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Energy Cost Savings Through Green Roofs: A Myth

Green Team at Green Roof Technology, - Monday, June 10, 2013

An Executive Summary of Facts by Jörg Breuning

It is unavoidable and common sense that wearing wet clothes in winter will end up in hypothermia. Wearing the same wet clothes on a hot summer day, might actually help to feel cooler - not to be confused with feeling more comfortable. If we have only one set of clothes, for all four seasons, they would typically be made up of two layers. The first layer protects against direct environmental impacts such as sunlight, rain or wind and the second layer usually consists of a breathable layer for comfortable wearing and controlled air circulation. 

Source: Columbia

I have learned on my travels all across different desserts on earth that these layers reduce temperature increase on hot, sunny days, but at the same time can reduce the loss of body heat during extremely cold nights. Indigenous people of extreme environments have learned this lesson over centuries and were able to survive under these circumstances with this simple layer strategy. My father always used to say: "What is good for the cold is also good for the warm."

 Any man-made structure is nothing more than a body that requires consistent 'body temperature' to make it usable for the purposed design. A building without reliable all-season clothes is worthless or requires a tremendous effort (energy or operating costs) to make it useful.

Helping to make a building useful for people, the 'coat' consists typically of an insulation layer covered with a layer to protect against the elements (waterproofing, roofing membrane). Since we all know that the protective sheet will deteriorate over time this sheet (waterproofing) has to eventually be renewed, a process experts call re-roofing, which usually happens every 18-25 years.  

It is proven by my experience (since I have been designing and installing green roofs for 35 years) that a green roof can double the lifespan of the roof. The green roof acts like an additional all season two-layer system on top of the roof where healthy plants are the first layer, protecting against direct environmental impacts. The green roof growing media (green roof soil) is the breathable layer.

There is only one difference; the breathable layer (growing media) on a green roof is also the basis for the well-being of the plants and must be able to store water and air at the same time for a healthy growth. If this layer doesn't fully support the plants (and only the plants) the entire coat does not function and the plants tend to indicate this by suffering or a change in plant varieties present.

Above we learned that a wet coat in winter causes problems because water is not a good insulator and so we have to consider heat loss in winter when speaking about green roofs. We also understand now that dry green roof soil in summer will store heat (in the aggregates) and increases the cooling needs.

A green roof (and green walls that grow on growing substrates on vertical surfaces with consistent irrigation) are only thermal masses with hardly any insulating values. Considering these facts, building owners should be cautious when someone tells them that green roofs are good insulators. This is just not the case, especially if the building envelope is not insulated correctly in the beginning. Fixing heating and cooling loss simply through green roofs and/or green walls is impossible or a short-term solution.

With all the current research in this field, it's surprising to me that people still claim green roofs are good insulators. Additional insulation below the original coat is necessary (waterproofing or walls) to make the most effective roof (cost wise and physically) compared to any vegetated layer combined with growing media of growing substrate.

However, the thermal mass "green roof" certainly has lifespan extending properties for the waterproofing (and again, I can confirm this with projects spanning over 35 years). This is the key to start thinking in long terms (50+ years) in the building industry and is the most sustainable approach. Longevity is hardly considered in LEED™ certifications and with less emphasis on longevity, many awarded LEED™ buildings might fail for a certification because they can't be upgraded easily when the costs of energy increase. I am not referring to how wasteful the footprints of many of these 'innovative' building designs are.

Photo DM Products: Penn State's futuristic Millennium Science Complex earns LEED Gold for this space-wasting empty over hang. The 'water head' of the campus (or of their bureaucracy). Pants can not even grow underneath - how can people survive?

In the last 35 years, energy costs increased eight to ten times (!) and are expected to grow accordingly over the next three to five decades (or the lifespan of a green roof). Knowing this, selling a green roof for insulation purposes will unavoidably end up in a costly disaster for the building owner. Removing a fully functioning green roof in less that 25 years after installation, simply to add to more insulation, meet future requirements or to keep heating and cooling costs low.

Green roofs do not extend the life span of selected, important building components dramatically. Increasing the lifespan of any building is the best environmentally friendly approach in the building industry and the most efficient way to reduce costs for the owner over decades. Although, if scientitst and green roof professionals often do not understand this unique property of green roofs and don't design underplaying components accordingly, the building owner won't be very happy in the future. In 20-25 years when parts star needing to be replaced, a second green roof will be the last choice of the building owner because it will simply be additional costs with few benefits as originally promoted.He might not understand why he should disassemble a perfectly functioning and well established green roof, precisely when certain individuals led him in the wrong direction in the past.

