Question: I'm not sure whether this is off-topic; if so, I do apologize and will fully understand votes to close.

That said: I live in a climate that's quite cold much of the year but gets pretty hot in the summer, so I have both heating and cooling to worry about. I'm about to replace my roof and am trying to figure out how much difference the shingle color is likely to make.

I think --- and please correct me if I'm wrong --- that a lighter color will make daytime heating more difficult (in the winter) and make daytime cooling easier (in the summer), because it reflects more energy from light.

I also think --- and again please correct me if I'm wrong --- that a lighter color will make nighttime heating easier (in the winter) and nighttime cooling harder (in the summer), because it radiates less. 

**Main question**: How significant are these effects? If I'm choosing between two shades of brown like these (the left one being a bit lighter than the right one), how much of a difference in energy consumption are we plausibly talking about over the course of the year?

![](https://www.panix.com/~wotw/missionbrown.jpg)![](https://www.panix.com/~wotw/barkwood.jpg)

**Secondary question:** I live in a place that's very cloudy most of the winter. Does that change the answer to the main question?

Additional info in case there are factors that don't scale in the obvious ways: The footprint of the house is 5000 square feet. With slopes, overhangs, etc., I'm guessing the roof is about 8000 square feet. The ceilings are very high (about 18 feet in most places.)

Answer: 
John G. Cramer discussed G4V in a recent Analog Alternate View Column (Mar. 2016), and how Advanced LIGO data could possibly falsify G4V, General Relativity or even both of them (Their predicted gravity wave signatures signatures differ.)

Cramer also stated that there would be no dark energy since G4v explains distant receding Type IIa supernova dimming as partially due to relativistic beaming leaving no need for a cosmological constant.

In other words, the accelerated expansion is an illusion because more distant Type IIa supernovas appear dimmer than previously predicted if G4V is correct.
Gravity is assumed to be attractive only. the cosmoconst/dark energy is Assumed to exist in order to explain the observed accelerating expansion.