/npsi/ctrl?lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?lang=fr Access and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. For the publisher's version, please access the DOI link below./ Pour consulter la version de l'éditeur, utilisez le lien DOI ci-dessous.http://dx.doi.org/10.1191/1365782803li064oaLighting Research & Technology, 35, 3, pp. 243-260, 2003-08-01 Monitoring manual control of electric lighting and blinds Reinhart, C. F.; Voss, K. Monitoring manual control of electric lighting and blindsReinhart, C.F.; Voss, K. NRCC-45701 AbstractThis paper reviews, validates and extends present knowledge of the degree and kind of manual control strategies of blinds and electric lighting systems that are used in private and two-person offices. A new monitoring setup was applied from March to December 2000 in ten daylit offices in Germany that featured manually operated electric lighting and automatically controlled external venetian blinds with manual override. The data shows that individuals consistently followed the same control strategy for their electric lighting and blinds. Groups of individuals tended to activate their electric lighting according to Hunt's probability function although there was a large spread between individual control levels. All subjects used their blinds to avoid direct sunlight above 50Wm -2 and incoming solar
Discomfort glare is an underutilized parameter in contemporary architectural design due to uncertainties about the meaning of existing metrics, how they should be applied and what the benefits of such analysis are. Glare is position and view direction-dependent within a space, rendering it difficult to assess compared to conventional illuminance-based metrics. This paper compares simulation results for five glare metrics under 144 clear sky conditions in three spaces in order to investigate the ability of these metrics to predict the occurrence of discomfort glare and to hence support the design of comfortable spaces. The metrics analyzed are Daylight Glare Index, CIE Glare Index, Visual Comfort Probability, Unified Glare Rating and Daylight Glare Probability. It is found that Daylight Glare Probability yields the most plausible results. In an attempt to deal with multiple positions and view directions simultaneously, the concept of an 'adaptive zone' is introduced within which building occupants may freely adjust their position and view in order to minimise the effect of glare. The spatial and directional extents of the adaptive zone depend on furniture layout and the freedom of occupants' tasks. It is found that applying the adaptive zone concept to a sidelit office with manually operated venetian blinds reduces the predicted hours of intolerable discomfort glare from 735 to 18 occupied hours per year and increases the annual mean daylight availability from 40% to 72%. Nomenclature L s luminance of the glare source (cd/m 2 ) ! solid angle of the glare source (sr) ! pos the solid angle of the glare source modified for its position in the field of view (sr) P weight factor based on position in a viewing hemisphere, the position index E v total vertical eye illuminance (lux) V solid angle of a viewing hemisphere subtended by glare sources (sr) L b background luminance determined by taking the average luminance of areas not identified as glare sources (cd/m 2 ) L adapt adaptation luminance (cd/m 2 ) L exterior average exterior luminance (cd/m 2 ) L window average window luminance (cd/m 2 ) E d direct vertical illumination (lux) E i diffuse vertical illumination (lux) E ave average illuminance for a viewing solid angle of 5 steradians
This paper proposes and validates a daylighting design sequence for sidelit spaces. Since the design sequence uses the daylight factor as a performance metric, it is aimed towards spaces that primarily receive diffuse daylight. It should be complemented by a design analysis that looks at direct sunlight for glare and energy considerations. The sequence interconnects and refines earlier proposed rules of thumb and is intended to be used during the earliest design stages when concepts regarding programming, floor plans, massing and window areas are initially explored. All steps within the sequence were ‘validated’ using Radiance simulations of over 2300 sidelit spaces. During step one of the sequence the effective sky angles are calculated and target daylight factors are defined for all potential daylit zones within a building. In step two a refined version of the ‘daylight feasibility study’ is used to help the design team to identify building zones with high daylighting potential based on a target mean daylight factor criterion. During step three suitable interior room dimensions and surface reflectances are determined using a combination of the Lynes’ limiting depth, ‘no sky line’, and window-head-height rules of thumb. Step four provides a more accurate estimate of the required glazing area for each zone based on the Lynes daylight factor formula which is also validated as part of this work. The effect of external obstructions is considered throughout the process. The paper closes with a discussion of the merits of the design sequence compared to the glazing factor spreadsheet calculation method promoted by LEED-NC 2.2.
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