These results are expected from basic solar
design principles. Increasing the resistance
of windows to thermal loss (low-e glazing)
while admitting high solar gains reduces
heating energy consumption if the building
is well insulated and there is enough thermal
mass to store the solar gains and prevent
overheating. Obviously, the thermal
performance of windows cannot be
separated from solar gains, which relate to
form, orientation and solar transmittance.
Optimizing requires rigorous energy
modelling and project-specific analysis.