What is a radiant barrier?

This was emailed to me and I thought was very interesting...

Radiant Barriers

What is a radiant barrier?
Radiant barriers are materials that are installed in buildings to reduce summer heat gain and winter heat loss, and hence to reduce building heating and cooling energy usage. The potential benefit of attic radiant barriers is primarily in reducing air-conditioning cooling loads in warm or hot climates. Radiant barriers usually consist of a thin sheet or coating of a highly reflective material, usually aluminum, applied to one or both sides of a number of substrate materials. These substrates include kraft paper, plastic films, cardboard, plywood sheathing, and air infiltration barrier material. Some products are fiber reinforced to increase the durability and ease of handling.
Radiant barriers can be used in residential, commercial, and industrial buildings. However, this fact sheet was developed only for applications of radiant barriers in ventilated attics of residential buildings. For information on other applications, see the references at the end of the Fact Sheet.
How are radiant barriers installed in a residential attic?
Radiant barriers may be installed in attics in several configurations. The simplest is to lay the radiant barrier directly on top of existing attic insulation, with the reflective side up. This is often called the attic floor application. Another way to install a radiant barrier is to attach it near the roof. The roof application has several variations. One variation is to attach the radiant barrier to the bottom surfaces of the attic truss chords or rafter framing. Another is to drape the radiant barrier over the tops of the rafters before the roof deck is applied. Still another variation is to attach the radiant barrier directly to the underside of the roof deck.
How do radiant barriers work?
Radiant barriers work by reducing heat transfer by thermal radiation across the air space between the roof deck and the attic floor, where conventional insulation is usually placed. All materials give off, or emit, energy by thermal radiation as a result of their temperature. The amount of energy emitted depends on the surface temperature and a property called the “emissivity” (also called the “emittance”). The emissivity is a number between zero (0) and one (1). The higher the emissivity, the greater the emitted radiation.
A closely related material property is the “reflectivity” (also called the “reflectance”). This is a measure of how much radiant heat is reflected by a material. The reflectivity is also a number between 0 and 1 (sometimes, it is given as a percentage, and then it is between 0 and 100%). For a material that is opaque (that is, it does not allow radiation to pass directly through it), when the emissivity and reflectivity are added together, the sum is one (1). Hence, a material with a high reflectivity has a low emissivity, and vice versa. Radiant barrier materials must have high reflectivity (usually 0.9, or 90%, or more) and low emissivity (usually 0.1 or less), and must face an open air space to perform properly.
On a sunny summer day, solar energy is absorbed by the roof, heating the roof sheathing and causing the underside of the sheathing and the roof framing to radiate heat downward toward the attic floor. When a radiant barrier is placed on the attic floor, much of the heat radiated from the hot roof is reflected back toward the roof. This makes the top surface of the insulation cooler than it would have been without a radiant barrier and thus reduces the amount of heat that moves through the insulation into the rooms below the ceiling.
Under the same conditions, a roof mounted radiant barrier works by reducing the amount of radiation incident on the insulation. Since the amount of radiation striking the top of the insulation is less than it would have been without a radiant barrier, the insulation surface temperature is lower and the heat flow through the insulation is reduced.
Radiant barriers can also reduce indoor heat losses through the ceiling in the winter. Radiant barriers reduce the amount of energy radiated from the top surface of the insulation, but can also reduce beneficial heat gains due to solar heating of the roof. The net benefits of radiant barriers for reducing winter heat losses are still being studied.
How does a radiant barrier differ from conventional attic insulation?
Radiant barriers perform a function that is similar to that of conventional insulation, in that they reduce the amount of heat that is transferred from the attic into the house. They differ in the way they reduce the heat flow. A radiant barrier reduces the amount of heat radiated across an air space that is adjacent to the radiant barrier. The primary function of conventional insulation is to trap still air within the insulation, and hence reduce heat transfer by air movement (convection). The insulation fibers or particles also partially block radiation heat transfer through the space occupied by the insulation.
Conventional insulations are usually rated by their R-value. Since the performance of radiant barriers depends on many variables, simple R-value ratings have not been developed for them.
What are the characteristics of a radiant barrier?
All radiant barriers have at least one reflective (or low emissivity) surface, usually a sheet or coating of aluminum. Some radiant barriers have a reflective surface on both sides. Both types work about equally well, but if a one-sided radiant barrier is used, the reflective surface must face the open air space. For example, if a one-sided radiant barrier is laid on top of the insulation with the reflective side facing down and touching the insulation, the radiant barrier will lose most of its effectiveness in reducing heating and cooling loads.
Emissivity is the property that determines how well a radiant barrier will perform. This property is a number between 0 and 1, with lower numbers indicating better potential for performance. The emissivity of typical, clean, unperforated radiant barriers is about 0.03 to 0.05. Hence they will have a reflectivity of 95 to 97 percent. Some materials may have higher emissivities. It is not always possible to judge the emissivity just by visual appearance. Measured emissivity values should be part of the information provided by the manufacturer.
A radiant barrier used in the attic floor application must allow water vapor to pass through it. This is necessary because, during the winter, if there is no effective vapor retarder at the ceiling, water vapor from the living space may condense and even freeze on the underside of a radiant barrier lying on the attic floor. In extremely cold climates or during prolonged periods of cold weather, a layer of condensed water could build up. In more moderate climates, the condensed water could evaporate and pass through the radiant barrier into the attic space. While most uniform aluminum coatings do not allow water vapor to pass through them, many radiant barrier materials do allow passage of water vapor. Some allow water vapor passage through holes or perforations, while others have substrates that naturally allow water vapor passage without requiring holes. However, excessively large holes will increase the emissivity and cause a reduction in the radiant barrier performance. The ability to allow water vapor to pass through radiant barrier materials is not needed for the roof applications.
What should a radiant barrier installation cost?
Costs for an attic radiant barrier will depend on several factors, including the following:
Whether the radiant barrier is installed by the homeowner or by a contractor.
Whether the radiant barrier will be installed in a new home (low cost) or in an existing home (possibly higher cost if done by a contractor).
What extra “features” are desired; e.g., a radiant barrier with perforations and reinforcements may be more expensive than a “basic” radiant barrier.
Any necessary retrofit measures such as adding venting (soffit, ridge, etc.)
Whether the radiant barrier is installed on the attic floor or on the rafters.

