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The variable refrigerant flow system is one of the best heating, ventilation, and air conditioning systems (HVAC) thanks to its ability to provide thermal comfort inside buildings. But, at the same time, these systems are considered one of the most energy-consuming systems in the building sector. Thus, it is crucial to well size the system according to the building’s cooling and heating needs and the indoor temperature fluctuations. Although many researchers have studied the optimization of the building energy performance considering heating or cooling needs, using air handling units, radiant floor heating, and direct expansion valves, few studies have considered the use of multi-objective optimization using only the thermostat setpoints of VRF systems for both cooling and heating needs. Thus, the main aim of this study is to conduct a sensitivity analysis and a multi-objective optimization strategy for a residential building containing a variable refrigerant flow system, to evaluate the effect of the building performance on energy consumption and improve the building energy efficiency. The numerical model was based on the EnergyPlus, jEPlus, and jEPlus+EA simulation engines. The approach used in this paper has allowed us to reach significant quantitative energy saving by varying the cooling and heating setpoints and scheduling scenarios. It should be stressed that this approach could be applied to several HVAC systems to reduce energy-building consumption.

To gain access to information on energy use in office buildings, the German Federal Ministry for Economy launched an intensive research and demonstration programme in 1995. In advance of the 2002 EU energy performance directive a limited primary energy coefficient of about 100 kW h [m.sup.-2] [a.sup.-1] as a goal for the complete building services technology was postulated (HVAC + lighting) for all demonstration buildings to be supported. A further condition was that active cooling be avoided. Techniques such as natural or mechanical night ventilation or heat removal by slab cooling with vertical ground pipes as well as earth-to-air heat exchangers in the ventilation system were applied. An accompanying research was established to keep track of the results and the lessons learned from about 22 demonstration buildings realized and monitored until the end of 2005. As one outcome this paper summarises the energy performance of a selection of characteristic buildings together with an overview on the summer thermal comfort situations achieved. The research program will proceed during the next five years. Detailed reports and future results may be downloaded from the internet:www.enbaumonitor.de. Keywords: Office buildings; Energy monitoring; Passive cooling; Thermal comfort; User behaviour

There is a strong interaction between the urban atmospheric canopy layer and the building energy balance. The urban atmospheric conditions affect the heat transfer through exterior walls, the long-wave heat transfer between the building surfaces and the surroundings, the short-wave solar heat gains, and the heat transport by ventilation. Considering also the internal heat gains and the heat capacity of the building structure, the energy demand for heating and cooling and the indoor thermal environment can be calculated based on the urban microclimatic conditions. According to the building energy concept, the energy demand results in an (anthropogenic) waste heat; this is directly transferred to the urban environment. Furthermore, the indoor temperature is re-coupled via the building envelope to the urban environment and affects indirectly the urban microclimate with a temporally lagged and damped temperature fluctuation. We developed a holistic building model for the combined calculation of indoor climate and energy demand based on an analytic solution of Fourier's equation and implemented this model into the PALM model. [ABSTRACT FROM AUTHOR]

There is a strong interaction between the urban and the building energy balance. The urban climate affects the heat transfer through exterior walls, the longwave heat transfer between the building surfaces and the surroundings, the shortwave solar heat gains and the heat transport by ventilation. Considering also the internal heat gains and the heat capacity of the building structure, the energy demand for heating and cooling and the indoor thermal environment can be calculated based on the urban climate. According to the building energy concept, the energy demand results in an (anthropogenic) waste heat, this is directly transferred to the urban environment. Furthermore, the indoor temperature is re-coupled via the building envelope to the urban environment and affects indirectly the urban climate with a time shifted and damped temperature fluctuation. We developed and implemented a holistic building model for the combined calculation of indoor climate and energy demand based on an analytic solution of Fourier's equation. The building model is integrated via an urban surface model into the urban climate model. [ABSTRACT FROM AUTHOR]

Energy performance factors for thermally activated building systems considering the control strategy. There is still great uncertainty in the field of operation management of thermally activated building systems and, in particular, the thermally inert concrete core conditioning. Despite the widespread use of these systems in new non-residential buildings, a uniform management strategy has not yet been established. On the contrary, builders and users regularly criticize too high or low room temperatures during the transitional seasons and in the event of a change of weather or, in general, a lack of controllability. On the other hand, monitoring projects often show high thermal comfort in these buildings. Obviously, subjectively perceived comfort and objectively measured comfort differ here. At the same time, radiant heating and cooling concepts are energy-efficient when the control concept is adapted to their thermal inertia. Good control therefore ensures high thermal comfort and results in the lowest possible energy consumption. The calculation method based on energy performance factors (in accordance with DIN V 18599) offers a good opportunity to evaluate plant concepts, including their operational management strategy. This makes it possible to adapt the operation strategy for radiant heating and cooling concepts to a specific building and to evaluate it uniformly. [ABSTRACT FROM AUTHOR]

