Saving Energy is SEXY! Especially when mixed with a little bit of science

When you strip down the walls, roof and floors of a building there is a simple and sexy story about how the building envelope that surround us tick.  At least us building science junkies think its sexy! Imagine building a structure that you KNOW will operate for a fraction of the energy costs. Is it possible? Absolutely. So why wouldn’t builders and architects look to science to do this?

A quick glance of the science behind building construction and it’s easy to understand how the roofs, walls and floors of our buildings dictate the amount of energy we use to heat and cool the structures we work, shop, dine and live in.

The science behind energy efficiency in our building walls, strips down simply into three areas:
1. Air Transfer/ Airtightness
2. Convective Looping
3. Thermal Bridging

One of the easiest ways to understand these three areas is to look at two side by side wall systems. One built from a conventional stick framed building, alongside one built with an advanced building product like SIPS (Structural Insulated Panels).

Science behind energy efficiency Part #1: Air Transfer/ Airtightness

SIPS, Air Transfer

A SIP System is made of LARGE panels (up to 8 ft by 24 ft). Air leakage is responsible for 40% of heat/cooling loss and in building construction. A huge number.  Air leaks through joints in sheathing and the inevitable gaps between lumber connections, and between wood framing and insulation. As shown in the illustration below, the arrows in the stud wall show the gaps and connections where air can transfer through the wall. The SIPS wall on the right side of the illustration dramatically reduce air transfer within walls and roofs by minimizing these joints and providing solid, continuous insulation across each panel’s height, width and depth.

Simple huh? Blower door tests in projects all over the country have confirmed the airtightness in SIPS, further showing how SIP buildings are better at keeping the hot/cold air just where you want it.  One impressive study at the Dept of Energy’s Oak Ridge National Laboratory had two identical test rooms built side by side: one stick-framed, one SIP-framed.  Rooms were tested for air infiltration and the SIPS room was FIFTEEN times more airtight and more energy-efficient then the stick-framed room. Used in commercial buildings or residential, the air tightness factor is the same.

Science behind energy efficiency part #2: Convective Looping

Not only are SIPS more airtight but the fact that they are manufactured with a SOLID engineered rigid insulated core (not batt fiberglass with gaps throughout) is the part that some might think is the scientifically sexy part of the system.

Inside our walls as warm air rises and cold air sinks in a conventionally framed wall cavity (the inside of the wall) a natural phenomenon called thermal or convective looping occurs, wasting valuable energy. Air is heated or cooled and then it naturally does the opposite as it rises and falls. Talk about a waste.

Check out this illustration to visually see what this means for the stick framed wall to the left:

When a building is insulated with a solid core to stop this air movement, it doesn’t matter what an insulation’s insulating (R-Value) is. What good is insulation if heat-carrying air can flow through it and the cavities in the wall? SIPS solid insulation core helps eliminate this.

Science behind energy efficiency part #3: Thermal Bridging

Rounding up the factors that dictate how efficient our buildings are is one of the most sexy terms out there… thermal bridging. It sounds scientific and complicated but its pretty darn simple.

Basically thermal bridging occurs where there is a continuous element between the cold and warm faces (between the inside and outside) of a wall. This could be wood studs within traditionally framed walls, or simply stud to stud connections where wood touches wood within a wall. These wood elements form a bridge between the inside and outside that can allow heat or cold to pass through by thermal conduction.

Because of factors like thermal bridging, simply installing R-19 batt insulation in a stick wall doesn’t mean the whole wall will have a R-19 R-value because there is still a significant amount of thermal bridging in traditionally framed walls that rely on lumber at regular intervals to provide support. 15-25% of the shell of a stick-framed building is lumber, compared to as little as 3% in the shell of a typical SIPS framed structure.

Another visual to illustrate this is through infrared photography. The picture at the top is stick walls that shows the transfer of heat through the lumber studs (indicated in yellow). The picture at the bottom is of a SIPS framed home, showing that SIPS structures dramatically reduce thermal bridging as shown with solid green walls.

Since buildings consume 80% of our energy it makes sense that we would want to try to reduce fuel and energy we require to heat and cool our built environments… not to mention send less junk back into our environment. One way to use less energy is to build smarter. Building with sticks and dimensional lumber is tried and true, but it really isn’t cutting the bill when it comes to energy efficiency. Time to look to future in how we build… and to build smart and sexy with science in mind.

