zonal model

This study introduces a novel conceptual design of a mobile DV cooling unit that is aimed to support the ventilation and reinforce the thermal stratification in DV rooms. Supplying filtered chilled air from at low height, the portable DV unit (PDV unit) functions as if it is a typical DV diffuser. Moreover, the PDV unit employs heat exhausted from the heat pump to reinforce the temperature gradient by injecting the hot air flow in the upper zone of the room. Utilizing the exhaust air makes the PDV unit entirely ductless which adds to its flexibility placed in to balance the airflow.

The impinging jet ventilation (IJV) system has been proposed as a new air distribution strategy and is expected to overcome the disadvantages of the mixing ventilation system (MV), which is the most widely used system, and displacement ventilation, which provides better air quality than MV.  

Very often the set point temperature is selected to satisfy comfort requirements and/or to save energy consumption in buildings. However, the thermostat location is usually outside the occupied space and located on the wall near a front door or in a hallway that is subject to warm and cold draughts. A discrepancy exists between the temperature at the thermostat location and the occupied zones.

Since 2007, more than half of world population lives in urban areas and its activity leads to an increase of building energy demand notably in summer. The temperature rise of densely built areas is mainly due to landscaping and anthropogenic heat fluxes such as air conditioning systems. Acting on urban landscaping, building density, surface albedo or green area can mitigate the urban heat island with direct and indirect improvement of building energy performances.  

The purpose of this study is to figure out the characteristics of thermal environment in a workshop at school in Japan and to propose the improvement method of the thermal environment without air-conditioning systems. In this paper, measurement results of thermal environment in the workshop and calculation results of vertical temperature gradient are shown. In the measurement results, indoor air temperature became very high in summer. Solar radiation was the main factor raising the temperature of PC roof, and large vertical temperature gradient was formed.

Recently, the hybrid air-conditioning system that used natural ventilation together with a mechanical air-conditioning was proposed. Hybrid air conditioning system is expected to be saving energy and maintain keep indoor thermal environment comfort.

Modelling thermal and aerial behaviour of unconditioned buildings requires an accurate knowledge of the air temperature and velocities fields inside the considered spaces. Furthermore, in ourMediterranean context, thermal and aerial aspects must be considered coupled together, because oftheir very strong interdependence. We have then developed a three-dimensional dynamic modularmodel of coupled heat transfer and airflow calculation.

The effect on ventilation effectiveness parameters of the recirculation of air is investigated. The results of work with respect to air change effectiveness parameters is explained and extended to the effect of recirculation on the contaminant removal effectiveness parameter of local air quality index. It is demonstrated, first with respect to a simple system with one supply and exhaust and then by extension to a system with multiple exhausts, that it is possible to calculate the effect of recirculation by means of a simple algebraic expression.

Highly-glazed spaces are attractive in many ways (solar heating, aesthetics, etc.), however, their thermal behaviour remains difficult to predict. In such spaces, the assumptions or methods generally used in building thermal simulation tools - e.g. homogeneous air temperature in the room, simplified calculations of radiative heat transfer between walls, absence of airflow modelling within the room - do not seem appropriate. We have developed a new model (AIRGLAZE) to improve the prediction of the thermal behaviour of large highly glazed spaces.

The light well located in the center of high-rise apartment building in Japan is called "Void". Gas water-heaters settled in Void discharge the exhaust gas into Void so that the enough opening area has to be designed at the bottom of Void to keep the IAQ in Void. In order to secure the IAQ in Void, a simple zonal model to calculate the ventilation rate induced by the wind force and the thermal buoyancy through openings at the bottom of Void with heat sources like water heaters is presented. And the accuracy of this calculation method is examined by wind tunnel test.