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Energy Efficient Hospital Patient Room Design: Effect of Room Shape on Window-to-Wall Ratio in a Desert Climate

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This paper reports on a research that utilized simulation techniques for identifying the most efficient hospital patient room designs and their associated window-to-wall ratios. Simulation of the energy consumption and daylighting performance of common patient room designs were conducted using a range of Window-to-Wall Ratios (WWRs). The paper focuses on arriving at solutions that balance between the reduction of energy consumption and the achievement of proper daylight distribution in the desert climate of Cairo, Egypt. Simulations were conducted using the Diva-for-Rhino, a plug-in for Rhinoceros modelling software to interface with the Energy Plus, Radiance and Daysim software. Results demonstrated that solar penetration is a critical concern affecting patient room design and window configuration in desert locations. Use of the outboard bathroom patient room design was found to be the least efficient among the tested alternatives. Although it has a smaller external wall size, it failed to provide energy consumption that is lower than that of the other options. Its best energy performance was 20% higher than that of the nested bathroom patient room design. However, the outboard bathroom design allowed for larger WWRs (70%-90%), which might prove useful for external view exposure purposes. The nested and inboard bathroom patient room designs provided better energy performance. However, this was on the expense of window size. The acceptable cases of these designs had smaller WWRs, (30%-40%). The results of this paper demonstrated the need for the careful consideration of the size of windows and openings in relation to different patient room designs. Simulation techniques can prove useful in this regard.
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Energy Efficient Hospital Patient Room
Design: Effect of Room Shape on Window-
to-Wall Ratio in a Desert Climate
Ahmed Sherif
Hanan Sabry
Rasha Arafa
Ayman Wagdy
[Department of
Construction
and Architectural
Engineering, The American
University, Cairo, Egypt]
[Department of
Architecture, Faculty of
Engineering Ain Shams
University, Cairo, Egypt]
[Department of
Construction
and Architectural
Engineering, The American
University, Cairo, Egypt]
[Department of
Construction
and Architectural
Engineering, The American
University, Cairo, Egypt]
ABSTRACT
This paper reports on a research that utilized simulation techniques for identifying the most efficient
hospital patient room designs and their associated window-to-wall ratios. Simulation of the energy
consumption and daylighting performance of common patient room designs were conducted using a
range of Window-to-Wall Ratios (WWRs). The paper focuses on arriving at solutions that balance
between the reduction of energy consumption and the achievement of proper daylight distribution in the
desert climate of Cairo, Egypt. Simulations were conducted using the Diva-for-Rhino, a plug-in for
Rhinoceros modelling software to interface with the Energy Plus, Radiance and Daysim software.
Results demonstrated that solar penetration is a critical concern affecting patient room design and
window configuration in desert locations. Use of the outboard bathroom patient room design was found
to be the least efficient among the tested alternatives. Although it has a smaller external wall size, it
failed to provide energy consumption that is lower than that of the other options. Its best energy
performance was 20% higher than that of the nested bathroom patient room design. However, the
outboard bathroom design allowed for larger WWRs (70%-90%), which might prove useful for external
view exposure purposes. The nested and inboard bathroom patient room designs provided better energy
performance. However, this was on the expense of window size. The acceptable cases of these designs
had smaller WWRs, (30%-40%). The results of this paper demonstrated the need for the careful
consideration of the size of windows and openings in relation to different patient room designs.
Simulation techniques can prove useful in this regard.
INTRODUCTION
Hospitals are typically considered one the most energy demanding building types. Patient rooms
compose the largest volume of hospital buildings. The external walls of patient rooms represent the most
significant part of the external surface area of these buildings. Windows can contribute significantly to
the healing process and reduction of pain and length of stay in hospitals through the provision of
daylight and allowance of external view (FGI, 2010). However, they can also contribute negatively to
the energy consumption of these buildings, especially in desert climates, where the cooling load
30th INTERNATIONAL PLEA CONFERENCE 1
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represents a significant percentage of total energy consumption.
Sizing the windows of patient rooms should be carefully considered in relation to patient room
shape. Some common patient room designs have a small external wall surface area with a large room
depth, while others have larger external room surfaces and a reduced depth of the work area. The
windows of patient rooms should minimize solar penetration, reduce overheating; yet at the same time
maximize daylighting and patient access to external view. The objective is to reduce the total energy
load while maintaining comfort and quality health care.
