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Lema Passive House
Chicago
Challenge
Selecting an HVAC system that would provide adequate heating at low ambient temperatures while
still operating efficiently enough to allow the home
to meet rigorous Passive House Standards.
Chicago residents Corinna and Rodrigo Lema
dreamed of finding a house that would represent
the best practices of the green building
movement. “Living in a drafty 1950s Georgian
home in Chicago, we were concerned about
energy performance,” Corinna said. “Our dream
was to find a house that was less dependent
on gas and oil. Every house we walked through
could not come close to our energy objectives,
so we decided to build a house that would meet
these goals.”
The Lema’s discovered an Oak Park, Ill., architect
named Tom Bassett-Dilley, AIA. He was a
Certified Passive House Consultant whose core
mission was the pursuit of lasting architectural
solutions and sustainability.
Corinna invited Bassett-Dilley to the house. A one
hour visit turned into three hours. “Finding an
architect is kind of like dating,” Corinna said. “We
felt an instant rapport with Tom and learned about
the many benefits of a Passive House system.”
The initial meeting with Bassett-Dilley convinced
the Lemas to proceed with Passive House plans.
It wasn’t long before they located an ideal lot in
Chicago with an old house that needed to be
torn down.
Understanding the Passive House
Bassett-Dilley told the Lemas that Passive House
design requires the most airtight and highly
insulated building envelope in the industry. Its
highly-disciplined design results in heating and
cooling loads that are minuscule when compared
to a conventional house. As an example, he
showed them a recent design in the Chicago area
that had an estimated peak heating load of 11.46
kbtu/h and peak cooling load of 7.94 kbtu/h – 75
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The Lema Passive House
percent lower than what a conventional home
of similar size in Chicago would require.
How to Cool and Heat an Airtight
House
Passive House standards require a 90 percent
reduction in energy used for heating when
compared to similar homes. Bassett-Dilley
explained that, due to the harsh climate of the
Chicago area, some cooling and heating is
needed, even in passive homes with extremely
tight thermal envelopes. “An engineer recently
introduced me to a ductless system from
Mitsubishi Electric [US Cooling & Heating
Division, Suwanee, Ga.], which is the perfect fit
for a Passive House,” he said.
A ductless system is comprised of an outdoor
condensing unit connected by small refrigerant
pipes to a matching, non-ducted indoor air
handler and a remote controller. Bassett-Dilley
explained that the Mitsubishi Electric system
came equipped with unique INVERTER-driven
compressor technology. He also said the
Hyper-Heat (H2i®) system would eliminate the
expense of adding a supplemental heating
system often necessary for homes in Chicago’s
frigid winters.
Because of the minuscule cooling and heating
demands of the Passive House, the variable
speed capabilities and minimum btu/h
capacities of the Mitsubishi Electric system
enable them to frequently operate efficiently at
the partial load conditions. “All other systems
would be overkill,” said Bassett-Dilley.
Bassett-Dilley also explained that proper
ductless system design for Passive House
certification starts with a good understanding
Project Location:
Chicago, Ill.
Completion Date:
December 2012
Project Team
Owner:
Corinna and Rodrigo Lema, Chicago, Ill.
Architect:
Tom Bassett-Dilley Architect, Ltd,
Oak Park, Ill.
Builder:
Weiss Building & Development LLC,
South Elgin, Ill.
Biltmore Insulated Concrete,
Highland Park, Ill.
Thermal Envelope Contractor:
Eric Barton, Highland Park, Ill.
HVAC Contractor:
Arrow Heating & Cooling, Inc., Batavia, Ill.
Mitsubishi Electric
Equipment Installed
(2) MUZ-FE09NA Outdoor Units
(2) MSZ-FE09NA Wall-mounted Indoor
Units
(1) PAC Simple MA Remote Controller
of the heating and cooling load calculations.
