1-s2 0-S0038092X17305790-main

Prévia do material em texto

Solar Energy 155 (2017) 679–697
Contents lists available at ScienceDirect
Solar Energy
journal homepage: www.elsevier .com/locate /solener
The study of effective factors in daylight performance of light-wells with
dynamic daylight metrics in residential buildingsq
http://dx.doi.org/10.1016/j.solener.2017.07.005
0038-092X/� 2017 Elsevier Ltd. All rights reserved.
q This article is retrieved from the Phd thesis of Amin alah Ahadi, in title ‘The
Optimization Of Light wells through Integrating of Day-Lighting and Passive Stack
Ventilation Systems at Deep-Plan Buildings in Residential Complex- Case study:
Tehran’ in Art University of Isfahan, School of Architecture and Urban Design,
Isfahan, Iran.
⇑ Corresponding author at: Assistant Professor at Faculty of Architecture &
Urbanism, Art University of Isfahan, Isfahan, Iran.
E-mail addresses: ahadi6688@yahoo.com, a.ahadi@aui.ac.ir (A.A. Ahadi),
saghafi@aui.ac.ir (M.R. Saghafi), m-tahbaz@sbu.ac.ir (M. Tahbaz).
Amin Alah Ahadi a, Mahmoud Reza Saghafi b,⇑, Mansoureh Tahbaz c
a Ph.D student of Architecture, Art University of Isfahan, School of Architecture and Urban Design, Isfahan, Iran
bAssistant Professor at Faculty of Architecture & Urbanism, Art University of Isfahan, Isfahan, Iran
cAssociate Professor at Shahid Beheshti University, Department of Architecture, Tehran, Iran
a r t i c l e i n f o
Article history:
Received 16 August 2016
Received in revised form 21 June 2017
Accepted 3 July 2017
Available online 12 July 2017
Keywords:
Light-wells
Daylight performance
Dynamic daylight metrics
Residential buildings
a b s t r a c t
Increasing housing demand and the precious value of city land have caused to the construction of multi-
storey, deep-plan and compact buildings. Architectural design needs to provide the appropriate penetra-
tion of daylight and ventilation into the deep-plan buildings. Therefore further researches are necessary
in the field of natural lighting and ventilation systems. Light-well is an architectural daylight system to
deep-plan building which is widely used in the residential buildings of the case study of this research
(Tehran, Iran). In this study, effective factors in daylight performance of light-wells are investigated with
dynamic daylight metrics. In this research, the continuous daylight autonomy (DAcon) is utilized for eval-
uating of annual illuminance for attached rooms to light-well.
The main goal of this research is to estimate the effect of some affecting variables on the daylighting
performance of light-wells (the area and horizontal section form, the optimal height of the light-well, ori-
entation variation and the slope of light-well surrounding wall) to provide suggestions for better utiliza-
tion of light-wells in residential building. 352 computer simulations using Daysim software have been
conducted to assess the expressed variables. Also, Autodesk Ecotect software has been used as graphical
user interfaces for Daysim. The findings of this study show the better daylighting performance of cylin-
drical light-wells compared with the common square light-well in Tehran. Also, the optimal height of dif-
ferent types of light-wells in residential buildings has been suggested with regards to the adequate
daylight autonomy (DA) in connected rooms to light-well. The results of this study show that the increas-
ing of the suggested optimal height for different types of light-wells is possible with increasing the slop of
walls of light-wells and the window size in the lower floors.
� 2017 Elsevier Ltd. All rights reserved.
1. Introduction
Population growth in big cities and the precious value of city
land, have led to the construction of high-rise, deep-plan and com-
pact buildings. Consequently, maintaining the high skin to volume
ratio that allows daylight to reach most building spaces is inappli-
cable. Deep plan building is a building in which the horizontal dis-
tance from the external wall is many times greater than the floor to
floor height. Useful daylight penetrates about 5–7.5 m (2–2.5 times
the floor-to-ceiling height) inside a building from the windows
(RIBA, 2007).
Three new strategies have been developed to bring daylight
deeper into the new building forms and to control and distribute
direct sunlight. One of them is improving the conventional tech-
niques (this strategy seeks to improve the conventional daylighting
technique capabilities to deliver daylight by using new optical
materials, elements and devices, such as overhangs, light shelves,
blinds, screens, and light filters), the other is developing new glaz-
ing systems (the glazing technologies are mainly concerned with
enhancing the thermal insulation properties, and thus allow more
glazing area to be applied in order to admit as much daylight as
possible while preventing transmission of as much solar heat as
possible). And the third strategy is inventing of innovative day-
lighting systems which is more concerned about delivering day-
light into remote and windowless spaces in buildings and aims
http://crossmark.crossref.org/dialog/?doi=10.1016/j.solener.2017.07.005&domain=pdf
http://dx.doi.org/10.1016/j.solener.2017.07.005
mailto:ahadi6688@yahoo.com
mailto:a.ahadi@aui.ac.ir
mailto:saghafi@aui.ac.ir
mailto:m-tahbaz@sbu.ac.ir
http://dx.doi.org/10.1016/j.solener.2017.07.005
http://www.sciencedirect.com/science/journal/0038092X
http://www.elsevier.com/locate/solener
680 A.A. Ahadi et al. / Solar Energy 155 (2017) 679–697
to maximize the utilization of the available daylight (Mayhoub,
2014).
In any strategy, newly developed devices and optical materials
are used. The produced daylighting systems additionally con-
tribute in conserving energy, protecting the environment, and
enhancing building users, productivity and well-being.
Daylighting systems without shading (such as light pipes and
light wells) are designed to redirect daylight to areas away from
a window or skylight opening. They may or may not block direct
sunlight (IEA, 2010). Increased housing demand and land prices
have caused to the construction of multi-storey residential build-
ings in the case study of this research (Tehran, Iran) and widely
application of light-wells in these buildings. In this study, effective
factors in daylight performance of light-wells are investigated with
dynamic daylight metrics and the design principles to optimize the
daylight performance of light-wells are suggested.
