A Fistful of Pencils – Measuring Solar Radiation on a Building

Lucas Hamilton

Earlier this week during a webinar I conducted on working with solar radiation, I gave an example to help people visual how the energy of solar radiation strikes a building or object. 

In physics and mathematics we would picture this energy as a vector component. I know that is not clear to a majority of non-science or non-mathematics practitioners so I often use an example with a fistful of pencils to help people visualize exactly what this means.  This is a fun little exercise but is not meant to be a scientific determination of the impact of solar radiation on a surface. This is simply a way to visualize the invisible.

Imagine the sunlight or energy coming across space and beating down on the surface of the roof at a normal angle which is a mathematical term for a 90-degree or right angle. To understand the impact of the solar radiation on that roof, take a piece of paper and draw a 1-inch square. Take a fistful of pencils (as many as will fit comfortably in your hand) making sure all the tips are even and bring your fist straight down on the paper striking it within the square.  Then count the number of strikes within that box and if you imagine each one of those strikes as being a unit of energy it gives you some idea of the impact of solar radiation on your roof.

If you want to imagine how that same sunlight is striking your wall, picture the angle that your wall is from that sun – usually about a 45-degree angle give or take.  Take the pencils in your hand and while sliding them to keep them flat to the paper turn your hand to a  45-degree angle and strike them into a 1-inch square box, you can see the number of strikes and what that impact would be significantly less. So if you again imagine that the pencil points are units of energy, you can see that only a fraction of the energy hits your wall compared to the roof.

This can be done with any angle and it gives you a very general idea of the solar energy impact on a surface.  While this does not give you scientific data to help you determine where your peak power would occur, it is one method that can be used to help visualize the best angle for solar panels on a roof. 

There are some online tools that can help calculate the intensity of the solar radiation based on geographic location. One example of such a tool can be found at: http://www.kahl.net/solarch/.

Lucas Hamilton is Manager, Building Science Applications for CertainTeed Corporation

Embodied Energy Versus Operational Energy

Lucas Hamilton

Recently during a webinar I was conducting, the topic came up of embodied energy versus operational energy.  This topic continues to come up as building scientists evaluate systems with regard to their sustainability.

There are two things that can make a product green. It can be green in its manufacture or it can be green in its application.  One of the important topics for understanding the manufacture or delivery of a product is the concept of embodied energy – how much cumulative energy went into the extraction of the raw materials, the manufacture of the product and the transportation of the product to its final application.  This is the concept of embodied energy. Operational energy relates to how much energy the product uses or can save once it has been applied or installed into a system. 

For instance, look at insulation. Many types of insulation are actually very energy intensive in their manufacture, however once they are installed they can save many times over within the very first year of their application. A perfect example of operational energy is fiberglass insulation. In its first year of use, fiberglass insulation can save 12 times the amount of energy it took in making and transporting the product.

So let’s not throw out the baby with the bath water. Sometimes, material that is superior in performance with regard to the life cycle of a building may have a little bit of negative upfront energy costs, however in its use can be very positive. 

So don’t make a judgment solely based on the embodied energy but rather on the life cycle of the project to determine if it is positive or negative for the project itself.

Lucas Hamilton is Manager, Building Science Applications for CertainTeed Corporation

The Accountability in Sustainability

Lucas Hamilton

CertainTeed recently released its first Corporate Sustainability Report.  What people don’t realize is that behind these efforts to produce and publish Sustainability Reports you have to do a great deal of homework. Some of that homework can include life cycle assessments (LCA) for products. LCA’s are similar to creating a personal inventory as you might do when facing a life event. You come up with a large amount of information that needs to be evaluated and acted upon, but if it is not acted on you are living in denial. Having these LCA’s provides companies with data that can be viewed in many different and valuable ways. LCA’s capture the holistic impact of a product from the energy involved in the extraction of the raw materials, to the manufacturing, to the transportation, to the installation, to the impact it will have on the building and the disposal or recycling after its useful life.

LCA’s represent a new way of evaluating building materials and building techniques which is why this is part of building knowledge. As we go forward, all building professionals will need to be conversant in LCA language and understand how to evaluate an LCA which will help you  compare things you couldn’t compare before.

For example, take a brick masonry wall, it is so basic, the materials are so earthy. It lasts so long that it must be a very green structure.  But when you do an LCA on the brick masonry cladding and compare it to a material that people traditionally view as un-green, like vinyl siding, you find that the vinyl siding actually has lower impacts and is more green than brick.

