architecture blog

Cool Roofs for Green Architecture: Six Basic Things to Know

Posted by Derek Leavitt on Thu, Aug 6, 2009 @ 06:08 AM

Cool roofs are not tricky. They are what they claim to be: roofs that are cool in temperature. So although the concept is simple, the result is a very powerful tool for architects in the growing need and desire for greener buildings.

1. The Basics

Cool roofs stay cool by doing two things:

a) reflecting heat from the sun (called solar reflectance).

b) quickly re-emitting any heat that is absorbed (called thermal emittance).

In essence, the goal of a cool roof is to reduce the amount of heat entering the building. As seen in the diagram below, these two properties, solar reflectance and thermal emittance are what determine if a roof is technically cool.

cool roof diagram

Diagram courtesy of the lovely people at the Cool Roof Rating Council.


2. Cool Roofs Are Not A New Idea

There's a lot of technical jargon you can get into when it comes to cool roofs. Leave that to us architects. In principal, cool roofs work because:

architects cool roof colors

Get it? White roofs absorb less heat than dark-colored roofs. A cool roof only absorbs 10-15 percent of the sun's heat versus 90 percent heat absorption for a  traditional dark roof.

The beauty of cool roofs is that they're a low-tech concept. Long before the days of electricity and air conditioning, warm-climate areas used light colors in their buildings to reduce heat gain. I think I even wrote something about this last year called Environmental Architecture in Greece.

Historical Green Architecture

In Santorini, Greece, cool roofs (and walls) are not a new idea.

However, since people don't always want white roofs, some smart scientist types have figured out a way to have cool roofs with darker colors by utilizing special highly reflective coatings. Cool roofs are versatile, coming in all types of materials that can be applied to a home just as easily as to an office or industrial building.


3. Cost

Inevitably, the first question we get after we describe a green feature to a client is "That's great, but is it more expensive?" Thankfully, for cool roofs, the answer is "not really." The added cost for a cool roof can be as little as 15 percent. This minor increase is far outweighed by the projected 20 percent or more savings in air conditioning cost (source). Besides, knowing you have a cool roof and are helping the environment will make you feel warm and fuzzy inside.

Compared to other green building features with high upfront costs, such as solar panels, cool roofs are an affordable option.


4. It's Not Just About You

Don't be selfish when selecting a new roof. Having a hot roof not only increases your cooling costs, it also affects the world around you through an ugly phenomenon called heat island effect. 

heat island effect

Diagram of Urban Heat Island Effect, courtesy of Lawrence Berkeley National Laboratory

Heat island effect occurs as result of the numerous heat-absorbing surfaces that cities contain such as dark colored roofs, streets and seas of parking lots. This effect overheats urban areas, increasing the demand for air conditioning and electricity. Another not-so-fun aspect of heat island effect is that it's known to increase smog formation.


5. For Remodels Too

Whereas many green building features are better suited for new construction or extensive remodels, cool roofs are a viable option for any remodel or simple re-roofing.

On our recent remodel of the Fashion Square Car Wash, we specified a cool roof to reduce the air conditioning loads and heat island effect from the surrounding paved areas.

cool roof start

The re-roofing of the Fashion Square Car Wash started out looking very similar to a typical roof. So far, not very cool.

los angeles architects cool roof

That's a little better.

los angeles architects cool roof

Now there's a cool roof.

So in this case, the roofing was pretty standard, but in the end it was covered with a white coating to increase its reflectivity.


6. Location, Location Location

There is a fair amount of debate as to whether cool roofs are beneficial in all climate zones. For us here in Los Angeles and other warm climates (hey Texas, Nevada and Arizona), it's a no-brainer: cool roofs work. The worry in cooler climates is that cool roofs don't allow for thermal gain in the winter. The good news is that there are numerous studies that have shown that cool roofs are effective in just about any climate.


heat island map

Potential net energy savings from changing roof reflectivity. Savings are measured in dollars. Note that the net savings are the savings of cooling energy use less the penalties of heating energy use. Image courtesy of the Heat Island Group.


If you have any thoughts on cool roofs, feel free to leave a comment or send us a fancy form message.



Tags: Materials, Green, Sustainable Design, Product Information, green homes

Using Old Jeans to Keep Your House Warm

Posted by Derek Leavitt on Wed, Mar 11, 2009 @ 10:03 AM

One of the major components the energy efficiency of any building is insulation. Insulation is critical to maintaining comfortable indoor temperatures by either keeping the heat in or out of a building.

Green Insulation

As sustainability gains momentum in the building industry, new products are available that rethink insulation. One of these is recycled denim insulation. Yes, old jeans. One of the leading manufactures of this green product is UltraTouch.


recycled insulation jeans  safe green insulation

It even looks like your old jeans. (images from UltraTouch & Victor Insulation)

Don't Eat the Pink Stuff

UltraTouch Natural Cotton Fiber Insulation is targeted as a replacement for traditional fiberglass insulation - the typically yellow or pink soft looking stuff you see between the studs during construction. Yes, you're probably also picturing the pink panther. If you haven't had the pleasure of handling traditional fiberglass insulation, don't. It's not pleasant stuff to to touch (itchy) or breath (can cause respiratory problems). I definitely wouldn't wear pants made of the stuff. UltraTouch on the other hand is made of safe, easy to handle, recycled denim.

green building products

UltraTouch comes in rolls and is easily installed. 

