Zai Shui Yi Fang

Building basics

Year of completion	2012
Number of units	54
Number of occupants	150 people
Elevation	10 m

Building areas

Residential space

5112 m2

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Special features

Solar powered street lights, Solar PV installation for basement lighting, waste water reuse capacity of 200 m³ and rain water harvesting facility.

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The external wall is made of concrete and it is heavily insulated on the outside with a double layer of expanded polystyrene (EPS) board to ensure Passive House standards for walls which is less than 0.15 W/(m²K).  All the layers are joined together by using full scraping adhesive mortar and anti-cracking nets. The outer layer is made using a set of weatherproof membranes. A thick fire resistant rock wool insulation has been added above the lintel. The parapet of the balcony is insulated as well, with a 270 mm thick insulation. Interior walls that separate dwelling units are insulated using 30 mm thick polyurethane board.

All above grade building floors except the ground floor above the basement are made up of concrete slabs are insulated using 30 mm thick polystyrene board insulation with an additional sound barrier. The ground floor above the basement is insulated using 160 mm thick B-1 grade polystyrene board insulation. Foam glass insulation has been used to insulate basement walls. 

Double glazed windows with vacuum trap and UPVC frame have been used. All the doors that open to exteriors/unconditioned hallways are specially sealed for air tightness. The U-value of windows and doors is between 0.8-1.0 W/(m²K). Thermal bridges are avoided by special details at all critical junctions such as the installation of outdoor unit for air-conditioning, vent and plumbing pipes. All the refrigerant pipes are specially insulated and are housed within the insulated building envelope.

A certified blower door test has been conducted to measure the air tightness of the house,  to seal any potential leakages and to meet passive house standard of 0.6/h at n50 value.

Type of construction	Heavy
A/V ratio	0.25 -1
Thermal bridging	Detailing for thermal bridge free design was carried out according to Passivhaus criteria.
Air tightness	Certified pressure test (blower door)
Air tightness value	0.40 1/h
Shading	Internal blinds

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Ground floor

U-value	0.150 W/m2K
Total thickness	44.00 cm
Total area	343 m2

Material	Thickness	Thermal conductivity λ
Screet and finish	6.00 cm	0.930 W/mK
Plaster coat	2.00 cm	0.930 W/mK
EPS insulation exterior	16.00 cm	0.042 W/mK
Concrete slab	10.00 cm	1.740 W/mK
EPS insulation interior	10.00 cm	0.042 W/mK

(From outside to inside)

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External walls

U-value	0.150 W/m2K
Total thickness	61.00 cm
Total area	3620 m2

Material	Thickness	Thermal conductivity λ
Plaster coat	1.00 cm	0.930 W/mK
EPS insulation board	22.00 cm	0.042 W/mK
Concrete wall	18.00 cm	1.740 W/mK
Cement plaster	20.00 cm	0.930 W/mK

(From outside to inside)

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Upper ceiling

From outside to inside.

U-value	0.110 W/m2K
Total thickness	44.00 cm
Total area	357 m2

Material	Thickness	Thermal conductivity λ
Cement plaster	2.00 cm	0.930 W/mK
Concrete slab	10.00 cm	1.740 W/mK
Self levelling	2.00 cm	0.830 W/mK
EPS insulation	27.00 cm	0.042 W/mK
Waterproofing-slope	3.00 cm	0.180 W/mK

(From outside to inside)

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Windows

U-value window	0.90 W/m2K
Total area	1040 m2

Glass infill	Argon
Coating/Tint	Low-E
Solar heat gain coefficient	0.30
U-value glass	0.70 W/m2K
U-value window frame	None W/m2K

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Passive strategies

Each house is centrally air-conditioned using a split ducted reversible VRV system with 75 % efficient heat recovery capability. The conditioned air is distributed from the central air conditioning unit to various rooms using ducts and the return air is collected from a single point. The air-conditioning system also supplies the required fresh air into the house.

Indoor design temperature summer	26 °C
Indoor design temperature winter	20 °C

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Heating system

The heating capacity is 3.3 kW with an input power requirement of 1 kW. The COP of the complete machine is 2.8 and is expected to perform at a COP of 2.4 when the ambient temperature is -10 °C.

1 individual heating system installed:

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Cooling system

The cooing capacity of the system is 2.7 kW with an input power requirement of 1 kW. In addition, the heat rejected during the cooling period is used in the production of domestic hot water with a tank capacity of 150 L.

1 individual cooling system installed:

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Hot water system

1 individual hot water system installed:

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Ventilation system

The fan power is 90 W. The return air from the system is directed towards the outdoor unit, which helps to keep up the efficiency of the outdoor unit.

1 individual ventilation system installed:

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Primary energy consumption	120908.00 kWh/year
Primary energy consumption (ref. building)	698298.00 kWh/year
Specific primary energy consumption	23.70 kWh/m2/year
Specific primary energy consumption (ref. building)	137.00 kWh/m2/year

Differentiated specific primary energy demand and production

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Accumulated specific primary energy demand and production

Efficient envelope and systems for Passive House cost a premium of 30 % compared to conventional envelope and systems. However, when the cost is normalised including the land cost, construction cost and other ancillary costs the premium comes down to 10.5 % and is approximately € 296/m².

Envelope costs	517469 EUR
Systems costs	190013 EUR
Total investment costs	707482 EUR
Cost:	138.00 EUR/m2
Total differentiated annual costs	53917 EUR
Specific differentiated annual costs	10.00 EUR
Yearly energy costs	2998 EUR/year

Cost and cost effectiveness

The area saved due to the implementation of innovative energy systems and minimized service areas led to more saleable space and thus offered a bargain for the extra premium. In addition, heating subsidy offered by local finance scheme and recurring reduced energy bills offer an attractive pay back period for the capital. The passive house is expected to save heating energy costs of approximately € 56,481 per annum.

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Investment cost

Absolute building investment costs

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Specific building investment cost

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Annual Costs

Absolute annual costs

Specific annual cost

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Assumptions

Local Currency	CNY
Currency rate to EUR	0.12000 (March 25, 2013)

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Energy prices

Electricity	0.0620 EUR/kWh
Gas	0.0270 EUR/kWh