Monday, June 18th, 2007
June 18, 2007 was a typically hot summer day with temperatures ranging from the low seventies to the high eighties (fig 1). Again, the CUE Optimizer capitalized on the low electric prices in the early morning hours (fig 2). Pre-cooling reduced HVAC operating expense by 24% and electricity consumption by 12% (fig 3).
Outside Temperature & Market Price – Figure 1 CUE uses forecasts of outside temperature, humidity, and solar radiation to anticipate building cooling loads. Forecasts of volatile hourly electric market prices create a CUE arbitrage opportunity – we shift cooling loads to low-priced hours using use building thermal mass. We execute this shift by sending OPT temperature setpoints to the building automation system from our central servers. |  |
 | Zone Temperature Setpoint Control – Figure 2 NSU (Night Set-Up) defines the normal temperature setpoints (or thermostat settings) that are programmed into the building automation system. Typically the setpoints are set up at the end of occupancy – thus shutting down HVAC operation – and set down in the early morning – to restart HVAC operation in advance of building occupancy. OPT (OPTimal) defines the setpoints recommended by CUE to reduce a building’s HVAC expense. |
HVAC Electricity Consumption – Figure 3 Using CUE’s set-point strategy, this building reduced its HVAC expense for the day by 24% and its total kilowatt-hour usage by 12%. |  |