Radiant
barrier
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.
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.
During the building
process - ask your builder to buy the roof panel with
the radiant barrier attached
to the bottom. This saves you additional installation
fees in the future and is usually very cost effective.
Roof panels with radiant barriers attached do not
cost much more then regular panels.
For
Radiant Barrier Products
Attic
vents
Attic
vents can be static or powered. These covered
openings allow air to escape the attic. Several of
these vents are usually required to properly ventilate
the attic. They should be placed evenly across the
roof. Choose from metal or plastic in round, square
or slant-back designs.
Electric-powered attic
vents use a thermostat to fight heat and a humidistat
control ("All Season" model only) to help
prevent moisture buildup inside the attic.
Featuring a low-profile
dome, the power attic vent is unobtrusive when installed
on the roof face slanting away from the front of your
home. It's an efficient option to replace wind turbines
or roof pots already in place.
For
Solar Attic Vents
Ridge vent installs
on the peak of the roof allowing exhaust ventilation
all along the roofline -- end-to-end.
Design features include
an external baffle and internal weather filter for
optimum airflow and weather protection. Less than
an inch in height, this molded, high-impact copolymer
shingle-over ridge vent permits capping of the ridge
with shingles like the rest of the roof.
Ridge Vent Benefits:
Works year-round
Provides
evenly distributed ventilation along the entire underside
of the roof
18 square inches of net free area per linear foot
(depending on type and model)
Slim
design, visual appeal
Provides
a higher volume of airflow per square foot of attic
area than any other fixed-vent system
Design
maximizes airflow across the entire underside of roof
sheathing
Changes
in wind direction have no significant effect on vent
performance
Design Considerations:
Ridge vents must have an external baffle to deflect
weather away from the attic and to create low pressure
over the vent openings to help pull air out of the
attic
May not
provide enough ventilation area on steep hip roofs
With
all roofs, install ridge vents along the entire length
of ridge for best performance and appearance. (With
vaulted or cathedral ceilings: Each attic [joist]
cavity must be ventilated, leaving 1-1/2" between
sheathing and insulation.)
Intake
vents must be installed to provide proper airflow
HVAC system
As much as half of
the energy used in your home goes to heating and cooling.
So making smart decisions about your home's heating,
ventilating, and air conditioning (HVAC) system can
have a big effect on your utility bills — and
your comfort.
Take these steps to
increase the efficiency of your heating and cooling
system.
Change
your air filter regularly
Tune
up your HVAC equipment yearly
Install
a programmable thermostat
Seal
your heating and cooling ducts
Consider
installing ENERGY STAR qualified heating and cooling
equipment
(12 seer or higher)
S.E.E.R. is an efficiency rating of HVAC. The higher
the rating the better. The actual operating SEER after
installation can easily drop to half the rated SEER
if the product is poorly applied, incorrectly installed,
has incorrect airflow, is improperly adjusted and
incorrectly charged.
Contractors may mix
and match the parts (furnace, coil, and components)
so be sure to carefully inspect the work.
Low E Windows Glass
Low-E, the abbreviation
for low emissivity glass, has an invisible, metallic
coating that admits the full spectrum of sunlight
but blocks radiant heat from escaping. During the
winter months, between 70 and 75 percent of the heat
that would otherwise escape from the house is reflected
back into the home for energy savings. Because the
coating also increases the inside window's surface
temperature, areas near them are more comfortable
on cold winter nights.
During the cooling
season, as much as 25 percent of the unwanted heat
that would otherwise enter the house is reflected
to the outside. The low-E coating blocks ultraviolet
light which would normally fade fabrics and other
materials.
It is applied either
to one of the inner surfaces of a sealed-double pane
window or suspended between the panes on a thin piece
of plastic glazing. Suspending it between the panes
has the added advantage of raising the window's insulating
value to that of a triple glazed window. Some low-E
window manufacturers fill the air space between the
glazing layers with Argon or other inert gases to
further increase the insulating value.
For existing windows,
low-E coatings are also available on films which can
be applied to the inside surfaces. They are less common
than the solar films designed solely to block sunlight.
Low-E windows can
achieve R-values as high as R-5, a marked improvement
over the R-1 single pane, or even R-2 double pane
windows. Low-E windows cost more than standard windows
and allow slightly less light to enter, but are often
cost effective in extremely hot or cold climates.
Insulation - R-value
R-value is a measure
of a material's thermal resistance, or how well it
holds back heat gain orloss. The higher the R-value
the better.
While high R-values
are primarily achieved through insulation, other factors
are also important. The materials used in building
the foundation, framing and roof - and how they're
put together - can play a big part in increasing the
potential R-value.
build "green" energy efficient homes with
high r-values
Different areas of
the home have different recommended R-values, depending
on how what materials are used and how much space
is available for insulation. The list below shows
the recommended R-values:
Attic = R-38 to R-44
Sidewalls
= R-11 to R-18
Basement
= R-10 to R-19
Crawlspace
= R-19
Keep in mind that
the elements of your home are designed to work together
- sacrificing efficiency in one area can reduce or
even negate energy savings in another area. The recommended
efficiency levels are intended to be part of a whole-house
"system."
Tankless Water
heaters
Tankless Water Heaters,
also called Instantaneous or Demand Water Heaters,
provide hot water only as it is needed. Traditional
storage water heaters produce standby energy losses
that cost you money. We do not leave our homes heated
while vacationing. We only heat our homes when there
is a demand for heat. In the same way, a Tankless
Water Heater is used only when there is a demand for
hot water.
Tankless
Water Heaters heat water directly without the
use of a storage tank. Therefore, they avoid the standby
heat losses associated with storage water heaters.
When a hot water tap is turned on, cold water travels
through a pipe into the unit. In an electric Tankless
Water Heater an electric element heats the water.
In a gas-fired Tankless Water Heater a gas burner
heats the water. As a result, Tankless Water Heaters
deliver a constant supply of hot water. You don't
need to wait for a storage tank to fill up with enough
hot water. Typically, Tankless Water Heaters provide
hot water at a rate of 2 – 5 gallons (7.6 –
15.2 liters) per minute. Typically, gas-fired Tankless
Water Heaters will produce higher flow rates than
electric Tankless Water Heaters. Some smaller Tankless
Water Heaters, however, cannot supply enough hot water
for simultaneous, multiple uses in large households.
For example, taking a shower and running the dishwasher
at the same time can stretch a Tankless
Water Heater to its limit. To overcome this problem,
you can install a “whole house” type Tankless
Water Heater or install two or more Tankless Water
Heaters, connected in parallel for simultaneous demands
of hot water. You can also install separate Tankless
Water Heaters for appliances—such as a clothes
washer or dishwater—that use a lot of hot water
in your home.
For
Tankless Water Heaters