Literature addressed the effect of environmental aspects on healthcare delivery. Ulrich
recommended that natural light improvement could help reduce stress and fatigue, while increasing
effectiveness in delivering care, patient safety and overall healthcare quality (Ulrich, 1991 and Ulrich et
al., 2004). In an attempt to develop patient room designs to create healing environments, the effect of
natural daylight on the patients’ average length of stay in hospitals was investigated. Studied factors
were patient’s average length of stay as an index of health outcome, and the differences in environment
during daylight hours, such as illuminance, luminance ratio, and illuminance variation in the hospitals
patient rooms (Choi et al., 2012).
In research work more relate to this study, energy efficient building envelope treatments were
examined for a generic reference hospital in Thailand. Parametric analysis was conducted. The overall
thermal transfer value, glazing material, Window-to-Wall ratio (WWR) and external shading devices
were addressed. The annual energy savings due to increasing daylighting reached up to 15.4% and
11.3% for the electrochromic and green tinted glazing respectively (Chungloo et al., 2001).
Optimization of window opening in a hospital patient room was addressed in a research that aimed
at providing daylighting, external view, while minimizing the energy consumption. An optimization
methodology was demonstrated through parametric computer simulations to determine the optimum
window design in the form of window width, sill and lintel heights and shading device depth (Shikder et
al., 2010). The impact of using various window shading systems and different window glazing types on
the energy consumption of a typical hospital Intensive Care Unit room space in Egypt was examined. It
was found that energy savings reaching up to 30% could be achieved by the use of externally perforated
solar screens and overhangs positioned at a shading angle of 45° (Sherif et al., 2013-a).
In another study, daylighting performance was simulated for a typical hospital Intensive Care Unit
room space located in Cairo, Egypt. Several window configurations were simulated in the four main
orientations, where the effect of adding shading and daylighting systems was examined. Successful
window configurations were recommended for different window to wall ratios (Sherif et al., 2013-b).
The above review of literature demonstrates that a limited number of publications addressed with
the relationship between hospital patient room designs and the associated window configurations.
Research work concerned with this relationship in desert environments is almost nonexistent.
Configuring the windows of patient rooms for energy efficiency, while providing acceptable daylighting
levels, could pave the way for reaching more sustainable hospital designs.
OBJECTIVE
This paper aimed to compare the energy consumption and daylighting performance of common
hospital patient room designs. Investigation focused on the design of windows facing the south
orientation under the desert clear-sky of Cairo, Egypt. The larger aim was to arrive at satisfactory patient
room designs that minimize energy consumption and maximize the utilization of daylighting, thus help
improve the delivery of sustainable healthcare facilities.
METHODOLOGY
The methodology was divided into two consecutive stages. Stage one investigated the energy
performance of the tested patient room design cases along with the alternative window configurations.
Stage two concentrated on the analysis of daylighting adequacy for the cases which achieved acceptable
performance in stage one. Three of the most common patient room designs were selected for
30th INTERNATIONAL PLEA CONFERENCE 1
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investigation. These were: Design A: the outboard bathroom patient room design; Design B: the nested
bathroom patient room design; and Design C: the inboard bathroom patient room design. The tested
rooms were assumed to have a similar floor area (22 m²). The layout, dimensions and parameters of the
tested rooms are shown in Table 1 and Figure 1.
Table 1. Parameters of the Tested Patient Room.
Internal Surfaces Materials
Walls
Reflectance
Ceiling
Reflectance
Floor
Reflectance
Window Parameters
Glazing Double glazing clear (VT=80 %)
Sun Breaker
Reflectance
Figure 1 The tested patient room designs
Seventeen window size values, expressed as Window-to-Wall Ratios (WWRs) were analyzed for
each patient room design. The values ranged from 10% to 90%, at 5% increments. The shape and
location of the tested windows alongside the external wall of the patient room space are illustrated in
Figure 2. A horizontal sun breaker was assumed to be positioned on top to the window. Its overhang
value provided a sun protection angle of 45°, as shown in Figure 3. This angle was based on the results
of previous research work (Sherif et al., 2013 b).
Figure 2 The shape and position of the tested window on the external wall at different WWRs.
Simulations were conducted using the climatic data of the city of Cairo, Egypt (30°6'N, 31°24'E,
alt.75 m) that enjoys a year-round desert clear-sky. The city is characterized by a hot-arid desert climate,
Design C:
The Inboard Bathroom
Design A:
The Outboard Bathroom
Design B:
The Nested Bathroom
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according to Köppen-Geiger (2006). The tested patient rooms were assumed to be located on the second
floor level of a hospital building, where windows were assumed to face no external obstruction. The
external ground surface was assumed to have a 20% reflectance value. Grasshopper which is a plugin for
Rhinoceros modeling software and a parametric modeling tool was used to automate the energy and
daylighting simulation process. By activating this function, the Grasshopper plugin generated a
parametric model for each WWR and ran a climate based analysis through DIVA interface. Energy
simulation was conducted using the EnergyPlus software. Daylight simulation was conducted using the
Radiance and DAYSIM software. The Diva-for-Rhino plugin for the Rhinoceros modeling software was
used as an interface.