2. Literature review
The related statistics to energy consumption in different coun-
tries show that artificial lighting is one of the highest consumers
of electrical energy. The global residential lighting electricity con-
sumption in 2005 was estimated by the IEA to be 811 TW h which
is 18.3% of residential electricity consumption (IEA, 2006). The
energy consumption for lighting varies greatly among different
countries. For example, in the US, Energy Information Administra-
tion (EIA) estimates that in 2016, about 279 billion kW h of elec-
tricity were used for lighting by the residential sector and the
Fig. 1. The examples of l
commercial sector in the United States. This was about 10% of
the total electricity consumed by both of these sectors and about
7% of total U.S. electricity consumption. Residential lighting con-
sumption was about 129 billion and the commercial sector, which
includes commercial and institutional buildings, and street and
highway lighting, consumed about 150 billion kW h for lighting
(EIA, 2017). In Iran (The location of case study of this research),
30% of the total residential electricity consumption (in the year
2012), is linked to artificial lighting which is almost 12% higher
than the global average (Iran Electric Power Industry Statistics,
2014). Therefore, electric lighting is one area where significant sav-
ings energy consumption is possible.
The studies have shown that 40% energy savings (In relation to
electric lighting energy) could be obtained by using appropriate
daylight (Dubois and Blomsterberg, 2011). In another study, a table
of lightingenergy savings has been reported by space type (private
office, open office and classroom) and controls type (multilevel
switching, manual dimming, daylight harvesting and occupancy
sensors). Their findings say that the lighting energy savings ranges
from 6% to 70% across eleven categories of space types and controls
types. It has been reported that integration of artificial lighting
with the use of energy efficient luminaires and architectural day-
light systems can help reduce the electrical energy demand and
improve vision efficiency of the occupants (Kumar Soori and
Moheet, 2013). Also, several studies have shown the positive
effects of daylight on improving human perception and mood
and also comfortable feeling (Kellert et al., 2008; Wasserman,
2011).
ight-wells in Tehran.
A.A. Ahadi et al. / Solar Energy 155 (2017) 679–697 681
In this research, light-well as an architectural daylight system
to deep-plan building is investigated. There are few studies about
the use of light-wells for daylighting. These studies have been con-
Fig. 2. The monthly average, high and low temperature of Tehran retrieved from Climate
Airport (Tehran, Iran) weather station from 1996 to 2012.
Fig. 3. Cloud cover of Tehran retrieved from Climate Consultant 6.0 software based on th
from 1996 to 2012.
ducted based on common static metrics (illuminanation level and
daylight factor). Considering the actual climate (the quantity and
character of daily and seasonal variations of daylight) for a given
Consultant 6.0 software based on the historical records of Mehrabad International
e historical records of Mehrabad International Airport (Tehran, Iran) weather station
682 A.A. Ahadi et al. / Solar Energy 155 (2017) 679–697
building site and a more accurate study, dynamic daylighting met-
rics are needed (Reinhart et al., 2006). Also, some variables affect-
ing on the performance of light-wells (such as light wells form) has
not been considered. In the following effective factors on the day-
light performance of light-wells and dynamic daylight metrics are
reviewed.
Table 1
The affecting variables on daylighting performance of light-wells and the steps of researc
Examined variables
Step 1
The horizontal section form
Step 2
The optimal height of the light-well (the number of
connected floors to light-well)
Step 3
Orientation variation
Step 4
The slope of light-well surrounding wall
(the vertical section form)
Table 2
The average value of DA300 and DA150 on the grid placed at height of work in attached r
different floors and directions.
Square light-well (1 m * 1 m)
South-facing
room
East-facing
room
West-facing
room
North-facing
room
DA300 DA150 DA300 DA150 DA300 DA150 DA300 DA150
Floor 1 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00%
Floor 2 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00%
Floor 3 0.04% 0.07% 0.04% 0.07% 0.04% 0.07% 0.04% 0.07%
Floor 4 0.13% 0.21% 0.15% 0.22% 0.17% 0.22% 0.14% 0.21%
Floor 5 0.98% 2.08% 1.11% 2.14% 1.12% 2.20% 1.03% 2.08%
Floor 6 11.1% 18.3% 12.6% 18.8% 12.7% 19.4% 11.7% 18.4%
Floor 7 74.2% 89.9% 75.9% 90.9% 75.7% 90.7% 76.5% 91.3%
2.1. Light-wells and the effective factors on their daylight performance
Light-well is a shaft within a building, open to the outer air at
the top, used to admit daylight and air through windows opening
onto the shaft (McGraw-Hill Dictionary of Architecture and
Construction, 2003). Also, light-well is defined as a small courtyard
h.
Description
Comparing the daylighting performance of light-well in square
(the common form) and curve horizontal section form in 4
different plan size
Determining the optimal height of light-wells for each of
dimensions of light-well
Estimating the daylighting performance of light-well in each
geographic direction for each type of light-wells in step 1
Changing the slope of light-well wall from 0� to 9� in 3� increment
oom to the square light well (1 m * 1 m) and cylindrical light well (area: 1 sq. m) in
Cylindrical light-well (area: 1 sq. m)
South-facing
room
East-facing room West-facing
room
North-facing
room
DA300 DA150 DA300 DA150 DA300 DA150 DA300 DA150
0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00%
0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00%
0.05% 0.09% 0.05% 0.1% 0.05% 0.09% 0.05% 0.1%
0.13% 0.31% 0.15% 0.32% 0.15% 0.33% 0.14% 0.33%
1.03% 1.99% 1.17% 2.05% 1.18% 2.10% 1.04% 2.21%
13.1% 19.5% 11.3% 17.9% 11.6% 18.3% 14.8% 21.1%
80.7% 91.3% 82.54% 92.62% 82.46% 92.58% 84.33% 93.60%
A.A. Ahadi et al. / Solar Energy 155 (2017) 679–697 683
commonly placed in large buildings to admit daylight into interior
areas not exposed to an open view (Illustrated Dictionary of
Architecture, 2012). In other definition, light-well has been defined
as a top-lit atrium without a roof separating the atrium from sur-
rounding spaces. This has significant implications for ventilation
and thermal performance of the connected spaces. In daylighting
function the external variant of the light-well behaves like a court-
yard with a very large height to width ratio (Baker and Steemers,
2014). A light-well is a daylighting system that brings daylight
(including sunlight and skylight) to the lower floors in a multi-
storey building and has a similar function to a light pipe or an
atrium, but its size is medium (Su et al., 2010). The working mech-
anism of the light-well depends on collecting daylight and trans-
ferring light by means of multi reflection down to lower spaces.
Fig. 1 shows examples of these light-wells in Tehran.
In a study to improve the daylight efficiency of light wells as an
additional light source in an energy conscious multi-storey resi-
dential building, three types of innovative light-guiding systems
with several variations were devised. The illuminance measure-
Table 3
The average value of DA300 and DA150 on the grid placed at height of work in attached r
different floors and directions.
