Autonomous, Net-Zero, or Passive: Demystifying Green Building Lingo

Updated: May 31, 2019

Solar energy, also known as radiant energy, is the most renewable and clean form of energy available to us at the moment. Unfortunately, what's stopping most of the world from transitioning is the comparably higher costs associated with producing energy this way. In Ontario, an 8.58 kW solar panel system would cost between $19,562 and $23,852 to install. On the other hand, energy from the electrical grid in Ontario costs about 9 cents per kWh. In 2016, the average Ontario family spent close to $1000 annually in electrical utilities bills. Despite long-run savings, the high upfront investment it takes to install a solar system makes it a difficult decision for many Ontario families.

To be labeled as a green building, a structure must be sustainable and resource-efficient throughout all steps in its design, construction, operation and maintenance processes. However, there are many categories of green buildings, and many ways for a building to be both sustainable and resource-efficient.

Passive vs Active

A Passivhaus diagram showing ultra-low energy consumption. By Passivhaus Institut - Copied to Commons from Original source Passivhaus Institut, Germany –, CC BY-SA 3.0,

Passive home construction involves the rearrangement of the interior and exterior structures of the home to maximize energy efficiency. This can include room orientation, window sizes or styles, and site selection. Passive homes also employ insulation technology and careful construction to ensure that no energy loss occurs, thereby creating an ultra-low energy use space.

Although passive homes can incorporate active solar mechanisms like solar panels or thermal heating systems, they are still connected to the grid and use municipal energy - albeit a minimal amount of it.


Net zero homes are connected to the municipal utilities grid; however they are unique in that they also produce their own energy and have the ability to sell it back to the grid. To be considered "net zero", a home must produce at least the same amount of energy that it consumes over the course of a year. As a result, the net amount of energy it purchases from the grid is zero.

You can learn more about what goes into building a net zero home by reading about this Windsor Park Net Zero house in Edmonton.

Diagram showing an ideal net zero water building, presented by the US Office of Energy Efficiency and Renewable Energy.

Off-grid or Autonomous?

The terms autonomous and off-grid both refer to a home that is not connected to municipal power or hydro systems. In other words, these houses are structurally engineered and fitted with the equipment necessary to generate all the resources they need to operate. The Queen's Solar Education Center is being constructed to be an autonomous (or off-grid) home - it has no gas supply, generates and stores its own power by harnessing energy from the sun, filters and recycles rainwater for plumbing needs, and deals with its own waste.

The Queen's Solar Education Center is an autonomous home!


LEED stands for Leadership in Energy and Environmental Design. It is an internationally recognized rating system and certification designed by the U.S. Green Building Council (USGBC) to evaluate any building on key sustainability metrics. It forms an extensive checklist and set of guidelines, including:

  • Selection of a sustainable site

  • Water efficiency

  • Energy sources and optimization of energy

  • Materials and resources used

  • Indoor environmental quality

Getting a new or existing building LEED-certified is a voluntary and market-driven decision. However, many commercial offices are becoming trailblazers in environmental stewardship. In Toronto, the TD Center, RBC Waterpark Place, Royal Blank Plaza, Barrymore Building, Berczy and many Starbucks locations are all currently LEED certified.

Written by Ioana Pitu, Commerce '22.

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