Cardinal Homes Energy Star Performance Testing:  To benchmark Energy Star performance levels for the modular home industry, certified energy raters, guided by an FSEC researcher, performed energy tests on four modular homes produced by Cardinal Homes in Wylliesburg, Virginia.  Each of the four homes was tested for airtightness and duct leakage.  In addition, a pressure pan test was completed on one of the four homes.  Cardinal was chosen for this research because of their interest in becoming an Energy Star Home producer.

Initial energy performance, using peak load indicators, found:

• Peak loads for heating were almost double that for cooling.
• Ducts accounted for the largest peak load on the homes, averaging 28% in the winter and 21% in the summer.
• All four homes had leaky ducts.
• Infiltration accounted for about 26% of the peak load in the winter and 9% during the summer. 
• Window peak load contributions also were significant at 13% in the winter and 15% in the summer.

Approaching Energy Star status in a cost-effective manner was a top priority for researchers.  Given that, the architectural design of the homes remained unchanged and energy improvements were added cumulatively until reaching an Energy Star level of performance (HERS score of 86).  Heating and cooling equipment upgrades, as well as programmable thermostats, were considered options to enhance energy performance.  Air infiltration rates were set to achieve 3.5 ACH at 50 Pa - considered a reasonable expectation for houses of this type.  Marriage gasket protocols were reviewed to determine ways to assure proper installation and site setup. Expanding foam was evaluated for sealing outlets, floor and wall plumbing penetrations in tubs and showers, and to supplement gaskets.  This supplementation could reduce the physical gasket compression required during manufacturing set.  To tighten ducts, mastic was considered for sealing joints, small gaps, and other points of leakage.  Additional insulation was examined as a way to reduce duct infiltration, and plenum redesign was investigated as a way to provide a more consistent quality return air system.  Mastic and fab-glas were evaluated for plenum repair use.

• Home 2 and Home 4 required additional duct insulation to reach Energy Star.
• Home 1 and Home 2 required improvements in heating equipment to achieve Energy Star.
• Home 2, which had twin low efficiency electric heat pumps, was unable to cost efficiently reach Energy Star with upgraded systems.  But, replacing the heat pumps with a conventional central air (SEER 10) and a high efficiency propane furnace (AFUE .90) did allow this home to reach Energy Star.  Though this Energy Star option is more efficient from an energy usage standpoint and is cost effective when compared to the current heat pump system, it may not be the best option from the homebuyers's financial standpoint.  The energy savings is greater for the existing heat pump system - with the home and ducts tightened and a programmable thermostat ($164 per year) - than with the high efficiency propane gas furnace ($73 per year), even with the lower HERS rating (81.9 vs. 86.1).  This apparent anomaly is due to the high cost of propane ($1.40/gallon) per energy content, relative to electricity ($.083/kWh) or natural gas ($.68/therm) prices in the region. An alternative that better aligns energy ratings with homebuyers cost might be a high efficiency natural gas furnace, assuming the availability of natural gas in the area.
• Tightening both Homes 1 and 4 reduced the energy load and equipment costs by allowing HVAC downsizing from two to one and one-half  tons.  (Please see Tables 6, 7, and 8.

	Home 1			Home 2			Home 3			Home 4
Cumulative Improvement	HERS	Energy Sav/Yr	Cum Cost	HERS	Energy Sav/Yr	Cum Cost	HERS	Energy Sav/Yr	Cum Cost	HERS	Energy Sav/Yr	Cum Cost
current system	82.1	0	0	79.6	0	0	86.4	$0	$0	82.9	0	0
reduce infiltration	82.3	10	39	80.2	32	39	-	-	-	82.9	0	39
tighten ducts	84.4	130	167	81.9	103	167	-	-	-	84.7	114	167
programmable therm	85.7	202	217	83.3	164	217	-	-	-	85.9	184	217
increase duct ins	-	-	-	84.4	211	253	-	-	-	86.3	212	245
increase heating effic	86.0	215	339	-	-	-	-	-	-	-	-	-
reduce AC size	86.0	$215	$284	-	-	-	-	-	-	86.3	$212	$127
heat pump ÿ LPG	-	-	-	86.1	$73	$218	-	-	-	-	-	-

	Home 1		Home 2		Home 3		Home 4
	Current	Proposed	Current	Proposed	Current	Proposed	Current	Proposed
window area	22%	nc	14%	nc	14%	nc	13%	nc
window U-value	0.35	nc	0.35	nc	0.35	nc	0.35	nc
window SHGC	0.31	nc	0.31	nc	.31	nc	0.31	nc
attic insulation	R-30	nc	R-30	nc	R-30	nc	R-30	nc
exterior wall insulation	R-13	nc	R-13	nc	R-13	nc	R-13	nc
floor above unheated area ins	R-19	nc	R-19	nc	R-19	nc	R-19	nc
basement wall insulation	R-5	nc	n/a	n/a	R-13	nc	n/a	n/a
crawlspace wall insulation	n/a	n/a	none	nc	n/a	nc	none	nc
duct insulation	R-6	nc	R-4	R-6	R-4	nc	R-4	R-6
heat (furnace AFUE, HP, HSPF)	AFUE .80	AFUE .82	HSPF 6.8	AFUE .90	HSPF 9	nc	AFUE .90	nc
cooling SEER	SEER 10	nc	SEER 10	nc	14	nc	SEER 12	nc
programmable  thermostat	no	yes	no	yes	no	no	no	yes
water heating	EF .82	nc	EF .88	nc	EF .92	nc	EF .92	nc
infiltration ACH50	10.1	3.5	9.5	3.5	10	3.5	7.3	3.5
duct leakage (cfm25out/ft2)	13%	3%	10%	3%	12%	3%	14%	3%

*nc = no change  **ACH = air changes per hour