Square light well (2 m * 2 m)
South-facing
room
East-facing
room
West-facing
room
North-facing
room
DA300 DA150 DA300 DA150 DA300 DA150 DA300 150
Floor 1 0.03% 0.07% 0.03% 0.07% 0.03% 0.07% 0.03% 0.08%
Floor 2 0.86% 2.01% 0.87% 2.03% 0.87% 2.02% 0.87% 2.03%
Floor 3 1.75% 3.12% 1.77% 3.13% 1.76% 3.13% 1.77% 3.14
Floor 4 6.15% 10.4% 6.16% 10.4% 6.14% 10.3% 6.25% 10.5%
Floor 5 16.3% 25.7% 16.5% 25.8% 16.3% 25.6% 16.7% 26.0%
Floor 6 43.2% 60.1% 44.0% 60.1% 43.4% 60.0% 44.6% 61.2
Floor 7 96.2% 98.9% 96.9% 99.1% 96.5% 98.9% 95.8% 98.8
Table 4
The average value of DA300 and DA150 on the grid placed at height of work in attached r
different floors and directions.
Square light well (3 m * 3 m)
South-facing
room
East-facing
room
West-facing
room
North-facing
room
DA300 DA150 DA300 DA150 DA300 DA150 DA300 DA15
Floor 1 1.66% 2.98% 1.65% 2.87% 1.60% 2.76% 1.70% 2.97%
Floor 2 4.77% 8.32% 4.75% 8.02% 4.60% 7.71% 4.89% 8.30%
Floor 3 11.1% 18.1% 11.2% 18.4% 11.7% 19.3% 11.2% 18.3%
Floor 4 17.4% 27.2% 18.4% 27.8% 18.6% 28.2% 19.5% 28.9%
Floor 5 42.3% 59.7% 44.8% 61.1% 45.4% 61.9% 47.5% 63.4%
Floor 6 67.0% 82.5% 70.4% 83.6% 71.9% 84.1% 73.5% 85.2%
Floor 7 98.1% 99.4% 98.43 99.59% 98.27% 99.34% 97.4% 99.28
Table 5
The average value of DA300 and DA150 on the grid placed at height of work in attached ro
different floors and directions.
Square light well (4 m * 4 m)
South-facing
room
East-facing room West-facing
room
North-facing
room
DA300 DA150 DA300 DA150 DA300 DA150 DA300 DA150
Floor 1 6.52% 11.0% 6.71% 11.30% 6.35% 10.78% 6.60% 11.1%
Floor 2 11.3% 18.1% 11.62% 18.59% 11.0% 17.73% 11.43% 18.26
Floor 3 20.5% 31.3% 20.89% 32.06% 20.95% 31.14% 21.71% 32.75
Floor 4 36.9% 53.0% 37.46% 53.26% 37.63% 53.38% 39.82% 54.02
Floor 5 63.0% 79.4% 64.1% 79.9% 64.3% 80.1% 65.9% 81.1%
Floor 6 88.1% 95.8% 89.29% 96.09% 90.09% 96.26% 90.58% 96.45
Floor 7 96.9% 99.0% 98.94% 99.8% 98.1% 99.7% 95.3% 98.6%
ments on the scale models were carried out under an artificial
sky. The measurements showed that the best results were obtained
by using light-well with wide upper and narrow lower part into
which the reflecting wall was placed(Kristl and Krainer, 1999).
In this research, the area of light-well and the number of floors
are considered identical and some changes are investigated on ver-
tical section form. Also, the criterion for investigating daylighting
performance of light-well was daylight factor (DF) which is accept-
able only in the regions with overcast sky.
In another study, in order to assess some criteria for light-well
design, a parametric study to assess the effectiveness of light-well
design was conducted. In this research RADIANCE simulation mod-
els was used to perform the parametric variations and The criteria
which were used for the daylighting analysis were as follows:
Changing the reflectance of the materials from 0.3 to 0.9 in 0.1
increments, changing the width of the windows from 1 m to 2 m
in 20cm increment, changing the dimensions of the light-well from
4 m to 7 m in 50cm increment and changing the orientation of the
whole building from 0� to 180� in 45� increment (Ahmed and
oom to the square light well (2 m * 2 m) and cylindrical light well (area: 4 sq. m) in
Cylindrical light well (area: 4 sq. m)
South-facing
room
East-facing
room
West-facing
room
North-facing
room
DA300 DA150 DA300 DA150 DA300 DA150 DA300 DA150
0.04% 0.07% 0.04% 0.07% 0.04% 0.07% 0.04% 0.08%
1.01% 2.23% 1.04% 2.30% 1.05% 2.28% 1.05% 2.31%
% 2.11% 3.65% 2.12% 3.67% 2.12% 3.66% 2.13% 3.69%
7.58% 12.8% 7.62% 12.9% 7.68% 12.9% 7.72% 13.0%
20.1% 30.9% 20.4% 30.9% 20.5% 31.0% 20.7% 31.3%
% 52.2% 69.6% 53.2% 69.5% 53.4% 69.6% 55.1% 71.2%
% 97.5% 98.6% 98.1% 98.9% 97.8% 98.7% 97.1% 98.4%
oom to the square light well (3 m * 3 m) and cylindrical light well (area: 9 sq. m) in
Cylindrical light well (area: 9 sq. m)
South-facing
room
East-facing
room
West-facing
room
North-facing
room
0 DA300 DA150 DA300 DA150 DA300 DA150 DA300 DA150
2.08% 3.87% 2.07% 3.74% 2.00% 3.58% 2.13% 3.86%
6.99% 12.3% 6.97% 11.92% 6.73% 11.4% 7.17% 12.27%
15.4% 24.1% 15.4% 24.6% 16.3% 26.3% 15.5% 24.5%
24.6% 37.3% 26.0% 38.1% 26.2% 38.6% 27.5% 39.6%
54.2% 71.2% 54.7% 71.4% 55.0% 71.7% 60.8% 75.6%
74.4% 89.7% 78.2% 90.9% 78.8% 91.5% 81.7% 92.7%
% 98.7% 99.6% 98.9% 99.7% 98.8% 99.4% 98.1% 99.2%
om to the square light well (4 m * 4 m) and cylindrical light well (area: 16 sq. m) in
Cylindrical light well (area: 16 sq. m)
South-facing
room
East-facing room West-facing
room
North-facing
room
DA300 DA150 DA300 DA150 DA300 DA150 DA300 DA150
8.47% 14.4% 8.73% 14.8% 8.25% 14.1% 8.58% 14.4%
% 13.9% 22.1% 14.30% 22.71% 13.53% 21.63% 14.0% 22.2%
% 24.7% 37.2% 25.2% 38.0% 25.2% 37.0% 26.1% 38.9%
% 43.3% 60.0% 43.96% 60.31% 44.16% 60.44% 45.08% 61.16%
68.7% 83.8% 69.8% 84.3% 70.1% 84.5% 71.8% 85.6%
% 90.4% 96.5% 91.5% 96.8% 92.5% 97.0% 92.9% 97.2%
97.1% 99.1% 99.14% 99.95% 97.37% 99.80% 95.57% 98.70%
684 A.A. Ahadi et al. / Solar Energy 155 (2017) 679–697
Nassar, 2014). Although this research is conducted to office build-
ings in Egypt with mostly clear sky, the simulations are conducted
under overcast sky. Also, because of using static daylight metrics, it
is needed to define a specified period of time to simulations that is
ignored in this research. In addition, other important criteria could
be investigated in daylighting performance of light-wells.
