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- Pacheco Diéguez, Alejandro, et al.
(författare)
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Daylight Utilization with Light Pipe in Farm Animal Production: A Simulation Approach
- 2016
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Ingår i: Journal of Daylighting. - : SolarLits. - 2383-8701. ; 3:1, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- Light pipes offer a passive way to bring daylight inside deep buildings, such as agricultural buildings. However, the lack of reliable performance predictability methods for light pipes represents a major obstacle preventing their widespread use. This paper evaluates a simulation approach for performance prediction and identifies key light pipe design parameters affecting their daylight transmission performance. The study was carried out through continuous monitoring of daylight in two full-scale, identical pig stables fitted with two light pipe systems, Solatube® and Velux®. The experiment included three continuously measuring sensors in each stable and an outdoor sensor during 2013 and 2014. A forward raytracing tool, TracePro®, was used for illuminance prediction and parametric simulations. The simulation results for overcast skies indicated discrepancies between the simulated and average measurement results below 30% in all cases. The discrepancies for clear skies were somewhat higher, i.e., below 30% for 67% of the cases. The higher discrepancies with clear skies were due to the overestimation of absolute sunlight levels and absence of an advanced and detailed optical characterization of the dome collector’s surface. The parametric results have shown that light pipes’ performance is better during summer time, in sunny climates, at low to mid-latitudes, which provides higher solar altitudes than during winter and cloudy climates at high latitudes. Methods to improve the luminous transmittance for low solar altitudes occurring in Scandinavia include: bending or tilting the pipe, increasing the aspect ratio, improving the pipe specular reflectance, tilting the collector to the south, and using optical redirecting system in the collector.
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| 2. |
- von Wachenfelt, Hans, et al.
(författare)
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Lighting Energy Saving with Light Pipe in Farm Animal Production
- 2015
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Ingår i: Journal of Daylighting. - : SolarLits. - 2383-8701. ; 2:2, s. 21-31
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Tidskriftsartikel (refereegranskat)abstract
- The Swedish animal production sector has potential for saving electric lighting of €4-9 million per year using efficient daylight utilisation. To demonstrate this, two light pipe systems, Velux® (house 1) and Solatube® (house 2), are installed in two identical pig houses to determine if the required light intensity, daylight autonomy (DA), and reduced electricity use for illumination can be achieved. In each house, three light sensors continuously measure the indoor daylight relative to an outdoor sensor. If the horizontal illuminance at pig height decreases below 40 lux between 08.00 and 16.00 hours, an automatic control system activates the lights, and electricity use is measured.. The daylight factor (DF) and DA are determined for each house, based on annual climate data. The mean annual DA of 48% and 55% is achieved for house 1 and house 2, respectively. Light pipes in house 2 have delivered significantly more DA than those in house 1. The most common illuminance range between 0 and 160 lux is recorded in both houses, corresponding to approximately 82% and 83% of daylight time for house 1 and house 2, respectively. Further, the daylighting system for house 2 has produced a uniform DF distribution between 0.05 and 0.59. The results demonstrate that considerable electric energy savings can be achieved in the animal production sector using light pipes. Saving 50% of electric lighting would correspond to 36 GWh or 2520 t CO2 per year for Sweden, but currently the energy savings are not making the investment profitable.
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