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Proceedings of 8th
Windsor Conference: Counting the Cost of Comfort in a changing world
Cumberland Lodge, Windsor, UK, 10-13 April 2014. London: Network for Comfort and
Energy Use in Buildings, http://nceub.org.uk
Daylight quality in healthcare architecture - Developing a framework
Alaa Sarhan1, Bakr Gomaa2, Mohamed Elcharkawi3
1 Architectural Engineering and Environmental Design Department, Arab Academy for
Science and Technology, Alexandria, Egypt;
2 Architectural Engineering and Environmental Design Department, Arab Academy for
Science and Technology, Alexandria, Egypt, [email protected];
3 Architectural Engineering and Environmental Design Department, Arab Academy for
Science and Technology, Alexandria Egypt, [email protected].
Abstract
Through history; a large body of research has found a relationship between the IEQ and the recovery of patients
in healthcare facilities. IEQ factors include natural ventilation, daylighting, acoustics, materials off gassing,
etc... This research is to identify the guidelines to healthy daylighting in hospital buildings. Research methods
include grounded theory finding through intensive literature review and analysis of successful international
examples. Following comes the theory testing to assess daylight quality in a regionally acclaimed self funded
"The Children Oncology Hospital" - locally known as 57357 - the study is expected to shed the light on the
architectural design principles for daylighting as well as the thorough investigation of the case study building. Keywords: Healing environment; Indoor environmental quality; Daylight quality; Energy saving; Design
guidelines.
1 Introduction
One of the most famous quotes in architecture is “Form follows function”, once said by the
American architect Louis Sullivan in his article “The tall office building artistically
considered”, (Verderber, 2010) in his book “Innovation in hospital architecture”; wrote that
“The very first requirement of a hospital is that it shall cause neither human nor ecological
harm”, a multi dimensional concept, he thought that the function of the hospital is to enhance
the healing process of patients, not harming them, also it should have the role of the
environmental stewardship in its urban context, promoting the concept of ecological health
and human wellness, and architects should help this concept by enhancing the design of
physical environment of the hospital, and so, the form of the healthcare building and its
indoor built environment follows its intended function. There are a number of scientific
evidence proving that a poor design works against the wellness of patients and gives negative
psychological indicators (Marberry, 1995), and in the 1990s there were some innovations in
the design of the hospital’s built environment based on some of these “Evidence based
medicine” published research, and these solutions were defined as “Evidence based design”
EBD. (Huisman, 2012).
“An optimal healing environment is one where the social, psychological, physical, spiritual,
and behavioral components of healthcare support and stimulate the body’s innate capacity to
heal itself” (Ananth, 2011). In the “Journal of science and healing” since August 2008, Sita
Ananth began to discuss and develop what she called “Optimal healing environment” OHE,
she set a number of settings to create it: Internal, interpersonal, behavioural and external, this
paper is considered with the factors of the “external criteria”; which is divided into two
topics: building healing spaces and ecological sustainability. The building healing space
factors are four sensory; colour and light, aroma and air, music and sound, and art.
(Urlich and Zimmiring, 2004) investigate the role of the physical environment in the hospital
by over viewing a large number of “evidence based medicine” research, and they concluded
that seven points contribute to IEQ including constrains on noise level, access to daylight,
and ventilation improvement. Also in 2010, Stephen Verderber in his book “Innovation in
hospitals architecture” stated that there are six patterns or healing agents that links built
environment to human health, and sustainability; two of which are natural ventilation and
natural daylight.
This paper is concerned only with the objective of design criteria for optimal daylight quality
as an important contributor to an important aim of better human health and experience in the
healthcare facility.
2 Built environment and human health check points in history
The importance of this study is evident through the history of healthcare architecture; it is
one of the criteria of creating or restoring the relationship between human health and the built
environment (H.H and BE); in ancient Greece, after the Hellenistic period, they believed in
the presence of gods skilled in the art of healing, and they formed a number a healing cults
for each god, the most famous cult was that of Asclepius son of Apollo. The Asclepieions,
the name of the temples referring to the cult of Asclepius, were considered the hospitals of
this ancient era, the strategy of positive distraction and supportive design was present using
the performing arts that had good effects on patients (Kjisik, 2009). The natural environment
was considered an important aspect of the care strategy, the interaction with nature,
vegetation and patients’ exposure to sunlight became with high priority (Verderber, 2010).
