Ten Tips for Curtailment Planning
Effective curtailment planning is a key success factor in any demand response strategy. Defined as a proactive planning process to temporarily decrease electricity consumption, thoughtful and creative curtailment planning can maximize cost savings, reduce emissions and generate revenue during voluntary and event-driven demand response.
EnergyConnect’s engineers and support teams work with each customer to review their specific operational environment and individual needs to develop a successful curtailment plan. To provide an example of the types of considerations, our Chief Engineer put together a sampling of some of the most effective and non-obtrusive curtailment actions most facilities could employ.
1) Reduce Light Levels
Lighting level reductions are realized through turning off lighting fixtures and/or the use of programmable dimmable lighting ballasts. Lighting controls can be activated manually, by lighting control systems, or by Building Automation Systems (BAS).
2) Pre-cool/Pre-heat Buildings
Take advantage of the thermal mass of your building structure and its contents by shifting energy consumption to night when electricity prices are lower. In the summer time starting the morning with a building with a cool thermal mass will have measurable impacts on how hard the AC needs to work in the afternoon.
3) Temperature Adjustment
Use your building automation system (BAS) to raise or lower the temperature of selected spaces by a pre-determined amount. In many cases building occupants will not notice the impact of a 2 – 5 degree temperature set point adjustment until later in the afternoon. In many cases, it is at the day’s end before any discomfort is detected.
4) Standby Generators/Cogeneration
Generation and co-generation is effective if the equipment can be operated for a few hours and is connected to large enough loads. Local environmental regulations must permit their use for any event other than emergency situations. Check with your local EnergyConnect account manager to see if back-up generation is allowable for your programs.
5) Utilize “Early Unoccupied” Mode
A common BAS control scheme is the Occupied/Unoccupied measure that is otherwise known as “scheduling”. During unoccupied hours one or more of the following three measures are deployed by the BAS: space temperature is set back; outside air dampers are closed; and fans go from a “continuous” mode to “on/off” cycling. By using existing controls in the BAS, this is an easy way to drop load. The time that the building goes into the unoccupied mode is moved to an earlier time. An example where this is effective is a college building that is virtually empty by noon on Fridays in the summer. Moving the unoccupied schedule from 7 PM to noon, or even 11 AM, would not affect users and yet would save significant kW.
6) Change Static Pressure Set Point (or VFD speed)
The supply air static pressure on variable air volume (VAV) systems can be reset to conserve fan energy. Alternatively, fans with variable frequency drive (VFD) speed can be reset to have a similar effect. Many building automation systems control the VFD on fans serving a VAV HVAC System. On the hottest day of the year, the VAV Box serving the most difficult space may be only 80% open. On a moderate temperature day, this same box may be only 70% open. Although this situation may be ideal for temperature control, there is an excess pressure drop in the ductwork. By reducing the static pressure, or fan speed, the VAV Box dampers will open up. The fan energy savings can be 10 – 20% of the fan motor horsepower.
7) Cycle Constant Volume Fans and Air Handler Units
Constant volume fans in air handler units run at one fixed speed continuously. If the unit is half loaded, one strategy is to turn the fan on and off as done in most homes. Outside air requirements need to be considered with this measure. Units with carbon dioxide sensors and controls can automatically ensure the proper amount of outside air is brought into the building.
8) Increase Chilled Water Temperature on Constant Volume HVAC Systems
Some building automation systems can regulate the chilled water temperature on chillers. By increasing the chilled water temperature, a facility can often reduce energy usage without affecting comfort. Each degree Fahrenheit that the chilled water temperature is raised results in chiller energy usage decreasing 1 – 2%.
9) Thermal Energy Storage
The production of ice or chilled water is particularly well-suited to shifting electric demand from daytime hours where it is expensive to night-time hours where it is relatively inexpensive.
10) Auto DR
EnergyConnect works with customers to install “Auto DR”. New programming creates three or more levels of load drop capabilities. Multiple curtailment strategies on multiple pieces of equipment can be activated at the touch of one button.
Posted on Monday, August 24th, 2009 - BlogConnect