Conclusions:

•  As a building owner be careful when people try to sell you green roofs as a good insulator without mentioning that additional insulation is necessary for the building for future energy needs.

•  Building owners have to understand that any available research about the insulation value of green roofs reflect only a current snap shot and potential savings in a very short time period (less that half life time of a green roof) and they are worthless when the intention is to build for half a century.

•  There are no energy  studies completed over a 50+ year time span comparing a green roof (plus additional insulation) and a conventional roof that will be re-roofed with additional insulation 20 years from now (typical re-roofing practice)

Trust only experts that recommend additional insulation under the green roof because then they expect that your investment will last a human lifetime, which will be profitable but also affordable during this time. Designing the roof (or wall) to last for five decades or more requires a lot of responsibility and expertise of the designers - if they value their customers.

 

Rooftop Farming an Environmental Nightmare

Green Team at Green Roof Technology, - Tuesday, June 04, 2013

By: Jörg Breuning

Companies spend millions of dollars on creating rooftop farms to demonstrate how "green" they are. There is no doubt advertising with living green is a good idea because it makes the customers believe that the company practices environmental leadership.

However, the reality looks very differently.

Recently a food company started a huge campaign promoting their rooftop farm (and their green leadership) by opening a 17,000 square foot rooftop farm on the East Coast.They were optimistic that they could grow 10,000 pounds of produce during the short growing season. This is approximately 25% over the average vegetable and berry crop yields estimated for New England on the ground during a good year, based on traditional irrigated farmland.

Since environmental conditions on rooftops are more extreme, achieving this goal seems ambitious and will require higher amounts of water and fertilizer. With more moisture in green roof soil the main benefit of green roofs (stormwater retention) is sacrificed and the run-off will most likely now contain more nutrients than in the run-off from traditional farms. Nutrients are already the number one pollutant in our waterways.

Based on these harsh environmental conditions growing crops on rooftops will be more labor intensive.

A 17,000 square foot rooftop farm requires approximately 300 tons of engineered growing media (soil) or 672,000 pounds in order to grow an average of 8,000 pounds of produce a year. In other words, it takes more than 80 years to grow the equivalent crop weight that was transported up onto the roof in the first place. This does not include the tons of water, fertilizer or structural support for the building that has to be shipped to the city and hoisted up on to the roof to start and maintain the garden.

Roof top farms ultimately increase the shipping (costs) of goods into cities. Shipping produce from a farm located on the ground is cheaper and more efficient because everything necessary to sustain the farm is already at hand. The food from rooftop farms is being transported a shorter distance creating a false sense of environmental responsibility. When in reality, the amount of materials essential to implement and maintain a rooftop farm outweighs the good in this situation.

Consider this: every person consumes 200-400 pounds of produce in a year (Profiling Food Consumption in America in 2000, Agricultural Fact Book) and an average of 8,000 pounds feeds around 20-40 people and requires at least one full-time, skilled farmer.

On a traditional field, one farmer can easily manage a 10-20 times larger area with a higher yield per acre using organic principals, which are not even discussed with most roof top farms.

Buyers of food from companies with rooftop farms are misled by advertising and are paying more for their goods while supporting a trend known as Greenwashing.

Jörg Breuning welcomes people who want to learn from decades of green roof experience - askjorg@greenrooftechnology.com

 


Green Roofs Don’t Work or People Don’t Work ?

Green Team at Green Roof Technology, - Wednesday, May 22, 2013

By: Jörg Breuning

 

Information spreads like wildfire in today's world; between the internet and numerous social media sites. It has become extremely easy to access relevant information anytime, anywhere. This is a fantastic technological advancement, with one weakness. Anyone can "publish" anything. 

Since the internet makes everything very easy to spread any kind of information around the globe in seconds, it seems that the quality of information provided to the public dropped at accordingly the same speed as it's distribution. Some people jump to conclusions; they are quick to talk and other are quick to responds via text and in most cases these are not the same people. I get the impression that one group is too lazy to write and the other group too lazy to think. They have a desperate need for attention - I like to call it Recognition Deficit or RD for short, which unfortunately results in misleading and false information to the reader. Many people in the audience often find it necessary to then add their own opinions and re-post the article, making things even worse.