The patient care setting in the Asclepieidon of Epidauras in Athens was in stoa form where
the patients’ beds lays in the entire length of the hall, so they could experience natural
ventilation and daylight through the portico, the hall had three enclosed sides and the fourth
opened side through the row of columns was exposed to the south allowing the maximum
amount of daylight to penetrate into the interior, and to allow visual interaction to the outside
natural environment (Verderber, 2010). Later in the Greek era, it was the rise of curative
strategies based on rational medicine (Longrigg, 1998). Hippocrates, father of medicine, was
the first to define medicine as an individual rational science apart from philosophy, he
believed that the site orientation strategy for cities and the environmental factors had an
impact on human health (Chadwick, Mann, 1983).
In Europe, during the middle ages, the dominating beliefs were again that illness is caused by
super natural forces and it can only be cured by religious actions (Kjisik, 2009), “with the
decline of secular city-states the catholic church emerged to fill the void in healthcare across
Europe” (Verderber, 2010). During this era, as the Christian religious orders are in charge,
the belief in nature and landscape as aspects of treatment diminished and the treatment
process was held in a network of cross-ward monastic hospitals where natural daylight and
ventilation were of minimal importance (Verderber, 2010).
In the Muslim near east the conditions was totally different. “Yet the Middle Eastern hospital
was one of the most developed institutions of medieval Islam, and represented, both
architecturally and medically” (Montague, 1984). There are different examples for the
hospitals in this Islamic era, Nuri hospital and Argham hospital in Syria, Ibn Tulun hospital
and Mansuri hospital in Egypt, Kulliyesi hospital in turkey. Montague states that in the this
era in the middle east, the medical institution was the beacon for all the upcoming eras of
healthcare, as for the architectural concern, according to Monatgue’s descriptions, there was a
high regard for the IEQ of the hospitals; day lighting quality, shading and ventilation offered
by the shape and orientation of the hospital’s mass’ and the thermal comfort which was
demonstrated with the difference between two courtyards one in hot climate of Baghdad with
no ceiling and one in the cold climate of Anatolia covered with a vaulted masonry ceiling. It
was also demonstrated through the use of water streams freely falling -that has an echo in the
Arab mentality- to offer security and comfort that there was a high regard for the concept of
the supportive design to reduce the patients’ stress.
“Florence Nightingale, the founder of the modern nursing, who was an outspoken advocate
for the use of the environment for therapeutic purpose.” (Marberry, 1995). Florence
Nightingale, began a healthcare architectural trend that dominated a period of 85 years since
1860 to the world war two 1945, after she was back from the war in turkey in 1855 to reform
soldiers’ barracks hospital she was praised for her remarkable achievements, then she wrote
two influential books; notes on nursing in 1858 and notes on hospitals in 1895. In these books
she assured the importance of what we call now the indoor environmental quality in the
patients’ wards (Verderber, 2010). “She stated five essential point in securing a sustainable,
health promoting environment: pure air, pure water, efficient drainage, cleanness and
natural daylight” (Verderber, 2010). In her book notes on hospitals she stated in the
introduction a number of defects causing hospitals to offer disease more than being a curative
environment, in between these defects there was two of them related to the environmental
quality: deficiency of ventilation and deficiency of light, she offered states and discussions
about how these two factors affect the recovery of the patients physically or by supporting
those morally (Nightingale, 1863). In another chapter of her book, (principles of hospital
construction), she offered criteria of 18 points leading to her functional and environmental
vision for a hospital, there was a number of points about ventilation and day lighting of
wards, and even the points stating a functional requirements were reasoned with an
environmental purpose concerning lighting and ventilation quality (Nightingale, 1863).
“Florence Nightingale main functional objection to what she had seen was lack of direct
visual supervision of patients, while her clinical objections centered on the lack of fresh air
and daylight.” (Kjisik, 2009).
In eras mentioned before there were no scientific proofs on the impact of the built
environment on the human health and healing process. As later in the 1980s evidence based
medicine research will begin. (Guenther and Vittori, 2008).
3 Evidence based medicine and supportive design strategy
When comes in mind the design of healthcare facilities, architects always think about
fulfilling the functional requirements, such as providing efficient space for operation rooms
and wards or the width of doors to allow stretchers movement, “This emphasis has often
produced facilities that are functionally effective but psychologically hard” (Ulrich, 1991).