Mit der Messung des Wärme- und Kälteverbrauchs im Labor gelingt es, sowohl thermisch träge als auch agile Flächentemperiersysteme unter praxisnahen, dynamischen Bedingungen messtechnisch zu bewerten. Werden Nutzwärme- und Nutzkältebedarf berechnet und ins Verhältnis zu den gemessenen Verbräuchen gesetzt, können die Aufwandzahlen für die Nutzenübergabe ece für verschiedene Flächentemperiersysteme und in Kombinationen mit anderen Übergabesystemen unter verschiedenen Nutzungsbedingungen und für unterschiedliche Betriebsführungsstrategien bestimmt werden. Damit stehen Aufwandszahlen auf Basis kalorischer Messungen zur Verfügung, die je nach Aufgabenstellung entweder produkt- oder objektbezogen in der Planung komplexer Energiekonzepte verwendet werden können und die tatsächlichen Aufwandszahlen eh, ce für den Heizfall bzw. ec, ce für den Kühlfall genauer als Literaturwerte bzw. projektbezogen beschreiben. Measurement of energy expenditure factors of various radiant heating and cooling systems. The measurement of heating/cooling consumption is used to evaluate both thermally inert and agile radiant heating and cooling systems under realistic, dynamic conditions in a laboratory. If the net heating/cooling energy demand is calculated, the ratio between calculated demand and measured consumption defines the energy expenditure factor for the heat transfer ece. Thus, ece can be determined under different conditions of use and for different operation strategies and in combination with other heat transfer systems. This provides energy expenditure factors based on caloric measurement which are available either product or object specific. The actual energy expenditure factors eh, ce for the heating mode or ec, ce for the cooling mode can be used in the planning of complex energy concepts since these specific values are more accurate than literature values. [ABSTRACT FROM AUTHOR]

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It is considered necessary to implement advanced controllers such as model predictive control (MPC) to utilize the technical flexibility of a building polygeneration system to support the rapidly expanding renewable electricity grid. These can handle multiple inputs and outputs, uncertainties in forecast data, and plant constraints, amongst other features. One of the main issues identified in the literature regarding deploying these controllers is the lack of experimental demonstrations using standard components and communication protocols. In this original work, the economic-MPC-based optimal scheduling of a real-world heat pump-based building energy plant is demonstrated, and its performance is evaluated against two conventional controllers. The demonstration includes the steps to integrate an optimization-based supervisory controller into a typical building automation and control system with off-the-shelf HVAC components and usage of state-of-art algorithms to solve a mixed integer quadratic problem. Technological benefits in terms of fewer constraint violations and a hardware-friendly operation with MPC were identified. Additionally, a strong dependency of the economic benefits on the type of load profile, system design and controller parameters was also identified. Future work for the quantification of these benefits, the application of machine learning algorithms, and the study of forecast deviations is also proposed. [ABSTRACT FROM AUTHOR]

Unter dem europäischen Programm Intelligent Energy for Europe (IEE) fanden sich acht europäische Partner zusammen, um im Rahmen des Projektes ThermCo Lüftungs- und Kühlenergiekonzepte für Nichtwohngebäude mit niedrigem Energieeinsatz im Hinblick auf die Energieeffizienz und den thermischen Raumkomfort zu bewerten (siehe Teil 1 dieser Veröffentlichung in Bauphysik 34 (2012), Heft 6. Mit Hilfe einer Simulationsstudie für ein typisches Bürogebäude wird das Potenzial unterschiedlicher Lüftungs- und Kühlstrategien unter Berücksichtigung von Energieeffizienz und Raumkomfort für verschiedene europäische Klimazonen bewertet. Die Ergebnisse weisen eine hohe Wirksamkeit von Nachtlüftungskonzepten im nord-europäischen Sommerklima mit verhältnismäßig niedrigen Außentemperaturen nach. Im mitteleuropäischen Sommerklima bietet das Erdreich ein ausreichend niedriges Temperaturniveau für den effizienten Einsatz von wassergeführten Flächentemperiersystemen. Im südeuropäischen Sommerklima kann eine aktive Kühlung über Luft die hohen und schnell fluktuierenden Kühllasten effizient abführen. Energy efficient cooling and ventilation concepts for thermal interior comfort: Simulation-based evaluation of cooling concepts in different European climate zones (Part 2). Under the framework of the European Program Intelligent Energy for Europe (IEE), the project ThermCo evaluates low-energy ventilation and cooling concepts for non-residential buildings all-over Europe using a standardized method based on existing monitoring data from best practice examples (part 1, in Bauphysik 6/2012). A simulation study investigates the potential of different ventilation and cooling strategies with regard to energy efficiency and thermal comfort in different European climates. The results demonstrate a high potential for night ventilation strategies in North-European climate with low ambient air temperatures. In the Mid-European climate, water based low-energy cooling technologies based on radiant cooling make use of the cool ground in summer. Active cooling provides good thermal comfort in South-European climate with high and fluctuating cooling loads. [ABSTRACT FROM AUTHOR]

