Martin Grohman, Director of Sustainability

Hi I'm Marty Grohman,  GAF's Director of Sustainability.  I look forward to your comments and collaboration as I discuss items of interest in the sustainability field.


What's a Heating Degree Day?

Whenever the subject of cool roofing or energy savings comes up, the next topic is usually Heating or Cooling Degree Days, and there seems to be a lot of confusion about what these mean.  It’s tempting to think that a Heating Degree Day is a day on which you need to turn on the heat, and a Cooling Degree Day is a day on which you need to turn on the air conditioning, but that is not the case.

So let me dive right in:  a heating degree day is a way of summarizing the annual heating (or cooling, in the case of Cooling Degree Days) requirements in a particular climate.  This is a complex sounding concept that is actually quite simple.  On a heating degree day (HDD), the temperature falls below a standard “comfortable” temperature (usually 65° F) so a building or home needs to be heated to maintain the target temperature; and a cooling degree day is one where the temperature is above that target, requiring cooling.  Turning climate data into a heating degree day or cooling degree day is a matter of simple math.  If the average temperature on a given day is 80°F, the building needs to be cooled 15°F to reach the target 65°F.  That day would be counted as 15 cooling degree days (CDD). 

Another example: consider a typical New York City winter day with high of 40°F and low of 30°F, for an average temperature of 35°F.  This one day would generate 65 - 35 = 30 Heating Degree Days.  A month of similar days would accumulate 900 Heating Degree Days, which gives you an idea how HDD can be added over periods of time to provide a rough estimate of seasonal heating requirements. In the course of a heating season, for example, the number of HDD for New York City is 5,050 whereas that for Barrow, Alaska is 19,990.  Barrow doesn’t have any more days in the year, it just has lower average temperatures!

Average daily temperatures tend to vary farther to the low side, particularly overnight.  Because of this effect, it is common even for warmer climates to have more HDD than CDD.  Some would argue that in any climate where HDD exceeds CDD, a cool roof does not make sense, but that is not correct.  That’s because building occupants and services generate internal heat, and with conventional equipment, cooling is generally more expensive than heating.

There are a number of online resources where you can find heating and cooling degree data for climate stations around the country.  Or, you can just log into the free GAF Cool Roof Energy Savings Tool (“CREST”), which taps into HDD and CDD data for you automatically and helps you compare roofing assemblies to better determine what is right for your project.   

Does this topic of HDDs and CDDs generate questions in your business?  I’d love to hear – post in the comments below.

Follow us on Twitter @gafroofing or visit Green Roof Central


Is a Ventless Clothes Dryer a Reality?

Ventless Clothes Dryer?

Clothes dryers use an intense amount of energy.  In fact, dryers use about 6% of all US electricity and  that number hasn’t been improving.

Plus, living here in the cold northeast like I do, it sure seems a shame to vent all that heated air outside, as conventional dryers do.  Regular readers of my blog will remember that I made a dryer vent box which we only attach in the winter.  It captures the heat (and the moisture) and uses it to warm the house.  However, it becomes more of a lint-blowing steam engine than anything, and I am sure you will be shocked to hear that it is not very popular with my very patient wife (who gets to put up with a lot of my sustainability-related projects).

However, there is a relatively new technology called a condensing dryer (sometimes called a ventless dryer) which has become common in Europe and is becoming more available here in the States.  It is based on a traditional heat pump, and does not require an external vent – the warmed air is kept in the house, and the water is collected in a tank. 

I’ll admit I was a little apprehensive about buying this dryer, because it is not cheap, and it is kind of small - about 2/3 the external size of a regular dryer (although the capacity is the same).  However, it is more efficient than a conventional dryer, using about half the electricity to do the same amount of drying.  Plus, you get to keep the heat in the house.  My wife has sent my heat capturing contraption to the recycle bin. 

As usual with my appliance purchases, I bought mine at The Home Depot, and as usual it was a positive experience.  You pick a delivery date on the calendar when you know you can be around, and they come in with the new equipment, and take the old one away (if you like).  Here’s a picture:

So what’s the verdict?  Everyone in the family loves this thing!  It puts out a mild steady heat at floor level while it’s working, so even the dog, who has figured out it is good to lie in front of, is a fan.  It does take about twice as long as a conventional dryer to complete a cycle, but it’s also much gentler on the clothes.  About every other load of clothes you empty the water receiving tub (or you can even pipe it to your washer drain so you never have to empty it).  And at least temporarily, I’m back in the good graces of my wife!! 

Anyone else using a ventless dryer, or any other new appliance ideas we can try? 


The US Green Building Council’s Greenbuild show

The GAF booth was really buzzing with activity this year!  In fact, our presence at Greenbuild has grown every year, as it has become increasingly strategic for us to reach the green building marketplace and this year was no exception.  To top it off, we recently became one of very few manufacturers (and perhaps the only roofing manufacturer) to be USGBC Platinum members. 

