Certified Energy Manager Practice Exam

What are degree days used to represent?

1. Measurements of annual asset depreciation

2. Units of energy consumption over days in a year

3. Units of temperature over days in a year

4. Annual financial assessments of energy systems

The correct answer is: Units of temperature over days in a year

Degree days are a valuable metric used in the field of energy management to represent variations in temperature over days in a year. Specifically, they quantify the difference between the average outdoor temperature and a baseline temperature, which is often set at 65°F (18°C). This measurement helps to estimate the heating or cooling needs of buildings. For example, when the average daily temperature is lower than the baseline, heating degree days are calculated to indicate how much heating is required to maintain a comfortable indoor temperature. Conversely, cooling degree days are calculated when the temperature exceeds the baseline, reflecting the need for cooling systems. Using degree days in energy studies aids in analyzing energy consumption patterns, forecasting energy needs, and comparing the energy performance of buildings. It offers a practical way to understand and anticipate how temperature fluctuations impact energy usage throughout the seasons, making it a critical tool in energy management and efficiency assessments.