INTERNATIONAL CASE STUDY NATURAL VENTILATION
Microclimatic envelope design
Exhaust air discharge
Exhaust air discharge Underfl oor air
conditionig
Operable window for offi ce natural ventilation
Chilled ceiling & underfl oor air conditioning
Fresh air Intake
Double-skin facade
Greywater recycling
Eco-well for hybrid ventiation
Daylighting
Eco-well for hybrid ventiation ETFE Roof
Double-skin facade Landscape sunken garden
Fresh air intake
Rainwater recycling
Greenery
Water-cooled air conditioning system
the Chyau Fwu Group. Its new 200,000m2 mixed-use scheme Parkview Green FangCaoD has been designed to be naturally ventilated for most of the year and has been awarded a LEED Platinum rating for its core and shell. The developer made it clear to the architect Integrated Design Associates that it wanted to set a new standard for sustainable design in Beijing. “Parkview Green FangCaoDi had an open brief, but with a strong sustainable agenda,’ says Ed Peter, IDA’s associate director. ‘We wanted to create a development where natural ventilation systems could be deployed.’ Arup was the consultant engineer on the
scheme and has worked with the developer since the planning stage 10 years ago. Dr Vincent Cheng, Arup’s director of building sustainability, says aiming for a high LEED rating made commercial sense. ‘One of the benefi ts of having LEED-CS is that it has helped it secure a lot of commercial tenants that have global corporate social responsibility policies, which require them to rent LEED certifi ed buildings,’ he says. Parkview Green FangCaoDi is pyramidal
in shape, and comprises two nine-storey and two 18-storey towers containing 82,000 m2 of offi ce space, a 100-room hotel and 50,000 m2
of retail space. A 236m pedestrian bridge
spans the complex, offering views across a public plaza. A boutique cinema, a mini-spa and a gym on a terraced garden sky lounge on the 18th fl oor are among the building’s commercial perks. The building blocks are encased in a double
skin façade of glass and an air-fi lled ethylene tetrafl uoroethylene (ETFE) envelope. ETFE fi lm is 1% of the weight of glass, and transmits more light. The ETFE roof is set 3m away
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Basement ventilation air reuse for cooling tower
Demand control ventilation
Retail air conditioning air reuse for common area
Binnacle for displacement ventilation at atrium
Exhaust vent opened
Summer season
Reduction of solar radiation Air conditioning energy use: -13%
Envelope exhaust vent opened Vent out stratifi ed hot air
Envelope inlet partially opened Reduce infi ltrated air and assist exhaust air vent
With additional system Atrium thermal comfort temperature 29C – 31C (0.5m/s – 1.0m/s)
Ground fl oor inlet vent opened
Exhaust vent closed
Winter season
Additional fabric insulation Heating energy consumption: -80%
Envelope exhaust vent closed Retain internal hot air
Envelope inlet vent closed Restrict freezing air infi ltration and retain internal air temperature
With additional system Atrium thermal comfort temperature 3C – 10C (< 0.5m/s)
Ground fl oor inlet vent opened
Heating and ventilation through the seasons
In winter the exhaust vent at the top of the roof is closed, as is the inlet vent. This increases the atrium’s air temperature and the double-skin façade lowers energy consumption of the heating system by reducing heat loss through the fabric. During summer, the intake opening at low level and the exhaust vent at the top of the building are both opened to allow ventilation through the space between the double skin façade. Air moves up and removes heat from the atrium by the
heat stack effect, and binnacles inside the atrium provide spot cooling to enhance the thermal comfort to their surrounding areas. The difference in atrium temperature in the summer and winter is due to its large area. If heating were used for the entire atrium, it would result in huge levels of energy consumption. When compared with the outside sub-zero winter temperatures in Beijing, 3-10°C is high enough to ensure adequate comfort conditions in the atrium.
September 2012 CIBSE Journal 55
Offi ce fl oors – Air-conditioning operating Retail fl oors – Air-conditioning operating Atrium – Hybrid ventilation operating
Exhaust vent closed
Offi ce fl oors – Air conditioning operating Retail fl oors – Air conditioning operating Atrium – Hybrid ventilation operating
Exhaust vent opened
Earth cooling tunnel for fresh air pre-cool/ pre-heat
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