Sometimes you just have to throw in the towel.  In the home comfort business this occasionally happens.  If you have a hot, uncomfortable room there is only so much you can do.  As I discussed in Part 1, you can try to keep the heat out by adding radiant barrier, insulation, attic ventilation or sealing open chaseways.  Or, pull more heat out by adding more airflow usually with larger ducts or additional air conditioning returns.

External unit of a ductless mini-split

External unit of a ductless mini-split

Sometimes you can do all this plus more and STILL have comfort issues.  It may never get comfortable or it’s freezing one minute and then too hot a few minutes later.

If you have given up and are ready to throw in the towel, then take another approach. You may  benefit from a Ductless Mini-Split Air Conditioner.  What’s a Mini-Split?  The best description is a  window air conditioner WITHOUT the window. If you have ever traveled to the Caribbean or the Orient you see them EVERWHERE.  The most common brands are Mitsubishi Mr. Slim, Sanyo, Daikin, LG, and Fujitsu just to name a few.

Ductwork is a very western idea. By using a ductless mini-split, you can easily bring more air conditioning (heat removal) to either an interior space or an exterior room without a noisy window unit.

Diagram of how a mini-split ductless system works

Diagram of how a mini-split ductless system works

An air conditioner basically has three parts: 1) Compressor 2) Fan 3) Coil. A window air conditioning unit has all three together.  In a ductless air conditioner, the compressor is OUTSIDE and the fan and coil are INSIDE usually connected by a ¼” or 3/8” copper tubing.  The beauty it that the inside unit can be as far as 100 feet from the outside condenser.

Installation is pretty simple since there is usually NO electrical requirements for the inside fan coil.  Power to the inside unit is brought from the outside unit along with the refrigerant lines.  This means that basically you can drill a hole in a wall, run a 3” bundle of copper tubing, hang the indoor air handler on the wall, connect condensation tubing, set the outdoor unit, connect power and just like magic supply additional cooling and heating to any problem area.

Inverter vs. Non-Inverter Units

WARNING:  Mini-split air conditioners all look very similar but operate very differently. Traditional air conditioner units act like light switches – they are EITHER ON OR OFF.  They turn on, run for a while and turn off.  A mini-split with inverter technology acts like a DIMMER switch that automatically adjusts based on the required “load”.

Indoor portion of a ductless mini-split system

Indoor portion of a ductless mini-split system

Inverter air conditioner units have several advantages.  First of all being comfort.  You will not have a big “swing” between feeling too cool and too hot.  Second is dehumidification.  By running longer at a lower level the inverter will pull more moisture out of the air resulting in better air quality and a “crisp” feel to the air.  Another advantage is energy efficiency.  Inverter air conditioners operate at a lower amperage and do not cause spikes in demand charge or light flicker when starting up.  Finally, the best feature of installing a mini-split air conditioner is CONTROL.  Whether it’s a bedroom, office or media room, you will be able to keep it cool and comfortable without having to cool the entire house.

Mini-split air conditioners are the fastest growing segment in the air conditioning industry.  Ease of install, efficiency, improved comfort and better dehumidification are just a few reasons never to throw in the towel on keeping comfortable.

Read Part 1: Hot Rooms in my House, How Do I Make Them More Comfortable?

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Window with solar screen installed

Window with solar screen installed

One of the most frustrating problems is having comfort issues with a particular room in your home.  These are rooms that you can NEVER get quite cool enough no matter how hard you try.  The usual suspects are: Rooms over garages, bonus rooms, media rooms, master bedrooms that “stick out” from the house, and home offices.  In this article, I offer tips to help fix these problem rooms.

In order to fix the problem, you must first ask, “What exactly IS the problem”?

The easiest way to view any room is simply to look at it as a big box.  Heat enters the box and the air conditioner pulls the heat out.  The problem occurs when you combine several rooms (boxes) on ONE air conditioning system.  The airflow to each room will dictate how fast each room cools off.  The problem is that the sun, exposure, windows and internal heat loads (lights, people, computers, etc.) are DIFFERENT for each room and can CHANGE throughout the day. The “problem” rooms usually gain heat faster than the other rooms on the same air conditioning system.

