Download Dalrymple Blower Door Test Results

3883 Route 30 (PO Box 457)
Jamaica, VT 05343
Ph: (802) 874-7222
Blower Door Test Results and Findings:
Introduction:
The blower door is a valuable tool to the energy auditor and is used to quantify air leakage in
buildings. The process is quite simple and involves sealing a large fan into an exterior doorway.
The fan is connected to a digital monometer that reads pressure and airflow. The pressure gauge
is set up to read building pressure relative to outside air pressure, and the flow is measured by
connecting an air hose between the fan and an input tap on the monometer that measures airflow
in cubic feet/minute @ 50 pascals (cfm50).
Once set up a building can either be pressurized by blowing air into the house, or depressurized
by pulling air out of the house. The most common method used by an auditor is to depressurize
a building 50 pascals relative to outside air pressure. After pressure is stabilized by either
reaching 50 pascals, or by maximizing the exhaust capability of the fan, the air flow is recorded.
This air flow measurement is exactly equal to the amount of air coming into the house through
air leaks in the building envelope.
Once the airflow is recorded a number of important ventilation calculations can be made, the
most important of which is determining the difference between the actual air exchange of the
house, and the standard for adequate ventilation of the structure. This standard is prescribed by
the American Society of Heating and Refrigeration Engineers (ASHRAE) and is referred to as
the Building Tightness Limit (BTL).
Blower Door Results
Building Depressurization:
-12.5 Pascals
Air Exchange: 16000 cfm50
Airflow measured through the fan during depressurization totaled 16000 cfm50. This air
exchange rate is extremely high and is slightly more than 3.5 times the rate required by
ASHRAE's ventilation standards for buildings. The minimum air exchange rate (BTL)
converted to cfm50 for the building is 4,500 cfm50. The excess air exchange in the building
represents a hole in the thermal boundary approximately 1,150 square inches in size.
Reducing the high air exchange rate should be one of the primary focuses of any remediation
work and will significantly increase comfort and reduce energy consumption. As a result many
of the recommendations made in this report are directed towards reducing air exchange. It is
important however, to consider how various building components are connected and that in
many cases one problem may not be solved without first addressing another.
Solutions and Recommendations
Upper Thermal boundary and attic areas:
The greatest reductions in energy consumption in Dalrymple will be attained by making
improvements to the air barrier and increasing thermal insulation levels along the upper thermal
boundary of the building. Many improvements to the buildings heat retention characteristics
have been made over the years, and the attic areas are no exception. These improvements
however, were not conducted recently and as a result do not reflect today's energy prices or the
likely higher energy costs of the future. Much of the work to improve efficiency was focused on
adding additional insulation. Simply adding insulation without first conducting aggressive air
sealing work will result in less than satisfactory results. Furthermore, the cellulose insulation
used at the time the building was insulated contained sulfates for fire suppression. These
sulfates, when exposed to moisture will create sulfuric acid that can corrode any metal such as
wiring, nails, and other metal building components. Cellulose treated with 100% borates as a
fire suppressant should be used on all historical buildings.
Due to the sulfur content in the previously used cellulose, and the need to effectively air seal the
flat attic areas of the building, Thermal House recommends removing all existing cellulose
insulation from the building. This can be accomplished by utilizing a commercial grade gas
powered vacuum. The vacuum can be located outside of the building. Large dust free bags are
placed inside a dumpster and a long vacuum hose is brought inside the building allowing the
insulation to be removed without creating substantial dust or disruption to the daily activities
within the building.
Once the insulation has been removed air sealing can take place. Air sealing will involve
plugging all air leakage pathways connecting the conditioned space of the building to the attic
areas. Plumbing and wiring penetrations will be sealed using expandable foam insulation. Rigid
foam board insulation will be used to block off the slanted ceiling sections, and caulking will be
used to seal interior wall openings. Weather stripping and rigid foam board will be used to
create airtight and insulated attic hatch openings.
After thoroughly air sealing the upper thermal boundary dense pack cellulose will be installed in
the slanted ceiling sections, and loose fill cellulose will be applied to the flat attic areas. The
goal for treatment of these areas will be a decrease of 50% in air exchange, and an increase in
thermal performance of R-50 on all flat attic areas, and R-30 along all slanted ceilings.
