Embracing a Green Lifestyle – Increasing Energy Efficiency through Insulation

Research shows that 10-20% of the cooling load in homes in Florida comes from heat conducted into the home through the ceiling, putting the major load on the air conditioner and greatly affecting the comfort level of the house.  An additional 25% of the cooling load comes from heat and moisture infiltration, some of which enters the house through ceiling penetrations.  There are several ways to reduce the load on the home through sealing, insulation, radiant barriers, and fans.  EPA says that adding insulation and improving the sealing of a home has the potential to curb total energy costs by 10%.

There are several ways to reduce the load on the home through sealing, insulation, radiant barriers, and fans.  EPA says that adding insulation and improving the sealing of a home has the potential to curb total energy costs by 10%.

Sealing sources of air infiltration: 

• Unwanted flow of air and moisture into the home is called air infiltration.  Much of this problem is caused by air leaking into the house from openings for electrical lines, plumbing penetrations, and other building components which go between the attic and living area below.

• Preventing or minimizing air infiltration from attics can be completed by sealing these areas with noncombustible materials.  Particular attention to ceiling lights and fan fixtures, water lines, switches, outlets, attic access doors and whole-house fans.  Also, around kitchen vents fans and chimney penetrations.

Attic Insulation/Radiant Barriers/Fans

The main purpose of insulation is to create a barrier around the building, that is, over the roof, on the wall, and beneath the floor which reduces the amount of heat entering the home on a warm day and reduces the amount of heat lost on a cold day.  Since the majority of heat is lost or gained through the roof and exposed walls, these areas are the most fundamental places to insulate in order to create a comfortable and energy efficient home. 

Insulation

• R-value refers to insulation’s ability to resist the flow of heat from one side of it through to the other.  The higher the R value the more effective the insulation.  In Florida, new building codes under Florida’s Energy Efficiency Code require ceiling insulation to have an R value between 30 and 38 is generally recommended. 

• Insulate the attic to R30-R38 instead of R19.  This can be done by adding insulation to what is already there. Note, however; that each added amount of insulation is not as cost-effective as the previous amount.

• Example: 1000 sf house (living area), adding R19 insulation to an existing R11 or R19 level will bring overall R value to R30 – R38 and will cost less than $500. 

• Depending on individual energy use, DOE says there should be a minimum savings of 20% on your energy bill; payoff for the cost in approximately 2 years.

Radiant Barriers

• They reduce radiant heat gain instead of slowing it. For example, as the sun bears down on your roof, the heat transfers through the material radiating into your attic and warming it.  While normal insulation slows this heat transfer process, reflective or radiant barriers reflect and absorb to keep the area tepid.

• Radiant Barriers, when paired with another, such as adding insulation, do not provide an appreciable increase in savings.  In our 1000 sf house scenario it would add an additional $1000 in cost and could take 3 to 5 years to pay for itself.  My contractor contact indicated that if there is a choice between the two options insulation should always be chosen first.

Attic ventilator fans

• While radiant barriers and adding insulation to the attic will help to keep hot air from infiltrating into the house, attic fans keep it from building up all together, decreasing temperatures in the attic up to 30⁰ F. 

• Savings from attic fans come from two directions.  1) By reducing the amount of work the A/C has to do to keep the house cool thereby increasing its efficiency and 2) keeping heat out of the attic will extend the life of a roof by 5-7 years, which could end up in a savings of thousands of dollars.  We will come back to roofs in a few minutes.

• Standard electric attic fans reduce your air-conditioning bills by blowing hot air out of the attic in warm weather, reducing the temperature differential between the attic and the living space below.  However, an electric fan can generate annual electricity bills between $150 and $250, which ultimately would not make much savings sense.

• Solar powered attic fans are more energy-efficient in the long run yet cost more at the time of purchase than a traditional fan.  At home improvement stores they often cost just $300 to $600, plus $100 to $150 for installation and carry 3-5-year warranties.  Installation is fairly simple so many homeowners do it themselves.  Depending on the size of the house/attic, there may need to be more than one attic fan.

• At this time solar attic fans qualify for Federal tax credit and since it could save up to 20% of your electric bill per month, they tend to pay for themselves in 2-3 years.

Think about instituting one of these features into your home to save on energy costs. However, be aware that occupant behavior can affect the effectiveness of any energy upgrades!

Read Full Post »