An Investigation of Annual Daylighting Metrics for Residential Houses (original) (raw)
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Building and Environment, 2017
This paper documents a field study that collected visual comfort feedback and High Dynamic Range (HDR) luminance maps to test the validity of laboratory-derived metrics in field settings. This study included 13 subjects for 149 daylighting evaluations. Similar to previous laboratory-based research, simple luminance-based metrics outperformed complex glare indicators in their predictive ability in this pilot field study. Also similar to lab studies, metrics derived using luminance data within the horizontal 40 band of human vision and a mask of just the window represented the majority of the top 20 squared correlation coefficients, considering all questionnaire items. While standard deviation of window luminance, a highly predictive metric derived in a laboratory setting, did not maintain similar predictive ability in these field studies, the field study supported previous laboratory findings that this metric may be useful in discerning visual discomfort in spaces that are very dim. Two new metrics, the ratio of the 98th percentile to mean window luminance and the coefficient of variation (COV) of luminance in the horizontal 40 band, yielded the strongest squared coefficients in field studies (adj r 2 ¼ 0.35 and adj r 2 ¼ 0.32 respectively). The COV 40 band was more stable across multiple positions within a scene than other luminance-based methods. These findings suggest that some metrics are better suited for use within a single room over time (for purposes of dynamic daylighting scene control), whereas other metrics are better suited for evaluation between spaces and from alternate positions within a room (for purposes of design guidance).
Model based evaluation of exterior daylight illuminance distribution
Building Simulation, 2009
Energy conservation in buildings is greatly influenced by natural daylight in tropical region. A vital step towards development and promotion of daylighting technology in buildings is a prior study on estimation of exterior daylight availability for illuminating its interiors. In view of this, the present communication depicts the preliminary work progress carried out to arrive at a comprehensive idea on assessment of daylight availability and its characteristics. The study is reported taking the representative case of Bangalore (India) (latitude 12.97° N, longitude 77.56° E),which in future work facilitates to device suitable interior illuminance models and lighting controls for a daylight-artificial light integrated scheme. The objective of this paper is to document the estimation of spatial exterior daylight parameters like exterior horizontal as well as vertical global and diffuse daylight illuminance in addition to their respective luminous efficacies computed using an established analytical model. The paper also highlights user friendly computer simulation tool developed, for the detailed estimation of daylight availability at a particular region by the inclusion of corresponding solar radiation data.
Daylighting metrics for residential buildings
2011
Abstract It is now widely accepted that the standard method for daylighting evaluation-the daylight factor-is due for replacement with metrics founded on absolute values for luminous quantities predicted over the course of a full year using sun and sky conditions derived from standardised climate files. The move to more realistic measures of daylighting introduces significant levels of additional complexity in both the simulation of the luminous quantities and the reduction of the simulation data to readily intelligible metrics.
This paper reviews the validity of the ubiquitous daylighting rule of thumb (DRT) that relates window-head-height to the depth of the daylit area adjacent to a façade, in the specific context of the tropical conditions found in Dhaka. The spatial depth in a room, up to which penetration of daylight ensures adequate daylight for a specific task, is defined as the depth of daylit zone. According to DRT, the daylit zone is considered, to be a depth of two and a half times the window head height. Deeper parts of a space are considered in 'dark zone', having inadequate daylight, and requiring artificial light. However, in the Tropics, parts of the daylit zone, may be over-lit, adversely affecting both visual and thermal comfort, thus influencing consequent energy consumption. This paper presents a simulation study evaluating DRT in recent tall office buildings of Dhaka, with the most commonly used shading devices, for the south, east and west orientations. Six selected fixed external shading devices, found from a field survey, have been assessed through the simulation study, during the overheated period of summer, considering related daylit zone depth and their resulting lighting/luminous efficiency. The simulation results support predictions made by DRT for specific shading devices. However, they also demonstrate the limitations of the rule, with differing relationships between window head height and daylit zone depth all day long, based on facade orientation, as well as on the geometrical, and the material characteristics of the studied shading devices. The results clearly indicate that, modification of the dimensional relations of light zone, by proper selection of shading devices, can enhance luminous efficiency in offices of Dhaka and similar Tropical areas.
