In response to an increased awareness of the impact of building related energy consumption on emissions of carbon dioxide, attention has turned to the task of making buildings more energy efficient. Although this is a key element in the design of a new building, it is important also that the occupants' expectations of a comfortable and healthy environment are met. Computer simulations of the airflow and thermal environment within a naturally ventilated building have been made using a finite volume CFD model.
When buoyancy forces, wind forces and envelope heat losses interact in a naturally ventilated building, the behaviour of the flow rate as a function of these parameters can be quite complex. This paper derives the equations for the flow rate in a two-zone building where one zone is above the other, and where each zone has a high and a low opening.
This paper attempts to answer questions like when thermal stratification is important and how to consider it in simple multi-zone models of natural ventilation. Both simple analytical solutions and comparison of CFO and multi-zone analysis suggest that the multi-zone modelling approaches with the assumption of uniform zonal air temperatures can significantly underestimate the neutral levels in buildings with large ventilation openings, indicating that the flow directions through some openings may not be correctly predicted.
In this study, a mixed mode building, namely the Portland Building at the University of Portsmouth is considered. It combines both Natural Ventilation and conventional Heating Ventilating and Air Conditioning systems to maintain the internal comfort. The paper presents the development of Sof1 Computing models to predict the internal temperature in one of the offices using information from neighbouring rooms, corridor and the outside. To derive this model, the so called Adaptive Neuro Fuzzy lnference System method is used.
During design phase, Liberty Tower of Meiji University, a high-rise building located at the center of Tokyo Metropolitan area, several testing methods were applied to ensure the effectiveness of the various components used in the principle of hybrid ventilation system design. Its special design feature is the "wind-floor'', whereby the central core is planned to induce natural ventilation for every floor by creating stack-effect.
Demand Based Ventilation systems are potentially valuable in terms of energy saving in building with fluctuating occupation patterns. Most demand based ventilation systems are controlled by C02 measurement. However this approach cannot take account of other polluting elements found in indoor air. This paper will describe the results of a study of the indoor air quality in a recently built university library with continuous ventilation. The literature relating to typical levels of naturally occurring gases, volatile organic compounds and microbes, in indoor air is considered.
Current thermal comfort standards and the models underpinning them purport to be equally applicable across all types of buildings, ventilation systems, occupancy patterns, and climate zones. A recent ASHRAE-sponsored research project (RP-884) critically evaluated this by statistically analysing a large thermal comfort field research database from 160 buildings scattered all over the would (n=22,000).
To develop guidance on effective ventilation strategies for buildings located in urban areas, it is necessary to have an understanding of the processes involved in the ingress of external pollution into buildings and its effect on indoor air quality. For naturally ventilated buildings, the combination of pressure forces and contaminant levels around the building is important in generating the level of internal contamination.
This paper describes the development of a model which can be used to explore the technical feasibility and policy implications of attempting to achieve 60 - 90% reductions in the C02 emissions from the UK housing stock by the middle of the next century. Reductions of this order are likely to be required across the industrialised countries in order to stabilise the atmospheric C02 concentration and global climate. In order to be able to investigate this problem, a highly disaggregated physically based energy and carbon dioxide model of the UK housing stock has been developed.
The conversion efficiency of solar cells is dependent on the cell temperature and they perform better the colder the cells are. The paper discusses cooling of solar cells by providing solar cell modules with an air gap behind the modules. The stack effect in the air gap drives the ventilation flow in a hybrid ventilation system. Expressions for the bulk flow properties (volumetric flow rate, mass flow rate and temperature) are presented as a function of the geometry of the air gap and the location of the heat input (configuration factor).
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