Figure 3 The overhang of the shading device protecting the tested window.
Methodology of Stage One: Energy Consumption Analysis
The aim of this phase was to investigate the energy consumptions associated with the three tested
patient room designs (cases A, B and C). The annual energy consumption resulting from the different
WWRs of each patient room design was calculated. The cooling, heating and lighting energy
consumption values were accounted for. The WWRs which resulted low energy consumption values
falling within 3% from the lowest value for a certain patient room design were considered acceptable
cases for such as design.
Energy simulation parameters were selected to focus on studying the performance associated with
room shape and window configuration. The effect of thermal transmittance through walls and ceiling
from the adjacent spaces was neutralized. Thus, the thermal transmittance from all walls and ceiling,
except that of the window wall, were set to be adiabatic. The effect of the adjacent rooms was considered
to be of no relevance to the thermal performance sought in this comparative study. The building was
assumed to be fully air conditioned and minimal thermal transmittance was expected from the other
internal spaces that would have identical set conditions. The external wall was defined as a 0.35 m thick
double brick insulated cavity wall with a U- value of 0.475 W/m² k that carried the tested window at its
center. The air conditioning system heating and cooling set points were assumed to be 22°C/26°C
respectively. The occupancy time of the studied patient room was chosen to be all day, at a rate of 10 m²/
occupant. The hourly lighting schedules that were generated through the annual Daylight Availability
analysis by the Radiance and DAYSIM software were used as basis for artificial lighting energy
calculations. This artificial lighting was set to be dynamically controlled by sensors according to
daylighting adequacy.
Methodology of Stage Two: Daylight Availability Analysis
The aim of this stage was to evaluate the year-round daylighting performance of the cases that
proved successful for each of the three design configurations in stage one. Simulation parameters used in
investigations were: ambient bounces = 6; ambient divisions = 1000. The occupied time of the patient
room was assumed to be from 06:30 AM to 10:30 PM. In this study, the reference plane on which
daylighting performance was simulated was the patient bed level plane (0.90 m height). The spacing of
the analysis grid was set at 0.7m * 0.7m. Four points were placed on the patient bed. The reference plane
contained 46, 54 and 53 measuring points in each of the three tested patient room designs A, B and C
respectively, as shown in Figure 1. The illuminance value was assumed to be 300 Lx (IESNA, 2000).
30th INTERNATIONAL PLEA CONFERENCE 1
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Three Daylight Availability evaluation levels were used (Reinhart & Wienold, 2011). First, the “daylit”
areas were those areas that received sufficient daylight at least half of the year-round occupied time.
Second, the “partially daylit” areas were those areas that did not receive sufficient daylight at least half
of the year-round occupied time. Third, the “over lit” areas were those areas that received an oversupply
of daylight, where 10 times the target illuminance was reached for at least 5% of the year-round
occupied time. Two daylighting acceptance criteria had to be satisfied. First, 100% of the patient bed
surface area should be “daylit”. Second, at least 50% of the patient room area should be “daylit”.
SIMULATION RESULTS
Results of Stage One: Energy Performance
The total annual energy consumption values expressed in Kwh/m² were calculated. The results are
as shown in Table 2. It summarizes the energy consumption results in the south orientation at different
WWRs for the three investigated room designs A, B and C. The cases that achieved the required
threshold were highlighted with a light tone in the table.
Table 2. Total Annual Energy Consumption for Layout Designs A, B and C
Annual Energy Consumption (Kwh/m2)
90
85
80
75
70
65
60
55
50
45
40
35
30
25
20
15
10
WWR%
176
175
174
175
173
176
176
177
177
178
177
182
184
186
189
192
180
Design A
183
180
177
174
171
167
162
158
154
150
147
147
147
151
153
168
169
Design B
183
180
178
177
174
169
163
161
160
158
155
151
154
158
166
175
173
Design C
Use of design B that has a nested bathroom resulted in the lowest energy consumption among all
three room design types. The consumption was as low as 147Kwh/m2 in WWRs 30%-40%. Moreover,
design C (inboard bathroom design) achieved a very close value of 151 Kwh/m2 in WWR 35%. Use of
these designs resulted in a better performance in comparison with Design A (outboard bathroom design)
which failed to produce a value lower than 177 Kwh/m2. Furthermore, use of Design A resulted in the
highest energy consumption among all alternatives. It reached 192 Kwh/m2 at 15% WWR. On the other
hand, its consumption was lower than the other two alternatives at high WWR values. Using a 90%
WWR with designs A and B resulted in comparatively larger energy consumption values, reaching up to
183Kwh/m2.
