Daylighting

DAY
LIGHTING
Case Studies - 17091AA044
Daylighting and Potentials of Day Lighting as an Energy Source - 17091AA051
Advantages and Design Tools in Day Lighting - 17091AA054
Behaviour of daylighting in Interior Spaces - 15121AA044

Daylighting
Daylighting is a renewable source of light whose utilization for lighting of building interiors during
the period it is available, could lead to energy conservation and promotion of a friendly
environment.
Daylight has been intimately connected with architecture from the days of early human
civilization as man's visual activities could be performed only under daylight even inside buildings,
before the invention of the early artificial light sources like the plain oil lamp or the candle.
Daylight is a renewable source of light whose utilization for lighting of building interiors during
the period it is available, could lead to energy conservation and promotion of a friendly
environment.
The sun is the main source of daylight, whereas skylight is the effect of scattering of sunlight by
the atmosphere.
Daylight Factor - It is a measure of the total daylight illuminance at a point on a given plane
expressed as the ratio (or percentage) which the illuminance at the point on the given plane bears
to the simultaneous illuminance on a horizontal plane due to a clear design sky at an exterior point
open to the whole sky vault, direct sunlight excluded.
The Chapel of Notre-Dame-du-Haut.

Sources of Daylighting
The primary source of light for daylighting is the sun. The light received by the earth from the sun
consists of two parts; direct solar illumination and skylight.
For the purpose of the daylighting design, direct solar illumination shall not be considered and
only skylight shall be taken as a contributing factor to the illuminance of the building interiors
during the day.
The amount of skylight depends on the position of the sun defined by its altitude, which in tum
varies with the latitude of the location, the day of the year and the time of the day.
The outdoor design sky illuminance varies for different climatic regions of the country. The
recommended design sky illuminance values are 6 800 lux for cold climates, 8 000 lux for composite
climate,·9 000 lux for warm humid climates, 9 500 lux for temperate climates and 10 500 lux for hot
dry climates.
Components of Daylight Factor
The daylight factor is the sum of all the daylight reaching an indoor reference point from the
following sources:
a) The direct sky visible from the point;
b) External surfaces reflecting light directly to the point; and
c) Internal surfaces reflecting and inter reflecting light to the point.
DF = (Ei / Eo) X 100% Ei – illuminance due to daylight at a point on the indoors working plane. Eo
– simultaneous outdoor illuminance on a horizontal plane from an unobstructed hemisphere of sky.
2% OR 5% DF are two common thresholds for daylighting.
Sources of daylighting
Components of daylight factor

GENERAL NOTES ON DAYLIGHTING OF BUILDINGS -
Because of the highly variable nature of daylight from hour to hour and from season to season,
no simple formula for daylighting can be given which is valid for the entire day and for the entire
year.
Direct sunlight admitted into a building could lead to glare and thermal discomfort particularly in
summer. However in latitudes above 23°N in India, admitting sunlight in winter may mean thermal
comfort and daylighting design may have to take into account. the shading devices for admitting
sunlight and avoiding glare depending on the NATIONAL LIGHTING CODE local climate and the
nature of the activity in the interior space.
When designing for an interior where specific visual tasks have to be performed, the time and
duration of the task have to be taken into account while designing for daylight and a suitable
provision made for supplementing with electric lighting as may be required.
For daylighting of building interiors two types of windows may be used, those situated in a side
wall and those placed in the roof. In the case of a side wall window, larger height and smaller width
would result in more light in the distant interior of the room than in the case of larger width and
smaller height.

Daylight Luminous Efficacy -
 Luminous efficacy is a measure of how well a light source
produces visible light. It is the ratio of luminous flux to power,
measured in lumensper watt in the International System of
Units (SI).
 Luminous efficacy is lumens per watt of input power. In the
case of daylight, it is lumens per watt of radiant power. This
differs for the different components of daylight.
 The luminous efficacy of a source is the product of how well it
converts energy to electromagnetic radiation, and
how well the emitted radiation is detected by the human eye.
 The average of sunlight is about 95 lrn/W, and, for diffuse
skylight it is about 120 lm/W.
 The thermal balance of any interior depends upon this
parameter in so far as this is an indication of the level of
irradiance associated with a given level of illuminance. While
outdoor luminous efficacy values are different for different
components of daylight .
Thermal efficacy -
 Thermal Efficiency refers to the ability of a building to retain
warmth in winter or keep cool in summer, therefore requiring
less energy to artificially heat or cool the building.
 This is done by using insulating and weather proofing building
materials and design during construction, or by retrofitting
them to existing buildings.
Luminous efficacy
Thermal efficacy