“People in the hospital world may claim the physical side can be dealt with successfully by
simply adhering to healing environment principles” (Kjisk, 2009), the healing environment is
a concept that lately investigated with a number of evidence-based researches, proving that
the physical environment of the healthcare facility affects the healing process (Kjisk, 2009).
“By the 1980s, a body of research emerged indicating that a connection to nature positively
influences medical outcomes and staff performance” (Guenther and Vittori, 2008). Until
2012; 65 scientific article emerged that fit a criteria Huisman has put in his review to fulfil
the concept of the Evidence Based medicine. (Huisman, 2012).
In 1984, Roger Ulrich published one of the first and most famous scientific papers about how
the built environment has an impact on recovery “View Through a Window May Influence
Recovery From Surgery”; in which an experiment was conducted; all physical characteristics
of two rooms were made identical, except for one of the rooms had brick wall, while the
other had a window to overlook a small stand of trees. Two different patients who have
identical status were asked to stay into the rooms for a certain period of time; it was found
that the patients in rooms with window to the view had shorter postoperative hospital stay
rather than those who overlooked a brick building wall (Ulrich, 1984). Also, Roger Ulrich
stated from another study that visual exposure to everyday nature has produce “significant
recovery from stress within only five minutes or less, as indicated by positive changes in
physiological measures such as blood pressure and muscle tension” (Marberry, 1995), the
findings are presented in (Fig.1).
Architectural design should do more than produce health facilities that are efficient only in
term of functional requirements, design should create physical environment that is
“psychologically supportive” (Ruga, 1989), “the effect of this supportive design are
complementary to the healing effects of drugs and other medical technology and foster the
process recovery” (Marberry, 1995). The supportive design strategy is important to help
patient deal with the stress parallel to his illness (Ulrich, 1991). “The effects of supportive
design are complementary to the healing effects of drugs and other medical technology, and
foster the process of recovery. By comparison, hard settings raise obstacles to coping with
stress, contain features that are in themselves stressors, and accordingly ass to the total
burden of illness.” (Ulrich, 1991). The stress can be manifested psychologically by the sense
of depression and helplessness, but to understand more its impact on the recovery process;
Figure 1 Urlich’s experiment findings (Marberry,
1995)
the physiological impact must be manifested: “Physiologically, stress involves changes in
bodily systems, such as increased blood pressure, higher muscle tension, and high level of
circulating stress hormones. A considerable body of research has shown that stress response
can have suppressive effects on immune system functioning. Reduced immune functioning can
increase susceptibility to disease and work against recovery.” (Marberry, 1995).
4 The impact of daylight quality on healing and recovery process
Daylight as a single factor within the settings of the healing environment and the supportive
design has its own specified scientifically proved impact on the healing process. After a
successful treatment for patients with seasonal affective disorder and Alzheimer disease with
exposure to artificial high-intensity light (bright light therapy), a belief has gown that the
exposure to natural daylight may also influence health outcomes (Van den Berg, 2005).
Marberry in her book “Improving Healthcare with Better Building Design” states after a
number of studies that “higher level of light exposure, compared to lower levels, are effective
in reducing depression” (Marberry, 2005), she stated also that (Lewy et al., 1998) proved that
the morning light is twice effective than the afternoon light in improving patients’ conditions.
Choi, Beltran and Kim in 2011 made a study on the impacts of indoor daylight environment
on patients “average length of stay” ALOS in a general hospital in Incheon in Korea, they
concluded that although the several critical factors that affects patients recovery which makes
it difficult to identify a single role for the daylight in the healing process, that “A significant
relationship appears to exist between indoor daylight environment and patients length of stay
(ALOS).” (Choi, Beltran, Kim, 2011).
“A recent prospective study of pain medication use among 89 patients undergoing spinal
surgery showed that patients staying on the bright side of the hospital (with an average
higher intensity sunlight) experienced less perceived stress, marginally less pain, and took
22% less analgesic medication per hour than patients on the dim side of the hospital” (Van
den Berg, 2005) after Walch et al. study in 2005.
5 Generating criteria from daylight science
5.1 Daylight and Sunlight
The “daylight” differs from the “sunlight”, as according to (IESNA, 2000) the daylight is
where the sky acts as a light source. (CIBSE LG10, 1999) expressed that the skylight is “light
which has been scattered by molecules of air, aerosols and particles such as water droplets
in clouds in the atmosphere; excludes direct beam”, and the sunlight is “the visible direct
beam solar radiation”.
