SystemVision Newsletter :: July 2008

In this Issue

 

Contact

SystemVision
919 857-9000
www.systemvision.org

SystemVision E-Newsletter

 

Intro: Summer 2008

We hope you all are enjoying the summer! There are now more than 1,700 affordable guaranteed SystemVision homes across North Carolina with new developers, builders, and sub-contractors joining regularly. Our website (click on “Single Family Housing” after visiting www.systemvision.org) holds a large assortment of tools for you: a list of partners across the state, workshop dates, the online Plan Review Input Form, standards, specs, checklists, how-to picture guides, and a new homeowner bill tracking tool. We hope these tools are useful to you. Please let us know how they could be improved.

On the other hand, SystemVisionReport.org is new tool designed to give you feedback. As a SystemVision developer you may login with your email address as username and last name as password. You wil see filters; use them as you like (you may leave any or all blank), and view your progress within the program. You’ll see all of the homes which have had at least one SystemVision site visit, the status of each visit, and comments as to how it fared. At the bottom of the report you’ll find a pass/fail pie chart for each inspection type. You may use these to track your progress within the program. This site is automatically updated each night. We hope you will use it to begin conversations regarding how we may be able to help you improve specific areas of your construction process.

Once again, enjoy the newsletter, website, new tools, and the rest of your summer—we’ll see you soon!

Krista Egger
SystemVision Program Manager


Technical Issue: Attic Bypasses, Troy Gilmore

For those who have been building in the SystemVision program, air sealing the building envelope has become common practice. One part of our air sealing strategy is to seal the bottom plate to the sub-floor. While the crack (air gap) between the bottom plate and the sub-floor may seem minor, it actually creates a significant opening in the envelope when multiplied by the total length of the bottom plate to sub-floor connection. We have found that sealing this air gap has a significant impact on the performance of homes when we test them in the field. As a result, this detail has become an essential part of air sealing strategy.

Now let’s carry the same line of thinking to another part of the house – the attic. Before it is insulated, we can stand in the attic and see the top plates of interior and exterior walls. Let’s kneel down and take a closer look at a section of the top plate. (Figure 1) If it is an interior wall, we see sheetrock on both sides of the top plate. Quite often we also see an air gap between the sheetrock and the top plate. Just like the bottom plate to sub-floor connection, the top plate to sheetrock connection can consist of a narrow air gap that runs along many linear feet of plate – resulting in a large opening in the building envelope.

In the past few months, Advanced Energy has conducted two case studies to determine the effectiveness of sealing top plate to sheetrock connections. In both studies we conducted a blower door test on the home to establish a baseline. Then we crawled in the attic and sealed all the top plates with a two-part polyurethane foam product. Afterward we conducted another blower door test to check for improvement in envelope tightness.

The first study was a typical stick frame home being built to SystemVision standards. Our initial blower door test resulted in 1251 CFM50 while our target was =941 CFM50 for the 1040 square foot home. In other words, the home would not have passed a SystemVision final visit because the blower door number was too high. After sealing the top plates another blower door test resulted in 940 CFM50. Our second case study was conducted on a home constructed of steel studs. Due to the nature of steel studs and the fasteners used, the air gaps in the attic were especially large. Again, we started with a home that would not qualify as SystemVision but after sealing the air gaps in the attic the home performed well enough to meet our standards.

While we used a two part polyurethane foam product, at least one builder has been using one part foam (the equivalent of Great Stuff) with success. Regardless of the product you might use, be sure to follow safety guidelines and wear appropriate personal protective equipment.

These case studies and other field experience have shown that while air-sealing framing details (such as chases and floor systems), open cracks in the sheathing and subfloor, around windows and doors, and the bottom plate / subfloor connection are essential to envelope air tightness, Sealing junctions in the ceiling plane present further opportunities for making the home airtight. In some circumstances, this may be just what is called for to bring the home in under target.


Homeowner Corner: Bill Tracking, Krista Egger

One of SystemVision’s most distinctive features is its heating and cooling energy guarantee. No other affordable housing high performance home program in the country has such a feature. Over the years we have seen the guarantee in action—it draws favorable attention to your homes and it provides security in terms of utility costs to your homeowners. The vast majority of SystemVision homes use less energy to heat and cool than is guaranteed—the guarantee holds strong. On the occasion that a home does use more energy to heat and cool than was predicted, the guarantee truly shows it value. The appropriate refund is sent to the homeowner and, when needed, corrective action is taken to ensure that the home’s heating and cooling energy use will recede below the guaranteed level. More than once, we have seen the guarantee send an alert and call for corrective action that has enabled a homeowner to stay in their home financially.

This guarantee and the SystemVision comfort guarantee are permanent fixtures of the program. But over the past year various utility providers in the state have increased their customer privacy protections, making it more difficult or impossible for any party apart from the actual utility customer to access energy usage data. This means that for some SystemVision homes we must rely on the homeowner to alert us when their bills are too high. Early in 2008 we implemented a system that enables homeowners to actively track their bills and will automatically alert Advanced Energy should any home exceed its guarantee.

