|
Home performance Diagnostics.
Below is a quick
summary of an audit
with the focus on basic techniques
Diagnostics start with a
comprehensive survey if the home, documenting obvious issues such as
clogged gutters and leaders to less obvious issues as leaky gas
plumbing. Gas leaks will be found by using a "combustible gas analyzer"
by tracing about every inch of visible gas pipe, in the building and
out. Any leaks found MUST be repaired before any work commences.
Early in the Comprehensive
Home Assessment (CHA) an accurate drawing of the home is needed to calculate
square footages and volume, to document insulation values, window and
door performance etc.
CO readings will be taken during the CHA and acted on by using BPI's
action tables listed in the BPI Building Analyst standards. CO readings
will be taken using an electronic carbon monoxide detector, which can
read down to 1 part per million.
After a survey of the home
we would decide if it is safe to check the infiltration of the home
using a blower door. Possible reasons for NOT using the blower door
would be deteriorated asbestos to an active fireplace.
From the earlier
measurements, the "building air flow" will be calculated.
From the building analyst standards ,
.35 x volume / 60 = Building Airflow Standard
OR
Occ x 15 = Building Airflow Standard
Whatever provides the
larger number will determine the method and result. At this point the
Blower door frame would be installed, the equipment zeroed, and the
house would be gently depressurized to -50 pascals.
Once the building is depressurized the real fun begins.
- Readings would be taken from a tool that give measurement's in
pascals.
These readings can be converted to a natural infiltration rate. (natural
meaning while the building is not under pressure.
For
example, 2500 cfm50 might translate to 172 CFM natural. (The cfm50
implys while under negitive 50 pascals.
To continue with this example we will use a home with 10,500 cubic feet
and with 3 bedrooms.
Method 1, 10,500x.35/60= 61 CFM natural
Method 2, 4occx15=60cfm natural.
Building Analyst standards say we use the highest of the two methods,
61 CFM is the building airflow standard (BAS).
The next step in this example would be to subtract the natural measurment
from the BAS to find the exact CFM over what is needed. 172-61 = 111 CFM over the BAS.
In this example home, on average, will leak 111 cubic feet of warm air
to outside conditioned space.
Some days it will leak more, some days less. To find out how many BTUs of
heat are lost we would
111 x 1.08 x 24 x 5500 x .75 = 11,868,120 btu's.
This example shows us that the house has an excess of 111 cu ft of
ventilation, at the very least we could try to stop 111 cubic feet of
heated air from escaping every minute of every day !
Ultimately we want to stop all infiltration/exfiltration and install an
ERV (Energy recovery ventilator) or HRV (heat recovery ventilator) to
provide adequate ventilation.
- Diagnostic tools as simple as a smoke pencil to thermal imaging would
now be used to locate large air leaks into the home.
- Zonal diagnostics should be used to determine how connected rooms are
to the outside. Zonal diagnostics are preformed with a second manometer,
that would be used to measure the difference in pressure between the main body of the
home and rooms while the doors are shut. A large pressure difference
between a closed door would indicate connection to that room with the
exterior. No pressure difference or a low reading would indicate little
to no connection to the exterior.
Other testing might include a duct loss test. More info on ductblaster
or duct testing can be found
here
Combustion Safety testing
should be done. During a combustions safety test we will look
primarily in a CAZ zone, or combustion appliance zone for eminent
failures. As heat rises in your home, the space in a typical boiler room
is being depressurized. We try to re-create the worst possible
situation where a cloths dryer could be running, maybe an exhaust fan
over the cook top is on. All of these "power venting" devices will
compete with a typical boiler or furnace flue and can cause a back draft
of the furnace flue. We
would certainly test for this and many other issues.
There are many other tests,
so many in fact that we have an 8 page type written sheet listing all
of the "standard" items to look for.
Ultimately we would find the
most cost effective, energy saving measures and prioritize repairs.
This would be considered our scope of work. The home owner can always
adjust the scope of work to satisfy there own wishes. The only time we
would not be able to adjust how things are done is if there were health
and safety issues that BPI standards dictate be addressed first.
If your interested in having
your home tested, to see where and how much you might be able to save,
call or email us !
rec-hers@optonline.net
Residential Energy Conservation
3771 Nesconset Hwy
Suite 101A
S. Setauket NY 11720
631-751-7911
|