Although the scope of this research is the daylight calculation methods and metrics; in hot
arid zones where clear sky is dominant all over the year, sunlight, sun movement and
directions must be taken in consideration to avoid discomfort from heat gain and glare
(Kensek, Suk, 2011).
5.2 Daylight source
“As sunlight passes through the atmosphere, a portion is scattered by dust, water vapor, and
other suspended particles. This scattering, acting with clouds, produces sky luminance.”
(IESNA, 2000).
“The (no-sky line) gives an indication of the area beyond which daylight may not contribute
to general room lighting” (CIBSE, 2002).
The sky dome is the source of daylight, and skies are divided into three categories: Clear sky;
Overcast sky; and Intermediate sky (partly cloudy in other refrences) (Muneer, 1997). These
three categories are standard and developed by the Commision Internationale d’Eclerage CIE
(Interational commission on illuminance); a worldwide commission concerned with the
matters of lighting (CIBSE LG10, 1999).
5.2.1 Clear sky
The clear sky is where the cloud cover is less than 30% (IESNA, 2000) or no clouds at all,
“The sky is brighter towards the location of the sun, and the sun is visible.” (Kensek, Suk,
2011). This model must be used in predominant sunny climate area as it is useful when visual
glare and thermal discomfort studies are made which is out of the research scope. “Incoming
sunlight can give warmth and brightness but it can also cause glare and thermal discomfort”.
(The desktop guide to daylighting, 1998).
5.2.3 Overcast sky
It is the sky 100% covered with clouds, and mainly adapted and used in simulation programs
to calculate the worst case scenario for daylight quality (Kensek, Suk, 2011). “An overcast
sky acts as a relatively bright, diffuse light source. This diffuse light is ideal for daylighting
design. Since it is not as bright as direct sunlight, diffuse light is an easier source control.”
(Daylighting guide for Canadian buildings, 2002).
5.2.4 Intermediate sky
It is when the sky is not completely overcast. As the sun is alternately sometimes revealed
and other times obscured during the day; the luminance of the sky dome varies and change
rapidly by large amount (IESNA, 2000).
5.3 Daylight factor DF
“The daylight factor is the percentage for daylight available inside the room, relative to
daylight available outside the room measured on an overcast day.” (Kristensen, 2010). It is
the Illumiance received at a point in the indoor expressed as a percentage to the diffuse
illuminance outdoors on a horizontal plane under an overcast sky (CIBSE LG10, 1999).
according to the (Daylighting rule of thumb, 2009) and is defined by the upcoming equation:
DF = [Ein / Eext] × 100 (1)
Where; DF is the daylight factor in percent, Ein is Interior illuminance at a fixed point on the
work plane, and Eext is exterior illuminace under an overcast sky.
5.4 Average Daylight Factor ADF
The different between the Daylight factor DF and the Average daylight factor ADF is that the
former is the value at a specified point on a work plan as stated previously, while the later is
the average of a number of values at a number of points on a work plane (IESNA, 2000). The
ADF is identified by the (CIBSE LG10, 1999) as “The average indoor illuminance on a
refrence plane or planes (Usually the working plane) as a percentage of the simultaneous
outdoor illumiance form the unobstructed sky.”
The Average Daylight factor ADF according to the (CIBSE Code for lighting, 2002) is
presented mathematically using the equation (2):
ADF = [Ag × θ × τ] / [A × (1-R)] (2)
Where; ADF is average daylight factor in percent, τ is the decimal transmittance of the
glazing, Ag the net glazing area, A is the total interior surface area including windows, R is
the area average reflectance of all interior room surfaces including windows, and θ is the
angle in degrees in the vertical plane of visible sky from the centre of the window.
Same reference as all codes and guidelines mentioned before in this section specified values
of Average daylight factor and its influence on a daylight appearance in a room. (Table 1)
Table 1: Average daylight factors and daylight quality in space
Average daylight factor Daylight quality in space
5% or more The space has a bright daylight, daytime electric lighting is unnecessary, but heat
control is needed.
2-5% The space has a predominantly daylight appearance, but electric lighting is needed
in rooms background.
Below 2% Electric lighting is necessary and dominant, windows gives only exterior view.
