SystemVision Newsletter :: January 2009

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SystemVision E-Newsletter

 

Intro: Winter 2009

We hope you all are looking forward to the new year!  There are now more than 1,900 affordable guaranteed SystemVision homes across North Carolina with new developers, builders and sub-contractors joining regularly.  Our Web site holds a variety 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 the homeowner bill tracking tool.  We hope these tools are useful to you.  Please let us know if you have any comments.  We welcome all feedback. 

We have received a lot of feedback over the past few months on one of our newest tools, www.SystemVisionReport.org.  As you know, as a SystemVision developer you can login (use your last name as your password the first time you login), use the filters and view your progress within the program.  You will see all of the homes that 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 will find a pass/fail chart for each inspection.  You may use these to track your progress within the program.  This site is automatically updated every 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. 

We have made a few internal changes over the past few months.  Dan Lutz, a former home inspector, joined the SystemVision team this summer.  He is currently managing the SystemVision field work.  Lauren Westmoreland and Nick Pastore also joined us in September as our AmeriCorps members for the 2009-2010 year. Look for them on site and at trainings through this summer.

One major change on the horizon is the creation of a new level of SystemVision.  We are currently calling it “SystemVision Plus.”  While the current model of SystemVision will not change, we are working with the NC Housing Finance Agency to develop another option for you and provide specific guidance on building your homes to a level that surpasses the current SystemVision model.  SystemVision Plus will include what you know as SystemVision and will focus on water efficiency measures as the next step.  Stay tuned for more information!

Once again, enjoy the newsletter, website, new tools and the beginning of the new year—we will see you soon!

Krista Egger
Affordable Housing Programs Manager


Technical Issue: How to 'Pass' a Final Inspection on the First Attempt, Nick Pastore

SystemVision focuses on improving the energy efficiency, health, safety, durability and comfort of affordable homes. These characteristics rely on many interactive variables within the home, including moisture, heat gain/loss, air movement, mechanical systems and of course people. To ensure that each home is built to tolerate risks associated with these variables, SystemVision helps you through three vital stages of high performance home construction: framing, insulation and final stages.  While the work you complete at the framing and insulation stages are critical to the quality of the home, we have found that the final inspection typically results in the greatest number of corrective work order (CWO) items.  This is largely due to the number of items inspected at this stage. 

We have created a guide below to help you avoid those final re-inspections.  The items listed below are items we find frequently overlooked when a final re-check is needed.  Each standard is an integral part of how the house functions as a whole. This list does not include all of the standards checked during the final inspection; however, it may be a valuable checklist to review prior to inspection in order to avoid the common pitfalls that require re-inspection.  Please let us know how we might be able to help you more.

  • Air Sealing: To ensure a reliable, affordable and comfortable home, the building envelope must be sealed tightly. The building envelope typically includes the floor, the ceiling and the exterior walls. The air barrier on the exterior walls (sheathing) and subfloor is completely sealed before insulation and drywall is added. The final step in creating a complete air barrier in the building’s envelope is to seal the ceiling. Builders must pay careful attention to all penetrations in the ceiling and ensure that any hole that has been cut into the sheetrock has been sealed with an appropriate air-sealant (caulk, fire-rated foam, etc.). Types of holes include:
    • Bath fans
    • Recessed lighting fixtures
    • Ceiling fans
    • Supply boots and returns
    • Sprinklers
  • Insulation: In order to reduce the amount of heat transmitted into and out of the home, it is necessary to create a complete and continuous thermal boundary around the entire building envelope.  This means installing insulation in contact with the entire air barrier. In order to properly complete the envelope’s thermal boundary, the attic insulation needs to be uniform R-38, paying particular attention to the perimeter. The raised heal trusses and baffles allow for insulation to be installed at the proper height and density throughout the entire attic. 
  • HVAC: A leaky duct system is a major source of increased energy consumption and can cause health and safety concerns. There are a few common issues regarding the HVAC system and its ductwork.  Some of these issues can be addressed at installation, while the others should be dealt with at system start-up, when the power is turned on. 
    • Installation Stage:
    • Ductwork: It is imperative that all seams and connections are sealed with bucket mastic.  Please provide all HVAC contractors with the SystemVision Duct Sealing How-To Guide to ensure that the system is sealed properly.  Areas that are often overlooked and cause problems with duct leakage include:

      • Splices and collars in a duct need to be sealed with bucket mastic.
      • Panned return boxes that use house framing to complete the return box are not recommended. However, if they must be used, the seams between the sheet metal and framing must be sealed with bucket mastic.

      **Tip**: To avoid failing a final inspection because of duct leakage, it is recommended that the ductwork is installed by the insulation inspection. The ductwork can then be tested and any issues can be resolved before the final inspection.  This will help prevent failed final inspections.

