| บทคัดย่อ(English) |
The use of natural lighting in buildings to substitute artificial lighting in air-conditioned building needs particular consideration on additional cooling load due to transmitting light. Prevalently, the difficulty in integrating natural lighting in architectures is a discrepancy of light distribution throughout a space, a gradation of high illuminance levels at the area near the opening to low levels at the rear of the rooms, which is insufficient for human performance. These inherent problems result in fruitless daylighting applications. This research, therefore, aims to generate an energy conservation index for estimating daylighting applications in side-lit buildings. The methodology to obtain the energy conservation index is by comparisons of illuminance levels collected from the studied buildings to those stated in Illuminance Recommendations Standard of IES. The research focused solely on the influences and relationships of various variables relating to daylighting applications in sidelit buildings by calculating illuminance levels based on Sky Factor. A number of variables involving in the calculation were configurations, proportions and areas of openings, sky conditions, the sun's orientation and altitude, internally-reflected component of the rooms, external-reflected component, atmospheric depletion, and light transmission. Theresults were used to establish the criteria for an assessment of illuminance levels (Lux) and the cooling load (Watt/ m('2)) in order to evaluate a productive use of natural lighting in side-lit buildings. From the research, an optimum use of natural lighting in side-lit domesticbuildings has an illuminance level of 250 lux and a maximum cooling load of 0.365 watt l m('2). The applicable value for office buildings was 350 lux and 0.731 watt / m('2), for an illuminance level and cooling load respectively. For each building category, any values surpassed these standard values suggested an excessive illumination, which contributed to high solar gains, and hence cooling loads. In contrast, should the values fall below these standard values, interior Illumination was inadequate for task lighting. Applying the energy conservation index, an evaluation on two domestic buildingsshowed that the selected typical house was rated as level 2, a fair utilization of natural lighting in buildings, while the tested energy-saving house was granted for level 4, a good level of natural lighting applications. The assessment was also carried out on two office buildings, which again measured the performances of natural lighting applications in a typical office and an energy-concerned building. In correlation to theresult of the typical house, natural lighting adopt in the conventional office was assessed as fair, with the rating of 2. A good level of natural lighting application was found in the energy-saving office which was classified as level 4. The results suggested that an effective use of natural lighting in buildings required internal illuminance levels in accordance to the recommended Standard which do not increase cooling load. |