Freewan et al., investigated some variables affecting on light-
well performance. The variables were related to light-well area,
height, top (collection unit) shape and orientation. Simulations
were conducted in Irbid, Jordan by Radiance lighting simulation
program based on static daylighting metric in 2 days in March
and June at 2 h (10 am and 12 pm). The results showed some better
scenario for providing better illuminance levels in lower spaces in
a four-flour building (Freewan et al., 2014). This research is con-
ducted in some limited time of year in a south-facing model of res-
idential building with 4 floors and its main criterion for deciding
about variables is the illuminance levels of one point in 0.5 m dis-
tance from window. Compared with the results from Freewan
et al., in this current work, besides determining the optimal height
of each type of light-wells using dynamic daylight metrics (with
more accuracy than static metrics), some suggestions for increas-
ing the optimal height of light-wells to 7 floors are presented
and evaluated. The variables of daylighting performance of light-
wells are investigated in all orientations and different area of
light-wells. Also, some different horizontal and vertical sections
forms of light-well are investigated.
In other work, Acosta et al., to analyze the performance of a type
of light-well skylights under overcast sky conditions, determining
the daylight factors and luminous distribution produced inside a
room evaluated the size and height/width ratio of the skylight,
reflection index of the skylight and height, width and length of
the room (Acosta et al., 2013). The results of this research are use-
ful for some types of deep skylights connected to only one room
and the regions with overcast sky.
Other aspect of utilizing light wells is natural ventilation. Light-
well or deep courtyard is commonly used in high-rise deep layout
plan buildings and are usually implemented to admit daylight and
Table 6
The average value of DA300 and DA150 on the grid placed at height of work in attached room
well.
The slope angles of light-well wall
0�
South-facing
room
East-facing
room
West-facing
room
North-facing
room
DA300 DA150 DA300 DA150 DA300 DA150 DA300 DA150
Floor 1 6.15% 10.4% 6.16% 10.4% 6.14% 10.3% 6.25% 10.5%
Floor 2 16.3% 25.7% 16.5% 25.8% 16.3% 25.6% 16.7% 26.0%
Floor 3 43.2% 60.1% 44.0% 60.8% 43.4% 60.5% 44.6% 61.2%
Floor 4 96.2% 98.9% 96.9% 99.1% 96.5% 98.9% 95.8% 98.8%
Table 7
The average value of DA300 and DA150 on the grid placed at height of work in attached room
well.
The slope angles of light-well wall
6�
South-facing
room
East-facing room West-facing
room
North-facing
room
DA300 DA150 DA300 DA150 DA300 DA150 DA300 DA150
Floor 1 9.28% 15.08% 9.31% 15.28% 9.28% 15.05% 9.53% 15.42
Floor 2 28.00% 40.60% 28.61% 40.78% 28.52% 41.42% 29.06% 41.78
Floor 3 56.95% 73.39% 58.00% 74.39% 57.21% 74.28% 60.82% 76.12
Floor 4 98.02% 99.71% 98.73% 99.9% 98.32% 99.71% 97.31% 99.48
to induce natural ventilation into targeted spaces (Farea et al.,
2015). There are some studies investigated the effect of the heat
magnitude and its source position, air velocity and void size on
the airflow rate, air temperature and airflow pattern in light-
wells (Farea et al., 2015; Kotani et al., 1997, 1996, 2003). This
research is focused on the daylighting aspects of light-well. In
future research the relationship between the variables of daylight-
ing and other aspect of utilizing light-wells will be investigated.
2.2. Dynamic daylight metrics
Daylight is the combination of sunlight, skylight and reflected
light from the ground. Considering the variety of issues involved
in good daylighting design, determining a quantifiable metric or
set of metrics that can define good daylighting is a complex task
(Architectural Energy Corporation, 2006). The desired purpose of
a metric is to combine various factors that will successfully predict
better performance outcomes (Mardaljevic et al., 2009). Illumina-
nation level and daylight factor (the ratio of indoor illuminance
and outdoor illuminance in overcast sky condition, which can be
measured for a specific point or for an average of a space (Baker
and Steemers, 2002)) are the most common static metrics used
for studying physical models to test daylighting designs. However,
considering the actual climate (the quantity and character of daily
and seasonal variations of daylight) for a given building site
together with irregular meteorological events, dynamic daylight-
ing performance metrics are needed (Reinhart et al., 2006). Car-
lucci et al., have collected 34 visual comfort indices from
previous researches. Although the aforementioned factors are pos-
sibly correlated with each other, an index usually focuses onlyon
one item. In the last two decades, research for identifying reliable
metrics for evaluating visual comfort has been addressed mostly to
glare and the amount of light. Daylight Autonomy (DA) and Useful
Daylight Illuminance (UDI) have been proposed as dynamic met-
rics in order to amount of daylight (Carlucci et al., 2015).
