Optimizing Shading and Thermal Performances of Vertical Green Wall on Buildings in a Hot Arid Region

1. Paper Review on
Optimizing Shading and Thermal Performances
of Vertical
Green Wall on Buildings in a Hot Arid Region
Presented by
Subash Kalathoki
079MSEEB017
Pulchowk Campus

2. Article on
Optimizing Shading and Thermal Performances of
Vertical
Green Wall on Buildings in a Hot Arid Region
Ahmed A. Freewan 1,*, Neda’a M. Jaradat 1 and Ikrima A. Amaireh 2
1 Department of Architecture and Design, Jordan University of Science and Technology, Irbid 22110, Jordan;
nmjaradat16@ad.just.edu.jo
2 Department of Architecture and Interior Architecture, German Jordanian University, Amman 11180, Jordan;
ikrima.amaireh@gju.edu.jo
* Correspondence: aafreewan@just.edu.jo

3. Framework
● Background
● Methodology
● Result and Discussion
● Conclusion

4. Background
❖ The exterior surface of building facades in snow climate regions
experiences a temperature reduction of (7.9-16)°C, while warm
temperature climates see a reduction of (1.7-13)°C.
❖ Jordan's annual maximum temperature has increased by (0.3-1.8)°C
since the 1960s.
❖ Jordan's annual minimum temperature has risen by (0.4-2.8)°C since
the 1960s.
❖ The average annual temperature in Jordan is estimated to rise by 2°C
by 2050.
❖ The residential sector in Jordan accounts for 21% of total energy
consumption and 43% of total electricity consumption.

5. Background
❖ Inadequate insulation, inefficient building service operations, and the
absence of shading devices contribute to high energy consumption in
residential buildings.
❖ Over 60% of the energy used in houses is for space heating and
cooling.
❖ The building sector has significant potential for energy savings and
future research.
❖ Previous research on green walls has focused on their benefits, such
as improving air quality, and has used simulation tools or real
experiments.

6. Methodology
In this research, real experiment measurements and computer simulations were
used to assess the impact of a green wall on wall surface temperature, room air
temperature, daylighting rate, relative humidity, and wind velocity. The study
focused on a four-story student building at the Jordan University of Science and
Technology campus. Two rooms on the ground floor and two rooms on the first
floor were selected, with different green wall cavity sizes. The construction
details followed Jordanian building code specifications. The study also
highlighted the shading efficiency of Hedera helix, an evergreen climbing plant,
which was chosen due to its prevalence on the campus and its characteristics
such as rapid growth and wide leaf area. The variables considered in the research
were limited to the building type, plant species, and the Jordan climate.

7. Figure 1. (A) View the building under investigation, (B) section in the investigated rooms without
GW, (C) section in the investigated rooms without GW, and (D) plan of the investigated rooms

8. Preliminary field measurement
Field measurements of spaces with direct green walls at the JUST campus
showed a positive effect on internal air temperature, with a recorded
difference of around 3.7℃ compared to identical spaces without green
walls. The constructed green wall, made of a galvanized iron structure and
covered with Hedera helix plant, was found to be a potential climatic
solution in hot climate regions, with the ability to reduce air temperature.
The measurements were conducted over a 15-day period in unoccupied
rooms with no electrical devices in use.

10. This figure depicts the cavity air depth of the green walls, with a distance of 0.8 m at
ground floor level and 0.2 m at the first floor, and showcases different design types of
directly attached climbing plants or green walls with a cavity ranging from 0.10 m to
0.02 m in steps.

11. During the measurement period from November 23 to December 6, the
weather was mostly clear with some cloudy days. The mean ambient
temperature was 18.3°C, with a highest recorded temperature of 21°C.
The average relative humidity was 46%. The ambient temperature
within the green wall cavity was on average 0.2°C lower than the
surrounding temperature, while the relative humidity within the cavity
was approximately 4% higher than the surrounding area.

12. Validation of the Simulation Model
1. The study aimed to simulate a green wall using a solid layer approach
similar to previous studies.
2. The simulation results revealed a notable difference between the simulated
green wall as a single layer and the actual wall temperature during specific
time periods.
3. However, when simulating rooms without green walls, the results matched
well with the real experiments.
4. To account for the complex structure of the green wall and its impact on
heat transfer, airflow, and performance, additional modules were developed,
resulting in four stages of development based on the structure of the green
wall. The green wall models were created using DesignBuilder software.