Visit our website to see how you can use SIPS in your next project….and keep it SEXY!

Tech Tuesday: Build Tight…But We Still Need Fresh Air Right?

Written by:  Joe Pasma, Premier SIPS Technical Manager, P.E.                                                                         (my two or is it too cents worth)

Everyone is talking about mechanical ventilation of structures.  Why bother?  The old guys say we build too tight today.  They claim structures don’t breath and that is why we have so many problems with today’s construction.  So, what’s the deal?

In my last posting, What’s in an R-Value, I talked about how tightening up a building, reducing air leakage, helps increase the energy efficiency of the house/building.  Tightening up the structure is great when promoting energy efficiency, but we must remember, people still use these buildings and we need fresh air to function properly.  So, from a buildings perspective, if we are going to tighten the building envelope up to increase energy efficiency, we had better plan on doing something for the occupants of these buildings to provide them the fresh air they require to function properly.  The adage from the building scientists is, “Build it Tight and Ventilate it Right”.

Some say you can never build it too tight but you can under ventilate it.  The key here being proper, controlled ventilation.  Building scientists and energy efficient construction advocates have numerous strategies on how to do this.  The important thing is to incorporate this planned, controlled ventilation into the building.  The actual details of the system used on a given building will depend on the climate zone, the type of occupancy, the mechanical system employed and a whole host of other factors.  But the main take away from this posting should be to plan on some sort of mechanical ventilation in any energy efficient building.

For those of you out there looking to make an existing structure more energy efficient, you undoubtedly will be tightening up the structure; don’t over look the fact that you will need to plan on adding mechanical ventilation to your building.  The same laws of physics and building science apply to both newly constructed buildings and older buildings that are remodeled.

Green Begets Green: Why Can’t We Get Past the ‘Perceived’ Cost of Building Green?

Written by:  John Vanderhoof, LEED GA

Unfortunately, the perceived cost of going green is what deters most from building green and energy-efficient.

Let’s use light-bulbs as an example; if you were to see two light bulbs on the shelf that provided equal lighting, yet one cost $0.50 and the other $2.50 which would you pick?

Incandescent vs. CFL – We will use the life-cycle cost of 10,000 hours; the lifespan of one CFL.

Incandescent – lifetime of 1,300 hours, so we would need 8 bulbs to complete 10,000 hours of lighting. A single incandescent runs around $0.50, so our total cost for bulbs over 10,000 hours would be $4.00.

As it uses 60 watts, over a period of 10,000 hours, an incandescent bulb would use 600,000 watt hours, or 600 kilowatt-hours. At the current approximate price of $0.10 per kilowatt-hour, you would have to pay $60.00 to run an incandescent bulb over this period.

Total cost of a 60 watt incandescent bulb over a 10,000 hour lifespan is $64.00.

CFL – lifetime of 10,000 hours and costs around $2.50; only 1 bulb needed.

As it uses 13 watts, over a period of 10,000 hours, a CFL bulb would use 130,000 watt hours, or 130 kilowatt-hours. At the current approximate price of $0.10 per kilowatt-hour, you would have to pay $13.00 to run a CFL bulb over this period.

Total cost of a CFL bulb over a 10,000 hour lifespan is $15.50.

Bulb Analysis: Cost Comparison & True Life Cycle Cost

 

The incandescent ends up being 413% more while creating 8 times the waste and keep in mind we haven’t even figured in the environmental impacts of 8 times the manufacturing, packaging & transportation. Now that you understand the life-cycle cost, which would you pick?

The most criticized issue about constructing environmentally friendly buildings is the price…the cost of building.  Photovoltaics, new appliances, and modern technologies (like the CFL) tend to cost more money. Most green buildings cost a premium of <2%, but yield 10 times as much over the entire life of the building. The stigma is between the knowledge of up-front cost vs. life-cycle cost. The savings in money come from more efficient use of utilities which result in decreased energy bills. It is projected that different sectors could save $130 Billion on energy bills. Also, higher worker or student productivity can be factored into savings and cost deductions.