On the other hand, the outboard bathroom design configuration (Design A) achieved larger window
sizes and larger number of options in comparison with the other two layout configurations. The
acceptable WWR range of Design A extended from 40 to 90%. Fewer acceptable WWR choices and
smaller window sizes were identified for the nested bathroom configuration (Design B). These ranged
from 20% to 45% WWR. A very limited range of WWRs was found acceptable in the inboard bathroom
configuration (Design C), where only three WWR cases (30 to 40% WWR) met the required criterion. In
design A, the bathroom location on the outboard wall reduced the size of the exposed external wall
surface, thus reducing the thermal exposure of the patient's room to the hot desert climate. However, this
was overcome by the increased artificial lighting energy load, as explained later. This was not the case in
the nested and inboard designs, where the size of the external wall surface was much larger.
To explain the behavior described above, the lighting, cooling and heating consumption values
were analyzed. As expected for a desert environment, cooling represented the highest values, followed
by lighting electricity then heating loads, which were almost negligible as shown in Figures 4, 5 and 6.
The performance of design A is shown in Figure 4. The lighting electricity load significantly
decreased with the increase of WWR. This could be attributed to the increase of daylighting use, which
resulted in a reduction of artificial lighting. However, the nature of the patient room plan type resulted in
overall higher levels of artificial lighting, with subsequent high cooling energy. On the other hand, the
30th INTERNATIONAL PLEA CONFERENCE 1
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cooling energy loads slightly increased with the increase of WWR. This allowed the acceptance of larger
WWRs, reaching up to 90%. The use of an outboard toilet with the resultant small external wall surface
dampened the effect of changing the WWR. This was observed in the gentle curve slope of the cooling
energy consumption for WWRs 20%-90% that it is almost flat.
Figure 4 Design A annual cooling, heating, lighting and total energy loads for different WWRs.
The performance of Design B is shown in Figure 5.The lighting electricity load decreased at a
constant rate with the increase of WWR, while the cooling energy loads increased considerably with the
increase of window to wall ratio (WWR). This is observed in the considerable increase and the curve
slope of the cooling and the total energy use from 40% to 90% WWR. This could be attributed to the
design of this patient room type that has a nested toilet that is associated with a larger external wall
surface. This increased solar exposure and allowed the window transmitted solar energy.
Figure 5 Design B annual cooling, heating, lighting and total energy loads for different WWRs.
The energy consumption of patient room Design C is shown in Figure 6. This design was found to
produce behavior almost similar to that of Design B. Both share a large exposed external wall. It was
noticed, thought that the cooling energy of design C was slightly higher than that of Design B. This
could be attributed to the cooling load resulting from the slightly increased lighting electricity.
30th INTERNATIONAL PLEA CONFERENCE 1
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Figure 6 Design C annual cooling, heating, lighting and total energy loads for different WWRs.
Results of Stage Two: Daylight Availability Analysis
In this stage, the cases that achieved successful energy performance in stage one were evaluated for
daylighting adequacy. Results are shown in Table 3. In Design A, acceptable daylight availability was
only achieved at large WWRs. Only 5 of the tested cases passed the daylight availability test in this case.
On the other hand in Design B, 4 of the 5 tested cases resulted in acceptable daylighting performance. In
Design C, all of the three tested cases resulted in an acceptable daylighting performance.
Table 3. Percentage of Daylit” Area Relative to Patient's Room and Bed Plane Areas
For more detailed discussion, eleven cases were analyzed for the outboard bathroom design
(Design A). Simulation results revealed that the amount of acceptable “daylit” areas was directly
proportional to the increase of WWRs values. Only large windows achieved adequacy in the case of the
outboard bathroom design. For WWRs between 70% and 90%, the “daylit” area reached 72% of the
space area, especially at 85% WWR. The partially daylit” areas dominated the patient room, where it
reached 50% of the space in average (40% to 65%). However, it decreased gradually until it became
unnoticeable at 85% WWR (15% of the space). In contrast, the “overlit area was almost constant (13%
as an average) in the tested WWRs.
On the other hand, when the bathroom was located in-between two adjacent patient rooms (Design
B: The nested bathroom), only four cases from five energy efficient ones achieved adequacy (30% to
45% WWRs). The “Daylit” area reached 80% of the space, at a WWR value of 45%. Although, the
“daylit” area of the patient bed plane achieved adequacy in the 25% WWR case, it was unacceptable in
relation to the overall patient room area testing (41% “daylit” area). The “Partially daylit” area decreased
gradually until it almost disappeared (1%), in the case of 40% WWR.