Properly installed radiant barrier foil

Properly installed radiant barrier foil

There are two methods to TRY to fix this:  1) Keep the heat from entering in the first place or 2) Pull MORE heat out.

1) Keep the heat out – We want to STOP heat from entering so we don’t have to deal with it in the first place.  Start with the windows. If a window catches direct sun you need to shade the window.  Solar screens, window film, awnings or natural shade (trees) will all help – take your pick.  Then focus on the thermal envelope.  Walls should be well insulated and have some form of sheathing (usually ¾” foam board) on the ATTIC side of any walls to fully encapsulate the studs and the batts of insulation between them.  We call walls that face an attic “hot walls” for a reason.

Radiant barrier foil should be applied above and around any problem rooms. Ceilings should be sealed airtight and have plenty of insulation and ductwork should be checked for leaks or constrictions.

Open chaseway showing missing "blocking"

Open chaseway showing missing “blocking”

Finally, if the room is on the second floor, look for what is called an “open chaseway.”  This is the area between floors that usually has electrical, plumbing or ducts running through them.  Older homes often are missing “blocking” and allow hot or cold attic air to slide BETWEEN the floors and cook or chill the room from the bottom.  Open chaseways needs to be sealed up.

2) Pull MORE heat out – If you have done everything to keep the heat out and you still can’t stay comfortable, then the only other option is to pull more heat out. This usually requires the expertise of a good air conditioning contractor. You could need larger ducts, more ducts, additional return vents or a combination of these.

Unfortunately, on many “problem” rooms these measures have limited success. In fact, you can do EVERYTHING and STILL have comfort issues in some rooms.  What do you do?

Look for part 2 of this article: When all else fails – how to keep ANY room comfortable.

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Ed Fritz on February 22nd, 2010
Return Duct with no seal

Return Duct with no seal

Everyday people ask me what is the single biggest thing they can do to improve efficiency and comfort in their home.

I usually ask a few basic questions like where they live, type of home etc.  Then I ask the two most important questions.  How old is the home and where are the ducts located?

When I hear “home over 25 years old” and “ductwork in the attic” big red flags go up.  Why?  Experience. I’ve helped thousands of people with home comfort issues and without fail this is the biggie.  Think of your house as one big refrigerator.  Leaky ducts are like leaving the door open.

Duct leakage is generally measured as a percentage.  For example, if you have 20% duct leakage this means that approximately 20% of the HOT or COLD air you are buying is being pushed OUT of the ducts and into the attic.  Or, duct leakage can also mean you are SUCKING hot or cold attic air INTO the duct system on the return side of the air handler. On new High-Performance homes, professional energy auditors are usually shooting for less than 2-5% duct leakage.  On older homes (especially with metal ducts) it is common to see duct leakage OVER 40%.

Older Metal Ducts with no seal

Older Metal Ducts with no seal

Why do older homes have such bad leaky ducts?  Back in the era between about 1950-1980 NOBODY cared about energy efficiency.  Energy was CHEAP, so installers usually didn’t bother to take the extra time or money to seal the ducts. For metal ducts this meant sliding two sections of duct together and using three screws to connect them.  Then, they would wrap the ducts with insulation to keep them from sweating or condensing moisture, not primarily to insulate them.

The ducts did not just start leaking; they were never sealed to begin with. If you have ever done some plumbing, this would be like connecting copper pipe together and NOT using solder on the joints.

As an example, think of an air conditioning duct as a long garden hose with a hundred holes in it.  Since water (or air in the ducts) is under pressure, the water will leak out of all hundred holes BEFORE it gets to the end.  Whatever does not leak out of the holes along the way is what ends up coming out of the end where you want it.  Air conditioning ducts are exactly the same and it’s pretty common to end up with only 50-75% of the air where we need it.

