Lighting Lecture 3 Notes PDF

9/30/2024 LIGHTING Asst. Prof. Dr. Bilge ŞAN ÖZBİLEN Sept.2024 LECTURE 3: VISUAL COMFO...

9/30/2024 LIGHTING Asst. Prof. Dr. Bilge ŞAN ÖZBİLEN Sept.2024 LECTURE 3: VISUAL COMFORT Lighting Requirements in Buildings Humanbeings perceive their surroundings primarily via their sense of vision and this is ideally assisted by sunlight. Lighting in our living and workplaces is critically important for our ability to accomplish tasks efficiently and safely. In addition, proper light levels prevent eye strain, which allows us to work comfortably for longer periods of time. 1  9/30/2024 Lighting Levels in Buildings We need to provide enough light to allow people to accomplish see their tasks, but not so much light that it is hard to see the tasks – over lighting is just as bad as under lighting. Detailed tasks like drafting require more light, while general tasks like walking can be accomplished with less light. Photometric Units 2  9/30/2024 Luminous Flux [lumen – lm - φ] - Işık Akısı The radiant flux or power emitted by a light source (the sun and the sky/ a lamp) as viewed by the humen eye. https://www.youtube.com/watch?v=V_bZhzCpCcs Luminous Efficacy – Işıksal Verim The lumens emitted by a watt of radiant power. Luminous efficacy of daylight is particularly high. It reaches 100 lumens per watt. Luminous Intensity – Işık şiddeti Luminous flux per unit solid angle in a given direction, I (candela, cd) Illuminance Level [lux - E] - Aydınlık The illuminance at a particular point of a surface is the quantity of luminous flux uniformly distributed over the surface. Luminance [candelas per square metre] - Parıltı The luminance of a lit surface is the illuminance received at the surface, modified by the surface’s reflectivity. 3  9/30/2024 LUMINANCE IS EFFECTIVE IN VISION. EVERYTHING YOU SEE IS VARIOUS COLORED SURFACES WITH DIFFERENT LUMINANCE. SO, IT IS NOT ILLUMINANCE LEVEL, IT IS LUMINANCE. EX: CHALK LINES OF DIFFERENT COLORS ON THE BOARD… Daylight values…1/3 ratio LUMINANCE IS EFFECTIVE IN VISION. EVERYTHING YOU SEE IS VARIOUS COLORED SURFACES WITH DIFFERENT LUMINANCE. Daylight values…1/5 ratio 4  9/30/2024 Visual Comfort Visual Comfort parameters are: Illuminance Level Contrast & Uniformity Glare Flicker (at lamps) Color Rendering Visual Comfort Illuminance Level [lux – lm/m²] : illuminance required in spaces used for different types of work Scale of Illuminance Levels in Lux: 5  9/30/2024 Visual Comfort IECC 2015 LIGHTING ROOM TYPE LIGHT LEVEL (LUX) POWER DENSITY (WATTS PER M2) Bedroom - Dormitory 200-300 lux 4.1 Cafeteria - Eating 200-300 lux 7.0 Classroom - General 300-500 lux 13.3 Conference Room 300-500 lux 13.2 Lighting Power Density (LPD) [W/m²]: Corridor 50-100 lux 7.1 Exhibit Space 300-500 lux 15.6 Lighting power density is the amount of Gymnasium - Exercise / Workout 200-300 lux 7.8 power used by lighting per unit of Gymnasium - Sports / Games 300-500 lux 12.9 building area. Kitchen / Food Prep 300-750 lux 13.0 Laboratory (Classroom) 500-750 lux 15.4 Laboratory (Professional) 750-1200 lux 19.5 Library - Stacks 200-500 lux 18.4 Library - Reading / Studying 300-500 lux 11.4 Most standards regulates the maximum Loading Dock 100-300 lux 5.1 allowed lighting power densities for Lobby - Office/General Locker Room 200-300 lux 100-300 lux 9.7 8.1 diffferent areas: Lounge / Breakroom 100-300 lux 7.9 Mechanical / Electrical Room 200-500 lux 10.2 Office - Open 300-500 lux 10.5 Office - Private / Closed 300-500 lux 11.9 Parking - Interior 50-100 lux 2.0 Restroom / Toilet 100-300 lux 10.5 Retail Sales 200-500 lux 17.1 Stairway 50-100 lux 7.4 Storage Room - General 50-200 lux 6.8 Workshop 300-750 lux 17.1 Visual Comfort Contrast : The difference between the light level of an object (or surface area) and its background (surroundings). It can be expressed in terms of luminance or illuminance. The reflectivity of surrounding surfaces are very effective on contrast. * the amount and the distribution of the light in the space - uniformity 6  9/30/2024 Visual Comfort Glare : Glare is a subjective human sensation that describes ‘light within the field of vision that is brighter than the brightness to which the eyes are adapted’ (HarperCollins 2002). Glare can be caused directly or by reflection: Direct Glare occurs when a natural or artificial light source with a high luminance enters directly into the individual’s field of view. Reflected Glare is caused by the specular reflection from light sources on polished interior surfaces. Visual