Published on October 5th, 2023
Updated on October 7th, 2023
What is a cool roof and how can it save you money? Hail season is upon us. If you need to change your roof, a cool roof can lower the temperature inside your house, which can lower your AC bills.
We’ll be extensively quoting energy.gov (1). The site shows how a variety of materials can contribute to a cool roof based on your roof slope and material choice.
What is a cool roof?
- A cool roof is designed to reflect more sunlight than a conventional roof, absorbing less solar energy
- A “cool” roof should have both high solar reflectance and high thermal emittance, says Berkeley Lab. Cleantechnica (2)
- Most cool roofs have high “thermal emittance”—the ability to shed heat by giving off “thermal infrared” radiation
- Lowers the temperature of the building just as wearing light-colored clothing keeps you cool on a sunny day
- Conventional roofs can reach temperatures of 150°F or more on a sunny summer afternoon
- Under the same conditions a reflective roof could stay more than 50°F (28 °C) cooler
- This can save energy and money by reducing heat flow from the roof into the occupied space
Benefits of cool roofs
A cool roof can benefit a building and its occupants by:
- Reducing energy bills by decreasing air conditioning needs
- Helping older inefficient (or undersized) air conditioners provide enough cooling for today’s hotter summers
- Qualifying for money-saving rebates from utilities or government programs
- Making it possible to downsize new or replacement air conditioning equipment
- Improving indoor comfort and safety for spaces that are not air conditioned
- Decreasing roof temperature, which may extend roof service life
- Lower local outside air temperatures, thereby lessening the urban heat island effect
- Slow the formation of smog from air pollutants
- Reduce peak electricity demand
- Decrease power plant emissions by reducing the demand for energy to cool buildings
- Help offset climate pollution by reflecting more sunlight to outer space
- Cool roofing products usually cost no more than comparable conventional roofing products
- A variety of dark colors are available by using special pigments to reflect near infrared radiation
- White roofing products reflect about 60% to 90% of visible sunlight
You would be forgiven to not have heard of a cool roof before, even though they have many benefits and cost about the same as a regular roof.
Caveat: in the winter, absorbing less sunlight on the roof reduces heat conduction into the building.
Cool roof vs green roof vs solar panels
A cool roof, green living roof, and solar panels all can reduce the heat gain into your living space. Which is most effective?
The Department of Energy produced a study comparing the temperature differences during the day and night between all 3 types of roofs.
Cool roofs reduced AC energy consumption the most, followed by green roofs and solar panel roofs. Energy demand was shown to be reduced by 16.6%, 14.0%, and 7.6%, when cool roofs, green roofs and solar panel roofs are deployed, respectively.
Cleantechnica (3)
Ask your roofer about cool roofs when you need to replace one. If they are like our local roofers, they’ll give you a blank stare. Tell them to compare that to the cost of a regular roof. Most major roofing companies in the US have a cool roof line.
A final note:
“If all eligible urban flat roofs in the tropics and temperate regions were gradually converted to white (and sloped roofs to cool colors), they would offset the heating effect of the emission of roughly 24 gigatons of CO2, but one-time only,” said Art Rosenfeld, a physicist at Berkeley Lab. “However, if we assume that roofs have a service life of 20 years, we can think of an equivalent annual rate of 1.2 Gt per year. That offsets the emissions of roughly 300 million cars (about the cars in the world) for 20 years!”
Cleantechnica (2)
Switching to a cool roof for everyone has an incredibly large impact.
What do you think of cool roofs? We’re looking for a cool, impact resistant roof next time we have to fix our roof.
Update:
Here is our preferred lost of changes to make to minimize your carbon pollution, weighted by lowest cost first
1 – Get an induction cooktop
2 – Replace a gas or tankless water heater with an electric, hybrid heat pump hot water heater
3 – Solar panels, preferably ones where you can expand the system later
4 – A cool roof as described here
5 – An electric vehicle
6 – Residential home batteries. We recommend waiting for LFP battery types for home storage.
On our list to write about, electric lawn equipment, composting bins, adding insulation, winterizing your home, and heat pump air conditioners.
Sincerely yours,
smilingdad
Copyright © 2017-2023 smilingdad. The content produced by this site is for entertainment purposes only. Opinions and comments published on this site may not be sanctioned by and do not necessarily represent the views of smilingdad, its owners, sponsors, affiliates, or subsidiaries.
Notes:
(1) energy.gov Cool Roofs energy saver https://www.energy.gov/energysaver/cool-roofs
(2) cleantechnica.com Cool Roof Technology Could Eliminate Billions Of Tons Of Carbon Dioxide https://cleantechnica.com/2023/06/23/cool-roof-technology-could-eliminate-billions-of-tons-of-carbon-dioxide/
(3) cleantechnica.com Can A Roof’s Material Cool The Outside Air & Lower Energy Demand? https://cleantechnica.com/2023/10/01/can-a-roofs-material-cool-the-outside-air-lower-energy-demand/
smilingdad 