Older ducts – especially metal ducts are notorious for leaking.  Studies show that there is generally a direct correlation between the age of the duct system and the percentage of duct leakage.  Additionally, wrapping a duct with insulation does virtually NOTHING to reduce duct leakage just like wrapping a leaky pipe with a rag won’t stop a water leak.

AC Duct Leaks

AC Duct Leaks

Not only do leaky ducts cause higher energy bills, they cause most homes to go under negative pressure.  This means that if there is 20% leakage, then an equal amount of air must be “made-up”.  Make up air usually enters the home through windows, doors, can lights and any other “holes” in the home. Air quality can suffer since outside air is often dusty, dirty, pollen laden or humid.  Dust on windowsills or stains on carpet around the baseboards indicate outside air is being pulled into the home.

Some air-conditioning companies would rather sell a new air conditioner for thousands of dollars, rather than sealing/replacing ductwork for a fraction of the cost often neglects leaky ducts.

How To Fix Leaky Ducts

There are generally 3 methods to fix leaky ductwork:  1) Strip off insulation, seal all seams and then wrap with radiant barrier covered duct blanket.  2) Tear out metal ductwork and replace with flex duct.  This is usually not recommended since metal ducts are great (and expensive) if sealed correctly. 3) Strip off the duct insulation and have a spray foam company spray about 1-2 inches of closed cell foam on the ducts.  The foam will both seal and insulate the ducts in one shot.  WARNING: Check your local building codes and fire officials on this one.  Some cities do not allow this method.

Just remember to think of your home as one big refrigerator that you want to keep nice and cool inside.  Yes, you can add more insulation, or wrap it with radiant barrier, but bang-for-the buck, start by closing the door.

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Here is a question I’ve been getting a LOT lately:  “How does AtticFoil® compare to a product called….”? The most common names I hear are eShield, Prodex, Green Energy Barrier, SolarGuard, Reflectix and the list goes on and on.  Consumers get very confused about the differences between these products and want to know how they compare to AtticFoil® radiant barrier foil.  They want to know if all these products are a SCAM or the real deal.


AtticFoil® is a pure RADIANT BARRIER ONLY. Other types of products take a sheet of aluminum foil (a radiant barrier) and attach it to a thin layer of insulation usually about ¼” thick.  This insulation is typically fiberglass, foam or plastic bubble wrap material.  The CLAIM is that when you COMBINE a radiant barrier with an insulating product (listed above) that has R-Value, the product MUST be better.

They come up with fancy names like “Attic Energy Barrier” or “Heat Shield” or “Attic Armor” and spend a lot of money on advertising, slick brochures and big sales commissions when in reality all these products are basically the same thing.  A piece of aluminum foil attached to a thin sheet of fiberglass insulation, bubble wrap or foam.

Typically eshield™ and other similar products sell for 5-30 times the cost of AtticFoil®.

Are they really better and are they worth it?

First, let me say all these products are NOT BAD products.  They are all GOOD products that are often being used for the WRONG purpose. These products work great in metal buildings and some commercial applications but have now found their way into residential attics.

In a residential attic application, they DO work. Why? Virtually ALL of the heat entering from a roof into an attic is RADIANT HEAT. So, here is the secret:  It’s the FOIL (radiant barrier) doing all the work. The fiberglass, foam or bubbles are just along for the ride and offer virtually no additional benefit in reducing heat flow into a home.  This is why AtticFoil® is the ONLY product needed for attic applications and for a fraction of the cost compared to other products.

I believe in giving good information and getting the best “Bang For The Buck” solutions to help consumers make their homes more comfortable and energy efficient.

Here is the bottom line. You DON’T NEED R-VALUE (insulation) ON YOUR RAFERS IN A VENTILATED RESIDENTIAL ATTIC. You need R-Value on your attic floor and you need a radiant barrier either stapled to the bottom of your rafters or laid out over the attic insulation.

