Senior project written by Riess Stanley
Nov 4, 2010
With economic strife on the rise, it has now become necessary to seek out ways to save money, as well as to find ways to “stay green”, and to do what you can to help the environment. Unfortunately, accomplishing both at the same time seems to be very difficult. Believe it or not, there is a smart, fairly simple, and very efficient way to succeed in these two areas in a way not often looked upon as a money saver, but rather a necessary and costly project when it doesn’t need to be; the roof. When you really get down to it, the roof is either costing too much, or saving plenty.
First off, if a building with a flat or low-sloped pitch was to have a black tar roof, it would be taking more money than one would realize. In warm weather, the black roof will absorb so much heat that an abundance of energy and money would need to be invested into cooling down the building. Moreover, all that heat beating down on the roof will make it crack, which in turn will cause it to leak once the rainy weather begins. This defeats the entire purpose of a roof. So, what is a low cost alternative for a black tar roof, that can keep the roof cool during summer months and can keep out the rain? The answer; PVC (Polyvinyl Chloride) single-ply membrane. Read the rest of this entry »
The term “green” has become very popular during the last decade and consequently overused, misused and abused. Anything and everything can be called “green” today. To make money and to attract environmentally-conscious customers, people will call themselves and their products “green”, even when it is just a blatant lie to confuse uneducated consumers. Being a roofing contractor, I will concentrate on roofing products and services. For example, many asphalt shingles manufacturers now offer “cool” and “green” shingle products – to me it’s just a shameless tactic to sell the same NOT-GREEN crap that is painted A different color (usually some shade of white). Excuse me, but asphalts shingles are not green, period! TheY are made with asphalt, can’t be recycled and end up in landfills in 10-15 years.
Since the term green is very vague and can be interpreted in many ways, I’ll offer my vision of “green” – a green roofing contractor to be exact, which describes the way I think and try to operate our roofing business. I want to mention that when I say “green roofing contractor”, it has nothing to do with with a roofing contractor installing green roofs or roof-top gardens. To me a contractor installing roof-top vegetation is a highly-specialized landscaping company, but not a roofing contractor (unless they also install the actual flat roofing membrane to waterproof the building).
In my mind a green roofing contractor is a company that works hard to help protect environment and reduce its energy consumption and green-house gas production or carbon footprint. Sure, almost any company will have a carbon-footprint as it’s nearly impossible to be carbon-neutral, but there are many ways to achieve a much lower carbon footprint. Read the rest of this entry »
From Editor: – this post has 40+ VERY interesting comments from “both sides of the isle” so to speak. We highly recommend you read these comments, after the post.
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If you are a building owner, facility mananger or even a home owner with a flat roof that leaks, and you are interested in or got a bid from a roofing contractor to install a new flat roofing system called TPO (Thermo-plastic olefin), this is a must-read article for you, because you will not find this information anywhere else.
Forewords: TPO is a hot-air welded thermo-plastic single-ply roofing membrane produced by numerous manufacturers. TPO was created to be better than EPDM Rubber roofing and cheaper than PVC roofs, while it would still provide all the benefits of hot-air welded seams. It was a good plan, and now TPO membrane covers billions of square feet of roofs and represents a multi-billion dollar roofing market, but there are some problems…
In it’s fairly short life (about 15-16 years) TPO went through at least 2 generations. 1st generation of TPO roofs began to fail in the late 1990′s and early 2000′s. Now, some manufacturers are on their 3rd generation (or major reformulation) of their TPO products. At the same time, TPO’s main rival – PVC roofing membrane such as IB Flat Roof, has not changed its formula in over 30 years. Read the rest of this entry »
Do you know how your electricity is generated? For a long time I kind of knew, but was too lazy to actually ask my father, who is a physicist, what exactly is going on in the power plant. Now it boggles me to live with the fact that in our modern time when an all-inclusive communication and Internet device (iPhone, BlackBerry, etc.) is smaller than a deck of cards, we still use 19th century technology and basic principles to generate our electricity. Once you actually give this idea a thought, it becomes a shocking notion that our best minds have not been able to create a better way to create electrical power than to burn coal and natural gas – two most commonly used sources of energy to create electricity.