5.5 Useful daylight illuminace UDI
The useful daylight illuminance UDI is a new scheme developed in 2005; used to assess the
daylight quality in a room as a replacement for the ADF scheme. UDI are defined as the
value of iluminance in between 100 Lux to 2000 Lux. This range is based on the review of
updated data from field studies concerned with human behavior under daylit conditions
(Nabil and Mardaljevic, 2006). The UDI index is as follow in (table 2) findings are quoted
from (Nabil and Mardaljevic, 2006):
Table 2 Useful daylight Illuminances UDI index
Illumances Scheme Findings Less than 100 Lux Fall short of
the useful
range
“Generally considered insufficient either to be the sole source of
illumination or to contribute significantly to artificial lighting.”
From 100 to 500 Lux
Useful range
“Considered effective either as the sole source of illumination or in
conjunction with artificial lighting.”
From 500 to 2000 Lux “Are Often perceived either as desirable or at least tolerable.” Higher than 2000 Lux Exceed the
useful range “Are likely to produce visual or thermal discomfort, or both.”
5.6 ADF and UDI use in the research
As stated previously, the values of the ADF are to predict the daylight quality under overcast
sky, and as the UDI is based on the variable amount of light all over the year (Nabil and
Mardaljevic, 2006); the UDI would be more suitable for a dominant clear sky as in Egypt. So
in the Case study the Illuminance values will be compared to the UDI Index to judge the
daylight quality in spaces.
The purpose of introducing the ADF method in this research is that after the review of a
number of published research and papers including the publications of the CIBSE and the
IESNA concerning daylight design; the component of the equation (2) to calculate the ADF
presents the architectural factors that affects the daylight quality in a room. The equation (2)
will be used to generate the design criteria for daylighting; by transforming its components
into categories presenting the factors of the built environment
Equation 2 comprises four different factors; and Each of the factors is impacted by a number
of sub-factors as indicated in (Table 3).
Table 3: Factors and sub-factors of equation (2)
Orientation and
surrounding context
Means of daylight
penetration
Space geometry Finishing materials
Ori
enta
tio
n
Sh
adin
g s
trat
egy
Vis
ible
sk
y a
nd
ob
stru
ctio
n l
evel
Mai
n o
pen
ing
tech
no
logy
Gla
zin
g
typ
e
Gla
zin
g a
rea
Ro
om
dep
th
Co
lor
of
surf
aces
Ref
lect
ance
of
surf
aces
θ Τ Ag and A R
6 Theories and previous research
The next section assesses through theory overview and other researches’ findings the best and
preferred specifications for each category to refine the criteria to be specified healthcare
facilities.
6.1 Orientation and surrounding context
6.1.1 Visible sky and obstruction level:
“If the sky is not directly visible from a point in an interior, the level of daylight at that point
will be small.” (CIBSE Code for lighting, 2002). The sky visible from a window is
constrained by the surrounding context, and so, the site choice is a major decision regarding
the daylight quality in subject building (Daylight in buildings, 2000). If the window will be
used as a main source of light; the surrounding obstruction facing it should not be higher than
25 degree above the horizon (The desktop guide to daylighting, 1998). The vertical angle of
sky is measured from the center of window, it varies between 0 and 90 degree. The vertical
angle is 90 if no obstruction is present (O’connor).
6.1.2 Orientation:
Each orientation in the four orientations can provide daylight but each orientation must be
treated adequately for best results. The (table4 ) is the visualization for the impact and
handling of each orientation by (O’connor):
Table 4: orientations and impact on daylight quality
Orientation Daylight quality Heat gain and loss Shading
North high quality consistent daylight minimal heat gains, but
thermal loss during heating
conditions
possibly needed
only for early
morning and late
afternoon
South Good access to strong
illumination (the original source),
although varies through the day
High heat gain special
during winter as sun is in
lower position than summer
Shading is easy;
horizontal
shading
East Annoying Sun during early
morning
High heat gain; especially
in early morning and late
afternoon
Shading is
difficult and
critical for
comfort West Annoying sun during late
afternoon
As a conclusion; (O’connor) states that “Windows facing generally north and south create
the fewest problems.”
The research made by (Choi, Beltran and Kim, 2011) indicated that ALOS in rooms located
in South East was shorter than that in the North west area. Marberry also stated after a study
by (Beuchemin and Hays, 2005) that patients having higher daylight and sun exposure show
better medical outcomes than those who are in rooms facing the shaded north (Marberry,
2005). Thus the range of the south orientations is preferred for inpatient rooms.