For the inboard bathroom design (Design C), the three energy efficient cases (30%, 35% and
40%WWRs) were acceptable for daylighting performance. The “daylit” area values for the patient room
space were almost similar (60% at an average). For the three design configurations, the "over lit" area
percentages did not exceed 15% in average for overall the patient room space in all accepted daylight
availability cases.
25 30 35 40 45 50 55 60 65 70 75 80 85 90
Room
26 28 35 39 43 48 54 61 63 72 70
Bed
0 25 100 100 100 100 100 100 100 100 100
Room 41 54 57 65 80
Bed
100 100 100 100 100
Room 60 58 62
Bed
100 100 100
WWR %
Design A
Design B
Design C
30th INTERNATIONAL PLEA CONFERENCE 1
16-18 December 2014, CEPT University, Ahmedabad
CONCLUSION
The energy and daylighting performance of three common patient room designs were simulated.
The performance resulting from use of a range of window sizes (expressed as Window-to-Wall Ratios -
WWRs) under the clear-sky desert sun of Cairo, Egypt was examined for each of these room designs.
Table 4 summarizes the range of WWRs that were recommended for each patient room design for
satisfying the energy and daylighting criteria. In addition, the balanced WWRs that satisfy both energy
and daylighting criteria at the same time were identified.
Results of this study demonstrated that solar penetration is a critical concern affecting patient room
design and window configuration in desert locations, like in Cairo, Egypt. Use of the outboard patient
room design was found to be the least efficient among alternatives. Although it has a smaller external
wall size in comparison with the other alternatives, it failed to provide an energy consumption that was
lower than that of other two tested room designs. Its best energy performance was 20% higher than that
of the nested bathroom design. This could be attributed to the increase of artificial lighting that resulted
from allocating the bathroom along the external façade in the outboard bathroom design. However, the
outboard design allowed for larger WWR values. This might prove useful for external view exposure
purposes. Although the nested bathroom and inboard bathroom designs provided better energy
performance, this was on the expense of window size. The acceptable cases of these designs had smaller
WWRs, between 30% and 40%.
The results of this paper demonstrated the need for a careful consideration of the size of windows
and openings in relation to different patient room designs. Simulation Techniques proved useful in
identifying the wiNdow configurations that satisfy both the energy and daylighting requirements at the
same time.
Table 4: Recommended WWRs for Patient Room Designs A, B and C
Patient Room Designs
Design A
Design B
Design C
Energy
40% - 90%
30% - 45%
30% - 40%
Daylighting
70% - 90%
30% - 90%
30% - 90%
Balance
70% - 90%
30% - 45%
30% - 40%
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FGI. 2010. Guidelines for Design and Construction of Healthcare Facilities. USA: Facility Guidelines
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IESNA, Rea M. S., (ed.). 2000. IESNA Lighting Handbook References and Application. 9th ed.
Köppen-Geiger, 2006. World Map of Köppen-Geiger Climate Classification. Retrieved 22 January 2010.
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Reinhart, C. F. and Wienold, J. 2011. The daylighting dashboard simulation-based design analysis for
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30th INTERNATIONAL PLEA CONFERENCE 1
16-18 December 2014, CEPT University, Ahmedabad
... Setpoint temperatures for the Nottingham climate were 21 o C for heating and 25 o C for cooling based on the CIBSE Guide A (CIBSE, 2015). In accordance with the literature for Cairo, the setpoints were 22 o C for heating and 26 o C for cooling (Sherif et al., 2014). Four out of the six workstations were assumed to be constantly occupied (Reinhart, 2013) (see Figure 2) resulting in a peak occupancy of 0.13 person/m 2 . ...
... This aspect can be critical when rating building performance, particularly considering that, for example, some certification systems such as LEED and WELL use sDA% for accrediting indoor daylighting. (Sherif et al., 2014). Conversely, for Nottingham, no cooling loads arose from the simulations for both façade designs in all tested orientations. ...
... Literature review shows that while there are many studies on glazing with regard to energy consumption, comfort and lighting in office buildings (Ochoa et al. 2012;Susorova et al. 2013) these topics have been less explored in hospitals (Alzoubi et al. 2010;Sherif et al. 2014). Most previous research on glazing performance mainly focus on energy, daylighting and comfort (Carlos and Corvacho 2015;Manz and Menti 2012;Ochoa et al. 2012;Sherif et al. 2014;Skarning et al. 2016;Stegou-Sagia et al. 2007;Vanhoutteghem et al. 2015) whereas the environmental aspects are less explored and the existing research mainly focuses on the LCA of building façade (Delem 2016;Kim 2011) or envelope (Azari 2014;Stazi et al. 2012). ...