India is a tropical climate lying between latitudes 8 degrees to 32 degrees north. With respect to
solar position and available exterior illumination, this is a wide range.
The skies are mostly clear except for the months of July and August, resulting in abundant
daylight available from 8 am to 4 pm, the primary daylit hours.
India receives on an average 300 sunny days annually and one can easily exploit architectural
features like fenestration for maximum daylight ingress while controlling thermal heat gain.
India ,Lying entirely in the Northern hemisphere the main land extends between latitudes 8°4'N
and 37°6'N and longitudes 68°7'E and 97°25’E.
The equator actually gets fewer hours of daylight than most other latitudes.
Earth is farthest from the Sun, and moving most slowly in its orbit, in early July. That’s why the
Northern Hemisphere’s spring and summer contain about eight more days than the Southern
Hemisphere’s spring and summer
Daylighting by latitude

Advantages of day lighting
The overall objective of day lighting is to minimize the amount of
artificial light and reduce electricity costs, but it can also lower HVAC
costs as well.
Electrical lighting produces a lot of heat, whereas, if properly
controlled, natural lighting generates hardly any heat at all.
For most buildings incorporating day lighting, the overall energy
savings ranges from 15 to 40 percent.
It also have an impact on the productivity and satisfaction of
employees, students, clients and retail customers.
People have a natural attraction and need for daylight. Studies
suggest that day lighting has a direct impact on well-being,
productivity and overall sense of satisfaction.
Students with the most daylight in their classrooms were found to
progress 20 percent faster on math tests and 26 percent faster on
reading tests over the course of a year.
Compared to those without windows, workers with windows and
access to natural daylight received 173 percent more white light
exposure during the work day.
They also slept on average 46 more minutes per night.
 Workers without windows reported poorer results for overall sleep
quality, sleep efficiency, sleep disturbances and daytime dysfunction.

Design tools in day lighting
Day lighting design is a creative process. It is both an art and a science.
Qualitative information and visual feedback on a given daylighting concept are usually as
important for the building designer as the quantitative figures that reflect the engineering aspect of
day lighting design.
Design tools are intended to help designers with the qualitative and quantitative elements of day
lighting design through features that commonly include:
Visualisation of the luminous environment of a given daylighting design.
Prediction of daylight factors in a space lit by diffuse daylight.
Identification of potential glare sources and evaluation of visual comfort indices.
Prediction of potential energy savings achievable through daylighting.
Control of the penetration of the sun’s rays and visualisation of the dynamic behaviour of
sunlight.
Design tools play a significant role in the decision-making process that characterises day lighting
design in a building project.
These tools support designers through the sequence of decisions that leads from original day
lighting concepts to their final implementation in a building.
These tools might even propose appropriate options.
No design tool will ever replace designers themselves, who must make the choices involved in the
day lighting design of a building.
However, these tools can accompany the designer in a creative process of devising an enjoyable
and productive built environment while saving energy through the use of day lighting.
These tools include:
Simple tools - which are most appropriate for early design phases and are best suited for basic
design problems, such as empirical equations, tables, nomograms, diagrams, and protractors.
Because decisions in the early stages of building design have a large impact on a building’s
daylight performance, simple design tools are essential to help designers navigate this phase.
Simple tools offer hints about key design parameters but cannot be used to evaluate a strategy in
detail or to model advanced systems.

