Is there is considerable difference in heat retainment between an exterior paint color with an LRV of 35 vs 70?

Depends on what you mean by considerable. The difference will be measurable.

Will an exterior paint color with a high LRV fade faster than one with a low LRV?

It's the other way around: High LRV is lighter colors. Low LRV is darker colors. Darker colors have more probability of fading than lighter colors.

However, "dark color" doesn't automatically equate to fast fading. Depends on the colorants and the color fastness of the specific colorants used to make the darker color. Always ask at the paint store. This is information they have and can advise about.

Will a paint color with a high LRV (such as those in the white family) tend to cause glare or cause one to squint when the sun shines on it?

It could. Lighter colors are brighter and the reflectance, luminance levels could be too bright for some people and cause them to squint. Glare is subjective, everyone responds to lightness, brightness differently.

Thank you for your informative reply. If I paint the exterior of my house an off white color with an LRV in the 70's, will my house not retain as much heat, hence causing a cooler interior temperature and the A/C not having to come on as much in the summer, compared to painting the exterior a "greige" color that seems to be popular now with an LRV in the low 40's?

Is there a reason there aren't more off white colored houses in the desert areas of Arizona? One would assume based on their high LRV they would provide a great benefit in the summer by reflecting light and ultimately heat, yet the majority of exteriors seem to be in the greige family.

I live in Phoenix. Lived in El Paso for 7 years.

I'm from Ohio, the Midwest - where people don't truly understand solar effects on the exterior of built environments, IMO.

Lighter colors are more reflective. That's a fact.

How much of a difference there is between a lighter color and a mid tone is up for debate; does it really make THAT much difference? Is it enough of a difference to choose a lighter color over a midtone that might be a better aesthetic fit for the house and the homeowner?

IMO, probably not.

LRV doesn't tell the whole story either. There's also this thing called Total Solar Reflectance that matters too.

With that said, LRV is useful -- it is a reasonably informative piece of color data that speaks to reflectance and energy accumulation (heat) cogently enough.

Plus, we have LRV notations for every paint color in every fandeck.

We don't have TSRs.

The reason you don't see a lot of white here is because it hasn't been on trend. Sand, desert, earth colors have been the choice for decades. Terra cotta tile roofing also dictates exterior color palettes.

Off white exteriors with the orange, terra cotta tiles is a newer trend. It's a wonderful way to update, put a fresh spin on the typical AZ stucco style home.

FWIW I specify Simply White by Benjamin Moore mixed in Dunn-Edwards about once per week these days.

seems like the "greige" family of color have low Chroma values (less than 2) and I when I have looked at these colors both up close and from a reasonable distance, they look washed out and like their isn't much intensity to the paint (I know that's what Chroma measures

Yep. Exactly right.

If a painter were to roll on the paint with 2 coats instead will it help make a house look like there is more paint applied to the wall and make it look more rich looking or is there nothing one can do to make these low Chroma value paints not appear washed out?

Two coats are the industry standard in order to achieve the proper film thickness and color resolution.

You should never do just one coat. The one-coat coverage claims are marketing. Just because a paint might "cover" in one coat doesn't mean one coat equals a proper paint job.

With that said, the chroma value is the chroma value. If you perceive low chroma colors a being "washed out" then more coats of the same low chroma color isn't going to change that.

The good news is you understand chroma - and where to find it, e.g. Dunn-Edwards.

Which means you can use chroma values as a framework to efficiently rule out lower chroma colors that you feel look washed out and find higher chroma colors that appeal to you more.

My basis for comparison on paints that I like the rich, intense look of for a house paint are the Warm Neutrals family in Dunn Edwards. A color example would be Warm Hearth DE6110.

Perfectly appropriate exterior color for the Southwest region.

Very insightful and helpful information. Will low Chroma value paints not last as long (meaning the washed out dull appearance look worse faster) than paints with higher Chroma values like Warm Hearth?

Will going from a darker color like Warm Hearth to Swiss Coffee require a separate coat of primer to prevent the darker color from bleeding through?

Chroma is not an indicator of light fastness. If a color fades or not depends on the colorants.

It's mostly about organic and inorganic pigments.

You can have low chroma colors mixed with organic pigments same as you can have low chroma colors mixed with inorganic.

It varies brand to brand, and color to color so you have to ask the paint store staff about the light fastness of specific colors - they should be able to tell you.

Tinted primer's function (when it's only about color and not about remedying some kind of substrate issue) is to create a supportive undercoat for the NEW color so it renders evenly and accurately in as few coats as possible.

Yellows and colors of white notoriously do not hide well - in all brands, in all tiers of paints.

In other words, the old color doesn't matter. Doesn't matter if you're painting over Warm Hearth or a light gray. The color either hides well or does not hide well and needs tinted undercoat.