete roofs that had no sufficient insulation before the retrofit. Most windows consisted of PVC-frames and double-glazing, but in some corridors and stairways single-glazed facades existed. The heating was generated centrally for all 4 buildings by two gas boilers that replaced an earlier system in 2004. Domestic hot water for the gym is generated by a heat exchanger based on the heating water. Ventilation systems without heat recovery existed for some indoor rooms, some rooms in the building of scientific classes and the gym. All 4 demonstration buildings in the School of the Future project have the same goals: • Reduction of the total energy use > factor 3, verified through monitoring • Reduction of the heating energy use > 75%, verified through monitoring • Improvement of the indoor environment quality (air, daylight, acoustic, thermal comfort) with impact on the pupils’ performance, analysed by short-term measurements and questionnaires The building envelope renovation measures at the school in Stuttgart included external thermal insulation systems and curtain wall facades with 14-18 cm polystyrene insulation, 16-22 cm of expanded polystyrene on the roofs and mostly triple-glazed windows. The new heating system is a co-generation plant in combination with the existing boilers. The ventilation of the classrooms is now realised by decentralised ventilation units with 80% heat recovery (main building) or by hybrid ventilation consisting of window opening supported by actuators at the upper part of the windows that are controlled by timers and manually by the teachers. CO2 visualisation systems show the teacher when window opening is necessary. The existing ventilation system in the building of scientific classes are improved by central heat recoveries of 80% - 90% efficiency. Also the lighting system was updated by T5 compact fluorescent lamps, electronic ballasts, daylight control and presence detectors. A one-year monitoring period will show whether the energy performance goals (reduction of final energy from 225 to 58 kWh/m 2 yr and primary energy from 215 to 54 kWh/m 2 yr) and the indoor comfort goals can be achieved.

In order to investigate the influence of a complementary south-oriented sun-space on the heat demand of a residential building a comprehensive study based on several calculations and measurements was performed. In comparing and interpreting the findings, special attention was paid to variations in the energy balance due to varied (combinations of) boundary conditions. Further, the energetic efficiency of a sunspace was compared to the performance of 2 devices designed for improved thermal insulation of a south facade, namely a triple-glazed window system and a double-glazed one with roller blinds. Lastly, a cost-benefit analysis was conducted for all systems under survey.

About 15 % of the primary energy consumed in the Fed. Rep. of Germany account for heating private households. In this respect, there are still many possibilities to cut down on energy consumption, both in renovating old buildings and in raising new ones. In the long run, the heating energy demand for dwellings in the Fed. Rep. of Germany could be reduced to less than a third of today's consumption by consequently applying all of the advanced building concepts and technologies presently available, which to date have only been applied with hesitation. By funding the present pilot project, the German Federal Ministry for Research and Technology intends to give an actual demonstration of the practical implementation.