Unter dem europäischen Programm Intelligent Energy for Europe (IEE) fanden sich acht europäische Partner zusammen, um im Rahmen des Projektes ThermCo Lüftungs- und Kühlenergiekonzepte für Nichtwohngebäude mit niedrigem Energieeinsatz im Hinblick auf die Energieeffizienz und den thermischen Raumkomfort zu bewerten. Die Analyse erfolgte auf Basis von detaillierten Langzeitmessungen über ein Betriebsjahr in acht Demonstrationsgebäuden in unterschiedlichen klimatischen Zonen Europas und einer standardisierten Datenauswertung. Im Quervergleich aller acht Gebäude werden die Kühlkonzepte gleichermaßen nach dem thermischen Kühlenergiebezug, dem thermischen Raumkomfort und dem Primärenergieeinsatz für die technische Gebäudeausrüstung und die Beleuchtung bewertet. Ein Energiekonzept ist erst dann zufriedenstellend, wenn mit möglichst geringem Energieeinsatz und bei hoher Anlageneffizienz ein guter thermischer Raumkomfort zur Verfügung gestellt werden kann. Mit entsprechenden Gebäudesignaturen werden diese Parameter in einen Zusammenhang gebracht und die Zielstellung überprüft. Detaillierte Komfortuntersuchungen nach der europäischen Komfortnorm DIN EN 15251:2007-08 geben Hinweise auf die Wirksamkeit der eingesetzten Kühltechnologien in den jeweiligen Klimazonen. Daraus lassen sich Handlungsempfehlungen ableiten. Energy efficient cooling and thermal interior comfort: comparison of eight European non-residential buildings. Under the framework of the European Program Intelligent Energy for Europe (IEE), the project ThermCo evaluates low-energy ventilation and cooling concepts for non-residential buildings all-over Europe using a standardized method based on existing monitoring data from best practice examples. The proposed approach is applied to eight demonstration projects in different climatic zones of Europe. The analysis is based on long-term monitoring campaigns in high-time resolution over one year of operation. In cross-comparison of all eight buildings, the cooling concepts are evaluated according to the thermal cooling energy consumption, the thermal interior comfort, and the building's total primary energy use for heating, cooling, ventilation, and lighting. [ABSTRACT FROM AUTHOR]

Abstract: A sustainable and environmentally responsible building concept aims at a high workplace comfort, a significantly reduced heating and cooling demand, a high-efficient plant system, and the use of renewable energy sources to condition the built environment. This paper presents a comprehensive analysis of the heating and cooling concepts of 11 low-energy buildings in terms of energy use, efficiency and occupant thermal comfort. All buildings investigated employ environmental energy sources and sinks – such as the ground, ground water, rainwater and the ambient air – in combination with thermo-active building systems. A limited primary energy use of about 100kWhprim/(m2 neta) as a target for the complete building service technology (HVAC and lighting) was postulated for all buildings presented. With respect to this premise, a comprehensive long-term monitoring in high time resolution was carried out for two to five years, with an accompanying commissioning of the building performance. Measurements include the useful heating and cooling energy use, auxiliary energy use for the hydraulic system, as well as end and primary energy use, occupant thermal comfort and local meteorological conditions. A new methodology is proposed for a holistic approach to the evaluation of heating and cooling concepts, which not only considers the occupants thermal comfort, but also the useful energy consumption and the efficiency of the generation, distribution and delivery of heating and cooling energy. [Copyright &y& Elsevier]

The increasing installation numbers of ventilation units in residential buildings are driven by legal objectives to improve their energy efficiency. The dimensioning of a ventilation system for nearly zero energy buildings is usually based on the air flow rate desired by the clients or requested by technical regulations. However, this does not necessarily lead to a system actually able to renew the air volume of the living space effectively. In recent years decentralised systems with an alternating operation mode and fairly good energy efficiencies entered the market and following question was raised: "Does this operation mode allow an efficient air renewal?" This question can be answered experimentally by performing a tracer gas analysis. In the presented study, a total of 15 preliminary tests are carried out in a climatic chamber representing a single room equipped with two push-pull devices. The tests include summer, winter and isothermal supply air conditions since this parameter variation is missing till now for push-pull devices. Further investigations are dedicated to the effect of thermal convection due to human heat dissipation on the room air flow. In dependence on these boundary conditions, the determined air exchange efficiency varies, lagging behind the expected range 0.5 < ε a < 1 in almost all cases, indicating insufficient air exchange including short-circuiting. Local air exchange values suggest inhomogeneous air renewal depending on the distance to the indoor apertures as well as the temperature gradients between in- and outdoor. The tested measurement set-up is applicable for field measurements. [ABSTRACT FROM AUTHOR]