... Literature review shows that while there are many studies on glazing with regard to energy consumption, comfort and lighting in office buildings (Ochoa et al. 2012;Susorova et al. 2013) these topics have been less explored in hospitals (Alzoubi et al. 2010;Sherif et al. 2014). Most previous research on glazing performance mainly focus on energy, daylighting and comfort (Carlos and Corvacho 2015;Manz and Menti 2012;Ochoa et al. 2012;Sherif et al. 2014;Skarning et al. 2016;Stegou-Sagia et al. 2007;Vanhoutteghem et al. 2015) whereas the environmental aspects are less explored and the existing research mainly focuses on the LCA of building façade (Delem 2016;Kim 2011) or envelope (Azari 2014;Stazi et al. 2012). Furthermore, only a limited number of studies concentrate on the environmental performance of window systems (Citherlet 2000;Papaefthimiou et al. 2008;Salazar and Sowlati 2008) Challenging Glass 6 6 and there appears to be no comprehensive and recent study that simultaneously takes into account the effect of glazing on the energy use, comfort, daylighting and the environmental performance of buildings. ...
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... Setpoint temperatures for the Nottingham climate were 21 o C for heating and 25 o C for cooling based on the CIBSE Guide A (CIBSE, 2015). In accordance with the literature for Cairo, the setpoints were 22 o C for heating and 26 o C for cooling (Sherif et al., 2014). Four out of the six workstations were assumed to be constantly occupied (Reinhart, 2013) (see Figure 2) resulting in a peak occupancy of 0.13 person/m 2 . ...
... This aspect can be critical when rating building performance, particularly considering that, for example, some certification systems such as LEED and WELL use sDA% for accrediting indoor daylighting. (Sherif et al., 2014). Conversely, for Nottingham, no cooling loads arose from the simulations for both façade designs in all tested orientations. ...
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... In a related study, horizontal blind slats were found to be most effective in providing adequate daylighting performance in a similar environment (Sherif, et al., 2016). While using a horizontal sun-breaker fixed at the window soffit, WWRs that suite different patient room designs were identified (Sherif, et al., 2014). In a similar type of space, utilization of multiple shading devices for control of solar access into an intensive care unit space was examined. ...
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Provision of adequate daylighting in hospital patient rooms can contribute positively to healthcare outcomes and reduce staff stress. This becomes challenging under desert clear sky conditions that typically result in uneven daylight distribution and discomfort glare in hospital rooms due to direct solar penetration. This is especially the case for the commonly used patient room design with an outboard bathroom that occupies a significant part of the façade. A daylighting system can prove useful in achieving adequate year-round daylight distribution and visual comfort. In this paper, utilization of a combined daylight redirection system that provides solar control is parametrically configured by Grasshopper and Diva for Rhino software packages. It consisted of fixed inner and outer window light-shelves. The study examined the effect of changing the shelves’ rotation angle independently on daylighting performance using the Spatial Daylight Autonomy (sDA) and Annual Sunlight Exposure (ASE) metrics. Analysis demonstrated that the outer shelf rotation is more influential on the sDA and ASE values in comparison with the inner shelf. Also, for adequate daylighting performance, usage of both light-shelves is required under the study conditions. Utilization of inner and outer light-shelves, rotated at 20°and 10° respectively, provided acceptable daylighting performance that satisfies LEED v.4 criteria.
... Grasshopper plugin-for-Rhino as a parametric modelling tool graphical node interface which includes various components, parameters, constraints to generate and mange any 3d parametric model [6]. All these features that Grasshopper has facilitate the exploration process especially at early design stage [7].Multiple parametric workflow succeed to optimize many environmental aspects such as daylighting and energy through genetic optimization as well as exhaustive search methods [11,9]. Their applications go behind optimizing static designs into dynamic responsive systems. ...
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The potentials of integrating thin-film photovoltaic technology into buildings make it the recommended renewable energy source not only for traditional architectures, but also the most innovative applications that favour envelopes characterized by free morphologies such as membrane structures. The integration of Photovoltaic technology into membrane structures offers a promising significant step in the market development. However, some challenges and questions are arising relating to the applicability of such systems and how they are significantly dependant on a list of complex aspects that have to be taken into account during the design phase. These aspects include the wide variety of membrane three-dimensional geometries that in turn govern the modules distribution, orientation and shadowing as well as the distribution of stresses and deflections for each single project and how both the structure and modules react to them.
... The range of Window to Wall Ratios (WWRs) that provides acceptable daylighting performance for each room layout was identified. In another research regarding the three common patient room designs, daylighting performance was addressed in combination with energy consumption (Sherif et al., 2014b). A range of window sizes was tested. ...
