hybrid ventilation

The objective of this paper is to assess methods of thermal comfort for use in mixed-mode office buildings located in hot-humid summer climate based on air-conditioning consumption of a predominant typology of real mixed-mode office buildings. Three methods to assess thermal comfort were analysed: (1) Givoni’s chart for hot and humid climates, (2) ASHRAE 55-2010 for determining acceptable thermal conditions in occupied spaces, (3) ASHRAE 55-2010 for determining acceptable thermal conditions in naturally ventilated spaces.

An existing computer model for dynamic hygrothermal analysis of buildings has been extended with a multizone airflow model based on loop equations to account for the coupled thermal and airflow in natural and hybrid ventilated buildings. In water distribution network and related fields loop equations have been widely used to resolve the flow of water and other fluids. In the field of natural ventilation the loop equation method have rarely been used in spite of its quality.

Natural ventilation is generally accepted as the preferred ventilation option as it is a healthy and energy-efficient means of supplying fresh air to a building. In the USA it is seldom being applied as most climate zones are considered unsuited to apply natural ventilation, mostly due to perceived uncontrollability and very humid and hot or very cold seasons. For mid and high rise apartment buildings the option of natural ventilation is virtually disregarded because the tradition of full air conditioning is so well established.

The energy consumption needed for establishing a good indoor climate in shopping centres is often very high due to high internal heat loads from lighting and equipment and from a high people density at certain time intervals. This heat surplus result in a need for cooling during most of the year, typically also during the winter, and often the needed cooling is provided by a mechanical ventilation system with integrated mechanical cooling.

Hybrid ventilation (HV), as a combination of automated natural ventilation (NV) and balanced mechanical ventilation (MV), provides opportunities to use the advantages of both ventilation systems during the seasons in order to reduce energy demand and at the same time obtain comfortable indoor climate.

BR10 requires that all new residential constructions should be built as low energy housing. In order to meet these requirements residential buildings must be equipped with far more complex technology, than conventional housing. This, for example, could be a combination of mechanical balanced ventilation, natural ventilation, heat pumps, solar heating, solar cells or automatic sunscreens.

This study proposes the hybrid ventilation system and its design methods for high-rise buildings. The proposed hybrid ventilation system uses natural driving power for ventilation based on air flow in the whole building and indoor and outdoor pressure distributions. Furthermore, it solves the troubles of the conventional natural or mechanical ventilation systems. This paper presents theories and a process for duct design for natural ventilation which forms the basis of a hybrid ventilation system in high-rise buildings.

Hybrid ventilation represents an interesting option both to guarantee good air quality for indoor environments and to reduce the energy consumption related to the mechanical motivation of the air.

Hybrid ventilation systems combine the superior properties of natural and mechanical ventilation systems to reduce energy consumption. In this study, hybrid ventilation simulations were performed for several cities in Turkey, which have different climate conditions. Matlab/Simulink was utilized to perform the simulations. The results of these simulations were compared with that of regular air conditioning units in terms of energy consumption.

Until the end of 90-ties all dwelling buildings in Latvia were equipped with mandatory natural ventilationsystems with stack effect. Nowadays in many cases in dwellings there are only exhaust mechanicalventilation but air tight windows prevent natural air intake. Such systems result in bad IAQ.