Ductless heat pump system selection is
based not only on the specific building loads,
but also on the climate in which the system
will operate. Unlike other types of green
building programs, in Passive House design,
detailed engineering data is used to calculate
the equipment’s performance at the actual
outdoor conditions expected during peak
heating and cooling operation.
With the mechanical systems determined,
Bassett-Dilley designed a 3,800-square-foot
October 2013
© 2013, Mike Crews Photography
case study
case study
Lema Passive House
Chicago
Solution
The Mitsubishi Electric ductless system provides
comfort and efficient operation at low load
conditions that results in the energy reduction
necessary to achieve Passive House certification.
house including a finished basement (recreation
room), a main level with living room, den/
office, kitchen, guest bath and an in-law suite
for Corinna’s parents. The second floor has
a master suite, two bedrooms and a bath for
the kids. He also designed a detached twocar garage with a 64 square-foot solar thermal
collector array to heat the domestic hot water. To
take advantage of passive solar heat, he placed
most of the triple-paned windows on the south
side, and the house is wired for a future solar
photovoltaic array on the main roof.
To build this house, Bassett-Dilley called on
Master Certified Green Builder and Passive
House Institute U.S. Certified Builder Brandon
Weiss, LEED AP whose firm, Weiss Building &
Development LLC, South Elgin, Ill., holds more
green building certifications than any other builder
in Illinois. Weiss is only one of 24 Master Certified
Green Professionals (Master CGP) in the U.S.
“The Lemas wanted a home that was
healthy, comfortable, efficient, super durable
and concrete. The Passive House concept
complemented by the low load, super-efficient
To achieve the 90 percent reduction in heating load required to achieve Passive House
certification, the Lema family selected an M-Series system, which could handle the low-load
conditions of the home.
Mitsubishi Electric system was the perfect
answer for comfort and energy savings,”
Weiss said.
Defining Healthy, Comfortable,
Super-efficient
“This was my first Mitsubishi Electric splitductless installation,” Weiss said. “The
technology is great—ideal for a Passive
House! The first thing that struck me was
that I had no need to call in the plumber and
electrician to figure routing for traditional
ductwork. Secondly, I admire the system’s
simplicity and efficiency—so easy to install;
fewer moving parts, less maintenance, less
costly to operate. And, once we got the system
up and running, it was so quiet no one could
believe it was operating.”
Two Mitsubishi Electric Hyper-Heating (H2i ®)
ductless systems—one on the first floor, one
on the second—were more than sufficient to
condition the entire house, Weiss clarified. “The
maximum design load for the Lema house is
13,500 Btu/h. That’s one-tenth of what a typical
built-to-code would be. In the summer months,
the Lemas can expect to use less than a ton of
cooling, when a similar sized, conventionally
built house would use more like five tons in the
same time period.” The selected Hyper-Heating
ductless systems feature patented technology
that allows the systems to operate efficiently
and at full capacity at temperatures as low as 5
degrees Fahrenheit and at 75 percent capacities
at outdoor temperatures as low as minus 13
degrees Fahrenheit—an essential feature to
accommodate Chicago winters.
“The fact that two indoor units were all that
was needed to condition this space, blew
me away,” said Chris Smith, owner of Arrow
Heating & Cooling, Inc., Batavia, Ill., who
installed the Mitsubishi Electric ductless
systems for the house. “We’ve had nothing
but positive feedback from homeowners for
Mitsubishi Electric split-ductless systems.
They are easy to install, operate and are
really quiet.”
First Chicago Home to Receive
Passive House Certification
The home achieved its energy reduction goals
and became the first home in the Chicago area
to receive Passive House certification.
The selected Hyper-Heating ductless systems operate efficiently and at full capacity at low
temperatures, an essential feature to accommodate Chicago winters.
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“We love our new Passive House!” exclaimed
Corinna Lema. “It is incredibly cozy and
comfortable. No more drafts; no more cold and
hot spots. It is so quiet I cannot hear the school
children during recess down the block until
I open a window. And, I am happy to report
that we recently received certification from the
Passive House Institute!”
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