Alternative Energy

By: Cooper McAden 4th

Efficiency Improvements


Efficiency improvements to the houses in the Lakewood Estates development in Coppell will produce the most savings to our homeowners electric bills and will cost the least to other alternative energy improvements. The 3 things I am proposing to be replaced are the windows, the AC unit, and the attic insulation. The homes in this neighborhood were built 20+ years ago and almost all the of these have the original equipment. The savings will come from 2 areas. Not only have there been dramatic improvements in energy efficiency, but the after 20 years of use, the equipment has significant degradation.

The 3 improvements will save energy in different ways.

  • Over time seals break on the windows letting the air between the 2 panes escape which is the only thing that keeps the hot and cold air from increasing or decreasing the temperature in the homes. By replacing the windows, the gas will be present and will have a much higher efficiency rating then the original windows when the home was just built.
  • Insulation height decreases by a significant amount over time which allows the outside temperature to transfer hot or cold energy into the home easier similar to the windows losing the gas. By adding more insulation, we will block the transfer of this hot or cold air exponentially.
  • AC unit technology has improved immensely and the original have already experienced a great loss in efficiency for the 20+ years they have been in use. So replacing the AC unit will most likely be the biggest asset in savings because it is the only source to heat and cool the home and how efficient it is will be the biggest factor in the cost of your energy bill.


The source of the savings will come from replacing the windows, adding insulation to the attics, and replacing the AC unit. Replacing this equipment with modern technology will save our homeowners in the Lakewood Estates by enormous amounts and will pay for themselves in a few years.


Energy Productivity: (calculations assume a home that is 20+ years old, 3,000+ square feet, and pays on average of 500/month for electricity)

  • Windows- Energy bills are reduced by around 40%. This would amount to approximately 2,400/year in savings with an assumed increased R-value of 2.05 from the new windows
  • AC unit- On average, replacing AC units can save you 20% by increasing the efficiency of heating and cooling in the home which would amount to $1,200/year.
  • Insulation- On average, adding 8 inches of insulation to an attic saves $600/year by having an R-value of 30 to slow the energy transfer.

Cost Savings:

The cost to add insulation and replace the ac unit and windows will be approximately $28,127. With the original cost of about $6,000/year for the energy bill; adding insulation, replacing the AC unit and windows will reduce the cost of the energy bill by $4,200/year. So in approximately 7 years, all of these improvements will be paid off and the homeowners will be living in a more comfortable and beautiful home.


1. New AC- $5,627

a. Installation: $3,000

b. AC unit: $2,627

2. Windows- $19,500

a. Installation: $450/window=$13,500

b. Windows: $200/window=$6,000

3. Insulation- $3,000

a. Installation: $1,000

b. Insulation spray: $2,000


The cost to spray a 1,500 square foot attic (3,000 square foot home has usually half that amount of attic space) is $2,000 for the materials and $1,000 to hire people to spray it. For windows it costs about $450/vinyl window to install and a modern window from Lowes costs $200 so with around 30 windows in a home it will be approximately $19,500. I decided to choose the 3 ton Winchester AC unit because it has a 14 SEER which is higher then the average modern AC unit and is in the middle of the price range at $2,627. The installation is around $3,000 to install a 3 ton AC unit for a home.


Science behind it: Thermal insulation is the reduction of heat transfer between objects in thermal contact or in range of radiative influence. New windows with gas put between the panes and adding insulation to the homes attics both increase the R-value (the measure of thermal resistance) significantly for these main points of entry for hot and cold air from outside. A factor that contributes to an objects R-value is it's thickness and by doubling the thickness of insulation we are increasing the attics R-value and therefore decreasing the transfer of heat and lack of heat into the home. Modern windows decrease heat transfer because just glass has an R-value of about .45 while glass with argon gas put between the panes has an R-value between 2 and 3 depending on the window so by replacing the windows with double pane, argon filled, windows there will be a huge increase in the R-value and decrease in heat transfer and therefore allowing the AC unit to run less and use less energy.

Advantages over alternative energy:

I chose not to pick alternative energy because this method would be the most cost effective. Converting all the houses in a development to a different source of energy would cost more, take more time, and this method will show a quicker return on the investment so there is no need to put in the effort and making a huge change when a few small changes can make a huge difference.

The appeal:

Residence would want these improvements because for one the home will look better. Modern windows look like higher quality products then the 20+ year old windows that are already in the home and are very noticeable considering windows cover around 30% of the house for most homes. Also windows and insulation will help keep the house at a consistent temperature throughout and not have any severe hot or cold spots. And the obvious reason for the homeowners is the huge savings they will see in their energy bills. These 3 improvements are commonly known to be the biggest factors in how much you're paying on your electric bill so by replacing each of these you're guaranteed to see a significantly lower energy every month and over time they will pay for themselves.