Let’s take a look at the ACTUAL R-Value of these other products mentioned above.  Most are about a ¼” thick or less.  Standard foam board by Dow Chemical or Owens Corning has a known R-value of about 3.5 per inch.  An R-13 batt of fiberglass insulation is 3.5” thick. So, common sense tells you that the ACTUAL R-value of eShield and similar products about ¼” thick can be NO MORE THAN AN R-VALUE OF 1.

When you read about claims that these products have R-10 – R-20 values be sure to look at the fine print.  These R-values are ONLY achieved in tightly sealed assembles like a wall and often require over 8” of “Dead” air space.

Since there is typically NO “Dead Air” in a ventilated attic, these products CANNOT achieve a higher R-value than the actual R-value of the ¼” layer of insulation product attached to the foil.

Often, products like eShield are stapled to the bottom of the rafters.  This method works fine to stop the radiant heat, but why waste your money for a small amount of R-value (typically R-1) when you NEED the R-value on the ceiling and not your roofline.  Plus, you can buy By R-19 of blown-in insulation material for about .25/per square ft.

Here is what I recommend.

AtticFoil® Radiant Barrier Foil ALONE will accomplish the same benefit as ALL THESE PRODUCTS to stop radiant heat for less cost. Then, spend the money you save on these other products and put in additional attic insulation, if needed. You can easily install R-19 or about 6” or more of additional attic insulation and the total cost will be the SAME OR LESS and you will end up with a BETTER OVERALL REDUCTION IN HEAT GAIN/LOSS.

Remember, traditional attic insulation has R-value. This works to slow conductive heat.  Radiant barriers reflect Radiant Heat.  BOTH types of heat are trying to enter your home on a hot, summer day. The sun heats up the roof and then heat is transferred by radiant heat until it hits the attic insulation.  Then, heat switches form to conductive heat to move through the attic insulation and into your home.  This is why you need BOTH Types. Traditional attic insulation and radiant barrier work together and each do their part.

Radiant barrier is your first line of defense and attic insulation is the second line of defense against heat gain.

Keep things simple, spend your money wisely and be hesitant when you hear outrageous claims for energy savings products. Follow this advise, and you are on your way to making your home more comfortable and energy efficient.

I've written several other posts on this that you might be interested in. Check these posts below:

  • New AtticFoil® Tape
  • Introducing an exclusive new radiant barrier: SuperPerf™ AtticFoil®
  • Installing Radiant Barrier Over Spray Foam Insulation
  • Introducing – for Commercial Applications
  • Enerflex® Radiant Barrier at Home Depot compared to AtticFoil® Radiant Barrier
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    Ed Fritz on February 8th, 2010

    Every day you probably hear ads about how much you can save by making energy improvements to your home.  Whether it’s a new air conditioning unit, double-pane low e windows, insulation, weatherization, radiant barrier, new LED or CFL light bulbs, the list goes on and on.

    Yes, we all know that these improvements will save money, but are they a good investment?  Here is a quick and easy way to figure out how much to invest in energy savings using the cost of money and return on investments.

    Let’s say our home averages $200 per month in utility bills.  Given an average home, it is pretty easy to drop a bill by 20% or $40 per month.  This is pretty basic stuff like air sealing, switching to a programmable thermostat, installing a radiant barrier, better attic insulation, duct sealing, changing light bulbs and new air filters just to name a few projects.

    So, if you could drop your bill by $40 per month it would put an extra $480 in your pocket over the course of a year.  It’s not retirement money, but I’m sure you will find something to do with it.  If you have a higher bill then the total will be even larger.

    This is just like getting an extra $480 bonus at work, but it’s actually BETTER?  Why?  This is AFTER TAX MONEY.  Which means if you were in the 20% tax bracket, you would have to EARN about $575 to end up with $480.