The theme of our booth this year was ‘RUv4 Ready’, which emphasized all that we have done to be ready for LEED® version 4 (commonly known as LEED v4).  It’s all about transparency: what is the content of the materials that are selected, and what are their energy and environmental impacts on the building over its lifespan.  To emphasize our readiness for LEED version 4, we published three Health Product Declarations (HPD’s) which are an extended listing of material ingredients for our EverGuard® and EverGuard Extreme® TPO, as well as our EnergyGuard® PolyIso insulation. Plus, we prepared Environmental Product Declarations (EPD’s) for EverGuard® and EverGuard Extreme® TPO.  So if you’re building a v4 project, GAF is ‘v4 ready’, and all of these documents can be found on Greenwizard. 

LEED v4 is all about the future of the building industry.  To emphasize that future, we also featured noted architect Wayne Visbeen in our booth.  Wayne's firm is the winner of 11 American Institute of Building Design awards in 2012 alone. Wayne knows how to communicate with architects at all levels of experience, but at this show he took the extra time to talk to architecture students about how to successfully transition from school to their professional careers.  Since we are all still learning about green building, this message was particularly powerful.   

To top it all off, we featured a presentation by Alex Wilson, president of the Resilient Design Institute and cofounder of Building Green.  Resilient design emphasizes a building’s readiness to withstand heavy storm activity and provide shelter for human occupants while the grid is down, such as during Superstorm Sandy.  Alex’s appearance drew a crowd and created great buzz through the show floor! 

Did you attend Greenbuild?  What were some highlights for you at the show?  What should we be thinking about for next year’s show in New Orleans?


Household Hazardous Waste Day

As a member of my town’s Solid Waste Commission, I recently volunteered at Household Hazardous Waste Day.   This is a very important chance to bring in material that should not be thrown in the trash, such as oil based paint, old fuel, insect killers, expired lawn treatments, etc.  I was very impressed at the level of participation.  The volume of material that arrived – cars were lined up for more than 2 miles – was simply amazing.  My job was to unload the material from the resident’s cars, and after a full morning of unloading trunks, my back was pretty sore! 

A common item that many people have to dispose of is old paint.  If handled properly, latex paint is not actually a hazardous waste (oil paints and thinners still are).  I took this picture of latex paint cans done right – opened and left to air dry, and if there is a significant amount of paint to absorb, kitty litter added as an absorbent.  This renders the material non-hazardous and it can be disposed of in the normal trash.  So actually, this person did not need to bring these cans of latex paint in to this event (although we did accept them and gave the resident an attaboy for handling the material correctly). 

It should also be noted that the American Coatings Association has set up a great program called PaintCare, which will soon begin accepting used paint for recycling in some states.  Also, it is perfectly reasonable to mix the unused paints together, stir them up, see what color you get (usually some kind of beige in my experience), and use the resulting mix in an unobtrusive area.  In fact, professional painters do this all the time even with paints of the same color (they call it ‘boxing’ paint), to eliminate variation between cans.

Does your town have a HHW Day coming up?  A quick tip: don’t put anything in the trunk that you don’t want gone, because with a long line, unloaders are in a hurry.  Everything in your trunk is going to get unloaded, whether you want it to or not!  And if you bring in old fuel, be sure to specify if you want your gas can back.  As always, if you need to recycle asphalt shingles (non-hazardous by the way), find a recycler at!


GAF Participates in Cutting Edge Green Building Forum

Every day the construction industry becomes more aware of the crucial role we play in addressing growing concerns property owners have about energy and water supplies, carbon emissions, and even climate change. As a leader in the industry, it is important that GAF keeps ahead of the trends in this market and is able to react quickly.

One of the most interesting ways we have been doing that is by participating in Vision 2020, a forum for the review of the future trends of residential and commercial building, with a particular eye on environmental trends.  Throughout the year the GAF sustainability department has had the opportunity to convene with some of the most-trusted and sought after thought leaders in sustainability, and dig deeper into their research, thoughts, projects, and projections.  We’ve worked with people like Tom Lent of the Health Product Collaborative, Dennis Creech of Southface Institute, and Paula Kehoe of San Francisco Public Utilities Commission, getting the chance to collect their insights on trends like transparency, solar design, and rainwater catchment that will likely shape our industry for years to come.  Through this interaction we’ve been able to collect perspectives from around the industry and around the world that will help shape the building products and practices of the future.  This forum also lets GAF share our views and make sure the things that are important to us are part of the discussion We want the contractors who have built their businesses around us to know that we are thinking ahead, and that we are helping our company and the property owners who buy our products to be “futureproof”.  

What emerging trends in green building are you seeing – and not just in the USA – that you feel readers of my blog should know about?