How much does it cost to heat your home? It all depends on the
outside temperature of the house. The colder the outdoor
temperature, the greater the heating cost. Engineers developed a
method to help homeowners calculate their heating costs. This
method is called the degree-days. The equation for degree-days is
defined as:
 
DD = (65 – To) ´ N
Where
DD = degree-days
To = Average daily outside temperature
N = number of days
Note: 65 means 65º F indoor temperature
The average daily temperature in Washington D.C. for the first 5
days in February was:
|
Day |
Average Temperature º
F |
| February 1 |
35 |
| February 2 |
38 |
| February 3 |
42 |
| February 4 |
32 |
| February 5 |
28 |
What was the total number of degree-days for the first five days
in February?
(65 – 35) ´ 1 day + (65
– 38) ´ 1 day + (65 –
42) ´ 1 day + (65 – 32)
´ 1 day + (65 – 28)
´ 1 day = 30 + 27 + 23 + 33 +
37
= 150 DD
Using a similar calculation for days that the outdoor
temperatures are below 65º F, we can find the total number of
degree-days for the entire year. Here are the degree-day data for
some U.S. cities.
|
City |
Degree-Days |
| Atlanta,
GA |
3,095 |
| Chicago,
IL |
6,127 |
| Duluth,
MN |
10,000 |
| Fairbanks,
AK |
14,279 |
| Honolulu,
HI |
0 |
| Miami,
FL |
206 |
| New York,
NY |
4,848 |
Marie lives in Atlanta, Georgia. The heating bill last year was
$900. She has a sister who lives in Fairbanks, Alaska. How much
would it cost her sister to heat a comparable house?
Estimate the answer:
 Less
than $900
Between $900 and $2,000
 More
than $2,000
 
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