As the Summer months are upon us, our attention turns to air conditioning, comfort, and energy usage. In modern smart buildings, one of the major energy consumers is the central plant, which produces the cooling for the building and is a key component in managing and reducing energy spend. In addition to the typical control strategies to produce cooling in the form of chilled water, there are opportunities to optimize production through smart building strategies.
As the temperature rises, the demand for cooling increases, and the resulting power needed by the building adds stress to the electrical grid. One driver of a high electric bill for commercial customers is the demand portion (how fast a customer uses electricity in a given timeframe). For example, when all chillers are running at full capacity due to high cooling demand in addition to the base electrical loads used for lighting and outlets.
One strategy is to implement what is traditionally called a demand response sequence to manage and control peak energy usage. This energy management algorithm looks at the current electric demand and activates control sequences to lower consumption in order to avoid hitting a high peak (utility companies hate peaks, hence the demand charge).
Another strategy that helps address shaving a building's peak energy usage is to create onsite storage that can be used to supplement the building's capacity. Traditionally, thermal mechanical storage is one means of building up a large reserve of chilled water (or in some cases ice storage). This strategy runs the chillers during off peak electric periods and chills a reserve of water to be used during the next peak cooling demand (essentially a thermal battery).
With the rapid developments in battery technology, a new form of storage has emerged to directly store energy in the form of electric batteries. There are a number of available options for battery chemistry, but the overall trend is that the cost per KWH continues to drop. Utilizing the energy stored in the batteries (electric storage) during high demand times helps offset the peak and thus saves on energy costs.