Department of Energy Radiant Barrier Fact Sheet

freshening older woodwork prior to your home sale

Cleaning Wood Cabinets & freshening older woodwork prior to your home sale


Difficulty: Easy
Instructions
Step 1
Wipe down stained woodwork that has been treated with linseed oil or tung oil with a lemon oil polish. Linseed and tung oil dry to form a hard, protective film that is virtually invisible. A soft cloth dampened with lemon oil polish wipes away any surface grime.
Step 2
Use lemon oil polish as well as a mild mixture of white vinegar and water for stained woodwork treated with a wax that can both be felt and seen. Remember to reapply the wax layer after this step of cleaning to protect the wood.
Step 3
Clean wood the same as you would clean painted wood that has a semi-gloss or gloss finish .
Step 4
Use moistened baby wipes to clean woodwork and trim that has been painted or coated in polyurethane or varnish. Purchase a large bag of refillable baby wipes. Do not spend money on the expensive, scented brand names. Instead, buy the fragrance free, discount brand which can often be found in bulk.
Step 5
Wipe along the door frames, baseboards and crown molding with the help of a step ladder or taller ladder for high ceilings. You may be surprised at the amount of dirt you see on the wipe, and if cleaned on a monthly wipes will keep your trim work clean and shiny. These wipes easily remove surface dirt and more stuck on grease and grime without damaging the paint.

I am a Realtor
Dubuque man picks a challenging time to jump into the business, but others say local market is about to take off
BY BEKAH PORTER TH STAFF WRITER