Just in case you were wandering, coal or gas is BURNED to heat up water which then becomes hot steam and drives the turbines. This is a basic principle and the actual process is more complicated, but even the “sophisticated” nuclear power plants work in similar manner.
Note: I did know that electricity can be generated in the old fashioned way, but I actually thought that there was some kind of a mechanism to directly convert energy stored in gas / coal / oil directly “into” electricity, instead of emulating the old steam-engine – oops… It is a shame that our 21st century society is still burning fossil fuels to make the turbine spin.
Aside from the fact that we get our electricity the same way as before WW I, natural gas, oil and especially coal are extremely dirty fuels, emitting dangerous pollutants, which affect our environment in such a drastic way that just a couple of generations from today, our children may not be able to enjoy the outdoors the same way we can today. I won’t even start talking about climate change and global warming. On top of everything mentioned above, humanity is quickly approaching a world-wide energy crisis. Our oil reserves are getting depleted, and if you believe in “Peak Oil” theory, we are about to approach the peak of the curve, which means that oil will continue to become more scarce and prices will keep on rising.
Although coal is very abundant, it is also becoming more expensive to mine, and delivery once again involves burning petroleum based fuels, creating more and more pollution. It is obvious to most intelligent people (except those heavily invested in oil, coal, cars, etc.) that we need a clean, renewable source of energy. Despite what may seem like rhetoric about renewables, I do honestly believe that this is the way we will power our world. However, the renewable energy must be affordable and/or competitive with current sources of energy.
So what is the answer – what is a modern and clean way to generate electricity? Well, there are a few, and the most popular ones are Wind and Solar. My personal favorite is Solar and here is why.
Wind Turbines require lots of open space and lots of (you guessed it) wind to work effectively. Although wind is a great source of renewable energy, and unlike solar can work at night, it is not “customizable” or adaptable for the urban environment. There is just not enough space or wind in the city.
Solar on the other hand works just as well in city as in the country side. All you need is southern exposure with no or minimal shading. Solar can be installed on a roof of a sky-scraper, on the ground or even on a roof of a car. Solar is also a scalable system, and you can add or remove PV panels and/or inverters at any time. The bottom line is that solar photo-voltaic power generation is much more practical, and can be implemented where that power is needed. Besides that, both ways of getting “free” electric power from renewable sources are great. Given the notion that solar is more practical and flexible, lets get to the solar PV systems design and implementation.
Getting solar for your home or business.
Despite all the positive aspects of solar, it is expensive – VERY expensive. Additionally, not every site is suitable for a solar system installation. Therefore, if and when you decide to get into solar, the system must be designed and installed to operate at maximum efficiency, to offset its high costs and speed up the pay-off time.
Step 1: Gathering information about a perspective site for the solar project, and how much solar electricity you will need.
As mentioned before, the first step in determining if a solar system should be installed, a basic site survey must be perfored. Sinse most solar PV systems are installed on roof tops, the basic requirements for a site survey ar as follows:
The roof plane where the solar system would be installed must have a southern exposure with some variations to the east and west. You can figure this out with a simple compas.
There should be no shading from trees and surrounding buildings and structures to achieve the highest sun light exposure. This gets tricky, as the sun has a different angle to the earth during winter and summer months. Thus, even in the winter, when the sun is at its lowest point, solar panels should have unobstructed exposure to it. The best way to determine where your shading is throughout the year is to use a special tool called “pathfinder”
Cool Roofs provide financial and environmental benefits and long-lasting protection from the weather.
Roofing represents only 3% of construction costs. Yet, many builders, architects / specifiers, roofing contractors and even home / building owners look to reduce their total construction and/or renovation costs, and all to often they find these savings in roofing. This cost cutting comes not only at the expense of installation quality, but also with the use of inefficient roofing materials. Two most common roofing choices are asphalt shingle for pitched roofs and Epdm ‘rubber’ for flat roofs. The former is made directly from oil, and the latter is made with oil by-products and other chemicals.