Daylight autonomy (DA) is a climate-based metrics defined as
the percentage of the occupied hours of the year when the mini-
to the square light well (2 m * 2 m) with the 0� and 3� slope angles of the walls of light
3�
South-facing
room
East-facing room West-facing
room
North-facing
room
DA300 DA150 DA300 DA150 DA300 DA150 DA300 DA150
8.65% 14.06% 8.80% 14.26% 8.83% 14.35% 8.97% 14.39%
26.49% 37.96% 26.81% 38.10% 26.64% 37.98% 27.14% 38.41%
53.06% 69.81% 54.41% 70.56% 54.4% 71.84% 56.64% 72.34%
97.53% 99.30% 98.20% 99.71% 97.83% 99.4% 97.75% 99.28%
to the square light well (2 m * 2 m) with the 6� and 9� slope angles of the walls of light
9�
South-facing
room
East-facing room West-facing
room
North-facing
room
DA300 DA150 DA300 DA150 DA300 DA150 DA300 DA150
% 11.29% 17.46% 11.44% 17.73% 11.71% 17.88% 11.90% 17.99%
% 32.17% 43.80% 32.27% 44.38% 32.20% 44.62% 33.03% 44.78%
% 61.33% 77.09% 62.68% 78.31% 63.67% 78.99% 64.86% 79.44%
% 98.89% 99.84% 98.90% 99.94% 98.89% 99.81% 97.96% 99.51%
A.A. Ahadi et al. / Solar Energy 155 (2017) 679–697 685
mum illuminance threshold is met by daylight alone (Reinhart and
Walkenhorst, 2001). The continuous daylight autonomy (DAcon)
and daylight autonomy max (DAmax) are two modification of day-
Fig. 4. comparing some results of simu
light autonomy. The first one allows for fractional levels of daylight
illuminance to be counted. This method attributes the partial con-
tribution of daylight to illuminance when it is lower than the min-
lation of horizontal section form.
686 A.A. Ahadi et al. / Solar Energy 155 (2017) 679–697
imum required illuminance level while the latter one only counts a
point as day lit if the daylight illuminance exceeds the required
illuminance for the given time (Xu and Yuehong, 2015). The DAcon
level into 80–100%, 60–80% and 40–60% is considered as excellent,
good and adequate daylight design (Rogers, 2006).
Fig. 5. The average value of DA300 and DA150 on the grid placed at height of work in atta
Fig. 6. The average value of DA300 and DA150 on the grid placed at height of work in atta
In this research DAcon is utilized. This method gives credit to
spaces that are not fully saturated with daylight, but do receive
some daylight contribution. The previous related studies were con-
ducted using the static daylight metric in some limited time of year
(For example, Freewan et al., simulated some suggested options
ched room to the square and cylindrical light-wells in different directions in floor 1.
ched room to the square and cylindrical light-wells in different directions in floor 2.
A.A. Ahadi et al. / Solar Energy 155 (2017) 679–697 687
using Radiance in March and June under clear sky at 10 am and
12 pm in their study). In current work the intended variables have
been investigated based on daylight Autonomy (DA) using EPW file
of Tehran (Weather data file saved in the standard EnergyPlus for-
Fig. 7. The average value of DA300 and DA150 on the grid placed at height of work in atta
Fig. 8. The average value of DA300 and DA150 on the grid placed at height of work in atta
mat; used by EnergyPlus energy simulation software, developed by
the U.S. Department of Energy; contains weather data that is used
for running hourly energy usage simulations in all days of year) in
Daysim.
ched room to the square and cylindrical light-wells in different directions in floor 3.
ched room to the square and cylindrical light-wells in different directions in floor 4.
688 A.A. Ahadi et al. / Solar Energy 155 (2017) 679–697
3. Methodology
The main goal of this research is to estimate the effect of some
affecting variables on the daylighting performance of light wells
Fig. 9. The average value of DA300 and DA150 on the grid placed at height of work in atta
Fig. 10. The average value of DA300 and DA150 on the grid placed at height of work in atta
(the area, height, orientation, the horizontal and vertical section
form of light well) to provide suggestions for better utilization of
light wells in residential building. This research is focused on res-
idential building in Tehran.
ched room to the square and cylindrical light-wells in different directions in floor 5.
ched room to the square and cylindrical light-wells in different directions in floor 6.
A.A. Ahadi et al. / Solar Energy 155 (2017) 679–697 689
Tehran features a semi-arid climate (Koppen climate classifica-
tion: BSk). Tehran’s climate is largely defined by its geographic
location (35�4104600N 51�2502300E). It can be generally described
as mild in the spring and autumn, hot and dry in the summer,
and cold in the winter. Figs. 2 and 3 show monthly average, high
and low temperature and cloud cover types of Tehran. Fig. 3 shows
mostly clear sky in Tehran.
According to literature review, the affecting variables on day-
lighting performance of light-wells and the steps of research are
defined in Table 1. Also, the role of increasing the windows area
of attached rooms to lower floors of light-well in increasing DA
level and the optimal height of light-wells is evaluated. With
regards to required illuminance levels for residential spaces, in this
research DA300 (daylight autonomy with respect to 300 lx optimal
lighting) and DA150 (daylight autonomy with respect to 150 lx opti-
mal lighting) are considered to investigate the daylight quantity in
connected spaces to light-well. According to CIBSE (Chartered
Institute of Building Services Engineers) the required illuminance
levels for residential spaces vary from 100 to 300 lx (lounge:
100–300 lx, kitchens: 150–300 lx, bathrooms: 150 lx, toilets:
100 lx) (CIBSE, 2002).
The quantity of daylight is evaluated in a defined model (a room
with 3 m width, 4 m depth and 3 m height, attached to different
types of light well) by computer simulations using Daysim soft-
ware. The reflectance of the walls of light-well and rooms, the size
of room window and the transmittance of the window were iden-
tical in all simulations. The reflectance of the walls of light-well is
considered 0.8 (equal to the high reflectance materials). Also, the
transmittance of the window is considered 0.7 related to clear dou-
ble glazing window and the size of windows in all models is 1 � 2
(1 m width and 2 m height).
In all simulations to calculate DA300 and DA150 in the examined
rooms, a two-dimensional calculation grid is defined inside the
rooms. This grid is composed of cells or nodes which are daylight
Fig. 11. The average value of DA300 and DA150 on the grid placed at height of work in atta
measurement sensors. DA300 and DA150 are calculated in all cells
or nodes of defined grid in all hours of the days of year by Daysim
software using EPW file of Tehran. The geographical conditions and
cloud cover of Tehran are considered in EPW file used by Daysim
software. Finally, the average of DA values of all cells or nodes is
considered as DA300 and DA150 in that examined room.
