Case Study: Suasana PjH Putrajaya

Suasana PjH, Putrajaya Suasana Putrajaya is a 14-storey mixed-commercial development in the city of Putrajaya. Comprising of two tower blocks with two basement levels, with a gross floor area of 77,837 square metres. In reflectance of the city and its Malay cultural identity, the building has two skins; external glass facade (Malay ‘Songket’ pattern fritted to provide necessary shading and cut out direct solar penetration into the internal spaces through windows), and internal building envelope (low-e glass with flux sensor).

SUN PATH CHART

The double-skin facade has vegetative balconies that enhances sun shading through the use of hanging plants. However, the office spaces in Suasana PjH are not naturally ventilated, hence this study aims to focus on the facade and effectiveness of its sun shading device. The building also does not use a typical shading device, thus we conducted an experiment to test the effectiveness of the sun shading device on North-East and North-West facade at Block A, through temperature recordings and interior sun shading simulations.

SOLAR EXPOSURE LEVEL

PASSIVE DESIGN: SUN SHADING DEVICE Based on the sun path chart and solar exposure level diagram, all facades of the building are exposed to the sun at different time.

CLIMBERS

North-East South-East

North-West facade and South-East facade receive direct sunlight from West and East respectively. Facade as the sun shading device can filter direct sunlight to the interior space North-West

However, sun shading facades at North-East and South-West are tilted to block the direct sunlight perpendicularly. Source: andrewmarsh.com

Green Balcony

Section of Green Balcony

South-West GLASS SUN SHADING FACADE TILTED GLASS SUN SHADING FACADE CLIMBERS

Source: SketchUp SunHours

“Green balconies” with hanging plants at the planter box act as sun-shading device. Climbers draping over to the levels below provide partial shading for the interior space, thus reducing solar radiant heat gain.

SUN SHADOW PATTERN GLASS SUN SHADING FACADE 9AM

12PM

3PM

21 MAR

The outer sun shading glass is made of glazed heat strengthened glass that has high resistance to thermal load. Glazing gives additional strength to wind load and thermal stress.

22 JUNE

Section of Double Facade

Double Facade Gap

The double facade prevents solar radiation from directly entering the interior office spaces by using air between the 2 facades acts as an insulator. The cavity between the external and internal glass facades is naturally ventilated and acts to cut down direct solar heat transfer.

22 DEC ‘Songket’

The eastern sun shines on the South-East and North-East facade. The adjacent building does not shade the building as it is situated further. North-East glass facade is tilted to avoid direct eastern sunlight to penetrate the interior.

The sun is situated right above the building, does not get much of daylight from the sides. The skylight in the middle of each blocks of building allows daylight to penetrate the interior.

South-West glass facade are tilted towards the western sun which reflect the sunlight. North-West of the building receives direct western sun. The facade at South-East and North-East help reduced the heat gain and glare.

Fritted Ceramic Glass

Exterior glass facade fritted with the ceramic Malay ‘Songket’ pattern provides the necessary shading to the building. The fritting takes 50% of the surface area, cutting out 50% of solar penetration into the internal spaces through window. The tilted facade is used to block the sun from East and West.

The space between the the sun-shading fritted glass and the internal building envelope is open to the sky, creating a chimney stack ventilation effect that will naturally evacuate hot air away from the lower level. The air between double wall gets heated by solar radiation and rises up through the gap between the floors, constantly moving, reducing the heat movement to the interior spaces, dropping air pressure. Low air pressure draws cooler air into space though gap on facade.

TEMPERATURE COMPARISON GRAPH

INTERIOR SIMULATION 12 PM

3 PM

ANALYSIS

North-West

North-East

21 March

22 June

Without external glass sun shading facade, the afternoon sun directly enters the space. The glare increases the interior temperature significantly.

21 Dec

(Data collected at Block A Level 6, Suasana PJH on 19th October 2018)

The North-East facade is tilted while the North-West facade is straight. From the graph, one can notice that both North-East and North-West facades effectively shield the building from solar heat gain as interior temperature at both sides is always lower than exterior. Nonetheless, the interior temperature increases corresponding to the rapid rise in exterior temperature when afternoon sun shines on the North-West facade. This shows that the sun-shading device is not effective enough to insulate heat.

PSYCHROMETRIC CHART

21 Dec

21 March

22 June

The sun shading facade serves as a shield, absorbing part of the direct sunlight from west in the afternoon, while allowing visual permeability to the exterior of the building. It reduces glare from the windows and the interior temperature for better thermal comfort.

21 March

22 June

The orientation and angle of the tilted facade prevent direct sunlight from entering the interior space in the morning. In the afternoon, the facade and the gap between tilted facades allow sufficient indirect light into the building.

Source: Climate Consultant 6.0 Based on the data collected on 19th October 2018, It is known that the temperature and humidity of the interior space on the North West and North East facade does not meet the thermal comfort (blue highlighted zone) of the building. Although the double skin facade helps to reduce interior temperature and energy consumption, the interior space does not meet thermal comfort as it was not designed to be naturally ventilated. Air conditioning is used to control the thermal comfort of interior space. Conclusion In conclusion, the glass sun shading facade is the main passive sun shading device of the building. It allows sufficient daylight and filter glare into the interior. Though it does not effectively cool the interior space for thermal comfort, it still reduces energy consumption of the interior.

21 Dec

North-East Facade Simulation (with glass sun shading facade)

North-West Facade Simulation (with glass sun shading facade)

North-West Facade Simulation (without glass sun shading facade)

9 AM

REFERENCES

Source: Sun shading study of 2018, simulated in revit

http://www.pjh.com.my/project/suasana-pjh/ | http://andrewmarsh.com/apps/releases/sunpath2d.html https://www.meteoblue.com/en/weather/forecast/modelclimate/putrajaya_malaysia_6697380

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