Untitled
Heating and Cooling Degree
Days
Energy
Consumption
Objectives:
-
To analyze
and interpret data.
-
To justify
and explain conclusions using supportive data.
-
To
investigate energy/power consumption as it relates to heating/cooling degree
days.
Introduction:
Heating/Cooling Degree Days (HDD/CDD) is a way to relate
each day’s temperatures to the amount of fuel needed to heat or cool a
building that day. If this lesson
is done during warm months, use cooling degree days (high temperatures); if it
is done during cool months, use heating degree days (low temperatures). You can obtain information
from the utility companies in your area about Heating/Cooling Degree
Days.
Heating degree days calculations are used when the
day is cool and heating may be necessary.
Find the average temperature using the high temperatures for the
day. If the number is above 65,
there are no heating degree days that day.
If the number is less than 65, subtract it from 65 to find the number of
heating degree days.
Cooling degree days calculations are used when air
conditioning may be necessary. In
this case, 65 is subtracted from the average temperature. The number is the number of cooling
degrees days that day.
Since 65 degrees is a level where most people neither need to turn on heating
or air conditioning systems, this is used as the factor to compute the amount of
heating or cooling energy needed.
Add the heating and cooling degree days for each day to determine the number
of degree days for the month.
Examples:
1.)
If the high today was 60 and the low was 40 degrees, the average
temperature is 50 degrees. When you
subtract 50 from 65, you determine that there are 15 heating degree days today. If the average is 65,
there are no degree
days.
2.)
If the high today is 90 and the low was 70, the average is 80. 65 subtracted from 80 is 15 cooling
degree days today. If the
average is 65, there are no degree days.
Procedure:
1.
Observe
historical data for one full month.
Data used from the AWS School Weathernet weather station:
NORTHERN GARRETT HIGH SCHOOL - ACCIDENT, MD
Helpful Hints
| Historical Observations from Northern HS Accident, MD |
Date |
High
Temp
°F |
Low
Temp
°F |
Rain
(day)
" |
High
Wind Gust
mph |
Last
Light |
Low
Pressure
"Hg |
High
Pressure
"Hg |
Low
Humidity
% |
High
Humidity
% |
| 1/1/2002 |
19.9 |
9.8 |
0.00 |
23.9 |
17:24 |
29.88 |
30.07 |
7 |
7 |
| 1/2/2002 |
26.0 |
5.8 |
0.00 |
12.9 |
17:24 |
29.91 |
30.15 |
7 |
7 |
| 1/3/2002 |
23.5 |
8.8 |
0.00 |
27.0 |
17:26 |
29.77 |
29.93 |
7 |
7 |
| 1/4/2002 |
26.0 |
16.9 |
0.00 |
27.8 |
17:26 |
29.85 |
30.01 |
7 |
7 |
| 1/5/2002 |
38.6 |
23.4 |
0.00 |
28.9 |
17:26 |
29.82 |
29.95 |
7 |
7 |
| 1/6/2002 |
38.6 |
28.5 |
0.00 |
19.9 |
17:22 |
29.36 |
29.82 |
7 |
7 |
| 1/7/2002 |
28.5 |
17.4 |
0.00 |
0.0 |
17:28 |
29.41 |
29.77 |
7 |
7 |
| 1/8/2002 |
28.9 |
15.4 |
0.00 |
19.9 |
17:30 |
29.73 |
29.87 |
7 |
7 |
| 1/9/2002 |
45.7 |
28.5 |
0.00 |
41.0 |
17:29 |
29.58 |
29.74 |
7 |
7 |
| 1/10/2002 |
46.2 |
43.2 |
0.00 |
31.8 |
17:27 |
29.68 |
29.80 |
7 |
7 |
| 1/11/2002 |
43.2 |
30.4 |
0.00 |
36.0 |
17:30 |
29.65 |
29.85 |
7 |
7 |
| 1/12/2002 |
45.7 |
29.0 |
0.00 |
29.8 |
17:34 |
29.43 |
29.85 |
7 |
7 |
| 1/13/2002 |
37.6 |
26.0 |
0.00 |
37.9 |
17:34 |
29.43 |
29.82 |
7 |
7 |
| 1/14/2002 |
50.6 |
28.5 |
0.00 |
25.0 |
17:30 |
29.65 |
29.85 |
7 |
7 |
| 1/15/2002 |
43.2 |
26.0 |
0.00 |
41.9 |
17:30 |
29.66 |
29.96 |
6 |
6 |
| 1/16/2002 |
37.1 |
25.9 |
0.00 |
25.0 |
17:32 |
29.80 |
30.05 |
6 |
6 |
| 1/17/2002 |
42.2 |
27.5 |
0.00 |
34.0 |
17:38 |
29.74 |
29.88 |
6 |
6 |
| 1/18/2002 |
28.8 |
21.1 |
0.00 |
34.0 |
17:39 |
29.84 |
29.98 |
6 |
6 |
| 1/19/2002 |
29.0 |
23.1 |
0.00 |
27.0 |
17:34 |
29.57 |
29.96 |
6 |
6 |
| 1/20/2002 |
32.1 |
19.9 |
0.00 |
21.9 |
17:41 |
29.71 |
29.96 |
6 |
6 |
| 1/21/2002 |
40.2 |
27.5 |
0.00 |
40.8 |
7:22 |
29.65 |
29.79 |
6 |
6 |
|
|
a. Determine the average temperature for each day.
b. Determine the cooling degree days for this month using the formula
above.
c. Determine the
heating degree days this month
using the formula above.
d. Compare the
heating/cooling degree
days computed to the average for your area for the month. This information can be obtained
from your local utility companies.
e. How does the difference relate to recent weather conditions?
f. On a sheet of
graph paper, graph the average temperature each day from the Monthly Table above. Also plot the line
y=65. can you identify which days were heating degree days?
Cooling degree days?
2. Observe the graph
below showing the high temperatures for
the each day for the last two days.
Data used from the AWS School Weathernet weather station:
NORTHERN GARRETT HIGH SCHOOL - ACCIDENT, MD
Helpful Hints
a. Where would the average temperature be plotted on
this graph?
b. On a sheet of graph paper, graph the average
temperature each day using data from the Monthly Table above.
Conclusions:
How is
average temperature data used to understand energy
consumption?
What data
did you use to support your assumptions about energy usage?
How
is energy/power consumption related to heating/cooling degree
days?
Extension Activities:
-
Write to
local utility companies to obtain literature on additional energy-consumption
related issues.
-
Obtain
information from a utility company in another part of the country where the
weather is significantly different from your own. Compare
HDD/CDD.
-
Think
about energy sources, the energy cycle, and how it relates to our
climate. How do heating and
cooling degree days relate to the possibility of global warming of our
environment?
-
National Standards:
Geography: #2, 3, 4, 14, 16,
18
Mathematics: Numbers and Operations, Algebra,
Measurement, Data Analysis and Probability, Reasoning and Proof,
Connections
Science:
Unifying Concepts and Processes, Science as Inquiry, Physical Science, Earth and
Space Science, Science and
Technology
Technology: #1, 3, 4,
5, 6
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