Lighting simulation tools, developed quickly during the last few
decades, are reliable ways for simulating the complex lighting
environment. There are not many software that allow performing
static and dynamic simulations at the same time and not all of
them have been extensively tested to assess their degree of relia-
bility. Many software are based on the Radiance simulation engine
and among them Daysim is certainly the most widespread and
studied one (Bellia et al., 2015). Daysim is a Radiance-based
dynamic daylight simulation program which uses the Radiance to
calculate annual illuminance and luminance profiles based on local
climate data and daylight coefficient. The hourly schedules for
occupancy, electric lighting usage and state of blinds from Daysim
could be readas input to other energy simulation software such as
Energy-Plus (Reinhart and Wienold, 2011).
4. Results and discussion
In this research, 352 simulations have been conducted to assess
the variables expressed in Table 1. Each of highlighted cells in
Tables 2–7 shows the result of one simulation (both of DA300 and
DA150 are obtained from one simulation in each case, e.g. south-
facing room in floor 1 in cylindrical light-well with 1 m2 area). At
the beginning of the simulation process, the simulations have been
conducted on a 1-floor model of each type of light-wells. In each
step one floor has been added to models and the simulations have
been continued up to the floor in which DA300 and DA150 are very
low. In this regard, the simulations of square and cylindrical light-
wells with 1 and 4m2 area have been conducted up to 4 floors and
ched room to the square and cylindrical light-wells in different directions in floor 7.
690 A.A. Ahadi et al. / Solar Energy 155 (2017) 679–697
the simulations of light-wells with 9 and 16 m2 have been done up
to 6 and 7 floors. In the following, to compare DA in examined
rooms in all floors of the different types of light-wells with each
Fig. 12. Some simulations to assess the optim
other, the simulations of all types of light-wells have been done
up to 7 floors like light-wells with 16 m2 area. Tables 2–5 show
the result of these simulations. The simulations of changing the
al height for different types of light-wells.
A.A. Ahadi et al. / Solar Energy 155 (2017) 679–697 691
slope angles of light-well wall (Tables 6 and 7) are conducted in a
4-floors model because in these cases there isn’t enough space in
light-well to continue sloped wall to the lower floors.
4.1. The results of examination of horizontal section form
In this study the daylighting performance of light-well in square
(the common form) and cylindrical form has been compared in 4
different plan dimensions and forms and in different floors and
directions (Fig. 4). Figs. 5–11 show the results of this comparison
in charts for each of the floors.
In Figs. 4, 12, 13, 14, 19, 20 and 21, the number of visible
nodes shows the number of daylight measurement sensors or
the number of cells of defined grid. The average value shows
the average values of DA300 or DA150 in all cells of defined grid.
Also, how to the distribution of DA300 or DA150 has been shown
by the heat map in which maximum value of DA has been shown
by yellow color and its minimum is shown by blue color. The grid
legend of each figure shows exactly which color is related to dif-
ferent values of DA.
The results show that with the same area of light-well, cylindri-
cal light-wells have better daylighting performance from 0.20 (in
upper floors) to 23.25 percent (in lower floors). The cylindrical
light-wells are better especially on the lower floors and smaller
size of light-wells.
Fig. 13. One example of simulations to assess the effect of orientation of connected room
Such this simulation has been conducted to other light-wells and other floors.
4.2. The optimal height for different types of light-wells
As it is shown in Figs. 5–11, the optimal height of light-wells is
related to its dimensions in plan. The optimal height of light-wells
can be defined in the floors in which the adequate DA300/DA150
level of connected rooms to light-well is more than 40%. The
results of Table 5 show that DA300 and DA150 from the highest floor
of cylindrical light-well with the area of 16 m2 reduce gradually
from 99% to about 40% in 5 floors lower than highest floor for
DA150 and in 4 floors for DA300. So the optimal height of this cylin-
drical light-well can be considered 5 floors for the residential
spaces with appropriate light level of 150 lx and 4 floors for the
residential spaces with appropriate light level of 300 lx. Similarly,
the optimal height of other types of light-wells has been estimated
with regards to Tables 2–7. Fig. 12 shows some of these simula-
tions. Table 8 shows the optimal height of light-wells for different
types of light-wells with regards to efficient daylighting level.
4.3. The effect of orientation variation
The effect of orientation variation is investigated with regards
to the DA300/DA150 level of connected rooms to light-well in each
geographic direction in each type of light-well and in different
floors. The results of simulations show that in upper floors in which
direct sunlight can come inside the rooms, east-facing rooms have
to light-well on its daylighting performance (4 m * 4 m square light well in floor 5).
692 A.A. Ahadi et al. / Solar Energy 155 (2017) 679–697
more level of daylight autonomy. In this case, west facing and
south facing room have more annual illuminance after east-
facing rooms and daylight autonomy of the north spaces is less
than all. For example in 2 m ⁄ 2 m square light-well in the upper
floor (floor 7) the DA300 of East-facing, west-facing, south-facing
and north-facing are 96.9%, 96.5%, 96.2% and 95.8% respectively
But in floor 5 those values change to 16.5%, 16.3%, 16.3% and
16.7%. So in the lower floors, in which there is not direct sunlight,
north-facing rooms are better with a slight difference compared to
other directions. In this case, the reflected sunlight from the wall in
front of the window and the sky light are the main source of day-
lighting for rooms. Fig. 13 shows one example of these simulations.
4.4. The effect of slope of light-well surrounding walls
In order to investigate the effect of slope of light-well surround-
ing walls on annual illuminance of attached rooms to light-well in
Fig. 14. The effect of changing slope of light-well surrounding walls on the D
different floors, the slope of a square light-well walls have been
changed from 0� to 9� in 3� increment and simulations have been
conducted in different directions. The slope is measured from the
center of the light-well wall. Fig. 14 shows some parts of these sim-
ulation in which DA150 of south facing room in lowest floor has
been investigated regarding to different slope of light-well sur-
rounding wall. In this case, DA150 has changed from 10.44% to
17.46% while the slope of wall has changed from 0 degree to 9�.
Such this simulation has been conducted to others room and
orientations.
Tables 6 and 7 show the results of the average value of DA300
and DA150 on the grid placed at height of work in attached room
to the light-wells in each case. Also, Figs. 15–18 show the results
of this examination in charts for each of the floors. The results
show that with increasing the slope of light-well surrounding
walls, the annual illuminance of attached rooms to light-well
increases significantly (up 80 percent on the lower floors), espe-
A150 of a south facing room attached to square light-well in lowest floor.
