daylilghting

• Daylighting


  The placement of windows or openings and reflective surfaces in order that sunlight can provide effective lighting into the building interiors
• Daylighting


  • Integration of natural light into the building interior spaces where task lighting is not the primary consideration, as in corridors, lobbies and residences
• Components of Daylighting


  • Direct sun
  • Diffuse sky
  • Indirect sun – sunlight reflected from the ground or adjacent structures
• Reasons for the need for Daylighting

  • The cost of money (buying power) is decreasing
  • Energy cost is increasing
  • Demand for "green" or sustainable design in buildings
• Benefits of Natural Light


  • Improved mood and morale – workers have greater job satisfaction
  • Less fatigue – people feel less "stressed out"
  • Reduced eyestrain – natural light is motivating and calming
  • Improved "connection" with outside environment – likely to have a sense of what is happening outside
• Spaces where natural light has positive impacts

  • Offices – improved productivity, reduced stress, lower absenteeism, and turnover
  • Educational space – improved attendance and academic performance
  • Healthcare space – reduced strain and fatigue for staff; improved well-being of patients
  • Industrial space – improved safety and productivity
  • Retail space – more customers and increased sales
• Methods used to introduce light into buildings

  • Perimeter Lighting – use of windows and light shelves
  • Top Lighting – use of skylights, clerestories, and monitors
  • Core Lighting – use of atrium and light wells
  • Optical Lighting – use of fiber optics, prisms, mirrors, parabolic reflectors, and other means
• Windows


  The most common way to admit light into a space. Their vertical orientation means that they selectively admit sunlight and diffuse daylight at different times of the day and year
• Ways to improve the amount of light available from a window

  • Place window close to a light colored wall
  • Slant the sides of window openings so the inner opening is larger than the outer opening
  • Use a large light colored window sill to project light into a room

  
• Rooms intended for any use, not provided with artificial ventilation system, shall be provided with a window or windows with a total area of openings equal to at least 10% of the floor area of the room, provided that such opening shall be not less than 1.00 square meter
• Toilet and bathrooms, laundry rooms and similar rooms shall be provided with windows or windows with an area not less than 1/20 of the floor area of such rooms, provided that such opening shall not be less than 240 square millimeters
• Required windows may open into a roofed porch where the porch abuts a court, yard, public street or alley, or open watercourse and other public open spaces, has a ceiling height of not less than 2.70 meters, and has one of the longer sides at least 65% open and unobstructed
• Eaves, canopies, awnings (or media agua) over required windows shall not be less than 750 millimeters from the side and rear property lines
• There shall absolutely be no openings on/at/within/through all types of abutments (such as firewalls) erected along property lines except for permitted vent wells
• Requirements for windows that must serve as emergency egress

  • Can be opened from the inside without the use of any tools
  • The minimum clear opening shall have a width not less than 820 millimeters and a height of 1.00 meter
  • The bottom of the opening should not be more than 820 millimeters from the floor
  • Where storm shutters, screens or iron grilles are used, these shall be provided with quick opening mechanism so that they can be readily opened from the inside for emergency egress and shall be so designed that when opened they will not drop to the ground
• Determining the average daylight factor (ADF) and Average light level (ALL)

  1. Step 1. Determine the Total Area of Indoor Surfaces of the Room (A)

  2. Step 2. Solve for the Average Weighted Reflectance

  3. Step 3. Solve for Reflectance (R)

  4. Step 4. Solve for ADF

  5. Step 5. Solve for Average Light Level (ALL) in the room

  6. Step 6. Check if the Average Light Level (ALL) in the room is within the range of the Recommended Daylight Level (RDL)

  7. Step 7. Recommendations if ALL is below minimum RDL

  
• The depth of the daylight penetration is about 2.5 x the height of the window opening measured from the floor to the window head
• Window Height to Depth of Penetration of Light

  • A 2.40 to 2.70 meter high window will give full daylight to a depth of about 4.50 meters. As window height increases, depth increases at a ratio of 1 to 2
  • A 2.40 to 2.70 meter high window will give partial daylighting (requiring additional artificial lights) to a depth of about 6.00 to 9.00 meters. As window height increases, depth increase at a ratio of 1 to 3
• Sidelighting - Window Width

  To get even light distribution, a window opening should be at least half (50%) as wide as the length of its wall
• Light Shelves


  • Enhances the entry of light through reflection at windows on the equator-facing side of a building
  • Projects beyond the window face and reflects sunlight upwards to illuminate the ceiling
  • This reflected light may contain little heat and typically reduces deep shadows, thus reducing the need for artificial lighting
• Types of Toplighting