By using data from the LCA’s you can actually evaluate products and apply a metric to each life cycle phase rather than going on gut feeling. You can choose to accept or deny the results but the fact is it is a real metric.  The problem is that LCA’s are complex which makes them difficult to perform and requires users of the data to be educated on how to use an LCA to understand life cycle impacts of products and materials.

To address this, the U.S Government has started a program that hopes to make these LCA’s more accessible so consumers can use them to select building materials. It’s called BEES (Building for Environmental and Economic Sustainability). This BEES program will publish the LCA’s so consumers can compare brick masonry verses vinyl verses stucco verses natural wood – you can actually make a comparison about everything that goes into the creation of these materials.

I have talked about labeling in a previous blog with regard to energy efficiency of buildings.  Labels essentially provide transparency and lead to better informed purchasing decisions. LCA’s do the same for building materials, not just for energy-efficiency, but for a variety of sustainability factors.

I see the publication of LCA’s in BEES as a way of allowing consumers and professionals in the building industry to evaluate things on a level playing field based on a set metric that is definable, quantifiable and repeatable.

Lucas Hamilton is Manager, Building Science Applications for CertainTeed Corporation

Reshaping the Built Environment Passively

Stan Gatland

The Passive House concept gained a great deal of traction over the past year and the 2010 Passive House Conference, which was held in Portland, Oregon in November, was proof of the growth and interest.  The attendance grew from 250 last year to 350 this year.

It is clear from the growth of the conference that building professionals in the U.S. and Canada are beginning to gravitate to the Passive House Standard. The primary goal of Passive House technology is to reduce your heating and cooling load so that very little energy is needed to maintain comfort.

The people who came by the CertainTeed booth were much more knowledgeable about passive house technologies and had practical experience with regard to designing and constructing passive homes in all parts of the U.S.  That was a significant change from previous years.

CertainTeed remains the only large building materials manufacturer sponsoring the Passive House Conference. The Passive House Institute has created a Passive House Alliance which will work closely with the Institute to promote Passive House building energy efficiency standards and construction in the U.S.  A grassroots effort like this could have significant impact on adopting standards that truly support energy efficient building.

Attendees were very interested in Saint-Gobain’s Isover Multi-Comfort House strategy. This passive house concept has been very successful in Europe. There were several colleges and universities at the conference and we took this opportunity to talk with them about the Multi Comfort House Student Competition which invites teams of architecture and engineering students from around the world to compete in a passive design competition.  Philadelphia University has participated in the past and the hope is that  other U.S. colleges and universities will consider participating in the 2011 competition.  

It was good to talk with designers who are using CertainTeed Optima® insulation with our Membrain™  smart vapor retarder in very deep cavities using TJI joists to achieve the insulation levels needed to meet Passive House standards. We have conducted hygrothermal analysis to assist designers who are using this system.

One of the notable speakers this year was Dr. Robert Hastings, architect and energy consultant from Austria who gave his perspective on this trend.  Dr. Hastings has been involved internationally in sustainable building and solar energy since the 1970’s when the first wave of concern regarding energy consumption hit the mainstream. Unfortunately, the progress that was made in the 70’s was quickly abandoned once oil became readily available again. 

Let’s hope that this groundswell will not be abandoned as in the past. As a nation, we need to continue to move toward energy independence.

Stan Gatland is Manager, Building Science Technology for CertainTeed Corporation

Even Professionals Can Miss the Obvious

Lucas Hamilton

It is true that even someone who is entrenched in Building Science and sustainability can be caught off guard when evaluating home situations.

We recently had to replace our hot water heater at home. Here was a combustion appliance right in front of my face a few times a week and I didn’t realize how badly it had been operating.  I suspected that when the dryer was running it was back drafting the hot water heater adjacent to it.  This is fairly common in basements because dryers are so powerful they can depressurize the space and pull the air back down the chimney.  I wasn’t really concerned because it was in the basement which is not very air tight since it dates back to the 1880’s.

However, when installing the new hot water heater I discovered that it wasn’t drafting properly even when the adjacent clothes dryer was not running.  The problem was much bigger than I thought. We had to move to a power vented water heater which includes a fan on top of the appliance so when the hot water heater fires up, rather than letting the buoyancy of the warm combustion gases rise up the chimney, they get sent through a fan and powered out the wall away from the house. I had become blind to the situation because it was something I saw almost every day.

