Even Small Jobs Affect the Whole House

When remodeling a house, take into consideration that the windows, walls, roof, foundation, ventilation, heating, cooling, lighting, and cooking are all related. Understanding how systems work together is more important now than ever.

April 30, 2008
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Always remember to slope finished grading 
away from the foundation.
Photos courtesy of PATH Partners

It’s not unusual for a good sports team to do OK, then trade for a blue-chip star to take them to the playoffs. Instead of a playoff run, the team tanks.

It’s proof that one good piece doesn’t always improve the whole.

It’s the same with a house, whose skin and bones work together as a system. The windows, walls, roof, foundation, ventilation, heating, cooling, lighting, and cooking are all related. Understanding how systems work together is more important now than ever, because energy prices are through the roof and construction and product tolerances are geared toward saving energy. Homes are tighter. Mechanical systems are more precise.

It’s not just about matching the components. In an integrated, whole-house system, everything must be installed and hooked up properly so its effects on the rest of the home, both good and bad, are predictable and controlled.

A house that works as an integrated system is not only more efficient, it’s more comfortable — free of drafts, mold and “too-something” (too hot, cold, uneven, humid, dry or stuffy) rooms. It costs less to condition the living space, and the home is healthier and easier to maintain. Customers are happy and glad to be the remodeler’s reference for future work.

What to Consider

Just because a project you’re working on only directly involves one or a few systems doesn’t mean that you can ignore the rest. In any home, these nine components are too closely interrelated to ignore how they work together:

Stormwater management. A new addition, a pop-out and even a new type or configuration of roof can affect water intrusion. Proper stormwater management controls moisture problems that come from outside the home. Don’t forget to regrade as necessary so water flows away from the home. Incorporate a capillary break over the footing, perimeter footing drains, and drainage planes for walls. Appropriate flashings are a must.

Proper framing practices. Easily implemented changes to traditional stick building practices can improve the envelope considerably. Use engineered lumber or even panelized prefabricated walls. Both tighten the building because tolerances are tighter. Another minor innovation, advanced framing, allows more insulation, uses less material and takes less time. The improved air sealing and insulation resulting from these practices means the heating and cooling systems can be sized smaller. The result is better moisture management and energy performance.

Interior water vapor management. Properly installed interior air barriers avoid moisture problems. Don’t forget to install air barriers in crawl spaces; tubs and showers; fireplaces; dropped soffits; and floor systems’ interior to rim joists. And remember that ventilation fans — and fan control — are important in bathrooms and the kitchen. Local ventilation affects the home’s bulk ventilation system and the associated air handlers.

Seal penetrations to keep conditioned air in and varmints out.

It is easy and cost-effective to add Low-E storm windows rather than replace the entire window, especially when aesthetics aren’t a consideration.

Insulation only performs to its R-value (i.e. insulation level) if it is properly installed. Fiberglass batts that have been crushed and compressed into the wall spaces or that are not backed up with proper air barriers — thus allowing outside air to pass around or through the insulation — will not provide optimal thermal control. In such cases, HVAC systems have to work harder and consume more energy to keep a home comfortable. The home is less comfortable because it’s draftier.

Good, tight construction. As with insulation, a leaky house will unnecessarily tax an HVAC system and can lead to drafts from leaks or oversized air handlers. It's always good to run a blower door test, which identifies how large a cumulative “hole” is in the home based on how many air changes per hour (ACH) naturally occur. [Note: The International Energy Conservation Code (IECC) targets 0.35 ACH. High performance homes aim for .22 ACH.]

Windows should have the right U-value (insulating value) and solar heat gain coefficient. These values vary depending on climate. Ample, properly located windows provide good daylighting so less artificial light is required. They also provide free solar heating. Without daylighting, some rooms will be too dark during the day or difficult to heat or cool. Find recommended U-factors and SHGCs at www.energystar.gov and click on “Products,” then “Windows.”

Mechanical ventilation is key to providing fresh air for healthy, comfortable homes. Ventilation requirements vary for kitchens, baths, bedrooms and general conditioned spaces, yet these spaces are all interrelated. Ventilation components must be sized to properly ventilate the local space without overwhelming the whole-house supply system. They should also be quiet and easy to operate, either by easily accessed switches or automatic timers, to make sure homeowners use them properly. Choose Energy Star-qualified fans for superior energy performance and quiet operation.

Right-size the new HVAC system to handle 
the loads of the remodeled home.

Combustion appliances must be direct- or power-vented directly to the outside — NOT near the intake for the home’s ventilation system — or the appliance must have sealed combustion. Otherwise, the home can develop two serious problems: 1) inefficiently operating combustion appliances due to inadequate fresh air supply; and 2) a build-up of poisonous carbon monoxide. Again, the tightness of the home’s construction and ventilation of combustion appliances are interrelated.

HVAC and ductwork. Properly size the HVAC and ductwork, then seal the ductwork. Size and design ducts using ASHRAE Manual J and D calculations. Rule-of-thumb sizing doesn’t work because the home’s solar orientation, windows and insulation can make a big difference. Insulate the outside of a duct when it is located in an attic or outside wall. Leaky or inadequately insulated ducts greatly diminish energy efficiency and comfort and, as with other poorly designed systems, unnecessarily overwork HVAC equipment.

Prove It with Performance Testing

So how do you show the owners that you’ve left them with a truly efficient home? You can wait to see how happy they are with their upgrades, but more immediate proof of the house-as-a-system approach is available from performance testing. Energy raters use scientific methods to determine the energy performance of the home. You can either hire a rater to do the work, or learn how to do it yourself.


Author Information
Glen Salas writes about better building practices on behalf of the Partnership for Advancing Technology in Housing (PATH). PATH is administered by the U.S. Department of Housing and Urban Development. Learn more at www.pathnet.org.

 

Resources

Useful resources for your project:

  • Storm management: Find proper grades and drainage requirements in PATH’s report, Durability by Design. Visit www.PATHnet.org and click on “Publications.”
  • Proper framing practices: Visit www.Toolbase.org and click on “Technology Inventory,” then “Whole-House Systems.”
  • Insulation: For guidance on proper air barrier installation, visit www.energystar.gov and search for “Thermal Bypass Checklist Guide.”
  • Insulation: Find proper insulation values at www.energystar.gov. Click on “Home Improvement,” then “Air Seal and Insulate.”
  • Performance testing: Find out more from Energy Star. Visit www.energystar.gov and click on “Home Improvement,” then “Home Performance with Energy Star.” To learn about training, visit the Building Performance Institute at www.bpi.org.

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