It sounds too good to be true. An office building built on the campus of the United World College South East Asia (UWCSEA) in Singapore in 2015 has a glass front that protrudes over the entrance like the bridge on a ship. Behind the facade with its ceiling-to-floor windows is a 550-square meter testing center for a building system technology that’s set to revolutionize high-rise construction. The technology allows three stories to be built at the height normally required for two — and without any reduction in the amount of usable height on each floor. This approach is expected to lower construction costs by reducing the amount of building materials needed. What’s more, buildings engineered in such a manner will consume much less energy than conventional office buildings in regions with similar climates.
Efficient Energy Use
Cool Solution Means Buildings with More Space
ETH Zürich – one of the world’s leading technology and natural sciences universities – Siemens, and the government of Singapore are testing new building system technologies that not only significantly reduce energy consumption but also make it possible to build three stories at the same height now used for two.
Hot and Sticky
The name of this fascinating pilot project is “3for2”. Conducted by the Singapore-ETH Centre Future Cities Laboratory (established in 2010 by ETH Zürich and the government of Singapore) and project partner Siemens Building Technologies, the project is being directed by Arno Schlüter, Professor of Architecture and Building Systems at ETH Zürich. The 3for2 project team has developed a series of innovative technologies that are designed to proactively address the major challenges faced by Singapore. One such challenge is the lack of space in the city-state, as Singapore is one of the most densely populated cities in Southeast Asia. Situated at the southern tip of the Malay Peninsula, Singapore is home to 5.5 million people spread across an area of only 720 square kilometers, making it the world’s third most densely populated urban center. The huge amount of energy consumed by the city’s air conditioners accounts for roughly 60 percent of all the energy consumed by its buildings, whereby the buildings themselves account for half of the city state’s electricity demand. However, this isn’t really surprising, says Schlüter, because “Singapore’s hot and humid climate is like the worst-case scenario for achieving a comfortable indoor climate.”
But it is exactly such challenges that enable new building technologies to prove their value. “We can test innovative energy-efficient technologies and building-system control strategies here and then utilize them later in other densely populated cities in tropical regions around the world,” says Helmut Macht, CTO of Siemens’ Building Technologies Division. Singapore’s new office building has been occupied since December 2015 and already consumes two-thirds less energy than an average conventional office building in Singapore, making it one of the most energy-efficient buildings in the city-state. Plans call for the system to be further optimized in order to reduce energy consumption by an additional 20–40 percent.
The centerpiece of 3for2 technology is a new type of climate control concept. Normally, traditional air conditioners are used to cool air down to six degrees Celsius because such units also dehumidify the air. Large fans and air ducts then blow the cold dry air into rooms via ceiling ducts, whereby the air is much cooler than it needs to be to ensure comfort. The concept employed by Schlüter’s team, on the other hand, involves separating the cooling and dehumidifying processes. Here, fresh air from the outside is sucked into the building in a decentralized system via several small openings in the facade. It is dehumidified in the process because it transfers moisture and a small amount of heat to air currents that simultaneously flow out of the building.
Outside air is then cooled with the help of chilled beams on ceilings that contain water. As warm air rises, it is cooled by the chilled beams, and then descends at the edges of the ceiling. A beam temperature of 17–19 degrees Celsius is sufficient for generating a light and comfortable temperature vortex.
This process offers several benefits. It makes less noise, its distribution paths are shorter, and the incoming air can be precisely apportioned and doesn’t need to be cooled down to a very low temperature. In combination with additional efficiency measures, such as LED lighting modules equipped with motion and brightness sensors, and forward-slanted windows that reduce the level of incoming sunlight, the new technology lowers both energy demand and operating costs. In addition, the chilled beams in the ceiling take up much less space than the equipment for conventional cooling systems. This gives office high-rise planners as much as 30 percent more usable space, which is enough to build three floors in the space normally needed for two — hence 3for2. Given Singapore’s sky-high real estate prices, this offers a major advantage.
Sensors that Soothe
In 2014, Schlüter’s team entered into a partnership with Siemens Building Technologies in order to assess the feasibility of its new high-rise concept. One of the fundamental problems encountered was that a conventional thermostat would not be sufficient for improving both energy savings and ambient comfort in a system with eight air inlet units and 130 chilled beams. “Intelligent control and regulation are essential for exploiting the system’s benefits,” says Schlüter.
Desigo CC from Siemens, the most extensive building management system now on the market, offers such intelligent control and regulation. In its current testing phase for the 3for2 project, Desigo CC’s controller program collects data from more than a thousand sensors linked to one another by Internet Protocol. It analyzes this data and can then adjust room temperature, humidity, and brightness in various parts of offices within seconds. “Over the next two years, we will learn how to use the controller program and the sensors in a way that will ensure maximum comfort with the lowest possible energy consumption,” says Thomas Liesenfeld, the Siemens project manager for 3for2.
The system has already successfully completed its first trial by fire. The question to be answered here was whether the automated controller program would be able to deal with drastic changes in a decentralized air conditioning system consisting of many small units — for example, when a room suddenly fills up with people, as was the case during a tour of the building at the beginning of 2016. “The system stayed quiet and the climate in the office remained comfortable,” Liesenfeld reports. The goal now is to create Singapore’s most energy-efficient office in the UWCSEA building by 2018. The Singapore-ETH Centre Future Cities Laboratory and Siemens are confident they will achieve this goal — and that real estate developers in Singapore and other cities with tropical climates will recognize the benefits offered by their new building concept.