Are Cool Roofs for everyone?
In theory, every roof should be cool. If that was the case, our nation would greatly decrease its energy dependence and consumption. We would also improve our environment and air quality, and less electricity would be required to cool our homes and buildings. Bear in mind that over 50% of our electricity comes from coal-burning power plants and coal is the dirtiest source of energy, and pollutes air with, sulfur, lead, arsenic, CO2 and other harmful substances and green house gases.
However, many people would argue that cool roofs are only for Sun-belt states, and that black roofs are better for northern states. This is completely wrong. Lets review the differences of Cool (white) roofs and black roofs in terms of energy savings and heat gain in the summer vs. heat loss in the winter.
First of all, let me state a notion that in the winter, the heat does not escape the building (unless you open your windows), but rather the cold enters the building and lowers the inside temperature. With that notion in mind, lets compare the energy cost advantage of a black roof in the winter and a white roof in the summer.
Energy Costs Calculation.
Heat gain through the roofing surface: As you can see from the chart above, on an 85 degree F day, IB cool white roof will only gain 6 degrees or about 8%, whereas a black surface roof such as a rubber roof or rolled asphalt or tar roof will gain 87 degrees (!) or more than double in temperature to a total of 172 F. If you get down on your knees, you will actually get skin burns. Imagine all this heat entering inside your home or place of business…
For comparison purposes we will use a White IB PVC roof and a regular Epdm black rubber roof. We will use DOE Cool Roof Calculator and with following parameters:
Gas will be used as a source of heat, but since gas rates differ from city to city, we will convert the BTU value of 1 gallon of oil to that of 1 therm of natural gas. The oil price used in this comparison is $2.39 per gallon which is the average here in Massachusetts for oil customers with delivery contract as of January 8, 2009. Please note that the price of 1 barrel of Oil today is $41.89.
Insulation R-Value: 6, 13 and 20 (6 is the average for existing residential building where we replace a flat roof)
Solar Reflectance: 85 for IB Roof and 6 for Black EPDM. Although IB’s reflectance is 87% the calculator will not let us use more than 85, and since with dust accumulation on the roof reflectance drops, it is safe to use this number.
Infrared (thermal) Emittance: 88 for IB Roof and 86 for Black EPDM.
Scenario 1 – Boston, MA.
Cost of electricity in the Metro Boston area is approximately $0.22 per kWh. The cost of heating the building we get by multiplying price of 1 gallon of oil by 0.71 = price of “1 therm of heating oil” – $1.70 / therm. Note that this is not the price of one therm of natural gas, but rather a BTU conversion from oil to natural gas. I use oil as it is the most common source of heat in the north east and New England in particular.
Scenario 2 – Los Angeles, CA.
I will assume the energy price in CA, as I do not live there. For electricity rates I will use 30 cents per kWh. This assumes peak rate (when most people actually use their air-conditioners) and all the surcharges, delivery charges, etc. This is the total cost per kWh.
Since gas prices in CA right now are jus a bit higher as compared to Mass. we will use $1.80 as the price of therm of heating oil. Bear in mind that in California, they rarely use heating and it is mostly natural gas or electricity or propane for remote homes.
Other calculation metrics:
AC efficiency: We use an average of 2.0
Heating System efficiency: We use an average of 0.7 or 70%. My brand new Burnham closed loop hot-water radiator system is 86% efficient. The older heating system it replaced was about 50% efficient if not less. Also note that this is the burner efficiency and not the total system efficiency. Total system efficiency is greatly dependent on how well your house is insulated, the type of windows you have and the type of heat delivery you use: radiant, air ducts, steam or copper pipes with hot water circulating through the system.
Results – Net Savings per 1 square foot of flat roof area per year: Boston:
With 6-r insulation Net saving is $0.079 or almost 8 cents.
With 13-r insulation Net saving is $0.037 or almost 4 cents.
