John Mardaljevic
De Montfort University
PDF Presentation (4.1 Mbytes)
PDF of Chapter 1 from Rendering
with Radiance (436 Kbytes)
John Mardaljevic
De Montfort University
PDF Presentation (2.2 Mbytes)
PDF of Chapter 6 from Rendering
with Radiance (588 Kbytes)
John Mardaljevic
De Montfort University
PDF Presentation (2.8 Mbytes)
PDF of “A Gold Standard Dataset for
the Validation of Illuminance Predictions” (1 Mbyte)
John Mardaljevic
De Montfort University
The evaluation of shading devices is generally carried out using a sequence of shadow pattern images showing the progression of solar penetration for particular times of the day or year. This approach can reveal when solar penetration may occur, say at the summer solstice, but it cannot give a quantitative measure of the degree and likelihood of solar penetration over a representative period of a full year. This paper describes a new image-based technique to quantify the effectiveness of shading devices. It is founded on predictions of direct solar irradiation using hourly meteorological data for a full year. In addition to numerical output, the technique produces synoptic images that reveal the spatial and temporal variation of solar irradiation. There are no practical limits on the scene geometry and buildings with thousands of individual shading elements can be evaluated. The technique is designed to be both fast and highly scalable making it suitable for the evaluation of a large number of design variants. This is demonstrated in the paper using a parametrically defined model of a complex roof shading system based on the Changi airport design. The three thousand six hundred fins that comprise the roof shading system were generated using a parametric scheme where the fin orientation has a random component. A total of forty-two design variants of the roof shading system were evaluated using the new technique.
PDF Presentation (1.7 Mbytes)
John Mardaljevic
De Montfort University
Scale model illuminance measurements in sky simulator domes are inherently subject to parallax errors. The magnitude of these errors under a number of CIE clear sky configurations is quantified using computer simulation techniques. In practical operation of a sky simulator dome, a second parallax error in the normalization measurements for horizontal illuminance is likely to compound the parallax error in the other illuminance measurements. This additional parallax error is accounted for in the simulations. The concept of a parallax-bounded volume is introduced. This is the volume of the dome which, on the basis of parallax alone, must contain a scale model if it is not to be subject to errors in the measurement of illuminance beyond a given tolerance. The findings indicate that, on the basis of a credible design goal for the sky simulator dome, high accuracy illuminance predictions (+-10%) are practically unattainable.
PDF Presentation (3 Mbytes)