DESIGN STAGE
3.1.4 Exterior Envelope Insulation
Daylighting Glazing
CSG-8 FVR 1-59 + 12A + 8C
VLT: 55%
Ref: 30%
SC: 0.42
Vision Glazing
CSG- 8 CEF 11-38 + 12A + 8C
VLT: 42%
Ref: 34%
SC: 0.35
Case study of Hong Kong
Science and Technology Park:
Low Energy Façades
• high performance low-E double glazing allows daylight
to enter whilst controlling solar heat gains
• optimise window to wall ratio (40%) to balance views,
visibility and daylighting whilst reducing solar gains
• external solar shading devices reduce cooling demand
by controlling the penetration of heat from the sun
• highly insulated façades minimise heat gains through
walls
Motorised Sun Louvres
• solar tracking louvres automatically adjust to minimise
solar gains to the entry lobbies
Figure 3.1.20 Smart louvers
(Source: Hong Kong Science and Technology Parks Corporation)
DESIGN STAGE
3.1.4 Exterior Envelope Insulation
Office
BUILDING
Office
BUILDING
Case study of Zero
Carbon Building:
Optimise Window to Wall Ratio (WWR)
To optimise natural ventilation and control
of heat gain/glare/daylight, appropriate
ratios of window to wall areas are achieved.
For north-west and south-east façades of
the office area, a high WWR is obtained
with fritted glass, external shades, and large
operable windows for cross ventilation.
High Performance Glass Wall System
The two main window systems for the
office area are a high performance glazing
system incorporating low-emissivity coated
glass panels, and actuator controlled
operable windows. A reduction in energy
consumption is expected from lower cooling
loads and reliance on artificial lighting due
to good thermal and optical performance.
Energy use for dehumidification would be
reduced by good air-tightness.
External Solar Shading
Vertical shading fins on the north-west
façade maximise the penetration of natural
daylight and blocks low angled sun in the
late afternoon. Solar heat gain is reduced
with better glare control.
Figure 3.1.18 Exterior of Zero Carbon Building
(Source: Hong Kong Construction Industry Council)
Case study of Energizing
Kowloon East Office:
Window to Wall Ratio
Reduce cooling demand via:
• Optimise window to wall ratio (~20%) to reduce
solar heat gain
• Insulate envelope using rock wool (U-value of
wall: 0.83 vs EMSD’s reference input 3.3, i.e. 75%
reduction in thermal transmission)
Figure 3.1.21 Elevation of Energizing Kowloon East Office
(Source: Energizing Kowloon East Office)
Case study of Hysan Place:
Solar-shading devices
Angled vertical fins were added to the west façade to block the
late afternoon summer sun, and were angled, slightly pointing
northwest to better block direct sunlight and avoid blocking
views to the harbour. The horizontal fins in addition to the
vertical fins were also found to improve the overall shading,
especially on summer days. The horizontal fins also added to
the internal illumination of the west side, functioning as external
light shelves.
Low-emissivity double-glazing
Allows sufficient visible light to enter the building while reducing
unwanted solar heat gain and exterior noise at the same time.
Figure 3.1.19 Solar-shading devices
(Source: Hysan Development Company Limited)
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