ASHRAE Journal - May 2024 - 62

2024 ASHRAE TECHNOLOGY AWARDS CASE STUDY

13,961 kWh of energy consumption for its
operation.
INDOOR AIR QUALITY
Indoor air quality is ensured by the constant 100 cfm
(47 L/s) fl ow of the energy recovery ventilator. The main
ventilation unit circulates 900 cfm (475 L/s), which is
TABLE 1 Energy performance comparison.
THEORETICAL PV
PRODUCTION
(kWh)
December 2021
January 2022
February 2022
March 2022
April 2022
May 2022
June 2022
July 2022
August 2022
September 2022
October 2022
November 2022
Total
Total kWh/ft2
1,091
1,510
1,818
2,304
2,325
2,407
2,392
2,465
2,388
2,213
1,701
1,315
22,838
MEASURED 2022
PV PRODUCTION
(kWh)
421
45
514
1,173
1,990
2,664
2,404
2,632
2,067
1,592
1,603
835
17,941
7.5
12,278
6,661
2,444
2,880
8,055
46,856
19.5
3,299
1,826
1,379
1,352
2,458
15,080
6.3
fi ltered with MERV 14 fi lters. Operable windows in each
room give occupants the opportunity to bring in outside
air and have as much contact with the outdoors as they
want. The only refrigeration equipment in the house is
a refrigerator that uses R-601 refrigerant, which is not
ozone depleting nor produces greenhouse emissions.
INNOVATION
The main innovation of the house is the active thermal
mass used to accumulate the excess energy from one
period to be used later at a high load demand condition.
The house fabric is in direct contact with the ambient
conditions. The major accumulation fabrics are walls
and ceiling gypsum boards totaling a capacity of
1.1 kW/°F (2 kW/°C) and concrete fl oor slab at 9 kW/°F
(16.2 kW/°C), thus giving an accumulation potential
of 50 kW for a 5°F (2.8°C) temperature difference.
Knowing that the peak heat losses of the house at -20°F
(-29°C) outside are 5 kW, this energy accumulation
permits a simple peak energy control.
62
ASHRAE JOURNAL ashrae.org MAY 2 0 2 4
90.2-2018
SIMULATION
(kWh)
14,538
operation.
PROPSED HOUSE
SIMULATION
(kWh)
4,766
Also, all the services such as piping and electricity were
installed inside the nonperforated airtight envelope
in the inside space created by the double-crossed
wood furring, creating channeling for services in
both directions. Maximized passive solar heating was
obtained with the selection of window size and glazing
characteristics. There was al so complete continuity of
the insulation around the slab, in
continuity with the wall insulation.
Active thermal mass optimizes
the solar energy accumulation
and reduces the house energy
consumption. The design of a house
based on its midlife performance is
a new approach that was used when
designing this project.
MEASURED 2022
CONSUMPTION PER 2
MONTHS BY UTILITY
(kWh)
4,484
2,970
1,735
1,350
1,295
2,127
13,961
5.8
COST EFFECTIVENESS
The highly insulated walls of the
house have been prefabricated
to minimize costs and ensure the
protection of the insulation from
the rain that often deteriorates
the insulation during on-site
construction. The prefabrication also
costs less than site-cost union-trade
labor. The cost and payback of the
PV system were analyzed in detail. The turnkey cost of
the PV system was $39,896 for an annual theoretical
production of 22,838 kWh. Based on a system life of 20
years, the cost of the energy was 8.73 cents/kWh. The
actual annual production is 17,941 kWh leading to a unit
cost of 11.1 cents/kWh, which is approximately the cost of
the electricity actually provided by the service utility at
10.25 cents/kWh. The added cost for superior insulation
construction and triple-glazed windows has been
estimated as $30,000 with an annual saving of $1,230 (at
10.25 cents/kWh) for a payback of 24 years, which is the
midlife criteria for the design of the house.
ENVIRONMENTAL IMPACT
The project is net positive in one year-it produces
more electricity than it uses. The operating carbon
is negative, as is the embodied carbon, due to
the use of wood for structure and fi nishing. No
chlorofl uorocarbons or hydrochlorofl uorocarbons were
used for refrigeration.
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