Product Info

So aside from this obvious point that it the product is safer for people to install, here are a few other interesting factoids:

  • The insulation is 85% post industrial recycled fibers.
  • Has acoustic ratings approximately 30% better than traditional insulation. Less outside or neighborly noise.
  • The cotton fibers are treated for fire resistance - Class A rating.
  • No VOC concerns - those little particles you don't want to breath.
  • Good mold resistance.
  • Obviously helps with LEED certification points.


A common question, as with most green products, is does it cost more? Well, yes, it does. How much more depends on the size of your project and the construction market. However, the short and long term benefits of this product far outweigh the upfront costs. 

At Modative, we are now specifying this or similar products instead of traditional fiberglass insulation. If you are concerned about the cost, we're happy to help you compare the cost of this green product to traditional insulation.


Tags: Innovation, Materials, Green, Sustainable Design, Building, green products

Southern California Fires

Posted by Derek Leavitt on Mon, Nov 17, 2008 @ 11:11 AM

As a very intense fire season continues to cause damage in Southern California, our thoughts are with those who have been displaced and lives upended by the recent fires. Since designing homes is such a large part of what we do here at Modative, we feel for those who have lost something so integral to their lives.

In an effort to help in the recovery, Modative is offering deep discounts on our architectural services for anyone affected by the Southern California fires. Whether rebuilding on the site of the loss or in a new location we are here to help. Please contact us if you are interested.

A photo I took while driving down the 101 freeway during last year's fires.

Tags: Property, Residential, Sustainable Design, Fires, rebuilding

Environmental Architecture in Greece

Posted by Derek Leavitt on Thu, Oct 2, 2008 @ 07:10 AM

I just returned from a vacation in the Greek islands and discovered some amazing historic examples of designing for the environment. The trip began on some of the Cyclades islands: Paros, Ios, and the better known Santorini. These islands contain the type of architecture one often pictures when they think of the Greek Islands; white painted flat roofed structures with minimal blue trim. These collections of white boxes stand out beautifully against the often barren brown landscape and deep blue color of the Mediterranean sea. This clean and practical style stuck with me as almost modern in appearance. Created only for pure function. No decoration necessary.

The Cyclades Islands: Santorini

This style that became so common among the Cyclades islands changed dramatically when we reached our final destination of Samos located in the lesser known North Aegean island chain. Samos, less than 80 miles away from the Cyclades islands contained structures with pitched tile roofs and much less white paint.

The North Aegean Islands: Samos

Intrigued by this dramatic difference in the architecture of these islands I asked a tour guide/ archeologist for an explanation. She explained that the reasons for the difference was simply climate.

The Cyclades islands were very dry, hot islands, so the buildings had flat roofs that could collect the minimal rainwater they received for reuse. This is especially important when you are on a small island with no other viable sources of water. These buildings were also all painted white to reflect rather than absorb the summer sun. The structures also had small windows to keep the heat out. Time inside these dark interiors is minimized by spending time on outdoor shaded patios.

Designed for Dry: Santorini

Samos on the other-hand has a much higher annual rainfall, which was evident by the abundant vegetation on the island and the fact that it rained most the time we were there. This is why the roofs are pitched; to get the rain away from the structures. This milder climate also explains why the windows were larger and the buildings were not all white.

Designed for Rain: Samos

This beauty of this contrast is that it shows how buildings had to be designed to their environments in the days before electricity and easy transportation. The buildings were not designed to a particular style to maintain a common appearance but to their particular microclimate. I love the sustainability of these simple design moves. Although the process of making our build environment more "green" involves utilizing innovative technologies, these simple lessons from the past have much to offer the design community as to how to move sustainability forward.

Tags: Greece, Green, Sustainable Design

Electric Car Parking?

Posted by Derek Leavitt on Fri, Jan 11, 2008 @ 06:01 AM

Having our office a block away from the historic Helms Bakery complex in Culver City/LA means hardly a day goes by without walking past its parking lot which features a solar array shading device. Utilizing photovoltaics (solar panels) to shade parking lots is a great idea to begin with. This device, however, built in 2003, takes it a step further by having the panels also provide power for an electric car charging station.


Imagine arriving at work daily to have your car charged up for free in an environmentally friendly way - seems perfect right? The only problem is that electric cars, for the most part, are nowhere to be found. The movie, "Who Killed the Electric Car?", clearly illustrates some of the circumstances behind the electric cars' demise in the 1990's. As the green movement grows, hopefully the electric car and its numerous possibilities will be revived.


As I walked by the solar charging station a few days ago I noticed a car parked in one of the charging spaces that clearly illustrated this problem.


Tags: Green, Sustainable Design, electric cars, Transportation, Parking, photovoltaic, Solar