About 15 years ago, Herman Lindborg decided he was tired of the noisy, drafty ventilation systems that produced uneven room temperatures in his laboratory at Lund University in southern Sweden. Inspecting the system, Lindborg realized that the biggest problem was the air diffuser—an essential component of the ventilation system that circulates fresh air into a room and removes stale air.
Working with Akademiska Hus, the real estate management company that owns the university’s buildings, Lindborg founded Lindinvent AB and set out to design a new type of air flow control system that would improve the indoor environment while cutting down on wasted energy.
Akademiska Hus is driven by a need to meet its tenants’ expectations on indoor comfort, while at the same time lowering expenses even as energy prices rise. Keeping lifecycle costs as low as possible became central to Lindinvent’s strategy.
An intelligent air diffuser
In most offices, the need for ventilation varies during the day according to the number of people working, and energy is wasted when the system runs at full capacity even though there’s little need for fresh air. Lindinvent claims its Intelligent Diffuser for Climate Control (IDCC) system saves energy by taking occupancy rates into account.
How can an air diffuser be considered intelligent? The unit has motorized louvers operated by sensors to adapt to ventilation requirements. When the need for air is low, the louvers close, and then open again as the need increases. The sensors can also be connected to lighting and other electrical devices to turn on and off depending upon the presence of people in the room.
By regulating air flow and indoor temperatures on a room-by-room basis, a building in effect becomes a series of individual climate zones. The system is based on air cooled to about 15°C, so lowering the temperature of a room is a simple matter of increasing the air flow. Monitoring is easily carried out using an Internet application or handheld PDAs.
A traditional ventilation system consumes about 150 to 200 KWh per square meter of floor area each year. But solutions built around diffusers from Lindinvent can lower consumption to as little as 50 to 75 KWh per square meter per year.
Lidninvent calls its product “Green Air Diffuser” to underline its extremely low lifecycle costs compared to conventional solutions. This Green Diffuser has been awarded two important Swedish prizes for innovative energy-efficiency solutions: Stora Inneklimatpriset (Indoor Climate Prize) and Stora Energipriset (Energy prize).
Variable airflow at Chalmers University
A practical application of the intelligent diffuser system can be found at Chalmers University in Gothenburg, Sweden. In connection with a reconstruction of a large building, engineers decided to install a variable flow air conditioner to replace an older constant flow system.
The rebuilt air treatment system now serves five floors, including offices, corridors and a basement storage space. Air conditioning runs only during normal business hours. If a room is empty and the temperature is below 23°C, the air diffuser provides a minimum flow of 5 liters per second. As soon as someone enters the room, a presence sensor orders the airflow to increase to 10 liters per second. When the room temperature reaches 23°C, each air diffuser can supply up to 40 liters per second to keep it from getting warmer. During the night and on weekends, the air treatment system can either be completely turned off or providing minimum air flow. The system saves 100 percent of the heating of supply air, 50 percent of the electricity for fans and 7 percent of the heat to the radiators.
Article published in March 2010