Comfort Glare : Glare should be limited to avoid errors, fatigue and accidents. Direct glare types are: Disability (Veiling) Glare Disability glare which reduces the ability to perceive the visual information needed for a particular activity and it is often caused by the inter-reflection of light within the eyeball. In interior work places disability glare is not usually a major problem if discomfort glare limits are met. Discomfort Glare Discomfort glare which is distracting or uncomfortable, which interferes with the perception of visual information required to satisfy biological needs, but which does not significantly reduce the ability to see information needed for activities. https://www.youtube.com/watch?v=PwHXut8lw4M 7  9/30/2024 Visual Comfort Glare : As far as glare is concerned, flat angles of radiation ranging between 45° and 85° are particularly critical. Visual Comfort Glare Index - UGR (EN 12464-1) : Glare index is a numerical evaluation of high dynamic range images using a mathematical formula that has been derived from human subject studies. The rating of discomfort glare caused directly from the luminaires of an indoor lighting installation shall be determined using the CIE Unified Glare Rating (UGR) tabular method, based on the formula: 8  9/30/2024 Visual Comfort Acceptable glare indexes of different functions VOLUME ACCEPTABLE GLARE INDEX Gı OFFICES general 19 drawing offices 16 working with computer 19 SCHOOLS classrooms 19 Knitting, Sewing rooms 19 INDUSTRY Fine works (Product control etc.) 16-21 Medium fine works (packaging, 22-25 woodworking etc.) Rough work (metalwork, assembly of 26-28 large parts, etc.) Visual Comfort Flicker: Flicker causes distraction and can give rise to physiological effects such as headaches. 9  9/30/2024 COLOUR ASPECTS Colour: The feature that enables the light particles of the same size and shape to be distinguished from each other when observed by humans. In perception of colors; - characteristics of the observed object, - available light and environment, - characteristics of the observer - direction of view is effective. RENK TEORİLERİ BOYA RENKLERİ IŞIK RENKLERİ 10  9/30/2024 Visual Comfort Coloured surfaces in an interior affect the visual comfort both quantitatively and qualitatively. The quantitative effect is on the illumination level, because interior surfaces reflect light related to their light reflectance and they act as secondary light sources. Light reflectance values (r) of surface depending on the colours can ben obtained through the Munsell values (v) r = v x (v-1) (%) Light-colored surfaces have greater light reflection coefficients than dark-colored surfaces. Visual Comfort Munsell Colour Classification System Classifies color in 3 aspects; 1. Color Name/Type: Hue Perceived colour like red,yellow,green and blue Rengin Adı/Türü/Ton 2. Brightness/Intensity:Value Emitting more or less light Rengin Parlaklığı/Yoğunluğu/Değeri 3. Saturation/Purity: Chroma Exhibiting more or less chromatic colour (compared with gray) Rengin Doygunluğu/Saflığı 11  9/30/2024 Visual Comfort Munsell Colour System Visual Comfort Colour Distortion: Colour Appearance: The colour appearance of a lamp refers to the apparent colour (chromaticity) of the light emitted. It is quantified by its correlated colour temperature (TCP). https://www.youtube.com/watch?v=igDZ8CMWq1k 12  9/30/2024 Visual Comfort Colour Appearance: 13  9/30/2024 Visual Comfort Colour Rendering: For visual performance and the feeling of comfort and well being, colours in the environment, of objects and of human skin, shall be rendered naturally, correctly and in a way that makes people look attractive and healthy. Visual Comfort Colour Rendering Index (CRI – Ra): (Renksel Geriverim Indisi) To provide an objective indication of the colour rendering properties of a light source the general colour rendering index Ra is used. The maximum value of Ra is 100. Daylight renders colours the most accurately and therefore has a CRI of 100. https://www.youtube.com/watch?v=EO_WZvuf_BY 14  9/30/2024 Visual Comfort Colour Rendering Index (CRI) The spectral distribution of the light source after it enters the building determines colour rendering For museums, retail, healthcare and other similar uses, accurare colour rendition can affect judgement and perception. Color rendering class Color rendering Application area Places for precise color matching, color Ra > 90 (1A/1B), very good printing..... 80< Ra< 90 Places where accurate color vision is important 70