"Lilies", China solar building - Beijing - Bianchini & Lusiardi Associati

Lilies – China Solar Building – “Solar Building Design Competition”
Promoter: International Solar Energy Society/ China National Engineering Research Center for Human Settlements/ Chinese Renewable Energy Society
Location: Beijing, People’s Republic of China
Architect: Bianchini & Lusiardi Associati
Year: 2007/2008
Awards: Prize for Technical Excellence
Design level: conceptual design

Project description
The “Lilies” project is divided into 3 independent blocks located in the middle of a water basin; the acronym LILIES comes from that: like water lilies, the buildings grow on water and use the Sun radiation to fulfill their energetic needs.
The electric power is produced by an array of 9 solar Stirling motors, a type of solar generator that utilizes the difference of temperature to generate electricity.
The heating/cooling system is based on a water heat pump that exploits the water basin at the base of the buildings. Natural ventilation is also widely implemented, especially in Summer. All the energy required by the buildings and their inhabitants is produced on-site.

Bird’s eye view

Site plan with the water basin running around the modular housing blocks

The apartments inside are made of modular units attached to a steel structure.
By aggregating such units it is possible to obtain within one block a diverse set of apartments, all with an outdoor terrace. The total gross surface is 7,200 square meters, while the surface of single apartments ranges from 38 to 100 square meters.

Typical floor plan (left) and modular dwelling units (right)

Typical cross-section

Dwellings
All dwellings are based on a 0,6×0,6m module/tile; the standard tile includes low-voltage wiring with power and signal sockets and 4 led lights. Therefore, every point in the space could be transformed into a light fixture, support for TVs, or into other kinds of electrical equipment.
The tiles are also provided with a soft rubber cover, allowing people to sit on them.
The concept is to eliminate the traditional subdivision of a room in predetermined functional zones: every part of the room can be freely configured and adapted as its inhabitants would like.

Views of the living area of a dwelling

The external cladding of the building is made with modular aluminum tiles, the interior spaces are coated in a translucent polymeric elastomer. A 180 mm thick cellulose fiber thermal and acoustic insulation is placed between the external and the internal layers. The load-bearing structure is made in galvanized carbon steel.

Climatic conditions
The building development is located at Chao Yang District, Beijing. The site area is 3887.5 m2, near the city artery and branch road. Latitude 39°48 and longitude 116°28 Measured point has 32 meters height above sea level. The typical Beijing climate conditions range from cold winters to hot, humid summers.

Active solar techniques
Each block is equipped with eight Solar Stirling engine units manufactured by SOLO Stirling GMBH which provide up to 8×8 KWP on Beijing average conditions.
Stirling engines are based on temperature difference into a hot chamber, heated by solar radiation via a tracking parabolic concentrator, and a cold chamber cooled by the water from the underlying water basin.

Advantages:
– high energetic output perused surface
– high efficiency (up to 50% solar energy/electric output ratio)
– low maintenance costs
– high durability
– resistance to various climate conditions and to pollution
– silent operation
– possibility of integration with conventional systems (i.e. methane gas burners).

Passive solar solutions
In winter
The facades allow sunlight to be transmitted into the dwellings, an additional contribution comes from sunlight reflection by water. The courtyard’s top is covered so as to trap the heat passing through staircases and other openings on the facades.
The main heating source is provided by ground heat pumps, fully powered by a series of Stirling engine units, thus reducing the net CO2 production to zero.
In Summer
The balconies avoid direct sunlight to enter the dwellings, climbing plants on the facades act as additional sun-shading systems.
Natural ventilation is incremented by exploiting the depression effect produced by the wing-shaped “concentrator” over the courtyards; the thermal mass of the water basin also contributes to the cooling effect.
The courtyard in the middle of each building works as a ventilation chimney, exploiting the differential density between the hot air on the building top and the colder one near the water basin, thus creating an ascending flow that naturally extracts exhaust and overheated air from the dwellings.

Building data
Usable area of dwellings: from 37 up to 76 sqm.
Site area: 1,680 sqm
Total surface of dwellings: 7,200 sqm
Internal dwelling height: 2.4 m
Building height: 15.9 m
Storys: 6 above the ground, 5 used for residencial functions