Development of an instrument for monitoring and data logging illuminance levels for interior daylighting applications

Smith, Kevin Charles (2015-03)

Thesis (MEng)--Stellenbosch University, 2015.

Thesis

ENGLISH ABSTRACT: Daylighting is fast emerging globally as a popular clean energy technology to compliment artificial electrical lighting. Unlike traditional artificial lighting, however, the variability of the sun due to geographical, geometrical and climatic variations presents a major challenge to engineers and architects involved in daylighting system design, particularly for critical tasks such as reading. This project evolved out of the need to be able to fully describe the performance of daylighting applications in order to aid and validate the design, improvement and installation of such systems. The primary focus of the project was to design, develop and test a system that is able to record and convey the variability of light, within an interior space, in terms of the spatial and time domains for the monitoring of daylighting applications, at a fraction of the cost of similar commercially available systems. Several potential sensors underwent stringent selection and testing procedures to determine which would meet the project requirements. The selected Sharp GA1A2S100LY sensing device proved to be the most suitable and was developed and included in a microcontroller based system to record illumination levels at multiple locations simultaneously. The sensor was selected and developed to match the spectral sensitivity of the human eye within the range of 0-1500 lux. The PIC18F8722 Explorer Demonstration Board manufactured by Microchip was selected to control all system operations. The board interfaces with each illuminance sensor and records the measured data, in text format in a .txt file on an SD card, in the PICtail daughter board SD card module. The system was able to record data from 64 sensors, simultaneously, at predefined time intervals and to store it for later processing. The data was then refined and used to generate easy to interpret visual representations of the illumination characteristics of the measured area as a function of time. The data is imported from the SD card text file to Microsoft Excel where a constant, predetermined, correction factor is applied to the data. A MATLAB program was developed to read the corrected data from the Excel spreadsheet and give an animated display of the progression of the illumination characteristics over the period for which the measurements were taken. Testing conducted with the system was done in an area supplied with daylight from two passive zenithal light pipes. The use of the system, under these conditions, proved effective with the system able to accurately convey the hourly, daily and seasonal variability of light within the measured area over a period of time.

AFRIKAANSE OPSOMMING: Dagbeligting ontwikkel teen 'n hoë pas wêreldwyd as 'n gewilde vorm van skoon energie tegnologie. Die doel van dagbeligting is om kunsmatige elektriese beligting aan te vul. In teenstelling met tradisionele kunsmatige beligting, bied die die son 'n verskeidenheid van groot uitdagings vir ingenieurs en argitekte betrokke in die ontwerp van 'n dagbeligting stelsel, veral vir take van kritieke belang insluitend die vermoë om te kan lees. Uitdagings sluit in: Geografiese-, geometriese-, asook klimaatstoestand veranderlikes. Hierdie projek het ontwikkel vanuit die behoefte om ten volle die werksverrigting van dagbeligting toepassings te kan beskryf om sodoende die ontwerp, bevordering en installering van dagbeligting stelsels te steun en te bevestig. Die hooffokus van die projek was om 'n stelsel te ontwerp, ontwikkel en te toets wat die vermoë het om die veranderlikheid van lig, binne 'n binneruimte, in terme van ruimtelike- en tydsdomeine op te neem en hierdie oor te dra vir die monitor van dagbeligting toepassings, teen 'n fraksie van die koste van 'n soortgelyke kommersieel beskikbare stelsel. Verskeie moontlike sensors het streng keuring- en toetsprosedures ondergaan om te bepaal watter sensors aan die projek vereistes sal voldoen. Die sensor wat gevind was as die mees toepaslike, bepaal deur die resultate verkry vanaf die keuring- en toetsprosedures, was die Sharp GA1A2S100LY sensor toestel. Hierdie toestel was ontwikkel en ingesluit in 'n mikroverwerker beheerstelsel om beligtingsvlakke by verskeie liggings terselfdertyd op te neem. Verder, was die sensor gekies en ontwikkel om die spektrale sensitiwiteit van die menslike oog te ewenaar, binne die reik van 0 – 1500 lux. Die PIC18F8722 Explore Demonstration Board vervaardig deur Microchip was gekies om alle stelsel bedrywighede te beheer. Die bord kommunikeer met elke illuminansievlaksensor en neem die gemete data op, in teks formaat in 'n .txt lêer wat dan op 'n SD kaart gestoor word, in die PICtail Daughter Board SD kaart module. Die stelsel kon data van 64 sensors, gelyktydig, opneem by voorafbepaalde tydsintervalle en dit dan stoor vir verdere verwerking later. Die data was dan verfyn en gebruik om maklik-om-te- interpreteer visuele voorstellings van die beligtingseienskappe van die gemete area as 'n funksie van tyd te genereer. Die data, gestoor as 'n .txt lêer, word ingevoer van die SD kaard in Microsoft Excel in waar 'n konstante, voorafbepaalde regstellingsfaktor op die data toegepas word. A MATLAB program was ontwikkel om die gekorrigeerde data te lees vanaf die Excel werkblad en 'n geanimeerde voorstelling, van die vordering van die beligtingseienskappe oor die tydperk waarvoor die lesings geneem was, terug te voer. Toetse uitgevoer met die stelsel was uitgevoer in 'n vertrek, voorsien met daglig van twee passiewe “zenithal” beligtingspype. Die gebruik van die stelsel, onder hierdie kondisies, blyk effektief. Die stelsel is in staat om akkuraat die uurlikse, daaglikse, asook die seisoensveranderlikheid van lig, binne die afgemete area oor ʼn tydperk van tyd, weer te gee.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/97106
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