The savings here are calculated in therms (the energy in about 100 cubic feet of natural gas). To relate therms to gasoline, coal, cordwood, kilowatts, Btus, and other outputs, check our Gasoline Energy Equivalents and Conversion Calculator.
| What hot lights you have! | Run time | What to do | Energy Savings per Year |
| 100-watt light bulb | 3 hours a day, 300 days a year (3.07 therms) |
Change to 14-watt compact fluorescent bulb (.43 therms) |
2.64 therms |
| 100-watt light bulb | 6 hours a day, 300 days a year (6.14 therms) |
Change to 14-watt compact fluorescent bulb (.86 therms) |
5.28 therms |
| 100-watt light bulb | 9 hours a day, 300 days a year (9.21 therms) |
Change to 14-watt compact fluorescent bulb (1.29 therms) |
7.92 therms |
| 100-watt light bulb | 12 hours a day, 300 days a year (12.28 therms) |
Change to 14-watt compact fluorescent bulb (1.72 therms) |
10.56 therms |
| 60-watt light bulb | 3 hours a day, 300 days a year (1.84 therms) |
Change to 14-watt compact fluorescent bulb (.43 therms) |
1.41 therms |
| 60-watt light bulb | 6 hours a day, 300 days a year (3.68 therms) |
Change to 14-watt compact fluorescent bulb (.86 therms) |
2.82 therms |
| 60-watt light bulb | 9 hours a day, 300 days a year (5.52 therms) |
Change to 14-watt compact fluorescent bulb (1.29 therms) |
4.23 therms |
| 60-watt light bulb | 12 hours a day, 300 days a year (7.36 therms) |
Change to 14-watt compact fluorescent bulb (1.72 therms) |
5.64 therms |
| What you drive | What to do about it | Energy Savings per Year |
| a vehicle that gets an average of 15 mpg |
Eliminate just 10 miles of driving per week |
42.94 therms |
| a vehicle that gets an average of 20 mpg |
Eliminate just 10 miles of driving per week |
32.24 therms |
| a vehicle that gets an average of 25 mpg |
Eliminate just 10 miles of driving per week |
25.79 therms |
| a vehicle that gets an average of 30 mpg |
Eliminate just 10 miles of driving per week |
21.47 therms |
| a vehicle that gets an average of 35 mpg |
Eliminate just 10 miles of driving per week |
18.44 therms |
| a vehicle that gets an average of 40 mpg |
Eliminate just 10 miles of driving per week |
16.12 therms |
| Where you live | Adjust your thermostat... | Energy Savings per Year |
| 1000-square-foot home | Lower by one degree when your heat is on; raise by one degree when your AC is on (figured for 300 days or heating or cooling; 65 days "neutral" temp.) | 30 therms (15 per 150-day season) |
| 1500-square-foot home | Lower by one degree when your heat is on; raise by one degree when your AC is on (figured for 300 days or heating or cooling; 65 days "neutral" temp.) | 45 therms (22.5 per 150-day season) |
| 2000-square-foot home | Lower by one degree when your heat is on; raise by one degree when your AC is on (figured for 300 days or heating or cooling; 65 days "neutral" temp.) | 60 therms (30 per 150-day season) |
| 2500-square-foot home | Lower by one degree when your heat is on; raise by one degree when your AC is on (figured for 300 days or heating or cooling; 65 days "neutral" temp.) | 75 therms (37.5 per 150-day season) |
| 3000-square-foot home | Lower by one degree when your heat is on; raise by one degree when your AC is on (figured for 300 days or heating or cooling; 65 days "neutral" temp.) | 90 therms (45 per 150-day season) |
|
Methodology The national average for heating and cooling requirements is roughly 60,000 BTU per square foot of heated living area, and about 105 million BTU per household. The rule of thumb we'll use here is to allow 10 BTU per square foot per heating degree-day. Thus, if you live in New England, a region that has an average of about 6600 heating degree-days in a year,and you have the house of 2000 square feet, you would need about 132 million BTU for heating in a year. If you lived in a similar-sized house in a warmer in area like the West South Central region, (Arkansas, Louisiana, Oklahoma, Texas), with about 2300 heating degree-days days in a year, you would require only about 46 million BTU for heating. Of course it works in a similar way for cooling degree-days, with the air conditioner energy required to pump warm air out of the home. The simplest way to assign a savings factor from a thermostat adjustment in the Therms and Barrels project is to equate the lowering of the thermostat by one degree for 150 days of wintertime with a one-degree rise in outdoor temperature over that time period. Similarly, raising a thermostat by one degree for 150 days of warm weather translates to a one-degree drop in outdoor temperature over that time period. The 150-day periods are based on the months in the temperate New England climate from early November to early April, when people generally have their heating systems running, and from mid-May to mid-October when air-conditioners (and sometimes heaters!) are in use. If we multiply normal heating or cooling degree-days by square feet of heated or cooled floor space, and then by 10 BTU per square foot, we get total BTU per dwelling. We then subtract 150 from the degree-days, to simulate the effect of turning the thermostat up or down by one degree for that many days, and subtract that result from the first. Basically, the savings are about 750,000 BTU or 7.5 therms per 500-sq. ft. change. Thus, turning down the thermostat one degree in a house of 1000 square feet makes a 15-therm difference. Turning the thermostat down by one degree in a 3000-sq. ft. house makes a whopping 45-therm difference in one 150-day heating or cooling season. If you live in a place where heating and cooling seasons are lopsided, feel free to adjust the 150-day seasons to something more accurate for your area. Also, the 10 BTU per square foot allowance assumes a living space that's already pretty efficient, without much leakage of the air that you've gone to the trouble and expense of heating or cooling. If you live in a drafty old house, or your windows are bad, or your insulation minimal, you should assume a higher figure for BTUs -- perhaps 15 to 25. In any case this is not meant to be exact science -- it's a guideline to help those who don't want to do their own arithmetic. The most accurate reading you can get will be by comparing your present energy bills to the bills you get after full month of active conservation.
Sources: |
Recent Comments