Fig. 15. The average value of DA300 and DA150 on the grid placed at height of work in attached room to the square light-wells with the 0�, 3�, 6� and 9� slope angles of the walls
of light-well in floor 1.
Fig. 16. The average value of DA300 and DA150 on the grid placed at height of work in attached room to the square light-wells with the 0�, 3�, 6� and 9� slope angles of the walls
of light-well in floor 2.
A.A. Ahadi et al. / Solar Energy 155 (2017) 679–697 693
cially on the lower floors. This results show how the light-well sec-
tional shape could affect the daylight performance of the light-
well.
In the multi-storey, deep-plan and compact residential build-
ings in which further increasing the area of light-wells may not
be rational, the increasing of the optimal height of light-well is
possible with increasing the window size of the lower floors and
the slop of walls of light-wells. As mentioned in Section 4.2,
the optimal height of 4 m ⁄ 4 m square light-well is 4 floors for
the residential spaces with appropriate light level of 150/300 lx.
Fig. 17. The average value of DA300 and DA150 on the grid placed at height of work in attached room to the square light-wells with the 0�, 3�, 6� and 9� slopeangles of the walls
of light-well in floor 3.
Fig. 18. The average value of DA300 and DA150 on the grid placed at height of work in attached room to the square light-wells with the 0�, 3�, 6� and 9� slope angles of the walls
of light-well in floor 4.
694 A.A. Ahadi et al. / Solar Energy 155 (2017) 679–697
Figs. 19–21 show how to increase the DA150 and DA300 to increase
the optimal height of this light-well to 7 floors for the residential
spaces with appropriate light level of 150 lx and 6 floors for the
residential spaces with appropriate light level of 300 lx. For this
purpose the size of windows is increased to 2 ⁄ 2 m from 1 ⁄ 2 m
and the slop of walls of light-wells is increased to 9� from 0�. In this
Fig. 20. Increasing the DA150 and DA300 with increasing the size of windows to 2 * 2 m from 1 * 2 m and the slop of walls of light-wells to 9� from 0� in the floor minus 6.
Fig. 19. Increasing the DA150 and DA300 with increasing the size of windows to 2 * 2 m from 1 * 2 m and the slop of walls of light-wells to 9� from 0� in the floor minus 7.
A.A. Ahadi et al. / Solar Energy 155 (2017) 679–697 695
Fig. 21. Increasing the DA150 and DA300 with increasing the size of windows to 2 * 2 m from 1 * 2 m and the slop of walls of light-wells to 9� from 0� in the floor minus 5.
Table 8
The optimal height of light-wells for different types of light-wells with regards to
efficient daylighting level.
Types of light-well The optimal height
DA300 DA150
Cylindrical light well (area: 16 sq. m) 4 floors 5 floors
Square light well (4 m * 4 m) 4 floors 4 floors
Cylindrical light well (area: 9 sq. m) 3 floors 4 floors
Square light well (3 m * 3 m) 3 floors 3 floors
Cylindrical light well (area: 4 sq. m) 2 floors 2 floors
Square light well (2 m * 2 m) 2 floors 2 floors
Cylindrical light well (area: 1 sq. m) 1 floors 1 floors
Square light well (1 m * 1 m) 1 floors 1 floors
696 A.A. Ahadi et al. / Solar Energy 155 (2017) 679–697
way, the average value of DA150 has increased from 11% to about
40% (adequate level) in the floor minus 7, from 18.16% to 54.28%
in the floor minus 6 and from 31.33% to 69.65% in the floor minus
5. Also, the changes of DA300 are shown in Figs. 19–21.
5. Conclusions
This research is focused on daylighting performance of light-
wells in residential building in Tehran. The impact of area, height,
orientation, the horizontal and vertical section form of light-well
on the illuminance levels of attached rooms to light-well have been
evaluated in different floors and directions by computer simula-
tions using Daysim software. In this research to in investigate the
expressed variables, the reflectance of the walls of light-well and
rooms, the size of room window and the transmittance of the win-
dow are considered identical in all simulations.
The results of this study show that the daylighting performance
of cylindrical light-wells is significantly better than the common
form of light-wells in Tehran (square light wells) especially on
the lower floors and light-wells with small area. The results show
that with the same area of light-well, cylindrical light-wells have
better daylighting performance from 0.20 (in upper floors) to
23.25 percent (in lower floors). The cylindrical light-wells are bet-
ter especially on the lower floors and smaller size of light-wells.
Also, the optimal height of different types of light-wells has
been evaluated. The optimal height of light-wells can be defined
in the floors in which the adequate DA300/DA150 level of connected
rooms to light-well is more than 40%. In this regard, the optimal
height of cylindrical light-well with 16 sq. m area can be consid-
ered 5 floors for the residential spaces with appropriate light level
of 150 lx and 4 floors for the residential spaces with appropriate
light level of 300 lx. This amount is 4 floors for square light-well
(4 m ⁄ 4 m) and cylindrical light-well with 9 sq. m area, 3 floors
for square light-well (3 m ⁄ 3 m), 2 floors for square light-well
(2 m ⁄ 2 m) and 1 floor for square light-well (1 m ⁄ 1 m) and cylin-
drical light-well with 1 sq. m area.
The results of this study show that better lighting performance
for light-wells is possible by using sloping walls. In this regard, the
investigation of the effect of slope of light-well surrounding walls
on annual illuminance of attached rooms to light-well shows that
by changing the slope of light-well surrounding walls from 0� to 9
increases, the annual illuminance of attached rooms to light-well
significantly (up 80 percent on the lower floors) increases. In cases
where further increasing the area of light-wells may not be appro-
priate, the increasing of the optimal height of light-well is possible
with increasing the window size of the lower floors and the slop of
walls of light-wells. For example, the optimal height of 4 m ⁄ 4 m
square light-well has increased from 4 floors to 7 floors with
increasing the size of windows to 2 ⁄ 2 m from 1 ⁄ 2 m and the slop
of walls of light-wells to 9� from 0�.
In relation to the orientation of attached rooms to light-well,
the results of simulations show that in the floors in which direct
A.A. Ahadi et al. / Solar Energy 155 (2017) 679–697 697
sunlight cannot inter inside the room, north-facing rooms are bet-
ter in daylighting with a slight difference compared to other direc-
tions. In this case, the reflected sunlight from light-well walls and
the sky light are the main source of daylighting for rooms.
References
Acosta, I., Navarro, J., Sendra, J., 2013. Towards an analysis of the performance of
light well skylights under over cast sky conditions. Energy Build. 64, 10–16.