With 20-r insulation Net saving is $0.023 or almost 2.5 cents.
With 6-r insulation Net saving is $0.217 or almost 22 cents.
With 13-r insulation Net saving is $0.1 or 10 cents.
With 20-r insulation Net saving is $0.062 or almost 6.5 cents.
Let us now assume that you home is 2000 sq. ft. and has 6-r insulation value of the roof. In Boston, MA you would save $160 per year in electricity alone if you replaced your existing black roof, such as epdm rubber or tar & gravel, with a cool IB roof. Also add a leak free performance of IB roofs, no more roof repairs and other costs associated with roof leaks. In Los Angeles you would save $440 each year! Also add the Energy Star tax credit for cool roof installation of $500. This is an actual tax rebate, and it equals to an average of $1800 worth of tax deductions. In conclusion, I’d say that Cool roofs are much more efficient in the southern states where there is a lot more sunshine and almost no snow. But even here in New England, a cool roof is a very attractive choice for people who are looking to get long term savings, lifetime leak free performance and/or are worried about the environment.
Cool roofs vs. Black roofs:
While asphalt shingle is the ‘de-facto champion’ of sloped roofing with its VERY low cost and severe price competition in both residential and commercial markets, when it comes to flat roofing, there are more choices. Old-timers will recommend a 3 to 5 ply Built-Up roof or a two-ply Modified Bitumen. With the abundance of these and other tar and asphalt roofs still in service, and some new roofs being installed (although each year there are fewer BUR, asphalt and bitumen roofs being installed, as the flat roofing industry is quickly transitioning toward single-ply roofing membranes), all of these roofs are destined to end up in our land-fills, as recycling programs for asphalt-based roofs are virtually non-existent. That is millions of tons and billions of square feet of oil waste are going into the ground each year.
Another problem associated with the above-mentioned roofing materials is their color – most are black, which attracts and transfers tremendous amounts of solar heat into the building or a house. As a result, the air-conditioning system must work over-time to maintain a comfortable working and living environment. This causes overloads and power outages on electrical grids, increased cost of electricity, and as a result – higher electric bills.
To offset the above-mentioned high cost of electricity, many people choose to install a Solar PV roof system. This is especially true in California where $0.35 – 0.40 per kWh of electricity is a normal residential rate. We wholeheartedly support nation-wide deployment of small and large scale solar photo-voltaic systems, but the first step, which many people should take before installing solar systems, is to reduce their average energy consumption. This is where Cool Roofs come in very handy.
Financial Benefits of Cool Roofs:
1 – Energy savings of Cool Roofs
Cool roofs provide tremendous reduction in cooling cost by reflecting 85-90% of solar heat and keeping your residence or place of work cooler in the summer. This directly reduces your electricity costs. This also puts less strain on your HVAC equipment, which leads to less maintenance, reduced repair costs and longer life for the Air Conditioning units.
2 – Cool Roofs last longer and leak less than black roofs.
Cool Roofs generally outlast their counterparts by 50-100% and require much less maintenance and repairs than Rubber roofs, modified bitumen and tar / asphalt roofing systems.
For a flat roofing market, the two major players are PVC and TPO membranes. These are single-ply, thermoplastic roofs which are hot-air welded together to provide decades of leaks-free services. There are also acrylic and urethane cool roof coatings which make existing black roofs cooler and increase their service life by 5-15 years.
Note: PVC and American-made TPO roofs are fundamentally different in terms of their chemical formulation and life expectancy, but both are considered cool roofs and Ideally should last 20+ years.Learn more about the difference between PVC and TPO roofing.
While 40 years ago there was no real alternative to asphalt-based roofing materials in the US market, for over 30 years we had cool roofs that are energy efficient, light weight and provide long-lasting protection with much flexibility to accommodate for any obstacle present on the roof. PVC Roofs were the first real cool roofs to hit the US commercial roofing market. Some US manufacturers of early PVC membranes (most notoriously Trocal) had problems with their product, such as membrane shattering in extremely cold temperatures. The problem was due to the membrane being non-reinforced with nylon scrim. All major PVC (and TPO) membranes on the market today feature reinforcing scrim.
