The influence of heat conduction though the edge seal on the U-value of the total glazing area of TVG and HVG is dependent upon the glazing size
. For a larger size HVG and TVG, the scenario discussed previously could be different and further optimization for the HVG design and its application under various environments will be undertaken in the next stage of the work.
192 configurations to analyze were obtained by changing insulation level, the kind of glazings, the glazing size, the windows distribution and the climatic conditions (table 2).
Triple Glazings with low SHGC (L): [U.sub.gl] = 0.602 W/([m.sub.2] K)/0.106 Btu/(h [ft.sub.2] [degrees]F); SHGC = 0.343 Glazing Size 1.
An additional 20% daylight level increase due to reflected light reduces the required glazing size by 20% while electric lighting energy use remains the same as the case in which only direct light is considered.
Internal heat gain levels do not appear to change the recommended glazing size for optimizing energy saving in a toplighting design.
There is a higher change in cooling and heating loads for a smaller glazing because solar radiation and heat transfer through the toplighting system are less significant for a smaller glazing size and the change in lighting power density plays a more important role in balancing the loads.
The determination of the glazing size must be approached from a total energy point of view.
The level of internal heat gain due to equipment loads does not appear to change the optimal daylight factor (glazing size) for energy and cost-efficient toplighting design.