Ahmed, B.M. Aly, Nassar, K.M., 2014. Parametric study of light-well design for day-
lighting analysis under clear skies. IACSIT Int. J. Eng. Technol. 6 (1).
Architectural Energy Corporation, 2006. Daylighting metric development using
daylight autonomy calculations in the sensor placement optimization tool.
Prepared for CHPS daylighting committee daylighting forum NWEEA.
Baker, N., Steemers, K., 2014. Daylight Design of Buildings: A Handbook for
Architects and Engineers. Routledge.
Baker, N., Steemers, K., 2002. Daylight Design of Buildings. James and James
(Science Publishers), London.
Bellia, L., Pedace, A., Fragliasso, F., 2015. The impact of the software’s choice on
dynamic daylight simulations’ results: a comparison between Daysim and 3ds
Max Design. Sol. Energy 122, 249–263.
Carlucci, S., Causone, F., De Rosa, F., Pagliano, L., 2015. A review of indices for
assessing visual comfort with a view to their use in optimization processes to
support building integrated design. Renew. Sustain. Energy Rev. 47, 1016–1033.
CIBSE, 2002. Code for Lighting CIBSE. Butterworth Heinemann, London.
Dubois, M.C., Blomsterberg, A., 2011. Energy saving potential and strategies for
electric lighting in future North European, low energy office buildings: a
literature review. Energy Build. 43, 2572–2582.
EIA (Energy Information Administration), 2006. International Energy Annual 2006,
Available in <http://www.eia.doe.gov>.
EIA (Energy Information Administration), 2017. Annual Energy Outlook 2017,
Available in https://www.eia.gov/outlooks/aeo/.
Farea, T., Ossena, D., Alkaffb, S., Kotanic, H., 2015. CFD modeling for natural
ventilation in a lightwell connected to outdoor through horizontal voids. Energy
Build. 86, 502–513.
Freewan, A., Gharaibeh, A., Jamhawi, M., 2014. Improving daylight performance of
light wells in residential buildings: nourishing compact sustainable urban form.
Sustain. Cities Soc. 13, 32–40.
IEA (The international Energy Agency), 2010. Daylighting in Building. AECOM, UK.
Illustrated Dictionary of Architecture, 2012. Edited by Ernest Burden. McGraw-Hill
Companies incorporated.
Iran electric power industry statistics, <http://amar.tavanir.org.ir/en/> [last date
accessed: 17.12.14].
Kellert, S., Heerwagen, J., Mador, M., 2008. Biophilic Design: The Theory Science and
Practice of Bringing Buildings to Life. John Wiley & Sons, New Jersey.Kotani, H., Narasakia, M., Satoh, R., Yamanaka, T., 1996. Natural ventilation caused
by stack effect in large courtyard of high-rise building. In: ROOMVENT96,
Yokohama, Japan, pp. 299–306.
Kotani, H., Satoh, R., Yamanaka, T., 2003. Natural ventilation of light well in high-
rise apartment building. Energy Build. 35 (4), 427–434.
Kotani, H., Satoh, S.R., Yamanaka, T., 1997. Stack effect in light well of high rise
apartment building. In: International Symposium on Air Conditioning in High
Rise Buildings, Shanghai, China, pp. 628–633.
Kristl, Z., Krainer, A., 1999. Light wells in residential building as a complementary
daylight source. Sol. Energy 65 (3), 197–206.
Kumar Soori, P., Moheet, V., 2013. Lighting control strategy for energy efficient
office lighting system design. Energy Build. 66, 329–337.
Mardaljevic, J., Heschong, L., Lee, E., 2009. Daylight metrics and energy savings.
Light. Res. Technol. 41 (3), 261–283.
Mayhoub, M.S., 2014. Innovative daylighting systems’ challenges: a critical study.
Energy Build. 80, 394–405.
McGraw-Hill Dictionary of Architecture and Construction, 2003. Edited by Cyril M.
Harris. McGraw-Hill Companies, Inc.
Reinhart, C.F., Mardaljevic, J., Rogers, Z., 2006. Dynamic daylight performance
metrics for sustainable building design. Leukos 3 (1), 7–31.
Reinhart, C.F., Walkenhorst, O., 2001. Validation of dynamic RADIANCE-based
daylight simulations for a test office with external blinds. Energy Build. 33,
683–697.
Reinhart, C.F., Wienold, J., 2011. The daylighting dashboard a simulation-based
design analysis for daylit spaces. Build. Environ. 46, 386–396.
RIBA (Royal Institute of British Architects), 2007. The Architects Handbook.
Rogers, Z., 2006. Daylighting Metric Development Using Daylight Autonomy
Calculations in the Sensor Placement Optimization Tool. Architectural Energy
Corporation, Boulder, Colorado.
Su, Y., Han, H., Riffat, S., Patel, N., 2010. Evaluation of a light well design for multi-
storey buildings. Int. J. Energy Res. 34, 387–392.
Wasserman, D., 2011. Depression. Oxford University Press, UK.
Xu, Yu., Yuehong, Su., 2015. Daylight availability assessment and its potential
energy saving estimation – a literature review. Renew. Sustain. Energy Rev. 52,
494–503.
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0005
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0005
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0010
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0010
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0025
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0025
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0030
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0030
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0030
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0035
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0035
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0035
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0040
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0045
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0045
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0045
http://www.eia.doe.gov
https://www.eia.gov/outlooks/aeo/
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0060
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0060
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0060
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0065
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0065
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0065
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0070
http://amar.tavanir.org.ir/en/
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0085
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0085
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0090
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0090
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0090
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0095
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0095
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0100
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0100
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0100
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0105
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0105
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0110
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0110
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0115
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0115
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0120
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0120
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0130
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0130
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0135
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0135
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0135
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0140
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0140
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0150
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0150
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0150
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0155
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0155
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0160
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0165
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0165
http://refhub.elsevier.com/S0038-092X(17)30579-0/h0165
	The study of effective factors in daylight performance of light-wells with dynamic daylight metrics in residential buildings
	1 Introduction
	2 Literature review
	2.1 Light-wells and the effective factors on their daylight performance
	2.2 Dynamic daylight metrics
	3 Methodology
	4 Results and discussion
	4.1 The results of examination of horizontal section form
	4.2 The optimal height for different types of light-wells
	4.3 The effect of orientation variation
	4.4 The effect of slope of light-well surrounding walls
	5 Conclusions
	References