China’s Broad Sustainability Group (BSB) has finally completed the construction of the world’s tallest prefab building at a rate of three-storeys per day after it was stopped at 20-storeys for one year.

At 57-storeys high, ‘Mini Sky’ does takes the title of the world’s largest flatpack tower but it was intended to be taller. The original Mini Sky was designed to top out at 97-storeys however this was reduced to 57-storeys and 800 apartments following reassessment of the building's impact on airspace

Ninety per cent of Mini Sky was fabricated offsite in three-storey blocks and packed onto trucks to be transported to the construction site and craned into place. The building was flat packed and transported in 120sqm portions per truck, which BSB claims afforded little to no dust pollution and saved 15,000 truckloads of concrete compared to conventional construction methods.

Each of Mini Sky’s three-storey modules has a 10 metre central atrium that is connected to other floors by the 3.6km network of ramps that run throughout the building. The idea is that these areas form ‘sky streets’ and communal spaces so residents will move away from elevators and towards a more traditional, collegial form of living.

Mini Sky strives for low operational costs and BSB have adopted a highly insulated envelope as well as their own air conditioning and air purifying technology for the building.

The envelope features 20cm of insulation and quadruple glazing in a punched window format. Thermal comfort is controlled by BSB’s own HVAC, air heat recovery and CHP systems, latter using exhaust from other services to power its own air conditioning capacity.

 The building’s air purification system is highly sophisticated and sees the building’s internal atmosphere run through a three-stage filtration system that removes particulates by 99.9 per cent and supplies the interior with 100 per cent fresh air.


With Mini Sky now complete, BSB now sets its sights on building one four times its size - an 838-metre skyscraper dubbed  ‘Sky City’.

BSB claims that all of Sky City’s 200 storeys could be built in seven months and that its quality, cost, energy performance and safety credentials would usher in a new era of high-rise design in China. Unfortunately for BSB, construction on Sky City has been put on hold reportedly because of political and community resistance.

Images are screen grabs from YouTube video.