By Nick Orrick
December 2, 2022

Electricity generators have the ongoing problem of matching supply to demand.  This
involves having enough generating capacity available to supply electricity when demand
peaks.  The most familiar peak occurs in the afternoon and early evening in summer
when there is heavy air conditioner use.  Less familiar are the dual peaks in cooler
weather which is driven in part by increased use of heat pumps for heating.  Pepco lists
its winter peaks on weekdays as from 6 - 9 am and 5 - 9 pm.  The accepted procedure
to save energy has been for people to turn down their heat during the day while they
aren't at home and at night when they are sleeping.  The problem is when they get up in
the morning and when they get home in the afternoon and they turn the heat back up. 
There is a surge in demand for electricity to supply extra heat to raise the temperature. 
In addition, many will be using electricity to cook breakfast and dinner, to heat water for
washing, and to run other appliances.  
Typically, electricity generators use less desirable units to meet peak demand.  These
units are usually less efficient, more polluting, and/or more expensive to operate.  This
means that customers who want to reduce the environmental impact of their electricity
use should avoid using electricity during peak times.  Ironically, the environment may be
better off if you didn't set the thermostat on your heat pump back during the day and at
night.  Depending on your unit's technology, it may not save you money either.  
Recognizing the increased cost of generating electricity during peak times, the Public
Service Commission has approved Pepco making time-of-day metering available to
residential customers. The price per kilowatt-hour is lower than normal during off-peak
times in return for a considerably higher price during on-peak times.  If you are willing
and able to restrict your electricity use during peak times, you could save money while
being more environmentally responsible.