Environmental Biology 2106

LAB 1: Personal Energy Consumption

Time to Complete: 1-2 weeks

PLEASE NOTE: This lab will require you to measure and record a variety of energy usages around your home. You will need at least 1 week to record all the data before you can answer some questions. Please make sure you give yourself plenty of time. You must turn in all logs and records kept for full credit on this lab.

Introduction

Here in the United States, we use more energy per person than in almost every other country in the world (the exceptions being small countries like Luxembourg, Bahrain and Oman). This has been true over the last hundred years or more. Since we have enjoyed abundant amounts of energy in the form of coal, wood, and some oil there has been very little interest in developing ways to use energy more efficiently, or using less overall. Only now with the current energy crisis in California and the Southwest, are people realizing that reduced energy consumption is critical.

There are several categories of personal energy consumption, that we as individuals have some control over: heating and air conditioning, heating water, washers,  dryers, lighting, transportation and the purchasing of electrical appliances. 

There are different ways to measure energy usage in the United States. Many kinds of heat are measured in British Thermal Units (known as BTU’s) while electrical energy is usually measured in metric measurements: kilowatt-hours.  Here are some examples of the BTU’s found in various amounts of fuel:

Source of Energy                              BTU’s

1 gallon of fuel oil:                                 145,000

1 cubic foot of gas:                                    1,031

1-kilowatt hour of electricity:                      3,412

1 ton of coal:                                      25,000,000

1 cord of wood                                  20,000,000

1 gallon of gasoline                                125,000

Lighting

Most of us simply switch on a light when we enter a room think nothing more about it. Traditionally only incandescent lights bulbs were available to most consumers. Now many of us use florescent bulbs which, although more expensive to buy, are cheaper to use in the long run.  What does it cost in energy to provide the type of light you use? And how much cheaper is it to use a florescent bulb?

1. Go to the web, and find out how much it costs to buy a florescent bulb versus an incandescent bulb (you can use a 100 watt bulb as you average) . You can also do this by going to a place like Home Depot or Lowe's and comparing prices. Note: Home Depot carries a better selection of florescent bulbs.

2. Now find out how much it cost to use a florescent bulb for 1 hour versus a 100 watt incandescent bulb. Again you can get this information on the web or it may say on the packages at the store. You can look on your electric bill to determine the price of a kilowatt of energy.

3. Using the information in steps one and two, caculate how long you have to use the flourescent bulb to have the costs of the two bulbs equal one another. Remember you are comparing the cost of replacing incandescent bulbs over time versus the initial expense of a florescent bulb.

4. GIven the lifespan of each bulb, how much money will you save in the long run using a flourescent bulb

5.      Go through your apartment or house and record the number of lights that you have in each room, and the type of bulbs

6.      For one week, log the amount of time that lights are on in each room. If you flip the light on for “just a minute” then record it as such.  It may be easiest to keep a notepad with you and jot the data down as you go. Only record the lights on in your home- do not count the hours spent at work. Record the data on the sheet attached at the end of this lab, and make sure to turn it in as part of your final lab. If you forget to record something, go back and make your best estimate. 

7. Calculate how much money you would save over 5 years if you only had flourescent bulbs. Remember to do this you will need to know a) how much light energy you use (extrapolate the data from the chart above) in 5 years, b) the initial costs of each type of bulb c) the replacement costs of bulbs as you use them up over 5 years

Money Saved =

Heating Water

 Water resists changes in temperature.  That is why the water in Lake Travis may seem very cold on a warm spring day.  Thus it takes a lot of energy to make a small change in the temperature of water.  Thus you can image that running your hot water heater is very expensive. It takes 1 BTU to raise the Temperature of a pound of water 1 degree.

MAKE SURE TO SHOW ALL YOUR CALCULATIONS

1.      Turn on a faucet so that is leaking as the rate of about 1 drip per second.

2.      Put a container under the water and collect the water for 15 minutes.

3.      Weigh the amount of water you have collected (in pounds) and record it here:

4.      Multiply this number by 35,040 to determine the amount of water wasted by a dripping faucet in 1 years time

5. Assume that water enters a water heater at 40F and leaves at 120F.

6.How many BTU’s of heat energy would be lost in one year if that leaking faucet were not fixed?

(# BTU’s/year = pounds of water in 15 min x 35,040 x 80 =

7.      How many gallons of fuel oil does it take to produce this much heat?

Heating and Air Conditioning

Most of our houses have insulation put between the studs in the walls and in the ceiling. Thus we can slow down energy loss through these surfaces.

We lose a lot of our energy, however, through the windows of our homes and offices. A single pane of glass window has an R-value of .9. By comparison, the recommended R-value for insulation used in walls is r-13 and for attics it is R-30. (The higher the R- value, the better the insulation). 1/R is equal to the number of BTU’s that would pass through a 1 square foot surface if the difference in temperature on the two sides of the surface were 1 degree Fahrenheit.

We can calculate heat loss of gain through a window by using the following formula:

Heat loss/gain in BTU = ft  x Difference in temp (F)

            per hour                              R- value

1.      Choose a single pane window in your home and measure its surface areas

2.      Measure the difference in temperature between the inside and the outside of the window, and record it here.

3.      Calculate the rate of heat transfer through the window using the formula listed above.

4.      What effect would a 10 F decrease in the temperature on the inside of the window have of the rate of heat transfer?

5.      What would happen to the rate of heat transfer if we increased the size of the window by 50%?

6.      Double pane windows have an R-value of 1.85.  What would be the effect on the rate of heat transfer if the single pane window were replaced with a double pane window?

7. Energy wise homeowners use double pane windows in their entire house. Count the number of window in your house, and record their area on a separate sheet of paper that you will turn in with this lab.  If you replaced all you windows with double pane glass, how much would this effect your total rate of heat transfer?

Electrical Appliances

Electrical appliances have revolutionized the 20^th century. Tasks that use to take hours can now be done in a few minutes. And in most cases all it takes is a simple push of a button.  Yet do you have any idea how much it costs in terms of energy to run their appliances? It is important to recognize that the total cost of a $100 appliance should also include the amount of money- such as $20 a month to operate the machine. Thus while some machines, like incandescent light bulbs may be cheaper to buy but may end you costing you more in the long run.

Manufacturers are typically required by law to label an appliance with the wattage it uses. These labels are found in the back of the appliance, or in the case of a refrigerator, on the inside on the wall.

1.      Keep a log of all the electrical appliances that you use in a one-week period.  List the appliances on the chart below and the number of minutes it was used per week.

2.      Record the wattage of the appliance from the label on the back. If the wattage is not on the appliance, you can either go the manufacturer’s web site, or go to an appliance store and look at the label of a similar item.

3.      Once you have the wattage, the number of minutes it was used, you can calculate the number of kilowatt-hours of energy used

Kilowatt-hours used = Watt Rating (total minutes used)

                                                            1000

4.      IF one kilowatt equals 3413 BTU’s, how does the energy used by electrical appliances compare to the energy used by an automobile or for heating and cooling your home? Give specific examples to illustrate your answer

List of Appliances