      Outside Air:  SystemVision homes are built tightly, so it’s necessary to have proper mechanical whole-house ventilation. Please provide all HVAC contractors with the SystemVision spec sheet.  Key concerns with the fresh air duct include:  installing a manual damper, a filter that is accessible to the homeowner, an insulated duct with a diameter of at least 6” ,installing the outside air intake at least 18” above grade or the roof deck and at least 10’ from any exhaust termination.

    • System Start-up Stage:

    Outdoor Thermostat:  Heat pump systems must have outdoor thermostats installed to lock out second stage strip heat above the system’s balance point (typically 35-40˚). Please read the HVAC Specifications sheet for more information.

    Sealing the Air Handler:  The last step in ensuring a tight air distribution system is sealing all seams and penetrations on the air handler. A typical air handler may leak more air itself than is allowed for the entire system. Yet, while these holes must be eliminated, your HVAC contractor must also be able to open the air handler panels for servicing. Therefore, this is the one location in the system which should not be sealed with bucket mastic. The air handler doors must be sealed with UL rated tape.

  • Final Items: The following items are important to the overall function of the home and must be completed to pass a final inspection:
    • Is 100% of the crawlspace covered with a poly vapor retarder?
    • Is the attic hatch insulated? (must be attached)
    • Have insulation dams been built-up around the attach hatch to protect the attic insulation?
    • Has weather-stripping been installed around the hatch to form a tight seal?

Homeowner Corner: Thermostat Setbacks, Dan Lutz

There is a lot of information in the market place about the reported energy savings of “setting back” your thermostat—that is, lowering the setting on your thermostat when you leave for work or go to bed for the night.  Unfortunately, the information out there varies widely.  Do a quick Web search on “thermostat setback” or “programmable thermostat,” and you will be told both that you can save more than 30% on your utility bill and that you will save no money at all.  The bottom line is that there are energy savings to be had by implementing a “setback” strategy, but it is important to use the right strategy based on the type of system installed in your house and to understand the potential consequences.

A Word of Caution about Heat Pumps

Many homes in North Carolina, including many SystemVision homes, are heated with heat pumps.  If your heat pump is not set-up to implement a “setback” strategy, you can actually use more energy by adjusting your thermostat too much.  This has to do with the way heat pumps work. 

Instead of burning gas or oil to produce heat, a heat pump uses special liquids, called refrigerants, to remove heat from the outside air and put it into the house.  Think of an air-conditioner running in reverse.  Even when it is fairly cold outside, there is some heat in the air. The heat pump moves this heat out of the outside air and into the house.  As the outdoor temperature falls, there is too little heat outside to effectively heat the house, so most heat pumps have back-up heat strips or auxiliary electric resistance heat. Like the electric coils in a toaster, the heat strips supply the extra heat needed when the heat pump cannot keep up.

While heat pumps are very efficient, electric resistance heat (the heat strip) is not. Heating the house with the heat strips costs two to three times as much as heating with just the heat pump.  It is like heating your house with your oven—not a good idea.  Typically, the heat strips will come on any time the thermostat is raised more than two degrees.* To effectively implement a “setback” strategy with a heat pump, you will need a programmable thermostat designed especially for heat pumps. This will bring the temperature up gradually, so the strips do not come on.

If your house is heated by a gas or oil-fired furnace, you will not have this worry.  Your furnace is essentially on or off.  If you adjust the thermostat one degree or five degrees, you still get the same output at the furnace.  Therefore, a programmable thermostat is not a necessary component of a “setback” strategy for a furnace, though having and properly using one will make it easier. 

Know the Risks

All homes are a system.  Changing one thing in the house affects the system as a whole.  This rule is no different for thermostat setbacks.  Thermostat setbacks have the potential to reduce house comfort and cause condensation on building components.  In the mornings or after work, as the heating system is working to return to the preferred temperature, there may be a window of time when the house is uncomfortable.  This is especially so for a heat pump, since they heat the house more slowly than a furnace. 

Likewise, as the house cools down during the setback period, it is possible that building components could get cold enough for water to condense on them.  This is most likely to happen on windows on a really cold day.

What about Cooling?

If a “setback” strategy works during in the winter, what about a “set forward” strategy in the summer?  The same principles apply—using your HVAC system less will use less energy, thus saving money.  However, discomfort can become a more significant issue.  On the hottest days, it may take three or more hours for your house to recover from the “set forward” period.  That is a long time to be hot, especially in August.

There is a compromise.  Both energy savings and comfort can be improved simply by permanently keeping the thermostat at a higher temperature in the summer.  It makes sense—the air conditioner is having to remove less heat from the house and therefore runs less.  Also, there is not a prolonged recovery from the “set forward” period.

As mentioned above—know the risks.  Keeping the house at a higher temperature may be too uncomfortable for some people.  Also, since the air conditioner will run less, indoor humidity levels will increase, adding to the level of discomfort.1

1  “Thermostat Setbacks—Do They Really Work?” Marianne Armstrong.  Home Energy Magazine.  Nov/Dec, 2008. 

