3. DAY LIGHTING
• Daylighting is a building design strategy to use
light from sun.
• Presence of natural light in an occupied space
brings a sense of wellbeing, increases awareness
of one’s surrounding and also increases energy
saving potential with reduced dependence on
artificial light.
• Appropriate use of windows, skylights,
clerestories, and other apertures in the building
provide means to harvest daylight.
4. DAY LIGHTING
• Remember that, more the sunlight that enters the
building, more the heat that needs to be dealt with.
• Thus, by placing apertures correctly, nature can
work with you.
• Integrating day lighting with artificial lighting can
considerably reduce energy consumption, but at the
same time may lead to higher air conditioning loads
due to heat gain.
• Thus design consultants and decision makers need
to appropriately balance daylight harvesting features
and minimize solar heat gains.
• Hence, day lighting becomes an integral part of a
building design strategy from early design phase to
lower the energy consumption of a building,
imperative to advance NZEB design goals.
5.
6. Orientation and form for daylighting
•
Buildings can be located and oriented to take advantage of sun’s
movement throughout the day, as well as seasonal variations.
• Buildings that are longer on their east-west axis are better for
daylighting and visual comfort.
• Larger and taller buildings should have thinner profiles to
maximize daylighting potential from side windows.
• Large buildings can get daylight into more spaces by having
central courtyards or atria, or having other cut-outs in the
building form.
• Focus should be given to maximum daylight factor, increase
uniformity of light spread, reduce glare, and minimise solar
gains.
• Increasing the height of each storey to allow for higher windows
also helps pull daylight further into the building.
• Plan for daylight by minimising floor plate depth, especially in
office buildings.
7. Windows
•
Amount of daylight that enters a room depends on the window location and its
dimensions.
• Determine the window size, height and glazing treatments for each facade separately.
• Maximize southern exposure and optimize northern exposure.
• North-facing windows provide consistent indirect light with minimal heat gains.
• Minimize eastern and western exposure when the sun is lowest and most likely causes
glare and overheating. They are more difficult to shade because the sun is closer to the
horizon.
• There is a direct relationship between the height of the window head and the depth of
daylight (Typically adequate daylight will penetrate one and one half times the height of
the window head).
• Allow daylight penetration high in a space. Windows located high in a wall or in roof
monitors and clerestories will result in deeper light penetration and reduces the
likelihood of excessive brightness.
• Use advanced daylight harvesting methods in case of large window area (such as use of
external light shelves, light tubes, a higher ceiling height and other similar technologies,
would help to distribute the daylight deeper into the building).
• Use skylights and roof monitors to areas without easy access to windows.
• Use of light coloured interior surfaces reduces luminance contrast and improves
coverage.
8. Windows
• Allow daylight penetration high in a space.
Windows located high in a wall or in roof monitors
and clerestories will result in deeper light
penetration and reduces the likelihood of excessive
brightness.
• Use advanced daylight harvesting methods in case
of large window area (such as use of external light
shelves, light tubes, a higher ceiling height and
other similar technologies, would help to distribute
the daylight deeper into the building).
• Use skylights and roof monitors to areas without
easy access to windows.
• Use of light coloured interior surfaces reduces
luminance contrast and improves coverage.
9.
10. Location, form and dimensions of
shading devices
• South-facing windows are the easiest to shade. Horizontal
shading devices are most effective as they can block summer
sun and admit winter sun.
• East- and west-facing windows are best shaded with vertical
devices, but these are usually harder to incorporate into a
building, and limit views from the window.
• The provision of glare protection devices will reduce the
amount of daylight harvested. A balance between glare
protection and daylight harvesting needs to be done carefully
to ensure that the design of the daylight harvesting system will
perform as intended.
11. TOOLS
• Radiance ( http://www.radiance-online.org/ )
Radiance is a suite of programs for the analysis and visualization of lighting
in design.
• Velux Daylight Visualizer (http://viz.velux.com )
Velux Daylight Visualizer is a validated simulation and visualization tool for
daylighting design and analysis. It is intended to promote the use of daylight
in buildings and to aid professionals by predicting and documenting daylight
levels and appearance of a space prior to realization of the building design.
• DAYSIM (http://daysim.ning.com/ )
Radiance based daylighting analysis software that models the annual
amount of daylight in and around buildings
• DIALUX (http://dial.de/)
Dialux can calculate electric light, daylight and the energy performance of
electric light.
• ECOTECT (http://usa.autodesk.com/ecotect-analysis/)
Autodesk Ecotect analysis is a sustainable design analysis software as a
concept to detail sustainable building design tool.
• Lighting layout Estimator Estimate the number of luminaires needed to light
an area to a specified light level.
(http://www.gelighting.com/LightingWeb/emea/resources/tools/lighting-
assistant-toolkit/lighting-layout-estimator.jsp)
12. ENERGY AND COST SAVINGS
• Daylighting is the one of the cornerstones of energy efficient
building designs. Several studies have proven the benefit of
daylighting, linking it to higher comfort, productivity, and
feeling of well-being in schools, offices, and hospitals.
• An appropriately designed daylighting features will provide
better indoor environmental quality, improve building
occupant performance and reduce the building’s energy
consumption at the same time. Daylighting can significantly
impact the energy use of a building by reducing the lighting
energy demand by up to 20-30%.
• NZEBs, which must be designed for 100% daylight potential,
can virtually eliminate daytime lighting energy use in most
spaces. The resulting saving in lighting energy use also
reduces cooling load while providing a better work
environment.
