The Effectiveness of Cool Roofs in Hot and Cold Climates

A relatively simple idea like light reflective roofing material can help reduce global warming. Research shows that cool roofs can provide significant benefits in hot climates, but there is some controversy as to whether cool roofs make sense in colder climates. In places where there are more hot days than cold days, cool roofs may not provide a net benefit in terms of cash savings or emissions. In northern countries like Canada this may seem intuitively obvious, but in the US the situation is not so straightforward. According to the US Energy Information Administration's, 2003 Commercial Buildings Energy Consumption Survey, heating accounts for 36% of commercial buildings' annual energy consumption, while air conditioning only accounts for only 8%. However, according to the Cool Roofs Rating Council (CRRC), "The roof is an insignificant source for heat gain in winter. While cool roof owners may pay slightly more to heat their homes, this amount is usually insignificant compared to the cooling energy savings during the summer".

Energy calculators often show a yearly net savings for dark-colored roof systems in cool climates.  Additionally, higher R values for insulating materials in the roof assembly and snow covering on roofs can lessen the impact of roof surface color.

In a 2001 federal study, the Lawrence Berkeley National Laboratory (LBNL) measured and calculated the reduction in peak energy demand associated with a cool roof’s surface reflectance. LBNL found that, compared to the original black rubber roofing membrane on the Texas retail building studied, a retrofitted vinyl membrane delivered an average decrease of 24 °C (43 °F) in surface temperature, an 11% decrease in aggregate air conditioning energy consumption, and a corresponding 14% drop in peak hour demand.

The average daily summertime temperature of the black roof surface was 75 °C (167 °F), but once retrofitted with a white reflective surface, it measured 52 °C (126 °F). Without considering any tax benefits or other utility charges, annual energy expenditures were reduced by $7,200 or $0.07/square feet.

Concordia Univeristy's Hashem Akbari is an engineering professor whose research indicates that in addition to driving down cooling costs, cool roofs can potentially delay the effects of global warming.  Before joining Concordia, Akbari spent 26 years at the Environmental Energy Technologies Division at Lawrence Berkeley National Laboratory (LBNL) at the University of California, Berkeley. Akbari is also a founding member of the board of the Oakland-based Cool Roof Rating Council (CRRC).

Akbari reports that dark roofs absorb 80 to 90% of sunlight trapping heat in the city. Those same surfaces covered with his reflective materials (white for roofs, lighter colours for pavements) will absorb only 30 to 65%. By decreasing absorption of roofs by 25% and pavements by 15%, the overall temperature of a city can be reduced by two to three degrees Celsius.

Together, pavements and roofs comprise over 60% of urban surfaces. Akbari states 10 sq m of white roof replacing a dark roof can offset one tonne of CO2. In other words, the temperature reduction due to radiation not being absorbed by the earth is equal to the increase in temperature caused by one tonne of CO2 in the atmosphere, effectively balancing any change.

Akbari's research indicates that if a city like Montreal resurfaced 60 percent of the 500 sq km of pavements and roofs with reflective materials, the city alone could offset over 12 million tonnes of CO2.

However, Akbari admits cool roofs may be more useful in hot regions, but he insists that even the coldest climates could positively contribute to the overall effect. “If major cities around the world adopt the technology, we’d be well on our way to making a very significant dent in rising temperatures,” he says.

Akbari estimates that permanently retrofitting urban roofs and pavements in the tropical and temperate regions of the world would create a one-time offset of 44 billion tonnes of emitted CO2.

US Secretary of Energy and former LBNL director Steven Chu, strongly supports cool roof technology.

For more information on Akbari's research click here.

© 2012, Richard Matthews. All rights reserved.

Related Posts
The Benefits of Cool Roofs
20 Cool Roof Resources from the CRRC and Other Sources
Cool Roof Savings Calculators
Three Types of Cool Roofs
Green Buildings Offer Many Benefits
The Extraordinary Growth of Green Building
The Implications of the Growth of Green Buildings
Green Building Environmental Benefits
Green Building Economic Benefits
Green Building Social Benefits
Green Buildings Resouces
Green Buildings Combat Climate Change
Green Buildings Health and Performance Benefits Part 1
Green Buildings Health and Performance Benefits Part 2
Green Buildings: The Many Benefits of Natural Lighting
Green Buildings: The Many Benefits of Ventilation
The Future of Green School Buildings
Top 10 Green Building Trends for 2010
25 Blogs Leading the Sustainable Building Revolution
Environmental Revolution: Building and Operations

Read More»

Green Lumber Certification Standards

Green certification of lumber is very important as the responsible harvesting of trees can go a long way towards protecting our environment. Forests are the lungs of the earth, they provide oxygen and help to remove carbon from the atmosphere. There are at least five eco friendly certification standards in use across North America: 1) American Tree Farm Systems, 2) Canadian Standards Association, 3) Forest Stewardship Council, 4) Programme for Endorsement of Forest Certification Schemes and 5) Sustainable Forestry Initiative. Of these programs, the Forest Stewardship Council (FSC) and the Sustainability Forest Initiative (SFI) are the most widely used for determining whether wood is green and sustainable.

