comparative measurements, an assessment could be made of increasing
the proportion of glazing within this wall.
(Note. Despite the accuracy of the model already described, the size of
window openings used in the model did not exactly match those
proposed for the building, as window mullions and other framing
elements had been omitted for simplicity of construction. Depreciation
factors were therefore applied to the measurements of the calculated
daylight factors in order to produce more realistic values. These
depreciation factors were based on an estimate of the relative areas of
the mullions etc. The incorporation of realistic glazing is also difficult
within a model and as such glazing is normally excluded; additional
depreciation factors based on the light transmission values of the
proposed glazing elements, are used to compensate for the reduced
light transmission. Other depreciation factors are used to allow for dirt on
the glass, the value of the factor depending upon the location of the
building and the proposed maintenance regime. CIBSE provided
appropriate values for these depreciation factors, based on experimental
studies.)
Once the daylight factor measurements had been corrected for
depreciation, the results were analysed and the average daylight factors
compared with the relevant guidelines.
Finally the artificial sky simulator at the Bartlett is provided with an
artificial sun that can be used for solar analysis, and this was used to
provide for some images of the solar penetration into the building when
subjected to sunny conditions at three-hour intervals for three periods of
the year... summer, winter solstice, and spring equinox, when the sun
reaches its highest, lowest, and mid elevations respectively.
58 Daylighting: Natural Light in Architecture
Sketch of the grid layout of the individual test
cells for a second-floor studioDP Archive