Introduction to Building Performance
Homes in the United States produce 21% of the
country’s emissions, which accounts for more CO2 emissions than
from autos and light trucks combined. Usually, homeowners don’t
realize that there is significant room for improving their home’s
energy efficiency and overall comfort, which would lower their
carbon footprint. Original construction and design flaws cause homeowners
to spend more money than they need to in order to keep a comfortable
home. The purpose of the BPI home energy audit is to identify areas
within your home that can be improved or upgraded to increase the
energy efficiency and total comfort of your home. We use both
diagnostic equipment and building science to determine areas that can be
improved and to identify the best solutions.
*REPORT EXAMPLE*
Throughout this report, we will address different aspects of
your home that contribute to energy loss and an uncomfortable
living environment. Test results will be presented, and technical terms
and concepts will be explained. Just a few of the areas addressed
include:
By taking part in this home audit, you are taking a step
towards living in a healthier, more cost efficient house.
Homeowner Information
Homeowner Concerns
• High utilities
• Uneven heating and cooling between rooms
Homeowner Wish List
• Create even air flow, heating, and cooling throughout the home
• Overall home safety, comfort, and efficiency
Energy Consumption
The graph above shows your utility costs throughout the course
of one year, which totals approximately $4511.68 for the year.
The yellow line represents your home’s average baseline
consumption, which includes lighting, water heating and general
day-to-day usages. Usage above this baseline is usually due to the
cost of heating and cooling the home, and we can calculate that it costs
roughly $2471.68 to run your HVAC system. Taking that figure, we
can determine that you pay approximately seventy two cents per square
foot to heat and cool your home.
Upgrading appliances to more energy efficient models can
help lower the baseline usage. Replacing incandescent light bulbs
with LED or fluorescent light bulbs will save energy, and
generally don’t need to be replaced as often. They also
produce less heat for your air conditioner to remove during the
summer.
Building Envelope Leakage
One common complaint within a home is the presence
of“drafts”. We completed a blower door test
to pressurize the house, which provided us with information about
the presence and intensity of drafts and air leakage. A healthy
home should have 0.35 ACH, which is the same as replacing 1/3 of
the house’s air every hour. A higher ACH means the house
is draftier than recommended, which wastes energy and brings in dirt,
dust, and outdoor contaminants. A lower ACH means that the house
is sealed tightly, and mechanical ventilation is recommended to
ensure healthy air.
Due to the extensive duct leakage throughout the duct system,
the home as a whole could not be pressurized to determine leakage.
In order to reach the recommended 0.35 ACH, the home needs to be sealed
to at least 3332 CFM50. Sealing the home tighter than this is still a
good idea, but at that point mechanical ventilation will need to
be added.
Insulation
Almost all homes have insulation of some sort, but are
usually under-insulated, or insulated with such low-quality insulation
that it is actually useless. Insulation has to be installed over
100% of a surface to be effective, as gaps and voids reduce the
effectiveness of the insulation exponentially. Upgrading insulation
R-values will usually have a dramatic effect on energy savings throughout
the year, as it will allow the home to stay cooler during the summer and
warmer during the winter.
HVAC System
Within most homes in California, heating and cooling accounts
for 30% of the total energy bill. These systems are usually
outdated, oversized, and inefficient. Having the system maintained and
tuned up every year or installing a high-efficiency and correctly sized
system can make a large difference in heating and cooling costs.
The current heating and air system is a 15 year old, 9.2
SEER package unit. This system should be replaced for efficiency
and safety reasons. When the HVAC system is replaced, ductwork
should be replaced as well, and re-routed for proper room
balancing. Once other efficiency measures have been taken, the
current system will be oversized, and can be downsized for proper
operation.
Distribution System & Duct Leakage
Having leaking ductwork not only lowers the efficiency of the HVAC
system, it can also negatively impact your indoor air quality and overall
home comfort.
- Efficiency: According to the US Department
of Energy, “You can lose up to 60% of your heated air before
it reaches the register if your ducts aren’t insulted and they
travel through unheated spaces, such as the attic or crawlspace.”
In the homes we test, we have found that most duct systems leak an
average of 30-40%. That is the equivalent of throwing away $0.40 for each
dollar you spend on heating and cooling!
- Air Quality: Ductwork is usually located inthe
attic or crawlspace, which can cause harmful indoor air quality. During
the winter months, the crawlspace usually gets damp, which combined with
the dark environment, encourages mold growth. Every time the heater comes
on, the leaking ducts can pull this damp, moldy air into the home!
- Comfort: A very common concern of homeowners is
that some rooms are too hot or too cold, and others don’t receive
enough air flow. Older duct systems don’t have dampers ,which help
balance air flows by room and direct heat where you want it.Fixing leaks
and installing dampers can alleviate most of these concerns.
Due to the catastrophic duct leakage throughout the duct
system, the ducts could not be pressurized to determine leakage. Large
rips and gashes are allowing conditioned air to escape the home. All
ducts should be replaced for maximum efficiency.
Photos of Your Home
 
Glossary of Terms
ACH Air Changes per Hour: The air-tightness of a home is
measured in ACH; the number of times the home’s air is replaced by
outside air in an hour. Air outside a building is constantly
infiltrating through cracks in a building’s shell and exchanging
with inside air. ACH is the measure of the rate at which this occurs.
Air Infiltration: Air infiltration is the unintentional
or accidental introduction of outside air into a home, typically
through cracks in the building envelope and when doors are open.
Infiltration is sometimes called air leakage.
Air Sealing: Air sealing is the process of sealing penetrations in
a building shell, which included the walls, floor, and ceiling
where outside air enters the home.
Baseline: This is the energy used other than that used for cooling
and heating your home. It typically includes energy used for water
heating, refrigeration, lighting and electronics. The baseline tends to
be fairly consistent year-round.
Blower Door: A blower door is a device used to pressurize the home
in order to locate areas of air infiltration and energy loss.
BTU; British Thermal Unit: The amount of heat required to
raise the temperature of one pound of water one degree Fahrenheit.
Building Envelope: The structural elements that separate
the interior and the exterior environments of a home. This includes
wall, roof, floor and foundation.
Phantom Load: A phantom load is the electric power used
by electronic devices which where are switched off or are in standby
mode.
R-Value: R-Value is the measure of insulation efficiency used
in the building industry. The bigger the number, the better the
insulation effectiveness.
Data Collection
Room by Room Air Flows
Accurate room by room air flows could not be gathered due to
the extensive damage to the ducts.
CAZ Testing Results
All combustion appliances passed all aspects of CAZ testing.
All CO levels are within safe and normal limits.
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