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Precast Concrete Can Be Habitat-Forming

Untitled-1A NetZero Habitat for Humanity home in Canada could become the prototype for the future of sustainable housing.

By Sue McCraven

Canadian engineers and architects have created a structure unlike any other in North America. Using the latest energy-efficient designs, materials and technologies, this experimental, one-of-a-kind building will house two families in cooperation with Habitat for Humanity Edmonton, Alberta. But this prototype’s purpose is more than humanitarian. The energy use of the occupied home will be monitored for three years, with the test results serving as both a learning experience in NetZero1 design and construction and as a model for the future of economical, sustainable housing. Given Alberta’s harsh winters – where peak low temperatures reach -30 F – this project will serve as a severe test of energy efficiency.

Habitat for Humanity Edmonton teamed up with Lafarge and Stantec, an Edmonton-based consulting firm, to build this first-of-its-kind, NetZero home. Klaas Rodenburg, sustainable design coordinator for Stantec, said, “This NetZero prototype can be mass produced and shipped to other locations at significant cost and time savings.” The project collaborators hope to attain LEED® Canada for Homes Platinum certification from the Canada Green Building Council.

Untitled-1How to design a zero-energy home
The design of the Edmonton home is so efficient that, over time, the resident families should receive no heating or electrical bills at all. Instead, they will rely completely on the home’s renewable solar and geothermal systems for all their energy needs.

The home generates its own solar power on sunny days during the summer and returns the collected solar and geothermal energy to the power grid for storage. During the winter season, the residents obtain their heat and electricity by drawing on the accumulated energy in the power grid. Energy transfer from the fluid in the underground geothermal pipes delivers heat for warmth while the photovoltaic rooftop panels provide hot water and electricity. The duplex’s interior finishes use sustainable materials throughout as well.

Rodenburg explains that, in terms of energy savings, the precast building envelope is the most important element of the NetZero home design. “Up to this point, a zero-energy house has been only engineering theory. But we hope to prove the energy efficiency of the Edmonton home’s performance through monitoring and testing.”

MIT versus “greenwashing”
Until now, most claims of energy efficiency and sustainability have been just that: claims. “Too often we hear of buildings that are pronounced LEED certified or targeted NetZero at ribbon cutting,” said Don Zakariasen, Lafarge director of precast marketing, “but no one sees the operating results.” To remedy this situation, Lafarge and Stantec engaged the Massachusetts Institute of Technology (MIT)2 to perform a third-party, objective, 24/7 monitoring study on the Habitat for Humanity home while it is occupied and in normal use by the resident families. The hope is that MIT’s test results will provide proof of the prototype’s energy-efficient performance and matchless design. An example of one test, said Rodenburg, will be “an air-blower door test to generate data on heat loss” through entranceways.

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How different families use energy
Monitoring the energy performance of the NetZero duplex home during a three-year occupancy will provide important information for designers. Performance data will compare each family’s energy use and will also see how results compare with Edmonton’s typical wood-frame housing. Results will reveal how many Joules of energy are transferred for every square inch of precast concrete used in construction. And because Edmonton’s winter temperatures average a bone-chilling 11 F, the energy performance of the prototype’s design and construction will reflect challenging conditions.

Untitled-1By recording the energy use of two different families, results can show how personal preferences for thermostat settings and electric lighting affect home energy efficiencies. For example, explained Rodenburg, the length of time family members leave doors and windows open can significantly affect total energy use. In addition to energy use, monitoring will measure temperatures and humidity inside and outside the home.

The human face of ultimate engineering design
“Habitat for Humanity Edmonton is a nonprofit organization working toward a world in which everyone has a safe and decent place to live,” said Alfred Nikolai, president and CEO of Habitat for Humanity Edmonton. “Innovative projects such as this NetZero home are imperative as we seek to provide sustainable and affordable home ownership to families in need.”

A most telling measure of the human value of the NetZero precast concrete home comes from one of people who will live in the modernistic duplex. “My family is so grateful to everyone involved in making home ownership a reality for us,” said Tracy, Habitat partner and mother of four. “My husband and I will soon be building equity in this NetZero home and be able to save for our children’s future.”

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1 NetZero means that the energy produced = the energy used.

2 Lafarge has been involved with the MIT Concrete Sustainability Hub on initiatives looking at concrete from the nanoscale to the urban building scale. The NetZero Edmonton home will serve as benchmarks to this research.


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