Building “Tight” Homes for Optimal Energy Efficiency
Today’s home efficiency standards are much more rigorous than they’ve historically been. In order to meet energy code requirements, builders need to be deliberate in their efforts to increase efficiency. At Tilson, we do this by constructing every home using techniques that create a tight thermal envelope.
You might ask, “what’s a thermal envelope?” That’s just industry-speak for every part of the house separating and protecting the inside living area from the outside world. (Think external walls, roof systems, windows, doors, air/vapor/weather barriers, insulation, etc.) When the thermal envelope is tight, the home will exchange very little heat or air with the outdoor environment.
How We Do It
Building a “tight” home is easier said than done, but with some forethought and know-how it’s completely doable. The reward for the effort is a home with incredible efficiency. As a homeowner, this translates to significant energy savings and lower utility bills. So how do we build a tight home? By controlling the free flow of air. This is accomplished by using numerous air-sealing techniques, including the following:
- Ladder tees at intersections between an adjoining internal wall and an external wall, in “T” fashion. This technique allows foam insulation to backfill what would otherwise remain an empty cavity if conventional building practices were used.
- California corners are built at external wall corners. Similar to ladder tees, this technique allows foam insulation into an otherwise inaccessible space.
- Polycell foam insulation is used around windows, exterior toe plates, and exterior doors. Micro gaps in these places allow unwanted air leakage. By sealing them with insulating foam, air exchange is stopped.
- Flashing tape adheres to a window opening’s head, jam, and sill. This technique helps to seal windows against weather and external air infiltration.
- Insulation is used to fill all external walls to complete the thermal envelope, keeping climatized air in and seasonal air out.
- Insulated headers are built using R3 foam sheathing instead of plywood spacers. This technique minimizes heat exchange with ambient temperatures outside.
Moment of Truth: Blower Door Test Scores
After completing a tight home buildout, building code requires the home to pass a “Blower Door Test” designed to determine how well-sealed the final home product actually is. The test consists of fitting a calibrated fan system to an external door and depressurizing the house. Readings will determine how much air is being sucked back in through all of the tiny nooks and crannies that you can’t see. Test results are measured based on how many times per hour the air in the home can be completely exchanged with outside air.
In Texas, the home must not exchange more than 3 to 5 air changes per hour (ACH). By comparison, when older homes are tested, they often score between 15 to 25 ACH. That’s a huge difference! It means that your cold, conditioned air is escaping into the hot Texas summer, which is why the A/C runs so much in older homes. A modern tight home avoids this air leakage, keeping your energy bills in check.
The Bottom Line
A home can be constructed of the finest material and quality. Still, if it isn’t purposely built from the ground up to have a tight thermal envelope, it will never reach its energy efficiency potential.
Interested to see more about our air sealing techniques mentioned in this post? If so, check out the latest Craftsmanship video of our Senior Vice President talking about the Tilson approach to building a modern “tight” home.
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