Whenever I would go down the basement, I could smell the gases but I just got used to it.  We weren’t experiencing any ill effects from it, thankfully.  But it was a potential tragedy waiting to happen either from the fumes or possible explosion and fire.

The moral of the story is even if you have been in construction your whole life, it’s good to get a fresh perspective from time to time. Pay a professional to inspect your heating and cooling systems (including hot water heaters)once a year.

Lucas Hamilton is Manager, Building Science Applications for CertainTeed Corporation

What is the Future of Solar Roof Technology? – Part 2

(Left to right) Rob Fleming; Dennis Wilde; Alain Garnier; Mark Stancroff; Jeff Wolfe

As I discussed in the previous Blog, CertainTeed hosted a luncheon and panel discussion at the 2010 Greenbuild Conference and Expo on The Future of Solar Roof Technology.

Jeff Wolfe, co-founder and CEO of groSolar, represented one of the largest installers of residential solar products in the U.S.  Jeff discussed the fact that the rate of adoption of solar in the U.S. is slow but there will come a time when integrated photovoltaics will be the standard.  

The first hurdle is integrating two elements: a roof and electricity. It’s hard enough to install a roof so it doesn’t leak. Now toss PV into the mix and the new assembly requires additional skills, tools, and knowledge. One key to successful applications going forward is to design integrated systems which simplify installation and maintenance.

The next challenge is the question of who are solar roof installers? Are they roofers, electricians, glazers (remember, some systems have a lot of glass in them)? And what department do you go to in City Hall to obtain the permits? Is it a roof or is it electrical? As a country, building codes and processes vary greatly from state to state and having to battle your way through the local building code department for each new application will dissuade roofers and consumers to take on this new technology.

Alain Garnier, Saint-Gobain Solar mentioned that the solar industry is growing by about 40 percent in other parts of the world.  That could be largely due to the energy costs.  Our “cheap energy” has been a hindrance to consumer demand in this arena. As an example; Europe is far ahead of the U.S. with regard to energy efficiency and passive house adoption largely because the economic case was clear.

The expediting of solar adoption in the U.S will most likely be determined by two things; first, energy rate increases that will cause pain to consumers and, two, federal and state incentives that encourage and reward consumers for taking a significant step toward more efficient buildings.

Lucas Hamilton

Lucas Hamilton is Manager, Building Science Applications for CertainTeed Corporation

Is there a Future for Renewable Energy?

Lucas Hamilton

An editorial appeared in the New York Times on October 27 entitled Remember Renewable Energy?, which discussed the slow moving progress by Congress (since jumping on board in 2005) with wind, solar and other projects focused on producing 10,000 megawatts by 2015.

It would appear that some of the talk about the White House needing to support alternative energy did not fall on deaf ears since the Interior Secretary Ken Salazar has approved several solar power projects in recent weeks.

This is good news because we need to step up our efforts to keep up with Europe and China who are already investing heavily in wind and solar manufacturing.

Three things are cited in the editorial that need to happen in order for the U.S. to catch up:

  • Generous subsidies or alternative funding for renewable energy projects so they can compete with fuels like coal, oil and natural gas.
  • Faster approvals by agencies such as Minerals Management Service.  Three to five years of negotiations is not acceptable.  As the editorial says, “The bureaucracy now has to deliver.”
  • The expanding and updating of the electrical grid to accommodate new energy sources is crucial to any success.  That will require partnerships and the giving up of control.

What are your thoughts on the future of renewable energy?

Lucas Hamilton is Manager, Building Science Applications for CertainTeed Corporation

Energy is a National Security Issue

Lucas Hamilton

I believe that energy is a national security issue.  We import too much energy and are too dependent on that imported energy.  What we pay for energy is much lower than other places in the world and we have grown accustomed to having all we want when we want it. This fact puts us in a precarious situation with regard to international policies. Do we want to be at the mercy of other nations to meet our energy demand? It is in our best interest to produce our own energy through alternative sources and we need to do this sooner than later.

President Obama also recently talked about energy as a national security issue on a podcast that he syndicates every week. He also discussed a company in the Mojave Desert that will produce solar energy to power 140,000 homes in California. This is progress.  Wind farms are also being built in many parts of the country.  Alone they won’t replace fossil fuels but over time we will identify and perfect these alternative sources  to minimize our dependence on fossil fuels.

