Net ZEB Case Studies - Modeling, Design, and Optimization of Net-Zero Energy Buildings - page 345

ÉcoTerra is the first of 15 demonstration houses that was selected to be built
through a competition conducted under the Canada Mortgage and Housing
Corporation (CMHC) EQuilibrium Healthy Housing Initiative (CMHC,
2010). The house was prefabricated in a factory in seven modules, including
one module for the mechanical room. The modules were delivered and
assembled on the chosen site in one workday in September, 2007.

Due to the prominence of cold sunny conditions in the region's winters,
passive solar design is emphasized. To maximize solar exposure in the
heating season, the house was oriented along the east-west axis with an
aspect ratio of 1.38 - a level that was found to be approximately optimal
for balancing solar gains potential with heat loss through the envelope.
The south-facing window-to-wall area ratio is about 40%, with nearly 20
m 2 oftriple-glazed low-emissivity argon-filledwindowsdistributedbetween
the basement and above-grade floors. The other façades have considerably
fewer windows with areas of 6.5, 0.82, and 5.0 m 2 on the east, north, and
westfaces,respectively.The U -valueofthemainwindowsis1.2W/m 2 Kand
the solar heat gain coefficient (SHGC or g -value) is about 0.5. The thermal
properties of the other ÉcoTerra surfaces are summarized in Table 7.3 .

Table 7.3 Calculated effective thermal properties of main envelope
components

Surface Type Thermal

Resistance (m 2
K/W)

Thermal
Conductance (W/(m 2
K))

Walls 6.3 0.16

Roof 9.1 0.11

Under slab 1.5 0.67

Basement walls (above
and below grade)

6.3 and 5 0.16 and 0.2

The southern part of the interior of ÉcoTerra has several thermally massive
surfaces, including
- A 15 cm concrete floor on the main level, topped with dark-colored
slate tiles.