6.1.3 Shading strategy
The sun path and movement mustn’t be neglected, as it may cause visual and thermal
discomfort due to solar gain as stated before. Decisions on shading devices especially the
fixed ones should be made carefully to avoid reducing daylight which could lead using
electric light (CIBSE LG10, 1999); as it could lead to more obstruct the visible sky form
window and so the angle of visible sky can be reduced. After (CIBSE LG10, 1999) and
(O’connor); shading strategies can be divided into a) Exterior devices; b) interior devices, in
(table 5) some common devices same references mentioned and described:
Table 5 strategies of shading
Strategy Favorable
orientation
Impact on light diffused to
interior
View to exterior
Ex
terio
r
Solid horizontal projection South More projection may
obstructed viewed sky
No restriction
Solid horizontal projections
distributed vertically
South Less projection from
building; more viewed sky
Restrict view
Canopy of horizontal louvers South More diffused light than
previous strategies as less sky
obstructed
No restriction
Fixed vertical Louvers facing
of the building
East and west depending and the angle and
position of louvers
Can restrict view
depending and the
angle and position
of louvers
Mesh form copper wire
facing of the building
Deals with high
or low angle
sun
Reduce permanently diffused
skylight
Permits filtered
view
External projecting awnings South Choice of material from near
opaque to translucent affects
the diffused light
No restriction
Inte
rio
r
Retractable Venetian blind
with fully control on slats
angle
Good shielding
against sun
beam
Obstruct sky when fully
drawn
Depends on the
angle of slats
Fabric roller blind Wide range to
restrict
penetrating sun
beam
Obstruct sky when fully
drawn
Obstruct view
when fully drawn
“An efficient shading device that can remove lighting stressors, while still maintaining a
proper level of illuminance is critical to a patient’s comfort and increases his/her level of
satisfaction” (Choi, Beltran and Kim, 2011). This statement is fitting to one of the settings of
the supportive design strategy to cope with stress developed by Ulrich, which is “sense of
control” (Ulrich, 1991). So, operable blinds and curtains are important for the patient to
control his environment.
6.2 Means of daylight penetration
6.2.1 Main opening technology
There are various technologies to let penetrate directly the daylight into the building, and
each technology has a number of application. The most important technologies can be
distributed into two categories: a) Side lighting; b) Roof lighting; and c) Supporting
techniques. These three categories are inspired and set after the combination between the
writings of (CIBSE LG10, 1999); (IESNA, 2000); (Kristensen, 2010); and (Daylight in
buildings, 2000) and for further description of application these references can be reviewed.
From the concept of “supportive design” access to nature is required (Ulrich, 1991). And for
this, side openings can be used to have views on nature, and this cannot be done through roof
openings. The experiment made by Ulrich proving the effect of views from patients’ rooms
on the recovery process was explained in a previous section.
6.2.2 Glazing type
Form the glazing transmittance calculator, there are two types of glazing, single or double
and each layer can be tinted green, blue, bronze or grey, and layers can be filled in between
with argon gas, and each type has a different transmittance. There is no mentioning for a
specified type preferred for healthcare facilities serving the concept of healing environment,
the choice will depend on the region and orientation of the building to cope with the heat
transfer, as for sure form a best daylighting point of view, a higher transmittance type is
preferred.
6.3 Space geometry
Concerning glazing area, according to the (Desktop guide for daylighting, 1998); a room can
have a day-lit appearance if the area of glazing is at least 1/25 (or 0.04) of the total room area,
and there are no specified specification for an inpatient room. Also (Daylighting rule of
thumb, 2009), identifies that the room limiting depth is decided by two factors Window head
height WHH and the presence of horizontal shading device. (Table 6)
Table 6: Impact on horizontal shading on rooms' depth
Horizontal shading device present depth less than (2 * Window head height)
No horizontal shading device depth less than (2.5 * window heat height
6.4 Finishing materials
No intensive information could be found regarding the adequate colors in healthcare facilities
to serve the concept of healing environment. Although form daylight quality perspective;
bright colors have higher reflectance than dark colors.
Indoor environmental quality design criteria is more interest in the materials choice in which
the priority is given to anti-bacterial materials. Comes second; high reflectance materials
which are beneficial to increase the daylight quality. There is a growing body of research
proving that hard and glossy materials such as vinyl have more advantages for patients than
other flooring material like carpets, and this fact is by regard to infection rates and bacteria
growing in mediums like carpets textiles (Ulrich, 2004), and so, also on the other side
concerned with daylight quality; a glossy material has higher reflectance than carpet’s textile.