IB PVC / CPA roofing feature a true Non-wicking scrim, which prevents the capilary water penetration between the two layers of the membrane. This is only one of many benefits of IB PVC Roofing which sets it apart from all other flat roofing systems.
3 – Cool Metal Roofs.
Residential metal roofing
For large commercial / industrial applications, there is structural metal roofing, usually found on space metal buildings, aluminum reflective coatings, etc. Although these do not meet Cool Roof requirements, they still are more energy efficient than black rubber and asphalt-based roofs.
For residential and some commercial / retail / restaurant applications there are various styles of Architectural Metal Roofing. Usually coated with Kynar / Hylar high-performance coatings (paint) these roofs carry a Cool roof lable and also greatly increase the energy efficiency of you entire home or building.
Even without a Kynar coating, metal roofs are always “cooler” than asphalt shingles. Since metals (especially aluminum) have a much lower thermal mass, they do not store the heat, and cool off much faster than any asphalt based roof.
The biggest financial benefit of metal roofing is its longevity. Most metal roofs carry a lifetime warranty – usually 50 years is considered lifetime. Most metal roofs will outlast their warranty, and many are known to last more than 100 years. As we always mention to our customers, the roof is only as good as its installer. An improperly installed metal roof may leak after the first heavy rain. This does not change the fact that a metal roof is the true life time product when installed properly.
Environmental benefits of Cool Roofs:
IB Roofs as well as other Cool Roofing systems provide enormouse benefits to the environment. From reduced CO2 polutions to reduction of roofing material waste going into our landfills, the whole chain of benefits is too complicated to fit into a general theme of this article. Therefore, I will only list the basic environmental benefits here, and in the future will dedicate an entire article to just this one topic.
General benefits to the environment: Again, I’ll use IB Pvc roof as the example, but most other cool roofs will “fit the bill”.
As a side note, I’ll mention that USA makes up about 5% of world’s population, yet we consume 25% of the world’s energy. It is also estimated that 30% of US energy consumption is just wasted. Therefore, we (Americans) waste 7.5 percent of the worlds entire energy. And we wonder why gasoline / oil / electricity is so expensive….
PVC roofs last an average of 2 times longer than other flat roofing systems. PVC is extremely durable & versitile – therefore rarely needs replacement. When you hear that PVC is not recycled bear in mind that most Pvc-based products are still in service.
PVC roofs are 99% recyclable and will find use in other application after they complete their life-cycle. PVC rarely ends up in our landfills, as it is cheaper to recycle it than to dispose of it. You will usually see it at landfills as a water-proofing liner that will prevent toxins and polutants from enetering the ground under large piles of junk and waste.
Although PVC roofs use fossil fuel as one of its basic components (natural gas – methane, to be exact), the also use chlorine as the 2nd major component – therefore PVC contains 50 less of fossil fuels than other plastics (such as TPO roofs) and do not use and carbon / oil-based products in it. Therefore PVC is not directly dependent on foreign oil supply, unlike Epdm / Modified Bitumen / Asphalt / Other Thermoplasics and oil-based products.
Cool roof properties of PVC (and other cool roofing systems) reduce electricity usage of many commercial / industrial / residential buildings year after year. As a result, less pollution is emmited into the atmosphere. In fact, if all roofs in the US were cool, we would reduce our nation’s energy use by an average 10% which is now just wasted!
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Cool Flat Roof - IB PVC flat roofs and Metal Roofing installation in Massachusetts Tel: 617-444-9020 - 19 Englewood Ave., Brookline, MA 02445 - Massachusetts Construction Licenses: MA HIC# 159364. MA CSL# 094373. Some roof installation work may be undertaken by our independent partners, who are also licensed and certified to install IB Roof Systems, and Metal Roofs in Massachusetts, Connecticut and Rhode Island.
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