Building energy-consumption status worldwide and the state-of-the-art technologies for zero-energy buildings during the past decade

Energy demand has been increasing worldwide and the building sector represents a large percentage of global energy consumption. Therefore, promoting energy efficiency in buildings is essential. Among all building services, Heating, Ventilation and Air Conditioning (HVAC) systems are significantly responsible for building energy use. In HVAC, ventilation is the key issue for providing suitable Indoor Air Quality (IAQ), while it is also responsible for energy consumption in buildings. Thus, improving ventilation systems plays an important role not only in fostering energy efficiency in buildings, but also in providing better indoor climate for the occupants and decreasing the possibility of health issues in consequence. In the last decades, many energy-efficient ventilation methods are developed by researchers to mitigate energy consumption in buildings. This paper reviews scientific research and reports, as well as building regulations and standards, which evaluated, investigated and reported the development of energy-efficient methods for ventilation in buildings. Besides energy-efficient methods such as natural and hybrid ventilation strategies, occupants’ behaviours regarding ventilation, can also affect the energy demand in buildings. Therefore, the influence of occupants’ behaviour on the energy use and the correlation between ventilation and the occupants’ health and productivity were also considered. The review showed that ventilation is interrelated with many factors such as indoor and outdoor conditions, building characteristics, building application as well as users’ behaviour. Thus, it is concluded that many factors must be taken into account for designing energy-efficient and healthy ventilation systems. Moreover, it should be mentioned that utilizing hybrid ventilation in buildings integrated with suitable control strategies, to adjust between mechanical and natural ventilation, leads to considerable energy savings while an appropriate IAQ is maintained.

Towards sustainable, energy-efficient and healthy ventilation strategies in buildings: A review

Personalized human comfort in indoor building environments under diverse conditioning modes

This paper identifies the parameters affecting the thermal and energy performance of buildings with double skin facades (DSFs). It reviews the state of the art of current body of literature about the application of DSF technologies in order to provide guidelines to optimise such designs in naturally ventilated buildings. Three groups of parameters are identified as having significant impact on the DSF performance: the ‘facade’ parameters, which comprise the features of the cavity and the external layer of the facade; the ‘building’ parameters, which are those related to the physical configurations of the building; and the ‘site’ parameters, which are related to the effects of the outdoor environmental conditions on the building and the DSF behaviours. For each group of parameters, a comprehensive table is compiled summarizing the main findings of the studies that directly and indirectly contribute to the understanding and implementation of such technology. Guidelines established for the design of naturally ventilated buildings indicated potential application of DSF for improving the indoor thermal comfort even in warmer regions. However, further investigations expanding the analysis beyond the cavity are needed in order to evaluate the influence of the DSF on the thermal comfort in the user space.

Perspectives of double skin façades for naturally ventilated buildings: A review

Buildings contribute to climate change by consuming a considerable amount of energy to provide thermal comfort for occupants. Cooling energy demands are expected to increase substantially in the world. On this basis, technologies and techniques providing high energy efficiency in buildings such as passive cooling are highly appreciated. Passive cooling by means of phase change materials (PCM) offers high potential to decrease the cooling energy demand and to improve the indoor comfort condition. However, in order to be appropriately characterized and implemented into the building envelope, the PCM use should be numerically analyzed. Whole-building energy simulation tools can enhance the capability of the engineers and designers to analyze the thermal behavior of PCM-enhanced buildings. In this paper, an extensive review has been made, with regard to whole-building energy simulation for passive cooling, addressing the possibilities of applying different PCM-enhanced components into the building envelope and also the feasibility of PCM passive cooling system under different climate conditions. The application of PCM has not always been as energy beneficial as expected, and actually its effectiveness is highly dependent on the climatic condition, on the PCM melting temperature and on the occupants behavior. Therefore, energy simulation of passive PCM systems is found to be a single-objective or multi-objective optimization problem which requires appropriate mathematical models for energy and comfort assessment which should be further investigated. Moreover, further research is required to analyze the influence of natural night ventilation on the cooling performance of PCM.

