Opportunity Points for Deep Energy Reduction

When making major changes to a home, consider opportunities for energy reduction upgrades. It will be much more expensive to make the energy efficiency upgrades at a later time. Homes that need extensive renovation work present important opportunities for cost-effective energy savings. For most homeowners, major improvements happen infrequently in the life-cycle of a home.

When replacing windows, appliances and fixtures, make sure they are at minimum Energy Star rated and/or conserve water. Consider windows that are significantly more energy efficient than Energy Star windows.

When replacing mechanicals:

  • First put all focus on maximizing insulation values
  • Ensure that the furnace is not over-sized (based on improved insulation values you expect to implement)
  • Locate all HVAC equipment and duct work in conditioned spaces and remove any below-slab duct work
  • Remove duct work from outside walls when possible
  • Evaluate tank vs. tankless water heating and insist on direct vented, condensing units

When excavating to waterproof or repair a foundation, take the opportunity to insulate the exterior of the foundation. In some cases the foam may only make sense below grade (in line with the rubber used for soil flashing), but in other cases the greatest benefit may come from running the foam board all the way up to the bottom of the siding. This can be covered with, for example, stucco, vinyl coil, or fake brick.

When replacing siding, install a complete layer of rigid foam board along with a house wrap, to achieve a continuous thermal barrier over the entire building envelope and improve insulation and air sealing. It’s already typical for vinyl siding installers to use thin layers of foam for leveling. Two inches of added exterior rigid foam has been shown in Cleveland to have a reasonable payback.

When replacing a roof, don’t miss the opportunity to improve the performance level of attic insulation. With the right details, there may be great benefit to creating a fully-conditioned, well insulated attic by installing rigid foam board on top of the old roof deck (below the shingles). With enough rigid foam insulation, you can safely eliminate roof venting. Or if that’s not within your budget, take the opportunity to blow in loose fill insulation in sections that would otherwise be inaccessible.

When insulating an attic that is not conditioned:

  • Be sure that air sealing takes place first
  • Be sure that bath fans are properly exhausted to the exterior (not disconnected in the attic)
  • Consider the use of a pre cast Styrofoam hatch/access
  • Consider upgraded insulation levels if funds allow
  • If HVAC ducting is located in the attic, include this duct work in the conditioned space
  • When the furnace is located in the attic, consider the value of re-locating it (when it’s an option)

When faced with a gut renovation on the interior, but when the outer shell is in good shape, consider installing a layer of rigid foam under the drywall. Make use of the Energy Star thermal bypass checklist.

When installing plastic over dirt in crawl spaces or when pouring concrete for a basement floor, consider the benefit of rigid foam board as a thermal break (including at slab edges).

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