A dynamic evaluation of glazing thermal performance.

摘要

Glazing systems are an influencing component of building thermal performance. Conventional steady-state methods are unsatisfactory for an accurate dynamic thermal evaluation of glazing systems. This thesis provides a theoretical and experimental basis of a new dynamic thermal simulation, which provides insight towards improved glazing system engineering, design and thermal evaluation.; A new solar calorimeter was designed and constructed to achieve testing under indoor and outdoor dynamic conditions. This calorimeter design abandons conventional fluid based methods and employs thermo-electrics as the measuring system. Thermoelectric modules are attached to a solar collector plate which is located behind the test glazing. Heating or cooling is provided to the collector plate as soon as a transition from setpoint conditions is detected. The result is an extremely responsive calorimetric device with an isothermal surface.; A comprehensive computer simulation provides results of complete daily performance. A glazing library defines glass element data of a glazing unit which is assigned a tilt and orientation. Weather data files, for any desired time interval, are applied. An anisotropic diffuse sky radiance algorithm together with a geometric division of the sky vault produces multi-directional diffuse solar radiation component. Total transmitted and absorbed solar energy is calculated based on angle of incidence of the direct and each diffuse component. The thermal simulation uses these transmitted and absorbed solar quantities together with wind speed and outdoor air temperature.; A simplified lumped heat transfer analysis provides a time-dependent computation, yielding extremely accurate results when compared with measurements. This new thermal simulation is an unsteady-state finite difference approach to computing temperature and heat transfer for a glazing unit. Conventional heat transfer and energy balance equations are applied together with a lumped estimate of the stored energy within each glass element providing an accurate analysis.