At the Beaverton Central Plant (BCP) energy efficiency is accomplished by aggregating loads; managing real-time information; utilizing high-quality, flexible equipment; and employing a sophisticated operating approach. The system evaluates the real-time data, projects the future need, and provides delivery of just the right amount of heating or cooling from the most economical source.
By combining the heating and cooling demands from a number of buildings with different uses (such as office, retail, and residential), the plant is managed to take advantage of the diversity of schedules and needs. Since not all loads are on at the same time (i.e., residential loads are highest in early morning and evenings, office loads peak near midday) the overall size of the plant can be smaller. Further, the aggregation of loads means larger equipment, which is typically more efficient (economy of scale) and cheaper per unit output. Finally, the aggregation of the equipment makes for more efficient operation and maintenance.
The first stage of cooling uses fans that bring in the air outside and uses little energy. This is often referred to as an economizer cycle. Being located in a maritime climate has real advantages, as during nearly two-thirds of the year we can utilize outside air for space cooling. The second stage of cooling - especially for data rooms that run warm and need constant cooling - is through the use of the cooling towers, often referred to as a water-side economizer. The only energy use is limited to pumps and fans to operate the tower loop, which acts like a large swamp cooler. The third stage of cooling brings in the chiller for mechanical cooling, which is the most energy-intensive. However, by using variable drives on all components of the system, even this source is highly efficient.
The first stage of heating begins with recovered heat from the internal gains (people and equipment) through recirculation of a portion of the air. The second stage comes from very high-efficiency boilers (95% efficient), which are called condensing boilers. There is a one million metric British thermal unit (one mmBTU) in the Central Plant and a two mmBTU unit in the mechanical room of the Health Club Building. The third stage is the high efficiency (85% efficient) conventional seven mmBTU boiler. Like the cooling system, the heating system uses variable drives on all pumps and fans to ensure high-system efficiencies.