Visit www.systemvision.org, click on “Single Family Housing,” and then look to the top right of that page. Homeowners may register and log-in there to begin tracking their home’s energy usage. There they will enter their name, address, phone number, housing developer, closing date, and utility information. Homeowners may login whenever they would like—every month to enter their data, once a year, or several times a year. All their information will be saved once they “Logout.” At the bottom of the page, they will enter their guarantee amount (found on the blue booklet they received once the home was certified). All of the calculations are taken care of—once 12 months of utility information has been entered, the system will determine whether or not the home has exceeded its guarantee. If so, an email will immediately be sent to SystemVision staff who will then contact the homeowner. See the “Sample Guarantee” under “Participant Tools” on the SystemVision webpage for full details behind the guarantee. We will be including a hard copy of the bill tracking form with all future guarantee packets so that homeowners without regular internet access may complete this on their own. We encourage SystemVision homeowners and developers to contact SystemVision staff if they are concerned about the performance of their home at any time. We also welcome feedback about this new tool.


Beyond SystemVision: HBA Green, Jamie Kingston

This is a section for those of our builders and developers who feel that they have gotten a good handle of the SystemVision program standards and are looking to see what comes next.

In our last issue we gave a brief introduction to ENERGY STAR’s recently released Indoor Air Quality (IAQ) package. To recap briefly, ENERGY STAR IAQ is a national program available to ENERGY STAR partners around the country. ENERGY STAR IAQ is a prescriptive program with a fixed set of standards that must be met in order to receive the label. The IAQ standards go beyond the ENERGY STAR standards in that they address such issues as bulk water flow, moisture management, pest control, pressure balancing, ventilation, and combustion safety. As we noted in our last issue many of these standards will be familiar to any builder familiar with the SystemVision program. In this issue we turn our attention closer to home, towards one of the emerging resources for green building in North Carolina.

In May of 2006, the Home Builders Association of Durham, Orange and Chatham Counties (HBADOC) organized an inaugural Green Building Home Tour. This was the first such tour initiated as part of the Green Building Initiative (GBI) of the National Association of Home Builders (NAHB). The twelve homes featured in the tour were all certified as ENERGY STAR but differed greatly in style and features. These homes all would go on to be certified in the new Green Building Initiative program developed by the Home Builders Association of Durham, Orange and Chatham Counties.

HBA-DOC’s Green Building Initiative (GBI) program is modeled after the National Association of Homebuilder’s GBI program using the NAHB Model Green Home Building Guidelines as the foundation for its standards. This set of standards provides details on many sustainable building practices in such areas of lot preparation, resource efficiency, energy efficiency, water efficiency, indoor air quality and homeowner education. By meeting specific “best practice” items, a builder is awarded points towards achieving a GBI certification from HBA-DOC for a specific home.

The certification program offers three levels: bronze, silver and gold. A builder obtains a certificate for a home by enrolling the project in the program, completing a score sheet to show that sufficient goals are being met in each of the program areas, and (after the home is completed) submitting a complete documentation package that is reviewed by a third-party verifier under contract with the program. A certificate is issued after the third-party review has been completed.

The Home Builders Association of Durham, Orange and Chatham Counties and the Home Builders Association of Raleigh-Wake County consolidated their efforts in January of 2008 to form the Green Home Builders of the Triangle. Their program is referred to simply as the Green Building program. In order to be a member of the Green Building program, you or someone in your company must be a current member of the HBADOC or HBARWC. If your company is not currently represented by a member, an HBA application and dues payment must be submitted.

“All very interesting,” you might say, “but how does this relate to me and to the SystemVision program I have so recently mastered?” While this point based, multi-tiered, green building program may appear intimidating or confusing to those of us more accustomed to a prescriptive set of seven standards, anyone who has successfully completed a SystemVision home is well prepared to take on this challenge. Consider for instance that without altering your building process in any way SystemVision homes already score enough points to achieve a “Silver” rating in the energy efficiency section of the Green Building program. Again, without altering your building process in any way, your homes score 46 out of the 48 points needed to achieve a “Bronze” rating in the indoor air quality section. Those of you who are already using advanced framing techniques such as ladder T’s and two-stud corners are scoring points in the resource efficiency section. Finally, by virtue of being a non-profit organization you will receive 2 out of the 5 points required to receive a “Silver” rating in the global impact section of the Green Building program.

For SystemVision builders and developers in the Triangle area this program offers a challenging put attainable next step. As a result of participating in SystemVision‘s program you are already well beyond square one when in comes to building a “green” HBA home. Similar programs exist elsewhere in the state.

Useful links:

 

Making the buildings in which we live, work, play and worship more
healthy, safe, durable, comfortable, affordable, energy efficient and environmentally responsible.