cooling

This paper reports on an experimental study dealing with the effects of an automatic shading device on the energetic performance of a dimmable lighting system and on a cooling system. Some equations related to fenestration thermal properties are reformulated under a theoretical approach. In order to collect field data, energy demands and other variables were measured at the "Test Tower" on two distinct floors with identical fenestration features. New data were gathered after adding an automatic shading device to the window of one of the floors.

Analysis of temperature trends for the last 100 years in several large U. S. cities has indicated that since -1940 there has been a steady increase in downtown temperatures of O. l-0.5°C per decade (-0.5°C for larger cities like Los Angeles and 0.1°C for smaller cities). Typically, electricity demand in cities increases by 2-4%/°C, hence, about 5-10% of the current urban electricity demand is spent to cool buildings just to compensate for the urban heat island effect. Downtown Los Angeles, for example, is now 3°C warmer than in 1940 leading to an increase in electricity demand of 1500 MW.

The air flow in a Passive Downdraught Evaporative Cooling (PDEC) tower has been modelled using a Computational Fluid Dynamics (CFD) code. Water is injected into dry warm air and the interaction between the water and the air is represented using a particle transport model. This models the transfer of mass, momentum and heat between the water particles and the air in addition to predicting individual particle trajectories.

This paper discusses summer cooling of buildings by means of natural ventilation. Computational fluid dynamics is used to predict the ventilation rate in a room with a Trombe wall. The effect of Trombe wall insulation on the room thermal environment is investigated. It is shown that to maximise the effect of ventilation cooling, the interior surface of a Trombe wall should be installed.

The year-round climate of Taiwan is warm and humid. Apart from the hottest months in summer, there are four months suitable for nocturnal ventilation to acquire indoor cooling. The urban Taiwanese apartments are small due to the limited usable land.

Temperature and cooling demand in a room summertime are influenced by numerous factors,like internal gains, ventilation, solar gain, behaviour of occupants, thermal inertia of the roomand outdoor conditions (climate).The thermal environment and cooling demand summertime are often analysed using detailedcomputer programs, which take into account the factors mentioned above (among others).Often the overview, transparency and some of the physical insight is lost using these advancedcomputer programs.In a predesign phase of a project it is preferable to do simple calculations of the thermalbeha

The paper outlines the value of roof intake air ducts to serve largely passively ventilatedand cooled buildings in urban areas. This approach improves air quality, reduces noisepollution and enhances security.A diagrammatic representation of night cooling using this approach is given followedby a description of experimental work at the Bartlett.

In the present paper a model for steady-state thermal analysis of ventilated and unventilated light rook is proposed. The aim of the work is tostudy the influence of thermo-physical and geometric parameters of the roof and boundary conditions (solar radiation) on the entering heat flowand the temperature distribution within the roof structure.

Evaporative cooling is an interesting alternative to conventional compressor refigerationsystems for air-conditioning. However, the use of evaporative cooling presupposes all-airsystems and is, to a large extent, limited by ambient conditions as well as the settled demandson the indoor climate. High outdoor humidity levels have a great influence on the supply-airtemperature achievable, i.e. cooling loads possible to meet. One way to reduce the influenceof these limitations is to use desiccant cooling, i.e. to dehumidify the ambient air before theevaporative stages.

We examine conditions under which the natural forces of wind and buoyancy may beharnessed in order to provide ventilation for cooling. Steady-state, displacement flows drivenby combined buoyancy and wind forces are simulated at small scale in the laboratory using aPerspex box to represent a generic room or single-spaced building. Density differencesnecessary to simulate the stack effect are produced using fresh and salt water solutions. Windflow is simulated by placing the box in a flume tank; the flume produces a flow of water pastthe box and this flow is used to represent the wind.