Classification of hybrid ventilation concepts.

This paper aims to identify major characteristics of hybrid ventilation systems, whereby a clear distinction is made between ventilation for Indoor air quality control and ventilation as part of a strategy for thermal comfort in summer. Various building projects are used as illustration for the classification.

Hybvent Forum '99 Proceedings.

Ventilated solar roof air flow and heat transfer investigation.

The governing parameters for flows generated by heat transfer from solar cell modules to air gaps are discussed. Experimental results are presented from measurements in mock-ups of ventilated facades and roofs. The heat transmitted from the solar cells to the air have been mimicked by the use of heating foils. The inclination angle of the roof, position of solar cell module and the height to width ratio (aspect ratio) have been varied. The bulk properties as the air flow rate in the air gap, local temperatures and velocities have been measured.

Hybrid ventilation and daylighting in a Norwegian school building.

Several energy efficiency and renewable energy principles have been implemented in a recently refurbished and extended primary school building in Grong, Norway,. The building is located in the centre of Grong, a small town slightly north of Trondheim. The local authority's aim was to build an economical and modern school building with an attractive and healthy indoor environment and a minimal energy demand.

Hybrid ventilation in a hospital building.

The use of air solar collector realised on the north facade of a new hospital building in Rome is hereby described. The integration of solar and structural element has been studied during the design phase; the development of air gaps integrated within enclosures is related to the possibility to activate both natural (ejecting indoor air outside) and forced (preheating outside air incoming to the air handling units) ventilation. The energy gained by the solar elements has been evaluated.

Five Years of Laboratory and In Situ Test Experiences to Verify Thermal Comfort Conditions in an Innovative Hybrid Ventilated Building

Climatisation and natural ventilation concepts are today, in most countries, considered to be an essential aspect of the building project. In fact they are utilised to guarantee summer thermal comfort and indoor air quality control. Also there are many other advantages including low energy use, reduction of noise levels and easy plant maintenance. In recent years the use of hybrid ventilation systems in office buildings has been developed. The achievement of thermal comfort conditions in buildings is an important aim in order to satisfy occupants.

How to Predict the Air Exchange Efficiency for Hybrid Ventilation Systems

A hybrid ventilation system combines both mechanical and natural ventilation modes. The natural ventilation mode, especially, causes some challenges for analysis tools since the varying nature of naturally driven flow means that transient calculations should be used to predict the flow fields. Analysis tools based on CFD have some advantages for detailed investigations since, in addition to evaluating the flow and temperature fields, it is possible to use CFD methods to calculate air exchange efficiency and other flow indices.

Measurements of Hybrid Ventilation Performance in an Office Building

This paper focuses on hybrid ventilation performance in an office building. It presents measurement results from the new headquarters of the company Bang & Olufsen, which served as one of the case study buildings in IEA ECBCS Annex 35. Ventilation and control strategy, as well as operational experience of the hybrid ventilation system is presented. Measurement results include long-term values of temperatures, CO2 and energy use for assisting fans and heating of ventilation air as well as electricity use for appliances.

Room Air Distribution and Indoor Air Quality of Hybrid Air Conditioning System based on Natural and Mechanical Ventilation in an Office

The characteristics of a hybrid air-conditioning system, utilising natural and mechanical 'task' ventilation, are investigated in an office setting. The characteristics of the indoor environment are examined by means of CFD (Computational Fluid Dynamics) simulations under various conditions of incoming outdoor air. The control of the task air conditioning system (VAV system) is included in the calculation through changing the supply air volume to keep the task zones temperature at a target temperature.

Numerical Analysis of Hybrid Ventilation Performance Depending on Climate Characteristics

This study, which formed part of the Annex 35 Hybrid Ventilation in New and Retrofitted Office Buildings project, was completed at LEPTAB and supported by the French Research Ministry and the ADEME (Agence De lEnvironnement et de la Matrise de lEnergie). It consisted of modelling a typical classroom and comparing different control strategies to estimate the performance of a hybrid ventilation system for different climates.

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