    Now the REAL value is $575 per year.  Ask yourself “How much would I be willing to invest to get a $575 bonus EVERY year”?  Currently, in the investment world a 10% GUARANTEED RETURN is impossible.  However, if you were to invest up to $5,750 in energy improvements and generate $575 in savings you would get a 10% return on your investment. In fact, on most homes you could probably get this much savings with less than $3000 worth of improvements which would result in over a 20% return on investment.  During a tough economy, this is a SPECTACULAR RATE OF RETURN.

    This is why so many people are spending (investing) the money to increase the energy efficiency in their homes.

    Finally, all these numbers and assumptions are based on energy rates staying exactly the same.  Over the long haul, do you REALLY think rates will stay the same?  If rates go up then the payback and return on investment is even greater.

    Is it worth it to invest in energy efficiency improvements?  Unless you can guarantee at least a 10-20% return on your investments the answer is YES.

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    Ed Fritz on February 2nd, 2010

    There has been some debate and confusion whether or not radiant barriers are included in the new energy efficiency improvements tax credits.
    Radiant Barriers do qualify for the tax credit under The American Recovery and Reinvestment Act of 2009.

    If you recall there was much excitement when the energy tax credits were extended or revised for 2009-2010.  The 10% tax credit was raised to 30% and the maximum of all tax credits for the period between 2009-2010 was raised from $500 to $1500.

    Then, in the Spring of 2009 it was determined that the definition of insulation was expanded to reference the 2009 International Energy Conservation Code (IECC).  Since radiant barrier is not specifically mentioned in the building code, it has been unclear whether or not they qualify.

    In December 2009, there was a meeting between the representatives of the reflective insulation industry and the IRS.  In this meeting, representatives presented the case for how radiant barriers should be included to be eligible for the tax credit.

    Radiant Barrier Tax Credit Information

    Based on this information, the IRS will allow the tax credit to be taken for products put into service between January 1st, 2009 and December 31st, 2010

    It should be noted now that the IRS has NOT made a final ruling on this subject and that this information is NOT binding until a final ruling is made.

    The manufacturer’s claim for the tax credit is valid until (and if) the IRS denies the claim.  If the claim is denied, it will NOT be retroactive meaning that you will not be able to claim the tax credit for purchases after the date of the ruling.

    Here is my opinion on this.  The IRS probably never intended for radiant barriers NOT to be included.  It’s just how the law was written that because radiant barriers are not specifically mentioned, the fell into a grey area.  Radiant barriers DO help control heat loss/gain and this is really the criteria used to determine if a product contributes to “Energy Efficiency”.  The whole purpose of giving a tax credit is to give incentives to taxpayers to make their homes more energy efficient. Radiant barriers can be an excellent product to move towards these improvements.

    For now, I’m comfortable to issue a Manufacturer’s Certification Certificate based on this new information. Please subscribe to this blog for updated information as it becomes available.

    I've written several other posts on this that you might be interested in. Check these posts below:

  • New AtticFoil® Tape
  • Introducing an exclusive new radiant barrier: SuperPerf™ AtticFoil®
  • Installing Radiant Barrier Over Spray Foam Insulation
  • Introducing – for Commercial Applications
  • Enerflex® Radiant Barrier at Home Depot compared to AtticFoil® Radiant Barrier
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    There is some debate in the radiant barrier business whether to use a perforated or a solid radiant barrier product in an attic application.

    In an attic application, you should ALWAYS use a perforated product. Period.

    Perforated Radiant Barrier Foil

    Perforated Radiant Barrier Foil

    Why? Solid products like bubble foil insulation are called “Vapor Barriers”.  A vapor barrier basically stops moisture from moving from point A to point B.  Or, another way to view this is that a vapor barrier will “TRAP” moisture.  I’m not going to get into the technical definition of what defines a vapor barrier (perm rating, etc), but here is an illustration of what IS and IS NOT a vapor barrier.

