Modelling Heat Transfer inside a Full Conservatory Installation
Finite Element Analysis
During summer months conservatories can become uncomfortably hot if the Solar Heat Gain (SHG) is high. In contrast, during winter months, window assemblies with high SHG and low U-values are preferred since this combination helps maintain warm internal temperatures (thereby reducing levels of energy consumption). Furthermore, during summer months the levels of light transmittance through conservatory glazing should be optimised so that levels of glare are low, yet the most effective methods for minimising glare (tints and films) are known to adversely affect the levels of light transmittance during winter. To reconcile these competing requirements, manufacturers have adopted increasingly sophisticated coatings (often sputtered) that are low-e and/or spectrally-selective and/or tinted, but this massively expands the range of possible glazing/coating combinations that may or may not be beneficial for year-round comfort levels inside conservatories. In these instances it is far more cost-effective (and much more illuminating) to use simulation tools to predict how changes in glazing type are likely to affect internal air temperatures all year round.
In this instance our client instructed us to build a comprehensive heat transfer finite element model of one of their conservatory installations. The door and window assemblies are double-glazed, with gas (either Air or Argon) between the panes. The model employs the surface-to-surface radiation physics interface available in COMSOL Multiphysics, and the Solar Position external radiation source. Wavelength-dependent surface properties have been specified for each of the pane surfaces (and in fact for all exposed surfaces). Heat transfer via convection of air within the conservatory was modelled using a heat transfer in fluids interface and a Nusselt number.
Alterations to the window pane glazing options (and their effects on internal air temperatures) were studied, thereby allowing our client to rapidly converge on the most suitable glazing options for their conservatory installations.