I was glad to see that the White House changed its position regarding solar power and acknowledged that the White House needs to lead by example and will put solar panels on the While House.

Given my recent blogs on both the Energy Star Pledge program and the Green Power Community Challenge it is clear that the educational component is kicking into high gear and we are all being encouraged as individuals, communities and businesses to assess our energy consumption and make changes to our lifestyles to lower our carbon footprints.  Things will not change overnight but if we are all focused in the right direction we can make quicker strides to ramping up alternative energy sources.

The two key areas where we can have a significant impact on energy reduction is to create a federal building code and changing our lifestyles with regard to home energy use. If you are making changes or upgrades to your home, consider solar reflective shingles, adding insulation or using programmable thermostats.

Make Energy Awareness Month 2010 your energy independence month and develop a plan to reduce your carbon footprint.

Lucas Hamilton is Manager, Building Science Applications for CertainTeed Corporation

Pay Now or Pay Later – Constructed Space per Person

Lucas Hamilton

I recently read a report in the Department of Energy’s 2009 Building Energy Data Book that referenced the amount of constructed surface area per person around the world.  The United States is second only to Canada in the amount of constructed space per person – the U.S. boasts 3,000 square feet per person. This concept of constructed space per person includes home, work, shopping centers, sports complexes – any constructed buildings where we live, work or play. 

This is far more than most of the world. Comparing the United States to the United Kingdom, for example, the average English citizen uses approximately one-third the space of Americans.  Americans have come to expect this right-of-space. But there is a price to pay if society continues to expect large buildings. If the goal is to move toward net-zero buildings we are going to have to become very creative to overcome our need for space.

One example to consider along these lines is the issue of rain water run-off. For the most part, constructed space represents hard surfaces which prohibit rain water from being absorbed into the ground.  This not only overloads our water treatment and sewer systems, as we discussed in a previous blog about Live Roofs, but it effects the sequestration of carbon dioxide. 

The new Leadership in Energy and Environmental Design (LEED) for Homes program sponsored by US Green Building Council is penalizing homeowners for having more space in their home than they need.  However, if a 4,000 square foot home for two people is still desired, the LEED program will allow it but will require more energy efficiency components in order to certify the home. This seems reasonable to me.

If Americans wish to build large spaces, designers and developers are going to have to work harder to offset the impact on the environment.

Lucas Hamilton is Manager, Building Science Applications at CertainTeed Corporation

Don’t Skimp on Insulation

Spray foam insulationOn February 5, Martin Holladay from Green Building Advisor.com posted a Blog entitled “It’s OK to Skimp On Insulation, Icynene Says.” This was in response to open-cell spray foam manufacturer, Icyene’s position advising builders to install less insulation than the code requires and for building officials to approve insulation that doesn’t meet minimum R-value requirements.

Martin makes some very good points regarding the flaws in this thinking.  Icynene’s position is that air-tightening a home will have a significant impact on the energy consumption of the home–which is absolutely true, but they are also saying that by doing this you can accept lower R-values.  There is no reason to accept lower R-values.  Builders should be able to do both:  air-tighten a home and have the R-values that the code requires.

Heat moves to and from a home in three ways simultaneously; conduction, convection and radiation.

R-value just deals with conduction and not with air loss.  So to say that building code officials can reduce our requirements on conduction because we are helping to deal with air leakage is a weak argument.  Why should we settle for less? The building code requires that homes be air sealed and have a minimum R-value. There is a reason for that. We have to deal with all three modes of heat transfer simultaneously.

Martin points out that there is language in the 2006 International Residential Code (IRC) that gives air sealing requirements.  Here are a few examples Martin publishes about where buildings are to be air-tightened:

  • Sealing all joints, seams and penetrations;
  • Sealing around windows, doors and skylights
  • Sealing openings between window and door assemblies…

These are not places we put thermal insulation. Putting insulation between two studs doesn’t even address what the code language is saying as to where buildings need to be air-tight.  Different measures need to be taken.  If you look at Icynene’s argument you might infer that because they are air-tightening between two studs they can reduce the R-value required between those studs or in the attic.  There is no reason to accept that.

We consumers can and should have both air-tightness and high R-values because energy is too important to have less than what the code requires. 

Lucas Hamilton

Lucas Hamilton

Lucas Hamilton is Manager, Building Science Applications at CertainTeed Corporation.