    If you take a wet block of wood and put it inside a bag or an envelope made of perforated radiant barrier attic foil the wood block would eventually dry out.  Therefore, perforated radiant barrier is NOT a vapor barrier.  Moisture ALWAYS goes from wet to dry.  If you did the same test with the wood block inside a plastic bag the wood would still be wet months from now.  If moisture in its vapor form cannot pass through or object won’t “dry” then the product IS a vapor barrier.

    Why is this important?

    Virtually all (over 70%) of home issues are due to mold, mildew, rot, decay, etc. And moisture is the common theme here.  DRY products don’t grow mold, rot or decay. The bottom line is that moisture in wall and ceiling assemblies is not a good thing.  You want DRY walls and ceilings.

    In cooler weather, the moisture INSIDE the home is greater than OUTSIDE.  Think cold and dry.  This is why our lips get chapped in the Winter and not in the Summer.  Since moisture will naturally move from wet (inside) to dry (outside) it will pass through sheetrock, insulation and then into a typical attic.  The LAST thing we want to do is TRAP moisture here.  Moisture, attic insulation and wood do not go well together.  A perforated radiant barrier will allow moisture to pass on through into the attic.  We want our attics to be cool and DRY.

    Using a perforated radiant barrier will not change the effectiveness of the reflectivity.  Attic Foil has tiny pinholes about every ½ inch that allow for water in its vapor form to pass through (see picture).  These holes make up a TINY percentage of the surface area and will not change the effectiveness of the radiant barrier.

    Solid products like bubble foil insulation are usually not perforated and are a recipe for disaster when installed inside an attic.  Solid (non-perforated) bubble foil is a great product when used correctly in applications like metal buildings.  The problem is that solid bubble foil products are often MISUSED in residential attics. This is especially true if the bubble type reflective foil products are laid directly over the attic insulation.  Moisture will pass through the sheetrock and will get trapped in the insulation below the bubble foil insulation.  This moisture will accumulate until it either condensates (turns to water) or freezes (turns to ice).

    This is why it is critical to use a perforated tarp-like radiant barrier product. It will give you all the benefits of reflective insulation without the potential for moisture to get trapped.

    I've written several other posts on this that you might be interested in. Check these posts below:

  • New AtticFoil® Tape
  • Introducing an exclusive new radiant barrier: SuperPerf™ AtticFoil®
  • Installing Radiant Barrier Over Spray Foam Insulation
  • Introducing – for Commercial Applications
  • Enerflex® Radiant Barrier at Home Depot compared to AtticFoil® Radiant Barrier
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    I still get this question all the time.  “Can you explain why an air space is needed for a radiant barrier to work?” Watch this video for a complete explanation.

    Basically it works this way.  Radiant heat is heat that is transferred across either an air space or a vacuum.  This is how the heat from the sun reaches the earth.  Radiant heat acts similar to a sound wave.  By definition, you MUST have either an air space or a void for radiant heat to even exist.

    If you don’t have an air space then you basically have a solid.  Heat can essentially only move through a solid by conduction. This is by direct contact.  This is how an egg cooks on a hot skillet.

    So, without an air space, you cannot have radiant heat. Without radiant heat there is no way to have a “Radiant Barrier”.  In fact, because of the conductive nature of pure aluminum, if you install radiant barrier foil WITHOUT the required air space it will actually work AGAINST you and INCREASE Heat flow.

    The bottom line is you MUST have an air space on one side of a radiant barrier for it to work.

    Looking for more videos on this topic? Check out my posts below.

  • The #1 Attic Ventilation Problem
  • Enerflex® Radiant Barrier at Home Depot compared to AtticFoil® Radiant Barrier
  • Radiant Barrier Installation Summary – Block the Heat
  • Green Energy Barrier (and other products) Compared To AtticFoil® Radiant Barrier Foil
  • Does Radiant Barrier Damage Roof Shingles?
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    WOW, it’s been cold lately.  Not surprisingly, I’ve received a bunch of calls and emails from people wanting more information on how installing a radiant barrier can help them in cold weather.