Studies have shown over a 20 year life period, some green buildings have yielded $53 to $71 per square foot back on investment. Confirming the rent-ability of green and energy-efficient building investments, further studies of the commercial real estate market have found that LEED and Energy Star certified buildings achieve significantly higher rents, sale prices and occupancy rates as well as lower capitalization rates potentially reflecting lower investment risk.

So where do we start? Beginning with a resource efficient, well sealed and effectively insulated building envelope is crucial for any home to be considered “green” and sustainable. Through the successful incorporation of a high performance SIP envelope with other green products and practices, builders can cost effectively build to green, LEED, Energy Star and NAHB Green Building standards.

SIPs are made from thick EPS foam cores sandwiched between OSB (Oriented Strand Board) panel faces. The OSB is made from fast-growing trees, and produced in a way that yields a large percentage of every tree. The foam itself is made from partially recycled material, and the final result is a large solid panel that arrives to the job site pre-cut.

Job-ready SIPs allow installers to install the roof, wall and floor panels without the need to cut, frame and trim excessive amounts of lumber and other materials. The job-ready feature of Premier SIPs panels reduces the amount of job site material waste by 60% when compared to buildings constructed with regular dimensional lumber and framing materials.  Less waste is obviously better for our environment.  In some cases, we have had projects that did not have hardly any waste at all.

When compared to buildings framed with dimensional lumber, Premier’s large SIPs cover greater surfaces with far fewer gaps in the walls and roofs, to be filled and sealed, offering home and building owners better indoor air quality, reduced infiltration of outside pollutants, smaller HVAC systems needs and superior indoor temperature control. Premier homes and buildings stay cooler in the summer and warmer in the winter than buildings framed with dimensional lumber.

The R-Values are similar to those of other products.  R-value is a static measurement of the resistance to heat flow.  Premier SIPs have consistently outperformed other methods of construction in both whole wall R-value comparison and energy efficiency. Read our Technical Manager’s latest blog post- What in an R-value.   The most dramatic results are the reports of the happy customers of PBS, but there is also a significant level of scientific data as well. One of the best measures of energy efficiency of an entire wall assembly has been developed by Oak Ridge National Laboratory (ORNL). This testing method considers energy losses for the structural members, corners, joints and around windows, as well as, R- value of the insulation.  Contact us for a full copy of this report.

While most of us are willing to invest a 500% premium on a light bulb that yields a return on investment, why is it such a hurdle to get people to invest 2-3% more on a structure and using process that is environmentally responsible and resource-efficient throughout the building’s life-cycle that will provide an even bigger return on investment?

“We do not inherit the Earth from ancestors, we borrow it from our children” – Native American Proverb

Visit Premier SIPs website for more information, technical bulletins, specifications, details & more.

Visit the Structural Insulated Panel Association

References:

Architectural Engineering Study from Polytechnic State University- Material Sustainability, by Jessica Meadows & Natasha Morris

Energy Star

Easy Web Calculator

Bringing Multifamily Housing Quality and Affordability…yet Energy Efficiency!

Written By:  Jeff Beason, Premier SIPs SW Regional Sales Manager, LEED GA

If you are designing or building a multifamily project, why not specify or build with a material that can save the design professional, the builder, and the developer time and money?

Sarann Knight Apartment Complex Courtyard

I was involved with the Sarann Knight project, which is a four-story apartment complex in Las Vegas, Nevada. The developer, Community Development Programs Center of Nevada (CDPCN) used our 6” SIPs for all of the exterior walls on all four levels. And all of these SIP walls are load bearing and self-supporting.

•       SIPs reduce energy consumption
•       Easier to become Energy Star Compliant
•       Reduced construction time
•       Reduced job site waste and dumpster removal
•       End up with a durable, long-lasting building

Sarann Kinight First Floor

CDPCN owns and operates this apartment complex; therefore, the heating and cooling bills are paid by the developer.  Heating and cooling costs constitute a significant portion of the operating budget in the hot Las Vegas climate…one of the reasons CDPCN chose to build with energy-efficient SIPs!  Building on the efficiency of the R-23 SIP walls, CDPCN specified low emissivity (low-e) windows  to further reduce solar heat gain, and used tankless water heaters.  By using Premier SIPs and these other energy-efficient measures, CDPCN expect to save about 60% on their heating and cooling costs.

ENERGY STAR did not require a blower door test because they used SIPs…Sarann Knight project automatically surpassed the ENERGY STAR certification.

Sarann Knight Second Floor Goes Up

Cycle time savings were also a factor on this project. The developer believes that SIPs durability is something else to consider. This project is actually the third project that I have worked on with CDPCN. The other two were a 58 single home development (Daisy Lee Homes), and a 240 unit senior housing project (Senator Richard Bryan Senior Apartments) . They are now realizing reduced call-backs for things like stucco cracking because their SIP walls are straighter and stronger than a typical stick framed wall.

Sarran Knight Third Floor Goes Up

And now we have more large-scale projects coming up with CDPCN in 2011.

View Other CDPCN/Premier Projects on Flickr:

• Senator Richard Bryan Senior Apartments
• Daisy Lee Homes

For more information on the companies involved in this project:

Community Development Programs of Nevada, 702.873.8882

Architect: Winston Henderson, Las Vegas NV, 702.893.9700

Builder: National Construction Providers, Las Vegas NV, 702.220.9690

Tech Tuesday: What’s in an R-Value?

Written by:   Joe Pasma, Premier SIPs Technical Manager, P.E.

What’s in an R-Value?  A good understanding of R-Value and air leakage in a home or building is crucial for any one that pays a utility bill.   Besides home owners, even professionals like builders and architects often have not thought through R-value versus air leakage and they too, need to be educated on the topic.

So what’s an R-Value?  Technically, it’s a measure of a material or an assembly’s ability to resist heat flow.  The higher the R-Value the lower the heat flow though the material or assembly.  This is why the new energy codes are requiring a higher R-Value.  The theory is that by mandating higher R-Values for walls and roofs, less heat will be transferred through the walls and roofs thereby reducing energy consumption and saving the country from over consumption.  (This is bad for the utility companies, and those on Wall Street that invest in the utility companies.)

Well that is all fine and dandy if that was the only way we lose heat from a home or building, but it’s not.  We also lose heat when warm air finds its way to the cold outside through openings (air leakage).  Take an open door for instance.  How cold does the room get when the kids forget to close the door behind them on the way out to play.  Well here in Minnesota, especially today with the high temp still below 0^o F, it doesn’t take long at all.

The same thing happens in our homes and buildings if care is not taken during construction to seal up all of the holes, protrusions, joints, openings, seams, cracks and all the other things inherent with typical stick construction.  It’s like the contractor left the door open permanently.  In fact Oak Ridge National Laboratory, ORNL, has a study that shows sticks are 15 times leakier than SIPs.

A way to look at the combined effect of R-Value and air leakage (al beit over simplified) would be to just think in terms of R-Value alone.  So for this over simplified model, let’s say that since SIPs are 15 times tighter than sticks, we’ll assign an R-Value of 15 to the SIPs and attribute this to the lack of air leakage.

Premier SIPs R-Values

Now let’s compare a stick framed wall and a SIP wall.  Here in Minnesota, the code required minimum R-Value for residential wall construction is an R 19.  The stick framed walls are built to that minimum.   So R 19 for the sticks.  A 6” SIP wall has R-Value on the order of R 21 or thereabouts.  Now when we add in the effect of air leakage, sticks stay at R 19 and a 6” SIP wall goes up to R 36.  R 21 + R 15. (Not really, but remember this is an over simplified model for most of us that just want to pay less for on our utility bill.)  That makes the SIPs almost twice as resistant to heat flow in this engineer’s mind.

The point of this simple model is to show that it’s not so much the R-Value alone that makes something more energy-efficient, but the combined effect of insulation with proper air sealing.

As a testament to these effects I need only look as far as my monthly utility bill.  Our local utility tracks our gas and electric consumption on a monthly basis and sends us reports bimonthly to show us how, we as individual users, compare to our neighbors.  I live in a home that used wall and roof SIPs for an addition and the original batt insulation, in the stick framed cavity walls was replaced by rigid insulation and the cracks were sealed up.  Our home consistently ranks in the top 5% energy-efficient homes in our square footage range.  This means our utility bill of $150/month is less than one-third of what my neighbors are paying each month.   You add it up.   It pays to build with SIPs.

The thing to remember about R-Value is that R-Value is only part of the story when you are looking at the energy efficiency of a home or building.  R-Value combined with the lack of air leakage is the real ticket and SIPs give you that combination now and they do it economically.

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