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Provision of daylighting and external view in hospitals is crucial as they create a positive healing environment. They could help in reducing patient stress, fatigue and length of stay, while increasing patient and staff safety and satisfaction. However, in desert locations that are typically characterized by year-long clear skies, control of solar penetration is essential. Window blinds were used to decrease patients’ visual discomfort and improve illuminance levels. The shape of blind slats influences daylighting performance and exposure to external view.
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Provision of a healing environment could help arrive at better healthcare outcomes. Healing environments that enjoy natural daylight have a positive impact on the health and well-being of patients and medical staff. They contribute to the achievement of shorter lengths of stay, reduction of stress and increase of patients and staff satisfaction. Several studies have emphasized the positive role of daylighting as one of the most influential factors for creating successful healing environments in healthcare facilities. This is especially important in patient rooms, which represent the largest component of hospital buildings. Provision of adequate daylighting is quiet a challenging task in desert locations which are typically characterized by year-long clear skies. External sun-breakers are typically used in these locations to control solar penetration, thus improving illuminance distribution and decreasing visual discomfort. This study aims at defining the main characteristics of the sun-breakers that could be used to control solar access into hospital patient rooms under clear-sky conditions. The study addressed two common patient room designs: inboard bathroom design and outboard bathroom design. The tested rooms had three equidistant sun-breakers that are externally fixed in front of a window facing south in Cairo, Egypt. The focus was on the impact of the sun-breakers’ cut off angle and the corresponding tilt angle on year-round illuminance distribution and visual discomfort. The main goal was to ensure adequate daylighting performance without discomfort glare inside these rooms. Parametric simulation runs were performed using Grasshopper, Diva-for-Rhino, and SpeedSim-for-DIVA, plug-ins for Rhinoceros modeling software to interface with the simulation engines Radiance and Daysim software. The outcomes of this study identified the range of sun-breaker cut off angles and their corresponding tilt angles which produced adequate daylighting performance for the two patient room types at different window to wall ratios. In general, the number of accepted sun-breaker cases increased with higher window to wall ratios for both patient room designs. It was noted that a wider range of accepted tilt angles was identified for the patient rooms having inboard bathrooms. Both the inboard and outboard bathroom designs had the same range of accepted cut off angles. It was observed that efficient daylighting performance was achieved in all tested WWRs for the two patient room layouts with cut off angles between 50° and 54° with the wall. Moreover, horizontal sun-breakers achieved successful results in all tested WWRs for the two patient room layouts. It was also noted that the cut off angles were more influential in providing adequate daylighting performance in comparison with tilt angles.
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This paper reports on a research that aims at identifying acceptable window configurations that suit the requirements of hospital Intensive Care Units located in the desert. It aims at achieving daylight adequacy and visual comfort in a typical assumed ICU space, in Cairo, Egypt. Annual simulations were conducted using Diva-for-Rhino, a plug-in for Rhinoceros modeling software that was used to interface Radiance and Daysim. Six window-to-wall ratios were investigated; in addition the effect of adding shading and daylighting systems was examined. Successful window configurations were recommended for the different window to wall ratios, for each of the four main orientations.
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An energy efficient building envelope can be achieved by implementation of the overall thermal transfer value (OTTV) in the 1992 Energy Conservation and Promotion (ECP) Act of Thailand, and by the utilization of daylighting through the building’s fenestration. The potential from energy efficient building envelope was investigated by parameterization studies of the OTTV’s parameters, glazing materials, window-to-wall ratios (WWRs), and external shading devices using weather data of Thailand for the generic reference office and hospital buildings. The existing OTTV recommended by the ECP Act is found to be an effective indicator of the thermal performance of the generic reference office building’s envelope, however for the generic reference hospital building the OTTV from simulation is more effective than the recommended one. The annual electric savings from side-window daylighting application are up to 15.4% and 11.3% from the electrochromic glazings and green-color tinted glazing, respectively.
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In a healthcare environment a window is necessary to transmit daylight and provide outside view to enhance therapeutic performance. However, a window impacts on several environmental attributes of the indoor space. Depending on the size, orientation and solar shading configuration, a window influences on visual and thermal comfort, as well as on the energy consumption of the building. It is thus necessary to optimise window design for maximum performance. Computer modelling and simulation techniques integrated with optimisation methodologies offer opportunities to evaluate design decisions considering various criteria. In this study a patient room window has been evaluated using computer modelling and simulation. The aim of the study was to demonstrate an integrated opitimisation methodology to identify the optimal design of a window considering daylight and thermal performances at the early stages. The window comprised a tall pane of glass and a light shelf, and was oriented toward the South. Four parameters were used to define the window: the width, sill and lintel level heights, and the depth of the solar shading. Performance of the window was measured for variable parametric values based on daylight factor and annual cooling/heating loads in the room. The study demonstrates a novel approach of optimising window configuration for daylight design using parametric computer simulations and evaluates the potential and limitations of the technique in daylighting design.
