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Understanding the Value

A Home’s Energy Efficiency Rating

The EnerGuide Rating System was developed by Natural Resources Canada as a tool to rate a home’s energy performance. The EnerGuide scale ranges from 0 to 100 and takes into account millions of houses across Canada, with various ages.

  • 0 = represents a house that has major air leakage, no insulation and extremely high-energy consumption.
  • 100 = represents a house that is very well insulated, airtight yet well ventilated, and heated by renewable energy sources, such as wind or solar power.

Many factors can affect the rating. Even if two houses appear identical, their ratings can be different if they have different levels of insulation, types of heating equipment,etc.

Nz website chart efficiency rating grey

For many older houses, a rating of 65 or higher is considered quite an achievement. New houses usually receive a rating of 65 or higher, because of improvements in building standards and practices over the years. Few houses achieve a rating of 80 or higher, and those that do represent the most energy-efficient houses on the market. Therefore, the EnerGuide rating scale shown below ranges from 65 to 100.

Energy efficient target

All new homes built according to the Ontario Building Code (2012) must achieve an 80 on the EnerGuide scale.

Energy Star qualified new homes are designed and built to save energy and provide comfort. They are also built airtight, which helps avoid air leakage problems that cause energy waste and higher energy bills. Compared to a typical home, an Energy Star qualified home is 20% more energy-efficient and must achieve an 83 on the EnerGuide scale.

R-2000 certified new homes are built to strict air tightness requirements and have the right amount of ventilation. The fresh-air ventilation device improves air quality. Special attention is given to design in order to optimize home comfort. Compared to a typical home, an R-2000 home is 50% more energy-efficient and must achieve at least an 86 on the EnerGuide scale.

Net Zero homes are airtight, well insulated, sufficiently ventilated and require no purchased energy on an annual basis. It must achieve 100 on the EnerGuide scale.


The R in R-Value stands for "resistance". When referring to insulation, this resistance is for heat.

Insulation resists the flow of heat through a home's walls, floors and ceilings. This resistance slows heat down and keeps it inside in the winter and outside in the summer, making the home more comfortable and energy efficient.

Therefore, the higher the R-value, the greater the insulating power. 

Below is a comparison of a home built to the Ontario Building Code compared to an Energy Star rated home by Reid's Heritage Homes. The improvements are impressive. For Net Zero homes, we have increased the R-value even further to provide the best insulated and air tight home possible. This results in more comfort for the homeowner, reduced noise from the outside, and increased savings on energy bills.

Nz rvalue chart

Blower Door Test

A home's air tightness is typically expressed in air changes per hour (ACH) at an indoor-outdoor pressure difference of 50 pascals (Pa). 

Blower door test

The air tightness of a home can be measured with specialized equipment commonly known as a “blower door.” For a Net Zero home, the targeted air change rate may be 1.0 ACH or less. In comparison, a typical code-built home would test at 2.5 to 3.5 air changes per hour or higher.

A blower door test was conducted on our Net Zero Discovery Home and the results were 1.36 ACH at the pre-drywall stage and an astounding 1.1 ACH once completed! This is one air tight home!

This result also means savings on gas and electricity for the homeowner.

Read about the savings