Computer-based tools - which can handle advanced day
lighting systems and provide a vast variety of output (images,
visual comfort calculations, etc.)
Computer simulation and image of an office space created
using a ray-tracing technique. Top: Reference room with
double pane window Bottom: Anidolic zenithal collector
Daylight Analysis in BIM

 Physical models - which are well-known and shared by architects and other building
professionals.
 Scale models of buildings are used all over the world for daylighting design. The
physical behaviour of light is absolutely the same for a 1 m2 area in a full-size room as
it is for the corresponding 4 cm2 area of a 1:50 scale model. In other words, even the
smallest of scale models can produce very accurate results.
View of the EPFL scanning sky simulator (Switzerland) The BRE mirror sky (UK)

Behaviour of day lighting in Interior Spaces
APPLICATION IN INTERIOR SPACES -
Daylight can be induced in residential spaces to office, commercial and even hospitality interiors.
It is a key feature of sustainability and green buildings. The various techniques not only saves
energy and cost, but also make the interior sophisticated, healthy and brings aesthetic touch
Daylight can be integrated almost everywhere, in any kind of spaces. But in order to do that, we
need to determine the location of the building and the space, local climate and availability of
sunlight and other architectural factors, like placements of façade, windows, doors, skylight, roof,
materials used, technology, etc.
Areas where we can use this also depends on function of the space and the occupants’ needs.
Commercial workspaces, educational institutes, malls, retails, restaurants, etc. uses daylight
integration using facades, windows and glass roofs. But in work spaces where there will be a lot of
uses of computers, direct sunlight is not advisable for glare issues.
Building architecture has an important role on deciding where we can use daylight techniques.
Windows and facades facing south, skylights, or sunlight portal in the middle of a building will allow
daylight access in any interior.
Daylight also should match with the lighting system analysis, where a detailed study must be
done on how much light we will receive from the sun and how much artificial lighting is applied.
LIGHTING ENTERING
THROUGH SAW TOOTHS
LIGHTING ENTERING
THROUGH SAW
TOOTHS

INSTALLATION TECHNIQUES -
WINDOWS - These are the most basic and ancient technique, which allows daylight and
ventilation. In modern days, we can implement south facing windows to utilize the most of natural
lighting. Smart solutions like automatic blinds or sensor consisting windows will only allow how
much of natural light is needed for that particular space.
FACADES - Widely used in commercial and hospitality environment and large residential spaces.
These also comes in various shapes, functions and technology according to the requirement and
location of the building. It is because the glazed facades can cause glare, privacy issues and
excessive heating inside the room if not installed properly.
SKYLIGHTS - Can be for both clear and cloudy skies. As these can not be controlled like windows
or facades using curtains, smart technology must be applied where the shade of skylight can be
remote operated and amount of light can be controlled in order to prevent unpleasant glare.
DIRECT PATHS - These are usually used in large commercial, hospitality or educational buildings,
where a daylight portal is created, which is an opening for the whole building to get access to
sunlight in each floor. Also natural sunlight can be piped and induce in other rooms.
USE OF SMART WINDOWS
Directing sunlight through
pipes to induce light

BENEFITS -
The most important benefit of using daylight is it can illuminate large part of an interior in an
uniform way, without any energy consumption . It is one of the best side of sustainability, that we
use natural energy to illuminate space in day time, or working hours to reduce almost 30-60% of
electricity use.
It reduces the use of artificial luminaries, which produce lot of heat. So the indoors are kept cool
and soothing.
Natural light is full spectrum light, which gives excellent color rendering index.
Sunlight kills many microbes and bacteria, keeping the interior environment fresh, healthy and
cheerful. This is tested and proved, that spaces where sunlight is used increase sales in commercial
places and performance in educational institutions.
Using daylight reduces a lot amount of cost which is usually spent on artificial lighting.
FACADES
SKYLIGHTS

Potentials of daylighting as an energy resource
Daylight has been recognized as a free energy and cost effective alternative to artificial lighting
for sustainable building design.
 It could also provide a more pleasant and attractive indoor environment for its good color
rendering and it matches the human visual response much better than artificial light source.
Daylight is an interest strategy for reducing energy consumption in buildings, especially for
nonresidential, which often operates in the period when there is daylighting. The correct adoption
of appropriate strategies for their use can not only reduce energy consumption, but promoting an
improvement in luminous and thermal comfort of the user.
The benefits of daylighting can be extensive, mainly because electric lighting accounts for
anywhere between 35% to 50% of electrical energy consumption in commercial buildings.

