07-08-2012, 11:52 AM
Near Net-Zero Energy ÉcoTerra™ Home Demonstration Project
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Summary
The ÉcoTerra™ house, built by Alouette Homes, is a 2,600 square foot (240 m2)
prefabricated home that was assembled in September 2007 in Eastman, Quebec – about 120
kilometres south east of Montreal. The NSERC Solar Buildings Research Network, and in
particular a team headed by Dr. Andreas Athienitis at Concordia University, led the energy
system design of the house. The approach that was followed integrates the passive and active
solar systems into the house design and optimizes energy efficiency technologies. The house
includes an innovative building-integrated photovoltaic/thermal (BIPV/T) roof linked to a
hollow core thermal storage system that is based on research carried out at Concordia
University. The BIPV/T demonstration was funded by Natural Resources Canada’s
(NRCan) Technology Early Action Measures (TEAM) program, championed by Josef
Ayoub of NRCan’s CanmetENERGY at the Varennes research centre. This is the first time
that a BIPV/T roof has been built as a system in a factory.
Background
In Canada, buildings consume 30% of the total secondary energy and about 50% of total
electricity1. The substantial energy consumption of the building sector presents a great
opportunity for savings.
In an effort to encourage innovation, public knowledge, industry expertise, and publicprivate
collaboration, the Canada Mortgage and Housing Corporation (CMHC) started the EQuilibrium™ Sustainable Housing Project Initiative. The initiative was an open design
competition for builder- or developer-led teams to submit house designs that were both
healthy and sustainable. Of the seventy-entries, the top 12 teams were selected to build their
design. Concordia University, and associated SBRN researchers, were involved in two of the
projects that demonstrate BIPV/T systems. They were the Alstonvale and ÉcoTerra™
houses.
Building-Integrated Photovoltaic/Thermal (BIPV/T) System
The south-facing upper roof area is covered by PV panels. These panels can produce as
much as 2.8 kW of electricity. The electrical utility (Hydro-Quebec) allows net-metering for
residential customers. When the ÉcoTerra™ home is producing more electricity than it is
consuming, the meter runs backwards.
The PV modules that were selected are amorphous silicon (a-Si). These flexible PV laminates
were integrated on the metal standing-seam roof in order to enhance the aesthetic appeal of
the house. In typical installations, a small quantity of the incident solar energy is reflected or
irradiated back to the surroundings. For a-Si modules, approximately 6-8% of the absorbed
solar radiation is converted into electricity. The remaining absorbed energy heats up the PV
modules. The innovative design proposed by Concordia University and SBRN researchers
cools the PV modules and also puts this otherwise wasted thermal energy to good use.
Ventilated Concrete Slab Storage
Due to the efficient passive solar design employed in the ÉcoTerra™ house, on a sunny and
cold day there is no need for mechanical heating. In fact, there is an excess amount of heat
that is recovered from the roof that can be stored for later use.
The heated air from the BIPV/T collector is ducted to the basement slab for storage. The
slab is unique in that it contains air channels that allow the slab to absorb heat as the air
passes through them. Once the slab is heated, it radiates heat to the basement. This process
happens gradually through the night and potentially into the next day due to the slab’s large
thermal inertia. Apart from allowing solar energy to warm the house well into the night.