hybrid ventilation

The aim of this study is to clarify the effects of indoor environmental characteristics of hybrid - natural and mechanical - air conditioning systems in office buildings during intermediate seasons. The other objective was to obtain design data.

In this paper a method to solve a design problem of hybrid ventilation system is proposedby building stack pressure around the ventilator using a flat bed, glass-shielded rectangular solarchannel. In support of this idea a CFD (Computational Fluid Dynamics) simulation based ontheoretical calculation is done. Here, natural convection and a k-e two-equation turbulence modelwere used together with the finite volume method.

The IAQ characteristics and the corresponding health symptoms and thermal sensation of the occupants of child care centers in Singapore under 3 different ventilation strategies are reported. The 3 child care centers studied were centrally air-conditioned and mechanically (ACMV) ventilated (Case A), naturally ventilated (Case B) and hybrid (natural and air-conditioning) ventilated (Case C).

This paper describes a study on the performance evaluation of a hybrid ventilation systemwith a heat exchanger. This system has two passive stacks and a heat exchange unit, which includes a heat exchange element, a supply fan, an exhaust fan and a bypass route with a damper. In order to evaluate the system performance, the experiments and numerical simulations using a full-scale test house have been performed in winter or mild seasons. In the result, the ventilation rate and the heat recovery rate under the various conditions of the fan and the damper operation were clear.

In order to clarify whether a combination of designs is optimal, design elements are divided intodesign variables and random variables in the inquiry process for the optimal design. Design variablesrelated to the model are selected by a genetic algorithm, and random variables related to outdoor condition are selected by the moment method. The whole process of optimization consisted of a two-step procedure to reduce the calculation loads for finding the optimal solution. This study carried out a simple analysis using a coarse mesh considering the calculation loads in the first step.

This paper discusses the concept and performance of a naturally ventilated building with a double-skin facade in Tokyo. The building incorporates a hybrid ventilation system (natural ventilation integrated with air-conditioning systems) that makes use of buoyancy forces generated in a vertical airshaft in the center of the building. Field measurements were made in order to evaluate the performance of the double-skin facade during the summer and winter and also the performance of the hybrid ventilation system during the spring and autumn.

In this paper, characteristics of the indoor environment utilizing hybrid ventilation system andtask-ambient air-conditioning system are investigated every hour in a year in various types of office spaces by means of dynamic cooling and heating load analysis and CFD (Computational Fluid Dynamics) simulation.Authors had investigated the characteristics of the indoor environment of a hybrid ventilation system, utilizing natural and mechanical ventilation, with CFD simulation under various conditions of incoming outdoor air [1].

Hybrid ventilation is one promising approach to reduce energy consumption in office buildings. On the one hand, a minimum air change rate is supplied to the rooms, even if the windows are closed. On the other hand, the energy demand for ventilation can be reduced if natural forces (wind and buoyancy driven air flow) are used to ventilate the building. The user behaviour has an important but often unknown influence on the thermal building performance and the indoor climate. Thus, an accurate user model should be used in designing hybrid ventilation.

The aim of the project is to study, develop, build (prototype system) and evaluate an energy efficient demand controlled hybrid ventilation system for dwellings in a cold climate. Hybrid ventilation in a cold climate means a ventilation system with low pressure drops, which result in a minimisation of the mechanical energy for ventilation, and that natural driving forces can play an important role.

Approximatly over 90 percent of buildings in Poland are ventilated in a natural manner. Thescale of problems in the functioning of ventilation in our opinion is serious.In about 3 million apartments inhabitants use gas water heaters, burning fuel in an openchamber. Therefore in these types of apartments the use of mechanical exhaust ventilation isforbidden.Experiences in using mechanical ventilation is not always positive (frequent complaints aboutthe excessive noise of the installation and the high consumption of energy by the fans).