In the summertime the heat created by electric lights can cause the building to overheat. Thus,
using daylighting techniques can reduce the energy used to cool these buildings by 10-20%.For
some commercial buildings, total energy costs can be reduced by as much as 1/3 through strategic
use of daylighting technologies.
In addition to saving money, reducing the amount of electrical energy used also reduces the
amount of greenhouse gases released that are associated with the production of said energy.
The most sustainable energy technique is to conserve energy as much as possible. Passive solar
building design can aid energy conservation efforts because building design is directly related to
energy use. Passive systems are structures whose design, placement, or materials optimize the use
of heat or light directly from the sun.
Buildings with passive solar building designs naturally use the sun’s energy for free of charge
heating, cooling and daylighting. This reduces the need to consume energy from other sources and
provides a comfortable environment inside.

UNStudio Tower, Amsterdam, The Netherlands
The 21-storey UNStudio Tower forms part of the Mahler 4 urban
complex, a cluster of six buildings located in the heart of the
South Axis in Amsterdam, each one carrying the name of its
designing firm.
In general, the sustainable solutions included four features:
materials, climate, thermal glazing and energy saving
installations.
Increased window surfaces in offices
Regarding daylight, two main concepts shape the building. First, the
central voids form a vertical accent and connect the inside-outside.
 This inside-outside relationship extends the facade envelope and
turns the surface of the tower into an active medium with a profound
effect on the quality of the interior user space.
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Custom coloured glass panes are incorporated into the vertical voids, offering different identities
and light qualities to the communal spaces which surround each void in the interior. These voids
further facilitate daylight penetration deep into the voluminous 40 metre by 40 metre floor plates.
Secondly, the horizontal articulation is provided by white, aluminium
bands which wrap the tower, whilst their varying size, depth and
transparency ensure the correct balance of sun screening .
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light penetration to the interiors on all levels of the building. Additionally, the thermal
glazing of the glass panes allows for sufficient daylight penetration, whilst reducing direct
sunlight.
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SURRY HILLS LIBRARY AND COMMUNITY CENTRE, Australia
Library / Reading Room & Café
People can enjoy the morning sunlight when they
Come to this area especially in the seating area and café.
Function Area
The adjustable windows create the dynamic for the space
when
The sun in passing through .
This offers the natural movement from the shadows of all
those windows .
The eastern interior spaces such as café, reading room ,
function room and outdoor play area .
All these area need an adequate and the comfortable light because people will be in these area
almost of time while they are using the services.
The position of the areas allow space receive a good daylight in the morning and get natural
indirect light during the day time ( afternoon ) .
While people is doing activities inside the building, they will be very cozy and be able to stay
longer because natural light and natural surrounding make them feel relax .
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The southern interior space such as library
collection, reading area, play Space and meeting
room.
All spaces receive the daylight during the day,
eventhough the whole façade is opened with
glass but it does not create Glare because the are
where people using the services, it is offsetted far
from the huge Glass window, so the light will be
diffused By the glass wall and the plant, then offer
The best natural light for people eyes.
The designers provided the plant in between the outside and inside, this could reduce the
Brightness from the natural light and heat from outside.
Moreover, when people look at green colour from the tree, they can relax their eye because
Colour vision is a result of cone cells.
People with normal vision have 3 cone cell types : red, green, blue, therefore their eye work less
To perceive colour.
OUT DOOR PLAY SPACE
No need the artificial light to illuminate this space, kids can enjoy the toys
with natural sand and light which is the best light for their eyes .
MATERIAL AND FINISHES
The bright ceiling, white wall, white furniture, dark floor
They all goes well with both natural and artificial light.
Most of them are natural tone colours and matt surfaces
So they do not create strong contrast and glare in the
space.
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BIBILIOGRAPHY
https://www.slideshare.net/azramaliha22/integrating-daylight-in-interiors
https://89114mdeslightingstudio1nilubon.wordpress.com/2015/03/26/lighting-
studio-week-5/
https://www.unstudio.com/en/page/8821/study-daylight-in-unstudio-
architecture
https://www.dezeen.com/2010/09/22/unstudio-tower-by-unstudio/
https://facades.lbl.gov/sites/default/files/Downloads/daylighting-c6.pdf
https://sigearth.com/the-benefits-of-daylighting-in-your-building/
National Lighting Code (guidelines)
https://energyeducation.ca/encyclopedia/Daylighting
https://www.semanticscholar.org/paper/T50-D.2-Daylighting-and-lighting-
retrofit-to-reduce-Dubois-
Gentile/bcfff1f3e0cd970705e5fd4eb70f34f08466a722/figure/1
https://www.sciencedirect.com/science/article/pii/S1110016817300911

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