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Prairie Crossing Homes: Case Study Buildings for
the 21st Century
Buildings that are more energy-
efficient, comfortable, and
affordable . . . thats the goal
of DOEs Office of Building
Technology, State and Community
Programs (BTS). To accelerate
the development and wide
application of energy efficiency
measures, BTS:
Conducts R&D on technologies
and concepts for energy effi-
ciency, working closely with
the building industry and with
manufacturers of materials,
equipment, and appliances
Promotes energy/money
saving opportunities to both
builders and buyers of homes
and commercial buildings
Works with State and local
regulatory groups to improve
building codes, appliance
standards, and guidelines for
efficient energy use
Provides support and grants
to States and communities for
deployment of energy-efficient
technologies and practices
PRAIRIE CROSSING
HOMES
B u i l d i n g A m e r i c a h o u s e s
t h a t u s e h a l f a s m u c h e n e r g y
OFFICE OF BUILDING TECHNOLOGY, STATE AND COMMUNITY PROGRAMS
ENERGY EFFICIENCY AND RENEWABLE ENERGY U.S. DEPARTMENT OF ENERGY
C a s e S t u d y
Although they use only half as much energy
as other houses in the same area of northwest
Chicago, the 315 homes being built here through
the U.S. Department of Energys Building
America program cost little or no more to build.
New building methods make the difference.
The Prairie Crossing homes in Grayslake,
Illinois, cost approximately the same as compet-
itive houses of the same size with the same
basic features, yet use approximately 50 percent
less energy to heat and cool. This clear incen-
tive to buyers plagued by the rising cost of
energy comes with a price tag comparable with
that of a less efcient homethanks to an
innovative whole house concept.
The idea, developed by the Building America
program, is to look at the whole picture, not just
individual pieces of the jigsaw puzzle. Building
America has brought together four teams drawn
from all sectors of the housing industry:
architects, engineers, real estate developers,
nancial backers, building materials suppliers,
and builders. The teams create designs that
incorporate from the start the best combination
of construction features to cut costs and energy
use. Through the Building America program,
DOEs Ofce of Building Technology, State and
Community Programs (BTS) is helping to pro-
duce energy-efcient, environmentally sensitive,
affordable, and adaptable houses on a
community scale.
The systems engineering approaches used to
develop the Prairie Crossing designs make
maximum use of the interaction between the
building envelope and its heating and cooling
system. The major premises are that a house
should be designed around its mechanical
system, and that its shell should t around the
living space tightly enough to retain the heated
or cooled air. As a result, the size and cost of
the heating and cooling system are signicantly
decreased and its efciency increased. The
costs of a more efcient envelope are offset
by those of the smaller system.
H O U S E
C H A R A C T E R I S T I C S
2-story with optional
screened porch
Average area:
2692 sq. ft.
Bedrooms: 3
Baths: 2
1 2
Living room, family
room, dining room,
eat-in kitchen P R A I R I E C R O S S I N G H O U S E S
I N C O R P O R A T E A S Y S T E M O F
C O S T - S A V I N G T R A D E - O F F S
The Prairie Crossing homes, built by the
Building Science Consortium through the
Building America program, demonstrate
new framing and insulation methods that
effectively increase energy efciency and
decrease costs. Using conventional wood
studs, but 2x6s instead of 2x4s, and set-
ting them 24 instead of 16 inches apart,
allows for thicker insulation. The labor
costs are signicantly lower, as 30 percent
fewer pieces have to be assembled. The
result? Thicker walls that provide 60 per-
cent more thermal resistance at less cost
than standard construction.
To construct a tight envelope, the homes
use a new double air-barrier system,
whereby the drywall, glued to the framing,
provides a second air-tight wall. Rigid
foam sheathing is glued to the outside of
the framing to seal the rst wall, eliminat-
ing the need for polyethylene vapor barri-
ers and housewrap. An interior air ow
retarder system is built into the walls.
High-performance glazing on the windows
completes the leakproof shell. Low-emis-
sivity (low-e) glazing costs more, but is
paid for by the savings from the smaller
mechanical system.
All the ductwork is placed within this enve-
lope, so the building shell stays tightly
sealed. Heated or cooled air owing
through the ducts conditions the interior
as it travels, instead of being wasted. The
tight building envelope allows for a smaller,
less expensive, higher-efciency heating
system. To increase comfort levels, a con-
trolled mechanical ventilation system
in the homes allows occupants to regulate
air ow.