7 Daylight criteria for healthcare architecture
Table 7 sums up the findings from all the previous sections and offering a final checklist for
the adequate daylight criteria for inpatient rooms in hospitals. The highlighted grey factors
are the best specification for the daylight quality in an inpatient room.
Table 7: Daylighting design criteria checklist
Ori
enta
tio
n a
nd
surr
ou
nd
ing
co
nte
xt
Window
Orientation
North
South
East
West
North east
North west
South east
South west
Shading device
None
Exterior
Horizontal
Vertical
Mesh
Interior
Venetian blind
Fabric roller blind
Angle of
obstruction from
the horizon
25 degree
Above
Under
Mea
ns
of
day
ligh
t p
enet
rati
on
Main opening
technology
Side opening
Roof opening
Glazing type Sin
gle
gla
zin
g Clear float (0.82)
Tinted green (0.66)
Tinted bronze (0.46)
Tinted blue (0.50)
Tinted grey (0.39)
Do
ub
le g
lazi
ng Clear float + clear float (0.70)
Clear float + low E glass (0.69)
Low E glass + Low E glass (0.65)
Clear float + Low E glass + Argon (0.69)
Low E glass + low E glass + Argon (0.65)
Sp
ace
geo
met
ry
Glazing to room
area ratio
1/25
Above
Under
Room limiting
depth
Horizontal shading
device available
2 * Window
head height
Above
Under
No Horizontal shading
device
2.5 * window
head height
Above
Under
Fin
ish
ing
Mat
eria
ls colors Dominant bright and light colors Yes
No
Materials Dominant glossy materials Yes
No
8 Case study – Children Cancer Hospital (CCH) 57357
A hospital belonging to the nongovernmental organisation of 57357, situated in Al-Sayeda
Zaynab in Cairo, Egypt. The idea of the inauguration of the hospital was because of the high
level of cancer infection between children all over Egypt. The impatient tower is in a form of
three circles attached into a central node. A Copper screen filtering the view is projecting in
some parts in front of the tower. (fig. 2).
Figure 2 Children Cancer Hospital
8.1 Case study methodology
To investigate orientation impact; two rooms with different directions without screen were
chosen; R1 South West and R3 East. And to investigate the screen impact; two rooms with
same orientation were chosen, one with screen (R2) and the other without (R1).
Figure 2 Children Cancer Hospital (57357 Cancer hospital engineering department)
8.2 Assessing rooms to criteria
Assessing the 3 rooms to the criteria checklist developed in the previous section (Table 8).
Table 8: Assessment of daylight design performance criteria
R1 R2 R3
Ori
enta
tio
n a
nd
surr
ou
nd
ing
co
nte
xt
Window
Orientation
North
South
East ●
West ● ●
North east
North west
South east
South west
Shading
device
None ● ●
Exterior
Horizontal
Vertical
Mesh ●
Interior
Venetian blind
Fabric roller blind ● ● ●
Angle of
obstruction
from the
horizon
25 degree
Above ● ● ●
Under
Mea
ns
of
day
ligh
t p
enet
rati
on
Main
opening
technology
Side opening ● ● ●
Roof opening
Glazing type Sin
gle
gla
zin
g Clear float (0.82)
Tinted green (0.66)
Tinted bronze (0.46)
Tinted blue (0.50)
Tinted grey (0.39)
Do
ub
le g
lazi
ng Clear float + clear float (0.70)
Clear float + low E glass (0.69)
Low E glass + Low E glass (0.65)
Clear float + Low E glass + Argon (0.69)
Low E glass + low E glass + Argon (0.65) ● ● ●
Sp
ace
geo
met
ry
Glazing to
room area
ratio
1/25
Above ● ● ●
Under
Room
limiting
depth
Horizontal shading
device available
2 * Window
head height
Above
Under
No Horizontal
shading device
2.5 * window
head height
Above ● ● ●
Under
Fin
ish
ing
Mat
eria
ls colors Dominant bright and light colors Yes ● ● ●
No
Materials Dominant glossy materials Yes ● ● ●
No
8.3 Measuring illuminance
The Illuminance measurmnets were taken using a (V&A) LUX meter model (MMS6610).
Measurements were taken in a clear sky condition. The measurements in each room were
taken in different times as in (table 9); in order to exclude the sun beam from measurement in
respect to the orientation of each room and the sun path.
