The computer disk

Abstract

This Atlas is supported by two sets of data on computer disk. One set of data are the horizontal data for the 340 sites, for which horizontal surface tables have been prepared. Each site has a separate ASCII file. The other sets of data are the inclined surface data for the sites for which inclined surface irradiation values have been calculated. There are two inclined surface files for each site, one computed for clear days, the other for monthly mean conditions. The horizontal data file structure used is described in Appendix 6 and the inclined surface data file structure in Appendix 7. Certain calculation methodologies suitable for use with this data in conjunction with spreadsheets are given in Appendices 4 and 5. Appendix 4 is dedicated to discussion of how hourly values of irradiance on horizontal surfaces can be easily estimated from the daily data on the disk and in the tables. This Appendix also considers the issues of the effects of site obstruction on the direct beam availability on horizontal surfaces. Appendix 5 explains how to convert the hourly irradiance values derived from Appendix 4 into daylight illuminance values on horizontal surfaces using the concept of luminous efficacy to convert from irradiance to illuminance. This approach is designed to provide support for daylighting studies in the European region. A European Daylight Atlas initiated by the European Commission is currently in the process of production. Appendix 5 thus interrelates the two projects through the radiation data base. A list of one or two interlinking computer programmes that can be harnessed to the data on the disk is given at the end of the list of references. The horizontal files are designed to read direct to screen in the format in which they appear in the printed tables. The inclined surface files are not formatted. It is envisaged that many users will find it valuable to be able to access the data to spreadsheets, graph plotting routines and word processing, so an open ASCII easily readable linear data format has been selected for the inclined surface files. The data stored in linear form includes important horizontal surface data.