The areas behind the knee walls along the fourth floor will be incorporated within the thermal
boundary. All existing insulation will be removed from the roof slants, and 6" of spray applied
closed cell foam will be applied from the top of the knee wall to the third floor upper exterior
wall plate. The gable end wall sections behind the knee walls will be insulated with 6" of open
cell spray applied foam, and all knee wall gable end vents will be permanently sealed. The work
behind the knee walls will not only significantly reduce heat loss, but will improve heating
system distribution efficiency by bringing the heat pipes within the thermal boundary.
Basement/Crawlspace and Combustion Appliance Zone:
Effective moisture management must be a top priority whenever significant reductions in air
exchange are incorporated in the work scope. This is especially true when working on historical
structures. Point sources of moisture such as the section of the basement where the old cistern is
located should be effectively sealed off from the building. The best way to accomplish this
would be to incorporate an internal drainage system that diverts all incoming water into a sump
pit, where the incoming water is then pumped out of the building. All exposed dirt would be
covered by a vapor barrier and sealed to the exterior walls. These walls could then be sealed and
insulated using a high density spray applied closed cell foam. The cistern would need to be
retrofit with an air tight water resistant cap that would eliminate water vapor from escaping into
the air.
Benefits of these improvements would include: effective moisture control, reduction in air
infiltration through the porous stone foundation, and decreased conductive heat transfer through
the un-insulated foundation walls.
For health and safety reasons, as well as improving energy efficiency the combustion appliance
zone should be isolated from the building. All air pathways connecting this are to the building
should be effectively sealed, and outside air should be ducted directly to the boiler. Depending
on the burner type, it is likely that an aftermarket outside air boot is available for the burner. If
not, ductwork from the outside can be vented into the area to supply necessary make up air for
the heating system. This improvement will help to reduce negative pressurization of the lower
floor area which in turn will reduce air infiltration. Furthermore, it will allow the building's air
exchange rate to be lowered without impacting combustion draft.
* Sizing of makeup air must be in strict conformance with manufacturer specifications.
Windows:
The majority of windows in the Dalrymple building are single pane glass windows that lack an
effective air seal. The thermal performance of these windows can be significantly improved by
adding weather stripping where needed, and tightening up the sashes. All loose or broken panes
of glass should be replaced, or re-glazed, and sash locks may be installed to secure any sashes
that are loose in the jambs.
Other than improving the air tightness of the existing windows, a strategy should be developed to
improve thermal performance by utilizing interior storm panels, insulated window shades
and/window quilts. The numerous southern facing windows that provide significant light and
potential for winter time solar heat gain should be retrofit with insulated interior storm panels. It
is important that custom made, and tight fitting panels be used to reduce condensation and
deterioration of the window sill and lower sash. Several custom made, but poor fitting interior
storm windows have been installed in the building already, and there is evidence of window
deterioration, most likely due to the formation of condensation over the heating months.
All northern exposure windows should first be air sealed as previously described, and then
equipped with insulating window quilts. Insulated window quilts have a significant ability to
reduce heat loss through windows. The only drawback is that they must be pulled closed when
light through the window is not required.
The eastern and western facing windows should undergo the same air tightness retrofit work, and
depending upon the amount of available light they offer, either an insulating energy panel, shade
or window quilt should be installed.
General Air sealing/Blower Door Directed Air Sealing
Significant blower door directed air sealing can be conducted along the exterior wall sections of
the building. The infrared images which capture numerous air leaks through the building
envelope can be used as a guide to effectively reduce air exchange. Weather stripping, caulking,
backer rod, and expandable foam insulation will be used where appropriate to seal openings to
the outside.
Exterior Walls
Currently there is a mix of old fiberglass and cellulose insulation in the exterior wall cavities of
the building. Adding dense packed (3.5#/cubic foot) cellulose insulation will not only improve
R-value, but will greatly help to reduce the buildings high air exchange rate.
The procedure would involve removing several rows of clapboards along the exterior facade at
each floor level. Once removed a 2" hole would be drilled through the sheathing and a wall tube
would be inserted into the wall cavity. Each stud bay would be dense packed with cellulose
insulation, the holes in the sheathing would be plugged, and the clapboards would be refastened
to the walls. Any damaged clapboards would be replaced with historically correct material.
Reducing electrical consumption:
See general improvements.
Alternative energy source potential
The excellent southern exposure of Dalrymple lends itself well to the incorporation of solar
energy. Either photo voltaic generated electricity or solar hot water are excellent options for
future consideration. The large cistern located underneath the building could be incorporated
into a solar hot water system and used as a storage tank. The tank could be super-insulated with
spray applied foam to efficiently store hot water. Hot water generated from this system could be
sued for both domestic hot water and heating of the building.