Winsome Homes Launches the Building Better Buildings Series with the “Brains and Bones of a Better Building”
Wednesday, June 8th, 2011
Wendy Stassens, Broker
Article by Bella Casa Realtor®
and Winsome Homes Owner
Wendy Stassens
The air was chilled and guests arrived bundled in coats and scarves for the evening tour of a McMinnville home under construction, marking the launch of Winsome’s Building Better Buildings series, “Brains and Bones of a Better Building”. The cold did not dampen the enthusiasm and curiosity of the crowd that gathered to hear Shan Stassens, with Winsome Homes, and Jay Jaeger, with Amvic, an ICF block company, talk about the structure, electrical, heating, cooling and ventilation systems of this home.
Guests had the opportunity to observe the Insulated Concrete Form (ICF) basement and came away with a better understanding of the benefits and limitations of using ICF blocks for daylight basement applications. Jay explained the benefits in sound insulation, conveying a story of an ICF block basement which was used as a shooting range, with no disturbance to neighbors or people in other parts of the home when the shooting range was in use. He also highlighted the superior performance of ICF blocks innatural disasters and other destructive situations. Jay gave an example of an ICF home under construction in a neighborhood hit by Hurricane Katrina and described an iconic photocommonly used to illustrate the strength of ICF block construction showing a neighborhood that had been leveled by the hurricane with only the ICF home still standing. He discussed the benefits with regard to resistance to water infiltration, often a consideration for basements and daylight basements in homes.
Jay explained that ICF blocks “go together like legos”. These “legos” are tied together with a web of steel rebar that goes into the footing of the home, tying the walls to the floor. The centers of the blocks are then filled with concrete. Shan commented that the concrete in the forms has close to a “perfect cure” because of the protected nature of the cure within the blocks,resulting in even stronger concrete. This tight construction system creates a strong, square, virtually airtight structure that will be here for a long time to come with low levels of maintenance. Such a building envelope results in superior energy performance for both heating and cooling. “You’re building a home that will likely still be here in 500 years,” Jay explains.
The strength, durability and airtight nature of the structure bring with it additional considerations. Shan explained the importance of properly ventilating such tight homes with aHeat Recovery Ventilator (HRV) to offer a constant source of clean, fresh air that has been preconditioned using the heat from the air that is being circulated out of the home to avoid unnecessary loss of heat or cool. Heat Recovery Ventilators are invaluable for maintaining healthy indoor air quality in the home and balancing the humidity in the home with the humidity found outside.
Shan also discussed methods of affixing siding and running plumbing and electrical through the block system. He fielded questions on changes or additions to ICF homes. Using a specific example of adding an additional garage door, Shan explained the process of cutting and altering the concrete structure. It is entirely possible to change, but, Shan says, “this process encourages careful planning and designing, for sure. It is important to ‘future proof’ as much as possible when thinking through your designs when building with ICFs, which is not a bad thing.”
Guests continued to the upper levels of the home to learn more about Advanced Stick Framing, window installation and heating, cooling and ventilating for healthy indoor air and energy efficiency. The home that hosted the event is what is called a hybrid home, built using ICF block for the basement and Advanced Stick Framing for the upper floors.
On the second stop of the tour, the guests were able to see the Advanced Stick Framing in the walls of the home. “One of the
many advantages of this type of wall framing,” Shan explained, “is avoiding thermal bridging.” A thermal bridge is created when materials that are poor insulators (like the typical stud used in the wall of a home) connect the heated interior of a home with the unheated exterior, allowing heat to flow through the path created. The offset timbers in the walls of an Advanced Stick Framed home provide a break so you do not lose energy through the wall studs. A second advantage is that the increased space in the wall cavity allows for more insulation, which further increases the energy efficiency of the home. “In this wall cavity we will use 1 ½” of spray foam insulation, put a web over the whole wall and fill with loose fill insulation that contains an acrylic binder to avoid settling. The spray foam is very efficient at filling up the seams of the home and a joint tape on the outside further ensures minimal energy loss through gaps. With this full insulation treatment, these walls will be in the range of R40 to R50, which is comparable to ICFs. When all is said and done, these walls will only cost about 2% more than a track stick frame home.” Shan explained.
With such tight wall systems, clearly windows can potentially be a weak point in the energy efficiency of a home if not carefully chosen and installed to avoid energy loss. There is a lot of information about the performance of a window on the National Fenestration Rating Council (NFRC) label. In most jurisdictions across the United States, building codes require that windows bear the NFRC label so that the code compliance of their energy ratings can be verified. The first thing listed on these stickers is “Low E Glass”, which stands for “Low Emissivity”. This means that a special coating that reflects infrared radiation is added to the window to avoid losing heat to the outside in the winter or gaining heat inside in the summer. The sticker will also tell you that a window is “Argon (Krypton or Nitrogen) filled”. Typically the void between the two panes of glass in a double pane window today will be filled with Argon, Krypton or another gas that insulates better than air does. They used to use Nitrogen, but have switched to Argon because it is a more readily available inert gas and is also cheap. Krypton has been gaining in popularity recently because it performs better than Argon. The U-Factor, which goes from 0 to 1, indicates the rate of heat loss of a window. The lower the U-Factor is the greater the resistance to heat loss and the better its insulating properties. Energy Star requires .35. “In our climate in Oregon, “Shan explains, “You can cost effectively get to .25.” The Solar Heat Gain Coefficient (SHGC), also a number from 0 to 1, measures the fraction of solar radiation admitted through a window, both directly or absorbed and subsequently released into the structure. The lower this number, the less the heat it transmits. The Visible Transmittance (VT) measures how much light the window transmits on a scale of 0 to 1. Most double and triple pane windows are in the range of 0.30 and 0.70. A high VT value is desirable because it maximizes the daylight in a structure. Condensation Resistance (CR) is a rating from 0 to 100 that measures how well a window resists condensation on the inside of the window. The higher the number, the better a window is able to resist condensation. The final rating is an Air Leakage (AL) rating, which is expressed by the equivalent cubic feet of air passing through a square foot of window area. The higher the AL rating the more leakage occurs, causing undesirable heat loss or gain. Both the Condensation Resistance rating and the Air Leakage rating are optional ratings at this time.
Shan went on to talk briefly about other important elements of window selection, including the framing material, the most common of which are Vinyl, Wood and a hybrid with an interior wood element bonded to an exterior fiberglass element. There are advantages and disadvantages of each with regards to their performance, maintenance and price and personal preference regarding aesthetics plays a significant role in the selection of the type of window framing selected.
In addition to the tours, the guests enjoyed a gourmet catered meal, local wine, beer and birthday cake in celebration of one of
the attendees that evening. Despite the frosty May evening in a home with only framing to keep guests warm, the atmosphere of the event was warm and inviting. Guests were interested and enlivened by the tours and continued to enjoy visiting and casual dinner conversations following the more formal, structured portion of the event.
What is a “better building”? It is not a simple thing to define, but a group of enthusiastic pioneers embarked on a journey of exploration to learn, question and discover together on that cool May evening. Join us as we continue our journey in September, 2011 for the “Features and Finishes of a Better Building”. Visit www.winsomehomes.com/events for more information.