13. Interior Surface Wall and Room Temperature
❖ The study focused on examining indoor thermal parameters, including the
interior wall temperature (Ts) and illuminance level (Ev).
❖ The shading effect of the green wall (GW) was evident in the first floor
rooms under investigation. The interior wall temperature of the covered wall
was consistently lower than that of the base case interior wall throughout the
study period, with a difference ranging from 0.5° C to 4.6° C on 23
November. On the ground floor, the temperature difference was slightly
smaller (ranging from 0.1 C° to 2° C) due to the south façade being
depressed by 0.6 m.
❖ Although there was a noticeable difference in the ambient temperature (Ta)
for the ground floor rooms under investigation, the room with the covered
wall was consistently cooler by 0.2°C to 1.9° C from 9:00 a.m. to 3:00 p.m.
on specific days (24 and 30 November and 2 December) during the study
period.

14. Result and Discussion
Real Experiment Results
❖ The weather during the measurement period, from 23 November to 6 December,
consisted mostly of sunny conditions with some partial cloud cover.
❖ The average daily ambient temperature (Ta) was 18.3° C, with the highest recorded
temperature reaching 21° C. The average relative humidity (RH) was 46%.
❖ The temperature inside the cavity between the green wall and the building wall, which
had a depth of 1 m, was on average 1.2° C lower than the ambient temperature of the
site during the measurement period. Additionally, the relative humidity within the
cavity was on average 4% higher than the surrounding area.
❖ Various variables were investigated and measured, including interior and exterior
wall surface temperature, interior ambient temperature, and cavity temperature. The
collected data can be found in the following sections.

15. Exterior SurfaceWall and Cavity Temperature
❖ Field measurements demonstrated that the average air temperature within the cavity
area, shaded between the foliage layer and the bare wall, was reduced by 1.1 °C
during daytime (8:00 a.m. to 4:00 p.m.). The thermal environment within the cavity
area was found to be better than the outdoor and unshaded environment, as
indicated by Ta (air temperature) results.
❖ Observation also revealed the relative humidity levels, with the highest levels
observed at 8:00 a.m. and 4:00 p.m. Notably, a significant increase in relative
humidity occurred during warm afternoons characterized by high solar radiation
and dry-bulb temperatures. In these conditions, increased evaporation rates resulted
in higher relative humidity values behind the foliage layer, reaching 11.4% higher
than those measured in the ambient environment.
❖ The measured data, including exterior surface wall and cavity temperatures, interior
ambient temperature, and relative humidity, were presented . These findings
highlight the positive impact of the green wall system on the microclimate within
the cavity area, providing reduced air temperature and increased relative humidity
compared to the outdoor and unshaded environment..

16. Simulation Results and Optimization Variables
Green Facade Foliage Scenario and Optimal Cavity depth
Different plant coverages and foliage percentage were investigated in order to optimize GW performance
and develop design guidelines. Six studied scenario with foliage percentage varied from 50 to100
percentage were studied and analysed and it was found that 60 percentage coverage represented the
best average performance for thermal and shading with reduction of temperature about 6.5 degree
centigrade and daylight intensity of about 3000lux.In the simulation process ten scenario of cavity air
depth was analysed from 0.02m to 1m with an increment of 0.02m and 0.6m cavity depth was found to be
optimal air cavity depth from thermal and saturation point of view

19. Above figure shows that how the optimised for best wall cavity and green wall
porosity 0.6m cativy and foliage coverage for around 60% help to reduce the
surface temperature for both interior and exterior wall which was obtained from
the simulation.

20. Conclusion
❖ Previous research has confirmed the positive impact of vegetation on buildings' microclimatic parameters, providing
cooling in summer through evapotranspiration and shading, as well as insulation in winter by reducing airflow,
particularly in hot regions.
❖ The current research focused on the performance of green wall systems using a simplified simulation method. A
prototype green wall system on a south-facing wall in Irbid city, Jordan, was studied to assess its shading effect.
Field measurements and computer simulations were conducted to evaluate different design configurations.
❖ The research demonstrated the effectiveness of green walls in improving buildings' performance in the Jordanian
context. The best scenario was selected based on reductions in surface and ambient air temperatures. Simulation
results indicated that a 60% foliage coverage reduced exterior surface wall temperature by an average of 6.5 C
compared to the basic case with varying cavity depth.
❖ The research findings align with a previous study that explored the thermal effects of vertical greening systems as
building envelopes. The green wall also proved to be an effective daylight system, enhancing both the quality and
quantity of daylight compared to the base case rooms.
❖ The research investigated over 100 scenarios with different green foliage coverage and cavity depths. The optimal
variables for green walls in Jordan were determined, such as direct green walls with 50% to 70% foliage coverage
and indirect green walls with around 60% foliage coverage and a cavity depth not exceeding 0.6 m. Other factors,
such as daylight and view, should be considered when using a high foliage ratio. In hot climates with direct sun
exposure, a smaller foliage coverage and larger cavity depth were found to be more effective for nighttime cooling

21. THANK YOU!!!