Table 9: times of taken measurements in rooms
Room Orientation Time of measurement Shading screen R1 South west 9:00 With screen R2 South west 9:00 No screen R3 East 14:30 No screen
The rooms are identical in shape and dimensions, so three contour (A; B; and C) were drawn
in different depths; each contour consist of 3 points, an additional point (Ent.) was set at the
narrow entrance corridor. At each point a measurement was taken. As also a measurement
was taken in the exterior in front of the windows (Out.) to measure the illuminance outside
(fig 3).
Figure 3 Contours of measurements
Measurements in the three rooms are presented in (table 10) as also the average (Av.) of the
three points of each contour.
Table 10: Results of measurements in room
Contour A Contour B Contour C
Room Out. A1 A2 A3 Av.A B1 B2 B3 Av.B C1 C2 C3 Av.C Ent.
R1 11000 1900 2000 1900 1966 700 700 700 700 350 360 350 350 60
R2 7000 1160 1200 1170 1175 180 160 175 171 60 60 60 60 10
R3 10500 1900 1950 1900 1916 600 650 600 615 300 300 300 300 60
9 Discussion
When analyzing the results of the criteria; the three rooms fulfilled the criteria in the majority
of factors, as they did not fit in some. The three rooms exceeded the limiting depth; 2.7*2=
5.4 meters, and the rooms depths are 9.65 meters. R2 was the only room with a shading
device installed in front; a cooper mesh that as mentioned before decrease the diffuse light
permanently. R1 and R2 had a south west orientation fulfilling the criteria as R3 did not by
having an east orientation.
When analyzing the measurements results; R2 had lower value at point (Out.) than the
approximately similar values of R1 and R3. And by comparing the factors of the identical
rooms in direction R1 and R2; the cooper mesh in front of R2 is the only difference, and it is
believed it is the reason of the low value of point (Out.); as the cooper mesh decrease the
diffused light before it reach the window. And as additional result; the values of illuminace
in R2 are lower than the close values of R1 and R3, the average of every contour in three
rooms is presented in Fig. (4).
Figure 4 Average of contours in rooms
In fig. (5); illuminance values of points of each contour are compared to the UDI index
mentioned before in previous section. Contour A containing point (A1, A2, A3) in the three
rooms was in the “useful range”, and as being between 500 Lux to 2000 Lux range so they
0
500
1000
1500
2000
2500
first contour second contour third contour entrance
room 2
room 1
room 3
are “acceptable” for the users. Contour B containing (B1, B2, B3) in the R1 and R3 are also
in the “useful range” above 500, as in the R2 the contour B is also in the “useful range” but
under 500 Lux so they are “considered effective as the sole source of daylight”. Contour C
containing (C1, C2, C3) in R1and R3 are in “useful range” but under 500 Lux, as in R2 it was
in the “fall short” range (under 100 Lux) and considered “insufficient to be the sole source of
daylight”. The point (Ent.) in the three rooms is in the “fall short” range.
Figure 5 Points of contours compared to UDI index
10 Conclusion
The Cooper mesh in front of R2 affected the Illuminance values if compared to R1; both are
identical in factors as shown in the criteria table and measurements were taken at the same
time. Further future research may find a coefficient for the presence of cooper mesh affecting
daylight quality. When excluding the sun beam; the rooms R1 and R3 had approximately
identical values even the different orientation, and as conclusion the diffuse skylight does not
depend on the orientation factor, but the sun movement and presence will give more variable
and higher values of illuminance.
The depth of the three rooms exceeding the limiting depth affected the illuminance values at
the entrance corridor of the rooms. But the Illuminance values compared to the UDI index in
R1 and R3 were in the useful range, as also in R2, except Contour C as believed due to the
mesh.
It is believed that the presence of the mesh in R2 will control the solar heat and visual
discomfort when the sun is available as also in the illuminance values will be higher than the
measured in this research. As also, the Values in R1 and R3 will exceed the useful range at
contour A when the sun is available especially with the absence of any shading strategy.
Acknowledgments
The Egypt’s children cancer hospital (57357) for it great moral, spiritual as well as medical
efforts with children struggling with devastating illness. All appreciation and thanks to the
hosptal’s research and engineering department for their outstanding support.
0
500
1000
1500
2000
2500
Room 1 Room 2 room 3
Illu
min
ace
val
ue
in L
ux
Points in contours
A1
A2
A3
B1
B2
B3
C1
C2
C3
Ent.
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