Luther Home of Mercy
Luther Home of Mercy is an organization founded in 1928 for the special purpose of caring for people with developmental disabilities. Located in Williston, Ohio, the organization serves approximately 250 people in 10 residential cottages on the Luther Home of Mercy campus and throughout the community, in family care homes built and staffed by the organization, as well in private homes.
Typically the subject of research conducted by families in search of care for their loved ones, the residential cottages recently became the focus of a different kind of study – one that compared The Kingspan KoolDuct System, from Kingspan Insulation to a more common duct system constructed with sheet metal and insulated with glass fiber duct wrap.
The Kingspan KoolDuct system is a pre-insulated phenolic ductwork system. Luther Home of Mercy first became acquainted with the product during construction of their family care homes.
“We’ve been quite pleased with the product, because it’s quiet, it offers a superior insulation value and it’s finished inside and out with foil, preventing the passage of fiber glass through the airstream,” explained Don Wukotich, executive director of Luther Home of Mercy. “So, when it came time to build two new residential cottages on our campus, we were prepared to use it again in both cottages.”
Those plans changed, however, with a suggestion from the duct work installer, Commercial Comfort Systems, Inc. (CCS), Maumee, Ohio. According to CCS owner Fran Lanciaux, because the two buildings, each one approximately 7,000 sq.ft, were identical and being constructed side-by-side, they presented an unusual opportunity to compare two different duct systems.
The T-shaped single-story structures house 12 residents, four in each of three wings. Where the wings meet, residents share a dining room, activities area and kitchen. Lanciaux’s proposal to install different duct systems in each of the two cottages was fueled by an interest in the leakage rates of both systems. “Because the buildings were so similar, we felt we could conduct a fair comparison of the duct systems and gain valuable information regarding their respective leakage rates, a topic that today, more than R-values, is the focus of the Department of Energy (DoE),” noted Lanciaux.
Lanciaux approached MDA Engineering, Inc., Maumee, to perform the comparison study, since MDA designed the heating, ventilation and air-conditioning (HVAC) systems and was familiar with both buildings. The HVAC systems consisted of four high-efficiency furnaces, cooling system condensing units and ductwork in the vented attic.
The installation & test
The KoolDuct System (using the R-6.0 insulation panel) was constructed using miter cuts and folds on the longitudinal corners, with a bead of room-temperature-vulcanizing (RTV) silicone adhesive at each corner. Transverse joints were also sealed with RTV adhesive to form the duct. All joints were additionally sealed with a UL-181-A aluminum foil vapor barrier tape.
Although CCS typically makes the sheet metal duct it installs, in the interest of an impartial comparison, the company competitively bid the duct (constructed to Sheet Metal and Air Conditioning Contractors’ National Association [SMACNA] seal Class B standards), and sections were assembled in the winning bidder’s shop to assure good seals on the longitudinal joints. Longitudinal Pittsburgh seams were sealed with RTV silicone adhesive before the lap was folded over in the shop. Transverse joints were assembled and sealed in the field with Hardcast 321 Duct-Seal. The metal duct system was insulated to match the KoolDuct insulation characteristics, with both systems designed to meet ASHRAE 90.1-2004 and 2006 IECC duct insulation requirements.
An independent Associated Air Balance Council (AABC) certified testing, adjusting and balancing (TAB) contractor performed the leakage test on the entire duct systems, from furnace discharge to registers, using new, certified Oriflow brand testing equipment. Measured leakages at 2 in.w.c. static pressure (469 for KoolDuct and 2306 for metal duct) represented 6.7 percent of the operating supply CFM for the KoolDuct system and 33 percent for the metal duct system. When these rates were corrected to the actual average duct operating pressure of 0.1325 in.w.c., they represent 1.73 percent of the supply CFM for the KoolDuct System and 8.5 percent for the metal duct system.
To conduct the analysis, three building models with the same physical characteristics were created in Trane Trace 700, a commonly used energy analysis program. Model 1 was a building with perfect ducts and no leakage. Models 2 and 3 represented the KoolDuct and metal duct buildings, each with their respective operating leakages. Actual energy bills provided utility rates – a blended 9.53¢/kwh and 99¢/therm. The Toledo, Ohio, weather file was used, and simulations were run for 8,760 hrs or one year. In addition, each model ran in four equal orientations 90 degrees apart, with findings averaged to create energy uses that are not orientation dependent.
HVAC costs in each building were determined by subtracting lighting costs from the total building energy and electric costs, while the life cycle analysis of each building included material and labor costs, finance costs, a five percent interest rate, a three percent inflation rate (applied to energy) and a 10% discount rate. Finally, because the buildings and the duct work are a long-term investment for Luther Home of Mercy, financing and project life were set at 30 yrs.
Summary & conclusions
It is interesting to note that although the metal duct system was constructed with great attention to sealing and was installed at the lowest price from competitive bids, minimizing any KoolDuct leak advantages and any material and labor cost advantages, the KoolDuct system leaked less and cost less.
The results showed:
- The lifecycle-cost payback of the KoolDuct system was immediate because all costs were less than those for the metal duct system.
- The KoolDuct system was faster and easier to install, because lightweight duct sections are easier to handle, require fewer hangers and require no additional insulation. In addition, longer sections – as long as 13 ft for KoolDuct compared to five-foot sections for metal duct – translate to fewer joints, less time making and sealing joints, and reduced opportunities for leakage.
- Operating leakage cost for the KoolDuct system was nearly 80 % less than the metal duct system.
- First-year operating costs, as a result of leakage for the KoolDuct system, were 70 % less than the metal duct system, with overall HVAC operating costs 7 % less.
- Using state average energy mix CO2 generation data, provided by the Trane Trace program, the KoolDuct system saved an estimated 12,528 pounds of CO2 annually when compared to the metal duct system. This is equivalent to reducing gasoline consumption by 639 gallons, according to the carbon equivalence calculator on the EPA’s web site.
Lanciaux was not surprised by these findings. “Our company has found that after hundreds of installations and independent testing, KoolDuct exceeds the performance of any other product on the market by demonstrating higher R-values and lower installed air leakage rates,” he said. “It is, quite simply, a high-efficiency, better indoor air quality (IAQ) solution for air-distribution.
“In addition, it offers benefits in the area of labor. It’s neat, clean and because it’s pre-insulated, I don’t have to worry about leaving room for insulation as I install the duct work, and I don’t have to hire an insulator to wrap the duct work after it has been installed. So, we’ve become a one-stop shop, reducing time on the job.“
The KoolDuct system was introduced in the United States approximately six years ago. As a result, educating engineers and architects about its benefits is critical to its widespread acceptance. Studies like this one should go a long way toward demonstrating the ability of KoolDuct to meet and exceed insulating and leakage requirements while providing a cost-effective, healthy and sustainable solution to air-distribution.