    I put together a video to help illustrate how traditional attic insulation and radiant barrier WORK TOGETHER to make a home more comfortable and energy efficient.

    Remember, traditional attic insulation – fiberglass or cellulose help to reduce Conductive Heat Loss.  A radiant barrier will help to reduce Radiant Heat Loss.  In cold weather, heat is lost in BOTH ways.

    Combining good attic insulation and radiant barrier will give your home the best defense to stay warm in the Winter and cool in the Summer.

    I've written several other posts on this that you might be interested in. Check these posts below:

  • The #1 Attic Ventilation Problem
  • Combining Radiant Barrier with Spray Foam Insulation
  • Four Silver Bullets For Saving Energy In Hot Climates
  • Attic Insulation & Radiant Barrier Work Together In Warm Climates
  • Attic Ventilation – Don’t Mess It Up
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    Ed Fritz on January 4th, 2010
    Paint applied as a Radiant Barrier

    Paint applied as a Radiant Barrier

    You may have recently heard some Radio/TV ads talking about an “Amazing Radiant Barrier Paint that is applied to the underside of your roof”. And how it “reflects” over 75% of the heat to keep your attic cooler and save you money on your utility bills.

    Let’s get some facts straight. There is NO such thing as RADIANT BARRIER PAINT.

    The term “Radiant Barrier” is supposed to describe products that “Reflect” over 90% of radiant energy (think light colored and/or shiny surfaces like aluminum, silver and gold) or have an emissivity of less than .10. This means they can only “Release” less than 10% of energy as radiant heat (think a potato wrapped with foil to keep heat from being released).

    The term “Radiant Barrier” has been hijacked by the paint installers to try to confuse consumers into thinking they are the same. This is like hamburger calling itself a prime steak.

    Paints like Sherwin Williams E-Barrier, STS Coatings HeatBloc or Solec LO/MIT are NOT the same as radiant barrier foil.  I’m surprised the FTC has not stopped this fraudulent advertising or a lawyer has not created a class-action suit on the behalf of customers who thought they were being sold a “radiant barrier” by installers.

    Paint products technically have their own name.  They are called Interior Radiation Control Coatings or IRCC’s for short. This is not as cool as being called a “Radiant Barrier”. Ironically, most paints don’t even qualify to be an IRCC since the definition of an IRCC is a product that reflects at least 75% or emits less than 25% of radiant heat.  Here are some test results of radiant barrier paints.

    Paints will NEVER perform as well as foil radiant barrier products. Foil always reflects 97% of radiant heat energy.  This is an indisputable fact.  Radiant Barrier Foil is always superior to IRCC’s. Paints run into other challenges.  Because radiant barrier paints are “applied” rather than “installed” you get inherent variables in the application process.

    First, how can you tell without testing if the product was put on too thick or too thin?  What about painting unprimed wood with paint?  Common sense says it will be absorbed by the wood and reduce the “smoothness” required for a good low emissivity surface. You will also need to paint the deck AND the rafters to get the maximum benefit.

    Finally, what about cheating?  These radiant barrier paints are really EXPENSIVE, like $50 per gallon.  I’ve seen guys use cheap silver paint, or mix water with the good paint to extend coverage and reduce costs, which will also reduce the effectiveness of radiant barrier paints.  I’m sure there are many honest installers, but watch out for the bad apples.

    The reality is that most radiant barrier paint products end up reducing radiant heat into the attic by about 20-40%.  This is far below the claimed rates of 75%.

    There are claims that foil is not effective unless you get the whole roof. This is NOT true.  Any product, whether it be foil or paint has a cumulative effect, the more coverage the better.  A tree over part of your home still helps, right?

    If you compare the math, you could actually put foil (reflecting 97%) over half the home and get more heat reduction than applying paint (reflects 20%-40% in real installations) over the whole home.

    Don’t believe anyone that says that radiant barrier paint is as good or as effective as radiant barrier foil.  And remember, there is technically NO such thing as radiant barrier paint.

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