  *This is why SystemVision houses with heat pumps are required to have an outdoor thermostat installed.  This simple device prevents the heat strips from coming on when the heat pump alone can meet the heating demand—typically below 38 degrees.  This prevents the heat strips from coming on most of the time.  However, this device will not prevent the strips from coming on when the temperature is below the balance point and the call for heat is more than 2 degrees. 


Beyond SystemVision: Closed Crawl Spaces, Lauren Westmoreland

In the SystemVision program, we come across several foundation systems – anything from slabs on grade to basements to piers to crawl spaces. Crawl spaces are quite common here in the Southeast; many of you find these typical wall-vented crawl spaces to be the most functional and cost-effective – especially important in the affordable housing market.

While the initial functionality and affordability of wall-vented crawl spaces is helpful for the developer or builder, there are several potential problems down the road for homeowners. These problems could include:

  • Mold or moisture damage in the crawl space or living area
  • Musty odors and/or high humidity in the living area
  • Condensation ("sweating") on air conditioning ductwork/equipment insulation, water pipes or truss plates in the crawl space
  • Buckled hardwood floors
  • High humidity in the living area
  • Insect infestations

One solution to these problems is to build a closed crawl space. While not a requirement for SystemVision, Advanced Energy considers a closed crawl space a best practice. If installed correctly, these spaces can lead to healthier and longer lasting homes. There are 6 categories in which Advanced Energy’s closed crawl space design recommendations focus on. They include moisture management, pest control, combustion safety, thermal insulation, fire safety and radon. We are happy to provide a resources for those interested in the details:

“Closed Crawl Spaces – An Introduction for the Southeast” located at www.crawlspaces.org. It provides envaluable information on closed crawl spaces as well as installation factors.

Many of you are probably wondering if anyone is actually doing this in the affordable housing market. The answer is a definite yes! We have recently seen closed crawl spaces under houses with Habitat for Humanity of Greater Greensboro. In addition, Advanced Energy had the opportunity to collaborate with Chatham Habitat for Humanity earlier this year and Habitat for Humanity of Durham late last year on the installation of closed crawl spaces.

From these experiences, we were able to gain insight into the closed crawl space process and how it might be different for a Habitat for Humanity (for example) than a for-profit builder who can hire a professional. Here are some construction tips:

  • Leave vent openings in the foundation perimeter wall to provide option for ventilation with outside air during the construction process.
  • Install a passive radon mitigation system during construction in case the completed house has elevated radon levels.
  • Establish exterior grade sloping away from foundation as soon as possible and interior grade sloping to one (or more) low spots. In addition, establish an interior grade that is equal to or higher than the exterior grade.
  • Put in temporary (4 mil or greater) polyethylene ground cover sooner so that the dirt floor doesn’t get saturated by rain before floor deck is on and/or house is dried-in.
  • To keep the crawl space dry during the construction period, try using a dehumidifier during humid periods and outside air during dry periods.
  • If there is mold to clean up during the install process, you can use a mix of borate and water or other standard cleaner (we do not recommend using bleach). If desired, you can use an encapsulating paint with anti-fungal properties to both kill and hide the mold.
  • Add a laminated sign to the closed crawl space after it has been installed. The sign will clarify to any contractors who enter the crawl that it is intended to stay as is – and demand that they do not damage the liner or add any penetrations through the vents, etc.

This might be a new process for many of you, but do not feel as if you are in this alone.  If you are considering a closed crawl space, we urge you to look through the “Closed Crawl Spaces – An Introduction for the Southeast” at www.crawlspaces.org. In addition, there are several other references and studies on our website which are all informative. If you still have other questions, please contact us here at Advanced Energy; we will be more than happy to discuss the benefits and installation process with you.


Statewide Specialists

As always, thanks go out to our building performance specialists across the state! They serve as an excellent local resource for your building science questions. Advanced Energy is always here for your SystemVision needs, as well as the building science specialists listed below:

SystemVision Scheduling Hotline: 866 936-2784

Asheboro

Adonai Building Science Services

336 626-8259

Asheville

Southern Energy Concepts

828 279-6723

Boone

Building Performance Engineering (formerly known as Southface Boone)

828 265-4888

Charlotte

Green Home Solutions (formerly Environmental Building Solutions)

704 849-7795

Charlotte

Southern Energy Management

704 631-8346

Lewisville

Energy Solutions

336 463-2005

Raleigh

Advanced Energy

919 857-9000

Raleigh

Southern Energy Management

919 341-8463


Feedback

We would love to hear from you.  If you have any questions or comments about the SystemVision program, specs, guarantee process, please go to our website to access new participant tools.

Contact Krista Egger

Affordable Housing Programs Manager
919.857.9000 | kegger@advancedenergy.org

Also visit www.systemvision.org to find:

  • Standards
  • Workshop dates
  • Plan review input form
  • Air sealing, insulation and duct sealing tips
  • Homeowner bill tracking tool
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