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To summarize briefly, key general points in this presentation include the following: To promote wellness, healthcare facilities should be designed to support patients in coping with stress. As general compass points for designers, scientific research suggests that healthcare environments will support coping with stress and promote wellness if they are designed to foster: 1. Sense of control; 2. Access to social support; 3. Access to positive distractions, and lack of exposure to negative distractions; A growing amount of scientific evidence suggests that nature elements or views can be effective as stress-reducing, positive distractions that promote wellness in healthcare environments. In considering the needs of different types of users of healthcare facilities--patients, visitors, staff--it should be kept in mind that these groups sometimes have conflicting needs or orientations with respect to control, social support, and positive distractions. It is important for designers to recognize such differing orientations as potential sources of conflict and stress in health facilities (Schumaker and Pequegnat, 1989). For instance, a receptionist in a waiting area may understandably wish to control the programs on a television that he or she is continuously exposed to; however, patients in the waiting area may experience some stress if they cannot select the programs or elect to turn off the television. Some staff may prefer bright, arousing art for corridors and patient rooms where they spend much of their time; however, for many patients, such art may increase rather than reduce stress. A difficult but important challenge for designers is to be sensitive to such group differences in orientations, and try to assess the gains or losses for one group vis-a-vis the other in attempting to achieve the goal of psychologically supportive design. Designers should also consider programs or strategies that combine or mesh different stress-reducing components. For example, it seems possible that a program enabling patients to select at least some of their wall art or pictures would foster both control and access to positive distraction. As another example, the theory outlined in this paper suggests that an "artist-in-residence" program, wherein an artist with a caring, supportive disposition would work with patients, might foster social support in addition to control and access to positive distraction. Running through this presentation is the conviction that scientific research can be useful in informing the intuition, sensitivity, and creativity of designers, and thereby can help to create psychologically supportive healthcare environments.(ABSTRACT TRUNCATED AT 400 WORDS)
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This study investigates how indoor environments with lighting during the day affect patients’ average length of stay (ALOS) in a hospital, by measuring and evaluating the daylight environments in patient rooms and comparing results to their ALOS. Patients’ ALOS data were compiled at a general hospital in Incheon, Korea, and the physical, environmental, and daylight conditions in the building were assessed. Data gathered were analyzed using a statistical package to determine the trends in the patients’ length of stay in hospital wards using 95% and 90% statistical significance levels. The data were categorized based on the orientation of each patient’s room and the positions of the heads of their beds in relation to window views. Comparisons were made between the different orientations of patient rooms in each ward of the selected hospital.The variables considered in this study were: each patient’s average length of stay as an index of health outcome, and the differences in environments during daylight hours, including illuminance, luminance ratio, and diversity of illuminance in the patient rooms of the hospitals. This study considered how these components affected patients’ ALOS in the hospitals. It discusses the relationship between indoor daylight environments and ALOS, as well as the seasonal weather factor effect on indoor daylight that could potentially influence the patients’ length of stay.This study can serve as a basis for the development of recommendations for designing patient rooms in healthcare facilities that will result in more effective healing environments.
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This paper presents a vision of how state-of-the-art computer-based analysis techniques can be effectively used during the design of daylit spaces. Following a review of recent advances in dynamic daylight computation capabilities, climate-based daylighting metrics, occupant behavior and glare analysis, a fully integrated design analysis method is introduced that simultaneously considers annual daylight availability, visual comfort and energy use: Annual daylight glare probability profiles are combined with an occupant behavior model in order to determine annual shading profiles and visual comfort conditions throughout a space. The shading profiles are then used to calculate daylight autonomy plots, energy loads, operational energy costs and green house gas emissions. The paper then shows how simulation results for a sidelit space can be visually presented to simulation non-experts using the concept of a daylighting dashboard. The paper ends with a discussion of how the daylighting dashboard could be practically implemented using technologies that are available today.
2013-a. Energy simulation as a tool for selecting window and shading configuration in extreme desert environment-Case Study: Intensive Care Unit in Aswan
  • A Sherif
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Sherif, A., El Zafarany, A., and Arafa, R., 2013-a. Energy simulation as a tool for selecting window and shading configuration in extreme desert environment-Case Study: Intensive Care Unit in Aswan. Proc. of the Sustainable Building Conf. (SB 2013), Cairo, Egypt.
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