Passage III
Heating degree-days (HDD) and cooling degree-days (CDD) are used to estimate the amount of energy needed to heat or cool, respectively, any building on a given day. HDD are calculated by subtracting the daily mean temperature (Td) from a base temperature of 65°F. Each degree difference is one HDD. CDD are calculated by subtracting 65°F from Td.
Table 1 lists, for each of 10 US cities, the latitude of the city and the city's total HDD and CDD for a 1 yr period.
For the state of Illinois, the annual total HDD and the annual total CDD were determined for each of the years 1985-2010 (see Figure 1).
19. Which of the following graphs best illustrates the latitude and the CDD for each of the cities listed in Table 1 ?
Your Answer is
Correct Answer is A
Explanation
The table in the question is arranged from south to north. Note that the question asks about CDD not HDD, and the starting point of the curve should be around 4000.