Hot Summer – Cool Roof

I am always fascinated by the names of odd things. Take for instance the white, inner rind of a citrus fruit.  It’s called an ‘albedo’.   Who thinks up this stuff?

I’m humored because green builders also use ‘albedo’ when choosing different types of cool roofs. By the way, cool roofs lower your home air conditioning requirements.

That’s right. Cool roof = cool cash.

So if you are uncomfortably hot and tired of high air conditioning bills, concentrate on your roof.

Let me explain.

In a nutshell, it all boils down to your roofing material and its color.

Costs of a Hot Roof

Does your house have black asphalt shingles? Maybe it is lighter colored but dirty?

If it is, then you likely pay 2 to 63 percent MORE for summer air conditioning than your neighbor’s white roof.

Dark roofs simply absorb and radiate more heat. Say today’s temperature is 100 degrees; a black roof in the sun can be 90 degrees hotter, making your roof a whopping 190+ degrees!

And as I explain on page 14 of Sneaky Solar Strategies that Pay Over & Over , untamed radiant heat drills into your attic and make the rooms underneath very uncomfortable.

In effect, your house becomes a giant summer radiator, even heating the air around itself.  It becomes a heat island.

The ‘heat island effect’ happens when your roof, siding and any pavements around your house absorb the sun and then radiate it back into the surrounding area.   Consider how it feels when this happens to a whole neighborhood in July!

Not good.

Benefits of a Cool Roof

A cool roof makes your house “greener” because it:
•    Increases your indoor comfort by keeping your home cooler with a more constant temperature.
•    Reduces mechanical heating/ventilating/air conditioner (HVAC) unit stress which prolongs the life of your air conditioning system and even allows downsizing your mechanical HVAC unit.
•    Reduces your air conditioning operating costs for decades.
•    Extends your roof life and lowers roof maintenance costs, less frequent re-roofing costs and less landfill waste.

The most important feature of an ideal cool roof is that its surface strongly reflects sunlight, having a high albedo. Ideally, the surface also should efficiently cool itself by emitting thermal radiation away from your home.

Solar light reflectance (SR) and thermal emittance (TE) are both measured from 0 to 1 and the higher the value, the “cooler” the roof.

Cool roofs are not only white. There are many “cool colored” products which have highly-reflective ingredients added to darker-colored pigments. These also effectively reflect the non-visible, near infrared light spectrum.

You neighbors should thank you too, because your cool roof mitigates your neighborhood’s heat island effect.  Simply reflecting the sun’s energy as light back to the atmosphere, you help reduce global warming.

Everybody’s hard working air conditioning units throw off heat and that adds up. Cooler outdoor temperatures create less smog which improves your family’s air quality.  Cool roofs shave off demand for electricity during the day’s hottest (and most expensive) periods.  Feel good you are helping to avoid blackouts or brownouts!

What is the Right Roofing Type for my Home?

Here’s the temperature trade-off between roofing material and color:

Source: Lawrence Berkeley Lab http://eetd.lbl.gov/coolroof/

Use this Cool Roof Rating Council Products Directory to compare various roof types and manufacturers.  Start your search with as little information as a roof type and color.

Here’s How to Get Cool Cash

Federal tax credits are available in 2011 for Energy Star qualified metal roofs and reflective asphalt shingles that are newly installed in existing homes.

Tax credits are very valuable because you get full credit deduction for each dollar available.

Here is more details at Energy Star Federal Tax Credits for Energy Efficiency page. Click on the word ‘Roofs (Metal & Asphalt).

Begin here and get immediate access to my FREE special report “Sneaky Solar Strategies that Pay Over & Over“.  I look forward to hearing which type of roof you choose.