Cool Metal Roofs And A Cool Vacation

By Scott Kriner, Green Metal Consulting

Even while on vacation I couldn’t get away from my interest in cool roofing. In late June my family went on a cruise with Royal Caribbean’s Explorer of the Seas to the beautiful island of Bermuda. The weather was perfect, the seas were calm, and we had a fantastic time. We gazed at the waters around Bermuda, with the different shades of blue and turquoise. We basked in the sun on the beaches where the pink sand is as fine as baby powder. And we marveled at how clean and pristine the island was, with a population of 62,000.

While my family was taking in all of the sites, sounds and experiences of Bermuda, I couldn’t help but notice all of the white roofs. Every building and home has a white roof, to complement the light pastel colored walls. On a ferry ride from Kings Wharf to Hamilton, I had the pleasure of sitting next to a local resident of Bermuda. We struck up a conversation on what else….cool roofing.

The Bermuda roofs are composed of slabs or “slates” of limestone, measuring about 18” x 12” x 1”. (today other materials are used such as aerated concrete, PVC and metal) They are applied over an open batten structure in a horizontal fashion, with each slate overlapping the previous row by about 9”. Then a mortar is applied over the top and edges of the slates. The whole roof is then given a thin wash of cement to create a monolithic structure. And finally a white non-toxic paint is applied. As I traveled the island using the local bus, I started to notice that there were no gutters on the buildings. Instead, a long concrete trough is sculpted along the lower edge to catch and direct the rainwater to a pipe on the side of the building. That pipe filters the rainwater and funnels it into a cistern that is beneath the building or buried alongside.

According to my friend on the ferry, the non-toxic paint is specially designed to keep the collected rainwater as clean and pure as possible. He told me that the paint is re-applied every two years. The average Bermuda resident uses 30 gallons per day, so there is a lot of rainwater to collect. And since the island has no other source of fresh water, they rely completely on rain to keep the cisterns full. In fact, the law requires that every house must collect 80% of water that falls on the roof.

This style of roof evolved over 400 years to protect the buildings from hurricanes, keep the inhabitants cool, and collect rainwater for household taps and plumbing. The first Bermuda roof was installed on the Carter House in St. George in 1640, and the original roof is still intact today.

My camera is full of photos of these white roofs showing the troughs and pipes leading to the cistern. It struck me that this tiny island has been using sustainable or green practices for centuries. The USGBC would be proud of their achievements! I wonder if their residents would be excited to know that their buildings could receive several LEED points for reducing urban heat island effects, optimizing energy efficiency, and harvesting rainwater.

The roofs are clearly a cool solution to a warm climate. Bermuda is at the same latitude as Charleston, SC, but enjoys warm weather year-round thanks to its proximity to the Gulf Stream. The British island has adapted to the realities of today’s world. With gasoline prices being the equivalent of $8-10/gallon, public transportation is commonly used. And the famous scooters are everywhere. Necessity is the mother of invention, and even 400 years ago, the inhabitants of the island needed to turn to the natural source of water – rain – to survive. As a result, a unique roof system was invented, and is still as efficient today as it was in the 1600’s. The green market has finally caught up to what Bermuda has been using every day.

To introduce their type of roofing system and colors to the U.S. would be a radical change from our conventional types of roofs. Can you imagine every house in your neighborhood with a light colored cool metal roof? What would your water bill be if you captured all rainwater from your roof and fed it to the faucets, washing machines, dishwashers and toilets? What would your cooling energy bills be if you replaced that dark roof with a more reflective and durable cool metal roof? Fortunately for the Bermuda residents, they don’t have to think about those questions. They don’t have time to think about those things when surrounded by the natural beauty of the island, the waters, the beaches, the lazy palm trees, and oh yes, those refreshing rum swizzles.

Scott Kriner is the president and founder of Green Metal Consulting Inc. He is a LEED Accredited Professional who began his career in the metal construction industry in 1981. His company is a member of the U.S. Green Building Council, the California Association of Building Energy Consultants and the Residential Energy Services Network (RESNET). Scott can be reached by email at skriner1@verizon.net, or by phone at (610) 966-2430.