Radiant Barrier

[z.monkey]

Howdy tallbaldguy,

The radiant barrier is going to cook the shingles only if it is directly underneath the shingles.  Usually it is on the bottom of the roof deck.  First the best way to reduce the cooling cost is to keep the sunlight from entering the house.  Large trees that shade the entire house would be best.  But this approach isn't a quick one, so we come up with alternatives in the mean time.

With any insulation or radiant barrier project you definitely do not want to block the attic ventilation.  In the summer this ventilation helps to cool the attic.  If you block the ventilation you will generating more heat in the attic driving up your electric cost.  The purpose of the radiant barrier is to block radiant energy from entering the home and heating it.  This is why I block the radiant energy below the roof deck and on the floor of the attic.

An attic door blanket will prevent living space air from flowing into the attic and attic air from flowing into the living space.

Attic fans are good and you don't have to worry about them sucking the cool air out of your living space if you have adequate static ventilation.

Ceiling fans circulate the air in the living space to make it seem a little cooler than it is.  This helps if you run you thermostat a little higher to save on electricity.

Ridge vents are the best way to evacuate the hot air from the attic because they are at the apex of the roof.

Don't put the thermostat next to a vent or return.  It should be in an area which is static air to get an accurate temperature reading.

Thermostat settings are a personal preference.  If you turn the thermostat up during the day, don't go beyond about 10 degrees above the normal temperature because the air conditioner will have to work extra hard to compensate when it comes on.

Multiple control systems will compete with each other.  It takes analysis and diligence to get them tuned to work together.

Insulating non-conditioned spaces helps because heat enters the whole system through these spaces.  I installed radiant barrier in my garage and it helps to keep the study cool because they share attic space.  Especially in the late afternoon when the sun is on the garage.

Any large areas of your house that are directly exposed to sunlight can be improved with radiant barrier material under the sheathing.  If this is impractical then you can grow trees, shrubs or climbing ivys to prevent the sunlight from heating the wall.

The best possible situation is to stop the sunlight before it hits your house.  Large trees improve the environment and save your house the wear from sunlight exposure.  If you don't have large trees yet then there are a lot of options to help save money on your electric bill.  Most of them do require a lot of work, but it is worth it on the electric bill savings, and you get to improve your house at the same time...

Blessed Be....

[broli]

Hey you made me very interested.  I'm still a semi student and live with my parents. I live on the attic to be exact. What bothers me most aren't summer but winters where I sometimes have to wrap a blanket around myself from the cold. Even though I have a small heater, all the heat just disappears. A reason for this is the lack of any kind of insulation or RB. Now I'm thinking of installing a radiant barrier just like yours z-monkey but our roof is not as "work friendly" or new looking as yours. Personally I have never been up in the roof area above my roof to really check it out. But I might do so and take pictures so you guys can suggest and recommend stuff.

[z.monkey]

Howdy Broli,

My attic is not new, its 30 years old.  The reason it looks new is I completely reworked it this spring.  The radiant barrier will reflect the heat back into the house in the wintertime.  It helps with the heating in the winter also.  Think about a moisture barrier.  The moisture on the outside stays out.  The moisture on the inside (or lack there of) stays in.  The radiant barrier works the same except with energy.  The energy on the outside stays outside, the energy on the inside (or lack there of) stays in.  In the summer the radiant barrier keeps excessive heat out of the house.  In the winter the radiant barrier keeps the heat in the house.  It will reduce your energy costs for heating and cooling both in the summer and winter.  Plus your house will feel a lot more comfortable.

Broli, if you room is in the attic you may have to tear out sheetrock to insulate the walls which are the roof (if you have angled walls).  You would lay in a sheet of radiant barrier and then use fiberglass insulation behind it.  Then replace the sheetrock.  My brother's apartment in Germany is like this.  He has a 3rd floor flat which is right against the roof.  Also there is a new spray in foam insulation that offers better R ratings that the fiberglass batts.  The most effective part of the process is the radiant barrier.  We started noticing a difference when I was installing the radiant barrier, long before adding extra fiberglass batts...

Blessed Be...

[broli]

Zm, I need to break the plaster plates or however you call them to put the barrier behind them. Maybe I need something more temprorary to pass this winter rather than do a full renovation. How about I just install the radiant in my room as is, meaning stick it directly on the current wall and ceiling. Besides getting used to the space look this might be more economic and simpler.

[z.monkey]

Howdy Brodi,

Yeah, the radiant barrier will work that way, like radiant barrier wall paper.  Your parents are going to think you are a space alien nutjob, but you know who cares about that.  Everyone here at overunity.com thinks I am a space alien nutjob, so well so what.  I think it would look cool.  You can even reapply you pictures and posters over it because it works in the whole spectrum of high frequency energy not just visible light.  Your parents might even like it because it will save them some money on their electric or gas bill.  I am going to apply the radiant barrier to the inside of my greenhouse roof to try and hold the heat in this winter.  Usually I have a little heater and some lights out there, so with the radiant barrier maybe I won't have to expend as much energy in the greenhouse...

Blessed Be...