The Chinese government has been instituting a series of policies that encourage land and energy-saving housing projects and small-size dwelling units (≤90m²). The concept proposed by the IAUS School of Architecture, Tsinghau University addresses these policies in developing a dwelling pattern, taking advantage of the benefits of steel construction, to hold more residents in the specified site white at the same time providing good living quality.

Members of the IAUS School of Architecture, Tsinghua University's design team for the Living Steel Competition concept submission are: ZHANG Yue, WU Minghui, HE Jianfeng and SUN Lingbo

Staggered Truss System 

Staggered Dwelling uses a staggered truss steel frame system which is not only economical and fast in construction but also brings more flexibility in the plan and section. The system consists of a story-high truss that spans the entire width of the building. The trusses alternate from floor to floor with the long axis of one truss mid-span between the trusses on the floors immediately above and below. The system works in harmony with a precast plank that provides a smooth floor and ceiling while achieving the desired low floor-to-floor ceiling height. The composite truss and plank system provides a safe and efficient structural system that resists both gravity and lateral loads.

The architects suggest three different dwelling types within the building. Type A includes living room, dining room and kitchen on an entrance floor with bedrooms, bath and laundry on a second floor. Depending on whether the unit is located at the top of the building or at the first levels, the second floor will either be an upper or lower floor. The unit floor plan is flexible so that the entrance floor can include a bedroom for elderly parents or two bedrooms can be turned into one as children grow up and move out. As well, a section of the unit can be used as an open space or as a garden.

Type B units are larger and have a second floor as well with the same flexibilities and customisation potential as Type A units. Type C units have the whole floor plan on one level.

Type C residents also can turn the balconies into an extra bedroom or living space. By adjusting the units on some floors, community space can be added, such as open air gardens, gymnasiums and other public areas.

The building stands on pillars, leaving the space underneath for car and bicycle parking as well as pedestrian circulation. There are two entrance halls and elevators. The building is divided into two separate parts with each entrance floor divided into two fireproof subdivisions. Each subdivision has one enclosed stairwell that exits to the street or to the roof.

To provide easy access to dwellings from the outside, the elevation divisions exactly coincide with the stagger of each dwelling unit. The central part of the building is horizontally divided into four belts accessed by four main corridors. The belts are colour-coded red, yellow and blue with small aberrations representing the different dwelling units, providing more definition of each dwelling and individuality at the different levels.

The staggered truss system allows for faster and all-weather erection than traditional post and beam, reducing the total cost of the superstructure. Significant cost savings also is due to the lighter frame and fewer foundations. Additional savings accrue because the building requires fewer columns and less steel tonnage. No transfer girders are required at the second floor over the extensive public spaces. This translates into lower costs for the fabrication of the steel, and foundation savings due to the reduced necessity for footings. The truss system uses precast planks, which provided a finished ceiling and eliminated the need and expense of gypsum board. The low floor-to-floor dimensions further reduced costs by reducing the overall building height and lowering its heating and cooling costs.

The staggered truss system dramatically improves the building layout by eliminating interior columns to create clear open space. This open space provides more aesthetic design options for a mini-theatre, bar, and reading room, and added to the inviting ambiance of the space as well. In the portion of the structure designated for residence, steel framing provides the ultimate in flexibility. It permits easy modification of the basic areas and simplified the process of changing ramification spaces.

The building incorporates energy saving features, such as minimum building exterior and dwelling unit walls. Cooling and heating is provided by unit-controlled air conditioning and is aided by ground-source heat pumps. Hot water is provided through a wall-type high rise building solar system. The heat collectors are located on the balconies and can be unit controlled and used for electric heating and hot water demands. Most of the exterior windows are shaded by the balconies to reduce heat absorption in summer months. Also every staggered dwelling unit opens to both sides of the building for good natural ventilation.

See right for a diagram of the Ventilation patterns of IAUS design concept.