“We Just Figured that’s the Way New Homes Were”
The owners of one post-group study home told the testing contractor, “we just
figured that’s the way new homes were” as a summary lament about comfort
problems in their modestly sized two-story home. But these homeowners were
unhappy. During the market research interview and site visit, they reeled off a
lengthy list of complaints. On-site observations and results from diagnostic
testing identified contributing factors.
The problems:
- General discomfort. When the home was built, the panning beneath
main-level floor joists, intended to carry return air from upstairs down to
the furnace, was never installed. There was little or no return air flow
through intended channels. This code violation was discovered by the
contractor hired to install after-market air conditioning. The owners called
the builder, who returned to install the panning; comfort improved
immediately. (The bigger concern with this oversight was the danger of
backdrafting the furnace or water heater in the basement.)
- Difficulty controlling heating and cooling system. Equipment
oversizing was significant; the furnace and air conditioner were sized at 188%
and 225% of design requirements, respectively. Oversizing leads to
short-cycling, a contributor to discomfort. In addition, ductwork was very
leaky, and the return air registers on the upper floor together moved only 100
CFM of air (seven percent of the total air flow). The builder was aware of
some compromises with the return system design, but told the homeowner that
was the only way that it could be done.
- Master bedroom above garage “freezing” in the winter. For many
reasons, living space over a garage has high potential for comfort problems.
Though not all factors were checked in this house, two specifics were noted.
The insulation on the knee wall on the end of the master bedroom vaulted
ceiling was poorly installed, with significant gaps between adjoining batts.
The measured supply and return air flows serving the master bedroom were very
low. Based on observations in homes under construction, one can also speculate
that the insulation in the floor above the garage may have been compromised by
installation flaws.
- Basement “pretty chilly” during the winter. The husband had a
basement office where he worked part time; he estimated the winter temperature
ran about 5°F colder than the main level. The home had a single thermostat
and a reasonable amount of south-facing window area. So the main level heated
up nicely on cold but sunny winter days, while the basement slowly grew colder
due to lack of south windows and no mixing of air between levels during
extended non-heating periods. Also, the blower-door test indicated a
considerable amount of air leakage coming into the finished basement—much of
it through a 10-inch diameter combustion air duct.
- Entertainment center cold during the winter. Large air leaks were
noted around the entertainment center during the blower-door test. The
entertainment center sat on a cantilever extending out from the back wall of
the house; typical cantilever insulation and air leakage problems likely
contributed.
- Upstairs bathroom hot during the summer. A primary contributing
factor for this problem was a skylight above the bathroom ceiling, with a
shaft that was never insulated.
This is not what this young couple expected when they bought their new home.
Unfortunately, there is no one step the builder could take to solve this broad
range of comfort problems. To successfully prevent these situations requires a
systems approach: better detailing of the home’s air barrier, closer supervision
of insulation installation, improved ductwork design, sealed ductwork and more. |
