In temperate climates, including most of California, March is typically the start of the shoulder season marking the transition from winter to summer. During shoulder seasons, highly variable temperatures present an operational challenge — as well as a potentially large payoff from demand management.
The following chart shows a year of daily weekday high and low demand readings from a Snapmeter customer. Daily minimums are fairly steady throughout the year. Daily maximums rise with cooling load in the summer. You can see the effect of warmer temperatures as early as February, but March is when demand really begins its upward climb.
Daily min and max demand, weekdays only.
So far, so obvious. But let’s focus in on March and August (again, weekdays only – excluding weekends removes some of the noise from the charts without affecting the analysis). Notice that the overall level of demand in August is higher, but March is far more variable. In August, about 100 kW separates the monthly max from the monthly min. March ranges over almost 300 kW.
Daily max demand, March vs. August
Further, the highs in March are more tightly concentrated. Curtailing on just two days, the 13th and the 26th, offers about 100 kW in savings. August offers a nice curtailment opportunity on the 12th, but the generally steady level of August demand means that only 50 kW of savings are possible. After that, opportunities for further curtailment are slim.
Of course, demand charges in August are typically much higher than in March. Summer demand management remains as important as ever. Nevertheless, opportunities in the shoulder months are often both easily capitalized on and sadly overlooked.
Shoulder season opportunities stretch beyond demand management. The chart below also shows daily min and max demand for the same building, but this time for weekends only:
Daily min and max demand, weekends only
Notice what happens starting in March and continuing through October: weekend peak demand, so constant during the winter, starts to spike up erratically. Even though the building is unoccupied over the weekend, cooling systems have to work hard to ensure tenant comfort on Monday mornings. Not all of this load is avoidable, but the excess use does add up. Shoulder months are a good time to keep an eye on baseload and figure out strategies for smoothing demand.
Last week’s daily use vs expectation
How can Snapmeter help? For starters, pay close attention to predicted peaks. As mentioned, the combination of high variability and mostly mild temperatures tends to serve up perfect opportunities for demand management. Even if demand charges are bit lower in the off season, March presents a good time to define and implement curtailment strategies in advance of the hottest months.
Second, keep your eye on the “use vs. expected” and “demand vs. expected” numbers in last week’s energy profile. A certain amount of fluctuation here might just be noise. But persistent upward shifts are often a sign that your building is responding to changing weather conditions in unexpected ways, and you may have to review your control sequences as you head into warmer weather.