The effect of architectural details on daylight distribution inside a room
2015
In Iranian historical architecture one of the most important design criteria is daylight accessibility and quality. To evaluate daylighting conditions in a historical house in Kashan city in Iran, one of its main rooms was examined according to field and simulation studies in the year 2012 and 2014. To evaluate the effects of architectural design details on daylighting conditions of the room, some elements such as balcony, ceiling shape and height, window size and frame, glass size and colour, where changed or eliminated by simulation. The amount and distribution of daylight inside the room was simulated in the morning, noon and afternoon of two sunny days in summer and winter on a horizontal mesh at 80 cm height. The important UDI (useful daylight illumination) levels on different parts of the room were calculated on this height in all months of the year. On a column diagram, the results of this calculation show the percentage of daylight accessibility in a year. The illumination a...
Daylighting: an approach from urban to room scale
2016
This paper aims to compare the daylighting results provided by two specific software tools dedicated to the preliminary design stage. The first one, DIAL+, focuses on the room scale while the second one, CitySim, aims to provide a decision support at the urban scale. On one side we have a bottom-up approach, which matches the point of view of architects or building designers and, on the other hand, a "top-down" approach that fulfil the needs of urban planners and energy stakeholders. The case study focuses on a small openspace office that we looked at from three different positions in a given building located in the neighborhood "Barrio de las Nieves" in the city of Bogota. The output of both tools are analysed on a annual basis, through the comparison of the number of hours during which the indoor illuminance exceeds 300 lux for two specific points respectively located at 1.50 and 4.50 m from the glazed façade. This work shows that, if the two approaches yield s...
A Computational Approach for Optimizing the Daylighting Performance of Existing Buildings
The 9th International Conference of the Arab Society for Computer Aided Architectural Design, 2021
Daylighting provision gives a significant contribution to the enhancement of the indoor visual environment and user comfort. This study aims to provide a methodology to assess and optimize daylighting performance in buildings. The paper utilizes simulation techniques for identifying the most efficient daylight performance by incorporating parametric optimization tools to enhance the daylighting performance of existing buildings. The developed workflow includes three consecutive phases. The first examines the daylighting performance of the existing building. The second phase is concerned with daylighting adequacy and the third aims to optimize the quality of light rather than just the quantity through the utilization of a simple shading system to parametrically investigate the effect of using different shading configurations on daylighting performance and to select the optimal solution. A louver system was parameterized according to a predefined process that associates its depth, count and rotation angle while a vertical screen was parametrized according to its scale and tilt angle. To examine the potentials of the proposed multi-stage method, it has been implemented on an office building located in new Cairo, Egypt. The results demonstrate that using the proposed optimization strategy drastically enhanced the Spatial Daylighting Autonomy of the building from 27% to 87% in comparison with the base case. Moreover, the optimum shading solution enhanced the daylighting quality by reducing the glare probability for better visual comfort from 60% to only 14%.
Development of annual daylight simulation algorithms for prediction of indoor daylight illuminance
Energy and Buildings, 2016
An annual daylight simulation method (ADSM) has been developed in this study to predict daylight illuminance under diverse sky conditions. The ADSM simulation results were validated by comparing them with Radiance software simulation results and field measurements. Classroom and small private office space facing south and north were used for validation. A classroom facing north and south was used for simulation of ADSM and Raidnace. Field measurements were conducted in a small private office space. Simulation of ADSM was conducted for the conditions of measurements to examine the differences between the results The results indicated that the daylight illuminance levels computed by ADSM and by Radiance correlated strongly under various sky conditions. Daylight coefficient approach and sun-matching method of ADSM were recommended to achieve higher prediction accuracy. The ADSM simulation results were consistent with actual field measurements of illuminance, even though they varied in accuracy under various sky conditions. The illuminance levels achieved from ADSM and field measurements correlated with each other strongly. Difference ranges between illuminance levels from measurements and simulations were effectively reduced when daylight coefficient approach of ADSM for sky was used with any other computational algorithms of ADSM for the sun.