  • Skylights - horizontal windows, roof lantern, light tubes placed at the roof and used to admit light to the spaces below
  • Light Tubes - admits light to a focused area of the interior
  • Clerestories - (Clearstory) is an upper zone of wall pierced with windows that admit light to the center of a lofty room
  • Monitor - raised section of a roof, usually straddling a ridge; has openings, louvers, or windows along the sides to admit light or air
• Guidelines for Toplighting


  • Skylight Opening - 5% to 10% (maximum) of ceiling area, space at 1 to 2 times the ceiling-to-work plane height
  • Clerestory (Clearstory) Opening - 10% of wall area. Space 1.50 times the ceiling-to work plane height. At a point 4.50 meter from the rear wall: for clear climate (5000 footcandle), provide 50 mm of glazing height per 10 footcandle on average work plane
  • Skylight/ Clearstory Spacing - Small skylights at 3.00 meter ceiling height should be spaced at 3.00 meters. Greater or less ceiling height can be determined by a ratio of 1:1. Clearstories at a 4.00 meter ceiling height should be spaced at 6.00 meters. Greater or less ceiling height to spacing can be determined by a ratio of 1:1.5. Large skylights (larger than 3.00 square meters) should be spaced at 6.00 meters

  
• Monitor


  Raised section of a roof, usually straddling a ridge; has openings, louvers, or windows along the sides to admit light or air
• Toplighting


  • Skylight Opening: 5% to 10% (maximum) of ceiling area, space at 1 to 2 times the ceiling-to-work plane height
  • Clerestory (Clearstory) Opening: 10% of wall area, space 1.50 times the ceiling-to work plane height, at 4.50 meter from the rear wall provide 50 mm of glazing height per 10 footcandle on average work plane for clear climate (5000 footcandle)
  • Skylight/ Clearstory Spacing: Small skylights at 3.00 meter ceiling height should be spaced at 3.00 meters, greater or less ceiling height can be determined by a ratio of 1:1; Clearstories at a 4.00 meter ceiling height should be spaced at 6.00 meters, greater or less ceiling height to spacing can be determined by a ratio of 1:1.5; Large skylights (larger than 3.00 square meters) at a ceiling height of 4.50 meters should be spaced at 9.00 meters, greater or less ceiling height to spacing can be determined by a ratio of 1:2
• North light


  Soft, cool, uniform illumination
• Sawtooth roof


  Used where north light is needed
• Skylights can be a problem due to heat gain from too much sunlight
• Skylights and clerestories can be used to deliver light deep into the interior of a building
• Clerestories can be designed to best avoid direct sunlight
• Light tubes


  Also known as Solar Tube, a device placed into a roof and admits light to a focused area of the interior, resembling recessed ceiling light fixtures, they do not allow as much heat transfer as skylights because they have less surface area
• Pipe lighting


  New form of daylighting
• Translucent roof membrane


  New form of daylighting
• Core lighting


  Light wells, atrium
• Light well


  Shaft within a building, open to the outer air at the top, used to admit daylight and air through windows opening onto the shaft
• National Building Code: Rule VIII - Light and Ventilation

  • Vent shafts: Minimum horizontal cross-sectional area of 1.00 square meter for every meter of height of shaft, no less than 1.00 square meter, no least dimension less than 600 millimeters; Unless open to the outer air at the top for its full area, vent shafts shall be covered by a skylight having a net free area or fixed louver openings equal to the maximum required shaft area; Air ducts shall open to a street or court by a horizontal duct or intake with a minimum unobstructed cross-sectional area of 0.30 square meter and minimum dimension of 300 millimeters above the street surface or level of court
• Fiber optic daylighting


  Evolving technology that uses fiber optics combined with solar light collectors to transmit daylight to spaces difficult to daylight using sidelighting or toplighting strategies, light in a fiber optic cable travels through the core by bouncing off the cladding
• Fiber optic concrete wall


  Embedding optical fibers in a concrete wall to make it translucent, allowing daylight and shadow images to pass directly through
• Prisms and mirrors


  Spandrel panel composed of an array of mirrors with computer-controlled servo motors that track the sun, directing light against reflectors that concentrate it and shoot the beam through the plenum
• Types of daylighting


  • Skylight
  • Atrium or Light Well
  • Light Tube
  • Fiber Optics
• Advantages and disadvantages of daylighting types

  • Skylight: Less likely to be obstructed, 3x more effective than vertical window / More light and heat in summer (strain on aircon)
  • Atrium or Light Well: Bring light to different floors / Too much to top floors, not enough to lower floors
  • Light Tube: Diffuse light efficiently, block out harsh light and heat / Only effective on top floors
  • Fiber Optics: Possible to pipe light anywhere / Directional, focused light, expensive