Building America Industrialized Housing Partnership
TRIP REPORT
Southeast Texas – 8/21/01
Energy Star, Manufactured Home Certification

DATE
September 18, 2001

ATTENDEES
David Chasar, Bob Abernethy - FSEC

PURPOSE

• Audit and test home to determine Energy Star certification.
• Verify compliance with Energy Star Manufactured Home Site Installation Checklist.

DESCRIPTION

• 4Bd / 3Ba home with 2,356 Sq Ft conditioned floor area
• Crawlspace was not skirted in the traditional fashion – siding installed to ground level
• Ground cover – monolithic concrete slab throughout crawlspace (see picture)
• Ducts are located in the attic including the crossover connection
• 4 ton Nordyne heat pump (12 SEER / 7.6 HSPF)
• Ventilation provided by whole house exhaust fan
• Water heater is a Seisco tank-less instant hot water unit

OBSERVATIONS

• The home passed all Energy Star certification guidelines
• Two porches were added to the South and West sides providing 10 foot overhangs for those windows
• No significant belly tears were found during a crawlspace inspection however pressure diagnostics showed the belly zone to be in much better communication with ambient air than with the inside of the home.
• HERS score – 88.6 (obtained with Energy Gauge USA v1.24)

TESTING

Blower door test

A blower door test was done to determine the airtightness of the building envelope.  A series of building pressures and associated airflows was recorded.  This provides the necessary inputs to determine the CFM50 of the house.  The ACH50 and natural air infiltration rate (ACHnat) were calculated from site-specific information about the home (volume, climate, etc).

The values of C and n can be used as inputs for the house airflow equation, Q=C* Pⁿ .  Thus, for any given pressure difference,  P, the airflow crossing the building’s envelope can be determined.

In addition to the standard blower door test, pressure differentials were measured across the marriage wall and belly planes with respect to the building interior. These were taken to determine the relative connection of these areas to the ambient environment. With the house depressurized to 50 pascals, a zone well-connected to the house will have a low pressure reading approaching zero and one that communicates more with the outside air will have a higher reading approaching 50.

Duct test

A duct system airtightness test was also completed.  A duct tester was attached to the air handler unit.  The supply registers were temporarily sealed off and the system was then depressurized to 25 pascals.  The total and outside leakage flow components were measured.  The Qn value was calculated by dividing the CFM25_out leakage by total conditioned floor area.

Duct System Airtightness

CFM25total  = 115

CFM25out   = 45 Qn  = 0.019

Pressure diagnostic testing

Pressure differential measurements were completed to determine a magnitude and direction of flow across the envelope when the air handler fan operates.  Interior door closure effect was also measured when the air handler fan operated.

Pressure Diagnostics w/ AHU (Note: moderately windy conditions)
Condition	Pressure differential (main wrt outside)
All fans off	0.0 pa
AHU on	-0.4 pa
AHU on & all interior doors closed(except util.)	-1.1 pa

The pressure difference was also measured across each closed door when the air handler fan was operating (all supply registers were open and exhaust was off).

Pressure across closed doors	Pressure differential (room wrt main)
Master bedroom	+2.4 pa
No. East Bedroom	+2.0 pa
So. East Bedroom	+1.8 pa
South Bedroom	+2.8 pa

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PICTURES