3for2 – Beyond Efficiency



The 3for2 concept


In new commercial buildings in Singapore, up to one third of the enclosed volume is typically occupied by technical systems and structural elements, consuming valuable space that could otherwise be devoted to occupants. Large ceiling plenums are the default condition.They accommodate the high volume ductwork required for air-based cooling systems, running below deep structural beams.


This practice results not only in large floor-to-floor heights that increase the volume of space to be enclosed and conditioned, but also in added material cost, higher structural loads and increased solar and transmission gains from additional façade surface. Finally, the standard air-based, packaged cooling systems in current use are typically oversized and over-cool the supply air in order to manage humidity levels, resulting in uncomfortable spaces with unnecessarily high energy demand.


We propose to reduce this space consumption by a third, and at the same time raise the comfort and increase energy efficiency by a factor of two. Through systems integration we propose to build 3 floors in the space of 2, hence 3for2, by eliminating the excesses of standard design, and at the same time achieve 2x performance. This is based on the basic research of the Low Exergy module in Singapore and the Chair of Sustainable Architecture and Building Systems at ETH Zurich.


Implementing LowEx technology allows to switch from air-based to water-based systems that drastically reduce the space in a building dedicated to energy transport. By using decentralized ventilation systems, this space requirement is further reduced. At the same time, LowEx technology increases system performance since supply temperatures can be reduced.   Within this project, suitable technology and its boundaries are identified, saving potentials in terms of energy and material are calculated and guidelines for design and implementation are developed.


Implementation in Singapore


As a next step, elements of this concept will be implemented in 2014/2015 in a building project in Singapore in collaboration with the United World College of South East Asia. Office space in an otherwise conventionally designed and operated multipurpose building will be equipped with LowEx technology.


The technology consists of passive chilled beams, distributed ventilation units combined with an underfloor air distribution network and new control systems. The setup is similar to the set of LowEx technologies that are currently studied at the BubbleZERO laboratory in Singapore.


This implementation brings together interested industry partners and will help to identify costs and economic benefits of this approach. After completion, the office space will serve as test environment and will permit to further improve control and monitoring systems. In addition, it will act as a showcase of high performance building systems in Singapore.



Dr. Adam Rysanek, 3for2 Project Manager (rysanek@arch.ethz.ch)


Further information

Beyond Efficiency Blog   UWCSEA masterplan




UWC_phase4_3for2_rendering copy

Rendering of the new megablock at UWCSEA with the proposed 3for2 facade (Adam Rysanek, 2014)

3for2 Technology

In the 3for2 concept technical systems are integrated with the structural elements of a building like the floor slab or integrated in the facade.