Looking at putting a new roof on the house after 15 years. Looking at replacing the original asphalt shingles and considering a metal roof. Have seen studies comparing metal to shingles which indicate a possible effect on the heating and cooling requirements. What are your thoughts?
There will be an effect.
Run a Manual J with asphalt shingles vs. metal roof and post your findings...
type of paint used
color of paint used
seperation between roof & sheating
type of sheating
amount of shading
roof orientation with respect to north
harvest rainwater,make SHADE,R75/50/30= roof/wall/floor, use HVAC mastic,caulk all wall seams!
Manual J 8th addition
"Under attic or knee wall, Vented with Radiant Barrier, Dark Asphalt Shingles or dark Metal, Tar and Gravel or Membrane, R-38 insulation"
The contributing factors are vented or unvented, Radiant barrier or No Radiant barrier, Dark or light color, and R-value.
If you are replacing a dark asphalt shingle with dark Metal, Manual J load calc will not change.
Tile or concrete will change your load.
No difference on type of roof, it's the insulation in the attic that will save money.
Majormickey--I can assure you the type of roof makes a world of difference as to how much radiant heat, in summer, is transfered to the insulation below.
The reason I asked was prompted by the following study:
"Initial results for a nine week period in the summer of 2005 show the white metal roof providing a 19% savings in air conditioner energy over the same period in 2004"
I believe that the 2005 temperatures in the subject area
were > than in 2004.
FSEC and a few other building sources provide
VERY Reliable, well-documented studies.
It's Not Rocket Science, But It is SCIENCE
with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE
Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities