Next-generation air sealing provides boost to home energy efficiency

Next-generation air sealing provides boost to home energy efficiency

Creating a tighter building envelope to prevent air leakage is one of the critical components of a green home.

Builder Tom Wade, president of Artistic Homes in New Mexico, has built more than 5,300 high performance homes since the company was founded 44 years ago by his father, Jerry Wade. The company now builds every home to LEED Silver, Gold or Platinum certification.Knopf air sealing

In 1999, Artistic Homes partnered with the U.S. Department of Energy's Build America program. All homes are built to a HERS rating of 54 or below. Annually, about 40 percent of Artistic Homes are built with either the company's net zero or solar 30 near-zero options.

"Air-sealing a home to reduce air infiltration has a huge impact on energy efficiency. Air tightness is the byproduct of doing building science correctly. When we hold air tightness as a goal, then we know we've built a house the correct way," Tom Wade said.

To further improve sealing performance, Wade began using Knauf Insulation's EcoSeal System, a water-based elastomeric spray used in conjunction with fiber glass blown-in or batt insulation. EcoSeal is applied with an airless sprayer and dries to a flexible tough film. Wade does not use open or closed cell spray foam insulation.

Wade said he does not use open or closed cell spray foam insulation because of its petroleum base and because he said it has a potential for off-gassing.

In the past, the company sealed a house by hand-sealing joints with caulk or expanding foam and using a BIBS insulation system. "We spent a lot of time caulking and foaming prior to insulation. EcoSeal is an ideal replacement for much of that work," Wade said.

Artistic first used EcoSeal in what Wade calls one of the "harshest testing environments we could have experienced." At the time, ambient temperatures were in the low single digits; dramatic for Albuquerque. "EcoSeal applied well even in five-degree temperatures. I was impressed with that," Wade said. Knauf Insulation's Jet Stream ULTRA insulation was used in a BIBS application with EcoSeal.

"In looking at the blower door tests for the two homes, they scored very well. EcoSeal performed for us," said Wade. "EcoSeal also allows us to address areas that currently aren't addressed in our regimen — spots where you just can't get in with expandable foam and caulking. We're going to use it again," Wade said.

"With Artistic, the EcoSeal System provided about a 35 percent increase in tightness," said Chris Brown, business development manager at Knauf Insulation. "They were already meeting the Energy Star standard of .35 natural air exchanges per hour, but we helped drop that to a .11 rate. Compared to spray foam, you get both air resistance and improved R-value," Brown said.

"With EcoSeal, we not only address the cavity, but we can deal with some of the individual framing idiosyncrasies that foam can't," he said.

Air sealingWith the ability to penetrate gaps as small as 1/16", EcoSeal takes care of areas that aren't effectively sealed by foam, also sealing joints and surfaces that many builders typically do not address, such as bandjoist areas, corner T's and partition T's, and jack, king and multiple studs. "We isolate the attic from the living area, sealing all potential paths of air leakage including any open chases in the attic and drywall penetrations like HVAC registers and can lights," Brown said.

"A basic aspect is framing — unless it's done correctly, you're not going to achieve energy efficiency. That's plain black and white. With thermal imaging, you can easily see the inefficiencies with poor framing," said Wade.

The net zero homes Artistic produces feature efficient 15-SEER air conditioning units. "Proper sealing and insulation make a huge impact with HVAC. We can right-size our equipment to create savings in equipment dollars," Wade said. Many of Artistic's near-zero customers have utility bills that are only around $35 a month. In addition to approximate energy savings of $200 a month, Artistic's net zero customers could also contribute to the grid with their solar power, earning payment for their energy production.

"If the house wasn't air tight," Wade said, "we would have to upsize all our equipment. That would result in a vicious cycle of inefficiency and a lack of in-room comfort. You'd have a hot-cold effect because your equipment's too big. Having proper insulation and air tightness allows us to maintain overall room comfort and right-size the equipment."

The comfort factor has tremendous importance for Wade, who has both allergies and asthma. "I've lived in almost all of our homes throughout the years, so I'm a great guinea pig concerning air quality, of which I'm very sensitive. With our last set of homes prior to focusing on indoor air quality, I told my father that they just weren't comfortable to live in because of the air quality. Temperature and everything else was great, but this was really the turning point that pushed us to expand our perspective and include high indoor air quality."

Artistic's homes are certified under Energy Star's indoor air package. Each home has HEPA-filtered fresh air ventilation and is backed by the builder's energy-usage and comfort guarantee. With EcoSeal, homeowners can rest assured that they have a low-emitting product since it is certified under both Greenguard and the more stringent Greenguard children and schools program.

"We owe it to our customers to build a home that is structurally sound. At the same time, we don't want to build a product that is going to make them sick," Wade said.

"Right now," he said, "almost all the code changes are about energy — there's not a lot of the traditional loss-of-life discussion on future code changes. As our enforcement agencies start adopting these energy codes, and builders who aren't fully knowledgeable on building science are forced to tighten these homes up, we could see the effect of creating poor indoor air quality and water management problems," said Wade.

"The performance you can achieve with EcoSeal and R-21 or R-23 fiber glass in a wall is unsurpassed," said Scott Miller, director of sustainability at Knauf Insulation. "You can't afford to do it with another product. Our tests have shown effectiveness to .09 natural air exchanges per hour. Fundamentally, for high-performance homes, you need R-value but you also need to seal up the structure," Miller said. 

As a single-component sealant, EcoSeal applies right from the bucket without any mixing and cleans simply with water. Since hazardous chemicals are absent, there is no off-gassing threat during EcoSeal application or during the ownership of the home, and no need for safety gear. 

The performance, speed and safety of EcoSeal add up to a better-performing product for insulation contractors. Start-up costs for providing EcoSeal application are low, at approximately $4,000.

"EcoSeal is the 'right next step' for builders," Wade said. "If you do building science and building techniques correctly, EcoSeal helps you create a more efficient, quality home."

As a speaker at the United Nations Global Climate Change Summit in Cancun, Mexico, Wade is thrilled at the potential international progress of high performance building. "There's a lot of international pressure to move homes to become much more energy efficient. Internationally, I think there are going to be a lot of synergies. When new innovations are made, hopefully Artistic will be at the leading edge with those. It's exciting to be involved at the global level.

"I'm really proud of the fact that over the last four years, in the deepest pits of the recession, is when we've made our biggest leaps not only in energy efficiency, but also tremendous progress in green and indoor air quality," Wade said.

"Jerry and Tom at Artistic are phenomenal builders," Miller said. "They understand and sell life-cycle economics and the sustainability associated with it, and they care about social, environmental and people impacts — the triple bottom line that we at Knauf Insulation value as a company. Artistic Homes reflect their innovative design and vision toward the future and we are very proud that they use our products."

For more information, see our Going Green at Home research center.

Topics: Building Green, Insulation

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