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Passive cooling of buildings with phase change materials using whole-building energy simulation tools: A review

Controlled natural ventilation for energy efficient buildings

Performance assessment of controlled natural ventilation for air quality control and passive cooling in existing and new office type buildings

Experimental Validation of Basic Natural Ventilation Air Flow Calculations for different Flow Path and Window Configurations

Bei zunehmend dichteren Gebaudehullen energieeffizienter Gebaude werden Luftungskonzepte immer wichtiger, um eine gute Raumluftqualitat zu garantieren und Feuchteschaden sicher zu vermeiden. Im Wohnungsbau stellt DIN 1946-6 Anforderungen zur Erstellung von Luftungskonzepten erstmalig auch fur den Feuchteschutz, die durch ventilatorgestutzte oder freie Luftung mit Ausendurchlassen erfullt werden. Eine entscheidende Voraussetzung fur die Luftungskonzepte ist dabei, dass diese nutzerunabhangig funktionieren mussen. Fur Nichtwohngebaude werden in DIN EN 13779 Anforderungen an Luftungsanlagen bezuglich des Luftvolumenstroms fur ein gesundheitlich unbedenkliches Innenklima vorgegeben. Daruber hinaus enthalt DIN EN 15251 Kriterien fur das thermische Innenraumklima von naturlich belufteten Gebauden.



Die kontrollierte naturliche Luftung durch ansteuerbare Fensterelemente ermoglicht eine konsequente Einhaltung von Raumluftqualitat und Feuchte, bietet daruber hinaus aus Energie- und Komfortgrunden ein hochinteressantes Potential fur die sommerliche Luftung und Gebaudekuhlung ohne Energieeinsatz. Bei der Projektierung und Auslegung der Beluftung von Gebauden werden derzeit die Moglichkeiten der kontrollierten naturlichen Luftung uber automatisch gesteuerte Fenster jedoch kaum genutzt, da die Berechnungen von Luftmengen aufgrund standig wechselnder Randbedingungen komplex und bisher unzureichend in Standards vereinfacht festgelegt sind.



In der vorliegenden Untersuchung wurden Rechenverfahren analysiert, welche die Planung luftungstechnischer Masnahmen durch kontrollierte naturliche Luftung unterstutzen und eventuell Eingang in die derzeitige Normung finden konnen. Durch Erstellung eines belastbaren Nachweises hinsichtlich der Funktionalitat der naturlichen Luftung (zur Anhebung der Raumlufthygiene sowie des Feuchteschutzes) wird Planern und Bauherren der Einsatz naturlicher Luftung erleichtert.



Method for simplified calculation of controlled natural ventilation. As the building envelopes of energy efficient buildings are becoming increasingly air-tight, ventilation concepts are increasing in importance in order to ensure good quality room air and reliably prevent dampness. DIN 1946-6 contains requirements for producing ventilation concepts in housing – for the first time also in order to prevent dampness – which are satisfied by fan-assisted or free ventilation through external openings. An important prerequisite for these ventilation concepts is that they have to be functionally independent of user interaction. For buildings other than housing, DIN EN 13779 contains requirements for ventilation systems regarding the volume of air flow in order to achieve a healthy indoor climate. Furthermore, DIN EN 15251 contains criteria for the thermal interior climate of naturally ventilated buildings.



Controlled natural ventilation through controllable window elements makes it possible to maintain adequate room air quality and humidity; in addition, this type of ventilation is interesting from the point of view of saving energy and increasing comfort levels as part of summer ventilation, and building cooling without energy consumption. However, the possibilities of controlled natural ventilation via automatically controlled windows are currently rarely explored in the design of ventilation systems for buildings, because the calculation of air quantity is complex due to continually changing boundary conditions, and simplified methods have not yet been adequately defined in the standards.



This study covers the analysis of calculation methods which support the design of ventilation systems based on controlled natural ventilation and which could be adopted in the current standards. By producing robust proof with respect to the functionality of the chosen natural ventilation (in order to improve room air hygiene and prevent dampness), designers and building owners will find it easier to use natural ventilation.

Tobias Schulze

Papers

Controlled natural ventilation for energy efficient buildings

Performance assessment of controlled natural ventilation for air quality control and passive cooling in existing and new office type buildings

Experimental Validation of Basic Natural Ventilation Air Flow Calculations for different Flow Path and Window Configurations

Methodik zur vereinfachten Berechnung kontrollierter natürlicher Lüftung