Title:
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Precision daylight and thermal modelling of shading devices
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The focus of this thesis is the performance modelling of shading devices with regard to
daylight illumination and thermal effect in non-domestic buildings - offices, classrooms based
on real time-varying conditions. The research is centred in quantifying the impact of
external shading devices on energy demand for electric lighting, heating and cooling. The
Unix-based Radiance lighting simulation program as the engine, and a nodal thermal
model processing irradiation inputs, have been used. An adaptation of suitable calculation
approaches and the development of custom-written data analysis programs have been
also performed on this behalf.
The thesis begins with a literature. review of current practice in modelling buildings
particularly examining the daylight and thermal modelling approaches used. Daylight
assessment tools and shading systems are also looked at.
A formulation of a novel hybrid dynamic lighting thermal model using the daylight
coefficient approach and Radiance, combined with a simple thermal model has been
developed. A range of external shading devices are reviewed and computer models
developed in order to simulate their lighting and thermal performance. These models use,
as input, real time-varying meteorological data and hence predict the internal illuminance
distribution and incoming irradiation through the window-shading device system.
Automated models obtaining heating and cooling loads from possible scenarios where
thermal loads are linked to daylight-linked electric controls are used. The validity of the use
of these modelling programs in combination is compared against an existing validated
computer model.
The results of energy consumption for electric lighting, heating and cooling are organized
and presented to easily compare and rate the performance of different shading options,
facade orientation and climates. The results show a significant influence of shading device
design upon some visual environment comfort parameters as well as upon energy
consumption for electric lighting. As regards of thermal loads, it is shown that the influence
of shading can be considerable if coupled with control switching strategies.
It is expected that this study and the methodologies proposed should be useful to
architects, building designers and developers, particularly those requiring research based
on precise modelling techniques or parametric studies. It may also be of use to developers
of such as shading devices, since it can assist them in their research on improving the
characteristics of their products.
Abstract
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