Prairie Crossing homes incorporate fea-
tures that do away with many of the war-
ranty and callback issues that increase
the cost of standard construction. These
mostly concern leaks or moisture, or
comfort issues. Moisture can condense
within a structure wherever cold surfaces
occur, so using fewer studs decreases
the incidence of thermal bridging, allows
for increased insulation, and reduces the
potential for condensation. In addition,
fewer studs means more exibility and
less cracking in the drywall, a major
cause of warranty complaints. Prairie
Crossing homes use up to 30 percent
fewer framing members and attach drywall
with innovative clips that result in oating
corners and signicantly less cracking.
I N C R E M E N TA L C O S T
S U M M A RY
Features
Difference in Cost
Advanced framing: 2x6s with R-19 in place of 2x4s with R-13
-$500
R-7 insulating sheathing, taped, in place of OSB and housewrap
+$300
Cost saving from not using OSB and housewrap
-$300
High-performance windows
+$500
Interior air ow retarder
+$200
No polyethylene vapor barrier
-$100
Basement insulation
+$600
Controlled ventilation system
+$100
Power-vented gas water heater*
+$300
90-percent-efcient condensing gas furnace**
+$500
Downsizing of AC unit by 1 ton
-$700
Total Incremental Cost
+$900
A far more efficient
house at nominal extra
costto achieve
Building America results
in a typical Chicago
house layout, these costs
and savings are incurred.
* Prairie Crossing houses feature a power-vented water heater, which allows greater exibility in placing the
unit. A direct-vent water heater could achieve the same energy performance for half the cost.
** These houses can achieve efciency improvements of 40 percent without the additional cost of a 90-percent-
efcient condensing gas furnace. The use of this furnace boosts efciency improvements toward 50 percent. PRAIRIE CROSSING
The energy-efficient features of the Prairie
Crossing homes considerably reduce the
annual estimated heating and cooling
loads compared to a reference house that
meets the 1993 Model Energy Code
(93MEC).
The energy efficiency measures applied to
the Prairie Crossing houses have reduced
energy consumption and costs signifi-
cantly. Cost savings estimates assume
natural gas at $0.6615/therm.
Heating
Water
Heating
Mbtu/year
99.7
59.4
40%
reduction
15.2
14.3
6%
reduction
Prairie Crossing
House
93MEC Reference
House
H E AT I N G A N D C O O L I N G L O A D S
E N E R G Y C O N S U M P T I O N
A N D C O S T S
Heating
Water
Heating
Mbtu/year
124.6
65.3
27.1
25.6
Prairie Crossing
House
93MEC Reference
House
Less
Energy
Efcient
-90%
-60%
-30%
0%
30%
60%
90%
More
Energy
Efcient
Prairie Crossing House
(45% more efcient)
93MEC Reference House
P E R F O R M A N C E C O M PA R I S O N
The 93MEC Reference House meets the 1993 Model Energy Code (MEC) and uses minimum efficiency equipment.
Standard Chicago
House
At Prairie Crossing, the Building America
team has demonstrated the benets of
applying sustainable energy principles
to building design and construction.
Reduced energy consumption, increased
affordability, and greater comfort make the
homes immediately attractive to buyers.
Comparable building costs appeal to
construction professionals, and reduced
environmental impact, more jobs, and
resource conservation appeal to everyone.
$392
savings/
year
$10
savings/
year For more information,
contact:
Building America
George James,
Program Manager
202-586-9472
George.James@hq.doe.gov
www.eren.doe.gov/
buildings/building_america
Building Science
Consortium
Betsy Pettit, Team Leader
978-589-5100
betsy@buildingscience.com
www.buildingscience.com
Energy Efciency and

Renewable Energy

Clearinghouse (EREC)
1-800-DOE-3732
Or visit the BTS Web site at:
www.eren.doe.gov/buildings
Written and prepared for
the U.S. Department of
Energy by:
Ofce of Building
Technology,State
and Community Programs
E N E R G Y F E A T U R E S
B
U I L D I N G
E
N V E L O P E
Ceiling/roof: Truss with R-40 insulation
batts, with vented assembly
Walls: 2x6 advanced framing, with R-19
batts instead of standard R-13, R-7
insulating sheathing, and interior air-ow
retarder
Basement: R-13 ful