SFI and FSC certification does not differ too much on the three central issues of sustainable timber production: 1) chain of custody, 2) labeling of products and 3) use of non-certified wood in final products. Participants are required to have an auditable monitoring system for all flows of wood that they deal with or a chain of custody from harvest all the way to the manufacture of finished wood designs. Both systems use their own set of labels to identify wood and wood products that adhere to their sustainable certification standards. These labels reflect the percentage of material from certified forests. Both the SFI and the FSC strictly prohibit the use of illegally harvested timber for use in certified products as illegal logging typically results in tremendous damage to the local ecosystem.

A new report by the Union of Concerned Scientists shows that most illegal hardwood comes from tropical forests for use in furniture, cabinets and home décor. The Union of Concerned Scientists (UCS) report was released on April 16, 2012 and it deals with how the US Lacey Act combats illegal logging.  The report outlines how illegal logging poses a significant threat to the US economy and endangers tropical ecosystems around the world.  

© 2012, Richard Matthews. All rights reserved.

Related Posts
The Economic and Employment Benefits of Forests
What The Business Community Can Do To Protect Forests
The Costs of Illegal Logging
The Lacey Act Combats Illegal Logging
Challenge to the Lacey Act
Scientists Defend the Lacey Act
The State of the Sustainable Furniture Industry
Sustainable Furniture at the Las Vegas Market
Challenge to the Lacey Act
Scientists Defend the Lacey Act
Video: Reducing Emissions Through Forest Preservation with REDD

Read More»

Manchester Wood Furniture

At Manchester Wood the environment matters, their goal is to create top quality furniture from beautiful American hardwoods with minimal impact on the environment. To meet this goal they use sustainable, eco friendly timber like white ash and soft maple. Their wood furniture uses hardwood lumber which is grown in sustainably managed forests in the Northeast by suppliers that meet strict State and National standards for forest management developed by the Sustainable Forestry Initiative (SFI).

Because they use solid wood in all their construction methods and American furniture, their wood products last for generations. Manchester Wood is part of a family tradition that dates back to 1891. They have designed and produced quality, affordable, eco- friendly solid wood American furniture in the Green Mountains of Vermont and Adirondack foothills of New York for over 30 years.

Certified Wood

All of the lumber that they use to manufacture Manchester Wood furniture is made from wood that has been certified as environmentally friendly and sustainable (SFI-certified).  They manufacture all of their furniture and accessories from eco friendly wood from sustainable Northeast hardwood forests which is grown and harvested in accordance with certified standards. All of the lumber they buy is certified by the Sustainable Forestry Initiative (SFI). Strict SFI standards include auditable monitoring of timber/wood flows, product labeling, and prohibition of any timber that is illegally harvested.  Manchester Wood looks forward to the day when eco-friendly lumber is the international standard for both the timber harvesting and wood manufacturing industries.

Locally Sourced Materials

Part of their philosophy at Manchester Wood involves the use of local materials. At Manchester Wood, all of the hardwood they use for their furniture comes from local forests across the Northeast. They are conveniently situated between the forests of New York’s Adirondacks and Vermont’s Green Mountains which provide much of their lumber. Using local lumber not only supports the local timber industry, but also cuts down on energy spent on transport. Local forests provide plenty of high quality hardwood and even the slate they use comes from local quarries. Buying their materials locally not only means customers can expect top quality, but it also means that each piece of our furniture is filled with the regional character of the Northeast.

American Forests

American-grown wood from sustainable Northeast forests are environmentally building material. Overall, US forests are healthy; while forests in other countries are disappearing, woodlands in America are actually expanding. Even though the population has grown over 165 percent since 1920, the US has approximately the same amount of forest land now as it did then. Currently, growth exceeds harvest by 47 percent. Wood furniture is commonly produced using illegal lumber unsustainably harvested from unhealthy forests. Manchester wood uses trees harvested from US forests. For every tree that is felled, six trees are planted. Other modern construction materials generate more pollution to manufacture and assemble while consuming more energy and relying on non-renewable natural resources.  

Harvesting Lumber

Foresters use green techniques to determine when wood should be harvested to keep forests healthy and productive. A good example of such techniques is selective harvesting. Instead of clear-cutting patches of land single tree are harvested which mimics nature. Single trees or small groups of trees that die and fall, or are blown down by strong winds are also harvested. Such harvesting practices encourage new timber growth and biodiversity. Eco friendly harvesting techniques help forests to regenerate and renew themselves. 

Manufacturing Practices

Sustainable manufacturing practices include minimizing waste wood and re-using byproducts (i.e. bark becomes mulch and trimmings are processed into paper). Wood furniture manufacturers are becoming increasingly efficient with the raw materials they use. Manchester Wood uses the latest equipment to obtain the needed cuts from their wood while utilizing the most material they can obtain from each board in order to minimize their impact on the environment. 

For more information on Manchester Wood go to their website by clicking here.

© 2012, Richard Matthews. All rights reserved.

Related Posts
The State of the Sustainable Furniture Industry
Sustainable Furniture at the Las Vegas Market
Video: What is Sustainable Furniture
The Lacey Act Combats Illegal Logging
The Economic and Employment Benefits of Forests
What The Business Community Can Do To Protect Forests
The Costs of Illegal Logging
Challenge to the Lacey Act
Scientists Defend the Lacey Act
Video: Reducing Emissions Through Forest Preservation with REDD

Read More»