Radiant Barriers Save Orlando Homeowners Money

What is a Radiant Barrier? Are they effective at reducing my energy bill?

We inspect a lot of hot dusty attics, some are 165° F. We see all kinds of situations where attic insulation is insufficient, ventilation is inadequate, and rarely find radiant barriers installed in attics. According to the Department of Energy Radiant Barriers work best in hot climates when used in conjunction with sufficient insulation and ventilation. Studies show that radiant barriers can reduce cooling costs 5% to 10%. The reduced heat gain may even allow for a smaller air conditioning system or improve effectiveness of an under rated systems.

Radiant barriers are installed in homes primarily to reduce summer heat gain and reduce cooling costs. Radiant barriers do not reduce heat conduction like thermal insulation materials. The barriers are comprised of a highly reflective substrate or foil that reflects radiant heat rather than absorbing it.

Heat Transfer

Like a cool spoon in cup of coffee conducts heat through its handle to your hand; heat travels from a warm area to a cool area by a combination of conduction, convection, and radiation. Heat flows by conduction from a hotter location within a material or assembly to a colder location. Heat transfer by convection occurs when a liquid or air, becomes lighter and rises. When liquid or air cools, it becomes heavier and falls. Radiant heat moves from hots surfaces and is absorbed by cooler materials or air. A car parked in the sun will absorb the radiant heat into the cars finish and transfer the heat thru the metal into the interior where it heats the air inside the car.

How Radiant Barriers Function

Most insulation materials work by slowing heat transfer. Radiant barriers and reflective insulation systems are designed to reduce the transfer radiant heat. Radiant barriers must have an air space to work. Radiant barrier are less effective when installed horizontally. Dust accumulation on the reflective surface reduces its reflective properties.

As the sun heats your roof, it makes your roof hot. The heat travels through the roofing materials to the attic side of your roof. It radiates the increased heat energy onto the cooler attic materials, the air conditioning ductwork and the ceiling of your home. A radiant barrier reduces the radiant heat transfer from the underside of the roof to the other surfaces in the attic.

Radiant Barriers help air conditioners cooling capacity

Radiant barriers are more effective in hot climates than in cool climates, especially when cooling air ducts are located in the attic. Some studies show that radiant barriers can reduce cooling costs 5% to 10% when used in a warm, sunny climate. The reduced heat gain may even allow for a smaller air conditioning system. In cool climates, however, it's usually more cost-effective to install more thermal insulation than to add a radiant barrier.

 

Frank Carr is the Owner / Inspector at First Choice Home Inspections in Deltona, FL serving Volusia, Seminole, Orange and Lake Counties.  Formerly in the building trades, Frank’s focus is a safe home and building FCHI. We believe that consumers have the right to expect the highest standards of thoroughness, fairness and effectiveness from their home inspector and that is exactly what we provide.

First Choice Home Inspections 
(386) 624-3893
Email:  home.inspections@aol.com
Website:  http://1homeinspector.com
Facebook: https://www.facebook.com/FirstChoiceHomeInspectionsLlc/
Twitter:  https://twitter.com/1stChoiceHomeIn

 

Dangers of Roof Dryer vents in Orlando

As a home inspector, one of the biggest safety hazards I see daily is dryer vents.  Dryer fires are among the top ten reasons for home fires and cause more than 15,000 fires annually.  Dryer exhausting through the roof should be ducted to a special dryer roof vent without screen.   

The roof vent or louvered plenum must be equivalent to a 4 inch wall termination in regard to resistance to airflow and back-flow prevention, and should require little or no maintenance to prevent clogging.

Home built in 2013 goose-neck looks shiny and new.

2013 home inside of goose-neck vent. 

There are many issues with this type of vent.  It must be a vent that has a back-flow prevention flap and it should not have a screen.  Many of the goose-neck type of vents come with screens and are unsuitable for dryer venting.  

Goose-neck vent with screen

Goose-neck that is totally blocked.

Inoperable back-draft damper.

Goose-neck with screen was clogged.  Improper duct type.  Lint exhausted into attic damaging roof decking.

1. Dryer ducts must be at least 4 inches in diameter or at least the size of the dryer outlet. The exhaust duct must not extend into or through heating or air-conditioning ducts. The exhaust duct system should be supported and secured by mechanical fasteners. It should be insulated in non-conditioned spaces to prevent condensation.
2. The maximum length for a clothes dryer exhaust duct should not exceed 25 feet. This length should be decreased by 2.5 feet for every 45-degree bend the duct makes, and 5 feet for every 90-degree bend the duct makes.
3. The dryer exhaust ducts should be constructed of rigid metal (galvanized steel). The interior of the duct should be smooth surfaced with the joints running in the direction of the airflow. There should be no sheet-metal screws, rivets or any other fastener used to connect the duct joints. Fasteners that penetrate into the airway will catch lint and block airflow. 
4. Foil duct tape (not plastic or vinyl) should be used to secure joints. Outside termination must be equipped with a back draft damper, which prevents air, moisture and rodents from entering. The termination must not have a screen covering the exhaust outlet.

 

I have seen all of these used for dryer roof vents.  Just because they are sold at the hardware store does not make them right.

 According to the IRC:

- M1502.3 Duct termination.

- - Exhaust ducts shall terminate on the outside of the building.  Exhaust duct terminations shall be in accordance with the dryer manufacturer’s installation instructions.  If the manufacturer’s instructions do not specify a termination location, the exhaust duct shall terminate not less than 3 feet (914 mm) in any direction from openings into buildings.  Exhaust duct terminations shall be equipped with a back draft damper.  Screens shall not be installed at the duct termination.

In the opinion of this home inspector, the biggest problem I see with the roof vent is out of sight out of mind.  Each year many people die in home fires that start at the dryer.  Prevention is often easy and requires little effort.  Dryer vents should be cleaned annually but in the case of roof top vents I recommend semi-annually.  

Clothes dryers a leading cause of home fires in Orlando

Frank Carr is the Owner / Inspector at First Choice Home Inspections in Deltona, FL. Formerly in the building trades, Frank’s focus is a safe home and building FCHI. We believe that consumers have the right to expect the highest standards of thoroughness, fairness and effectiveness from their home inspector and that is exactly what we provide. Http://1homeinspector.com


First Choice Home Inspections 
(386) 624-3893
Email:  home.inspections@aol.com
Website:  Http://1homeinspector.com
Facebook:  https://www.facebook.com/FirstChoiceHomeInspectionsLlc