An excellent example of RD was recently posted in the American Scientific. I believe this certainly affected their reputation in the scientific world and hopefully leads to better supervision of the people who have permission to post. Their article was copied and pasted onto numerous other websites, regardless of the comments left on the original page. In this instance, RD wasn't the only symptom, a combination of ignorance and laziness was also thrown into the mix.

Modern green roof technology is a well-established technology around the world. If some researchers think that there is room for improvements, they should consider previous research from around the world in addition to what might be sacrificed along the way. Focusing on one aspect of the issue won't work in a complex ecosystem. There are no defining traits of complex ecosystems, where Mother Nature undergoes consistent changes. Having a tunnel view sometimes helps, however we can't afford to lose the bird's-eye perspective of the decades of experience and hands-on professionals.

To all the skeptics out there, let's make a long story short:

Green Roofs do work, but many people don't!

Extensive verses Intensive - Which Would You Choose?

Green Team at Green Roof Technology, - Tuesday, April 16, 2013

By: Samantha Yurek 

A lot of thought goes into the design process when starting a green roof project. One of the biggest questions involves the type of green roof you want; extensive or intensive? This decision will dictate everything that will need to happen for your green roof to become a success. Let us take a quick look at the differences between intensive and extensive green roofs.


Extensive Green Roof: Swarthmore College of PA, Photo Credit: Green Roof Technology

Extensive green roofs are considered the simpler version because the roof structure is usually equipped to withstand the little bit of extra weight. With only a maximum of 6" of growing media and mostly ground cover covering plants, and extensive roof is certainly of a lower profile. The plants consist mainly of sedums and other succulents, herbs, grasses, mosses and low-growing perennials. An extensive roof is mainly for environmental benefits and and occasionally accessible to the public. Extensive green roofs can be excellent combined with Solar panels what increases the environmental benefits and increases return of investment substantially.


Intensive Green Roof: The Ledge Restaurant in Boston, Photo Credit: High View Creations

Intensive green roofs on the other hand can become quite extravagant. The roof must be very sturdy in order to hold foot traffic, deeper growing media and larger plants. The plants found on an intensive green roof range from shrubs and perennials to larger trees. Accents such as ponds and recreational spaces are a possibility. An intensive green roof is a busy and more expensive system with more potential for greater designs and biodiversity.

Living Green in Airports

Green Team at Green Roof Technology, - Wednesday, April 10, 2013

Incheon International, Seoul

Photo: penny_7b /Flickr


Seoul's massive airport is a popular destination for connecting fliers headed to other parts of East Asia from the Americas and Europe. Thanks to its comfortable transit seating areas, expansive duty-free shopping mall and airy main terminal, Incheon earned the highest overall score on the 2012 Skytrax customer satisfaction survey. Incheon also is one of the world's most family-friendly airports. Not only does it have a children's play area, but also childcare lounges and nursing rooms. Older kids might enjoy spending some pent-up energy at the Ice Forest, a large skating rink in the airside terminal.  
 
Other bonuses: This is one of the few airports in the world where you can get free access to a computer and Wi-Fi. Incheon has an impressive seven gardens in the passenger terminal and one in the transportation center. Finally, a free cultural center features exhibits on Korean culture and traditional dance and folk music performances.

Photo: penny_7b /Flickr

10 airports where you'll welcome a layover at mnn.com

New Optigrün Edging System Type SKL for Extensive Green Roofs

Green Team at Green Roof Technology, - Thursday, March 28, 2013

Optigrün International AG (1-800-627-4955) recently released a completely redesigned green roof edging system.  Created from 3.5 mm recycled ABS (with UV stabilizers of course), the new edging system uses hinge and click connections.  The 3-point connection system is quick and makes laying perfectly straight edges a breeze.  

The Type SKL edging system is available in 8 cm & 12 cm heights.  The edging system consists of two types of pieces, 1100 cm lengths and 300 cm corners.

The versatile and easy to ship system can be designed for numerous applications such as separations, terminations & drainage channels. For more information and purchase opurtunities in North America please contact us at Green Roof Technology.

Ideal for roof slopes up to 5°.

Picture: Optigrün / Green Roof Technology


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