Photo by: Jessica Reilly
James Patterson is a real estate agent, but also works as a bouncer at the Mississippi Moon Bar at the Diamond Jo Casino. Patterson picked a difficult economic time to start that career, but he says he's had some success.
The band blares.
Pumping, throbbing, pulsating -- the music captivates the crowd.
While the audience inside the Diamond Jo Casino's Mississippi Moon Bar sways, one man stands apart.
"I am a bouncer," he said, "but it's my night job."
While James Patterson's eyes remain alert and on the crowd, his mind wanders to his day job.
"I have houses to sell," he said.
'I like a challenge'
In September, America's bubble burst, and the resounding "pop!" echoes across the nation. When the recession struck, it hit the housing market first -- and it hit hard.
A record 1.8 million Americans were ousted from their homes in the first half of this year, according to RealtyTrac Inc. In May alone, officials reported 300,000 foreclosure filings.
That means for-sale houses flood the market in a time of rising unemployment and shrinking incomes.
"Everybody knows the real estate business is tough nowadays," Patterson said.
In October, Patterson completed his classes
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and received the certificate that makes him an official real estate agent.
"What can I say?" he said. "I like a challenge."
'Some interesting trends'
Dubuque real estate agent Rob Cook craved that challenge when he jumped into the industry six years ago, and with each passing day, he notices a shift.
"I won't say that it's a difficult market now, but I will say it's a different market," he said. "Just look at the numbers."
Cook compiles statistics for his real estate blog, riverbankstocornfields.com, and the numbers speak for themselves, he said.
In 2006, Dubuque area Realtors assisted in the sale of 496 homes between January and June. In 2007, that number dropped to 449. Last year, 344 houses were sold in the six-month period, and this year, sales lag with 321 homes in the Dubuque area having been sold so far.
"But they are still selling," he said. "And while they are selling, they are showing some interesting trends."
Sales are down, but the average selling price for a Dubuque home is up. According to Cook's figures, the average sale price increased from $140,798 to $155,285 from June of 2008 to June of 2009 .
"That doesn't mean that house values have gone up that much, but the houses that are selling -- and granted, there aren't many of them -- are selling at a higher price this year," he said.
'Now was the time'
Everybody told him to wait before becoming a real estate agent.
"Even my financial adviser said now was a bad idea," he said.
Some dreams don't die, though.
"I've wanted to do this since I was a kid. Some boys dream of being a fireman or a police officer or a professional athlete. I wanted to sell houses," he said. "So I decided now was the time, and it was just a matter of ignoring the people who told me not to do it. I wanted to prove them wrong, and I'm doing just that."
Patterson took a position with Ruhl & Ruhl Realtors in Dubuque. On Dec. 15, he closed his first deal, and since starting, he has sold eight houses.
'Your body, your soul'
Being the best takes time, said Dubuque agent Gwen Kosel, of Re/Max Advantage Realty.
"You will most likely lose money the first year," she said. "The second year, you might make a little bit of profit. But around here, people have the idea that you become a real estate agent, and you make a ton of money. That's not the case. You have to figure that there's a five-year ramp, and during those five years, you are going to be pouring into it 24/7 your whole body, your whole soul."
Kosel maintains the career is worthwhile, and those dedicated to it can find success.
'Selling yourself'
Patterson knows the battle will be fought uphill.
According to local real estate agents, 15 percent of homes on the active market are selling monthly. An estimated 370 houses remain unsold in the Dubuque area.
"Nobody's saying it's not hard," Patterson said. "This isn't for everybody. You have to be dedicated, and I mean really dedicated. This is definitely a tough business to be in."
Home values dropped 3.3 percent nationally at the end of last year, according to the Federal Housing Finance Agency. Iowa ranks 11th best in maintaining home values, only having fallen 1.2 percent in the last year.
Another obstacle is finding new clients looking to purchase in the poor economy, but here's where Dubuque differs from other American cities, local Realtors say.
'No matter'
Kosel's and Cook's combined 10 years of experience tell them the same thing: Dubuque's housing market is primed to peak.
Both talk about the one group ready to take Dubuque's market to the next level -- the incoming IBM employees.
"If it weren't for the IBM folks, our housing numbers would be much worse off," Cook said. "Those IBMers are the driving force behind our housing market."
Cook specializes in corporate relocation work, which means he helps business people moving in and out of town buy and sell their houses.
"Right now, I have a couple who wants to move here, and they have even found some houses they absolutely fell in love with," he said. "The problem is that the housing markets are terrible where they live, and they can't sell their houses there."
The problems run deeper than the troubled national economy.
"Good agents recognize that no matter what the economic conditions are, there is still stuff going on," Cook said. "Divorces, deaths, young couples starting families, older couples downsizing -- this happens all the time, no matter what the local or national economy is doing, and we have to be there to help our clients."
'Make it work'
Patterson grasped onto this concept when he signed up for his job.
"I can make a go of this," he said. "You just have to make a plan and stick to it."
But making it takes time. The 31-year-old family man works solely on commission. "You do what you have to do to make it work," he said.