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Net Zero vs Passive House: What Are the Similarities and Differences

Canada’s commitment to tackle climate change is evident in its programs to decrease overall dependence on fossil fuels and reduce carbon emissions. The housing and construction industry has been particularly identified as one area that can have an immediate impact.

According to Environment and Natural Resources data, buildings account for 13% of Canada’s greenhouse gas emissions. The National Inventory Report 1990-2017 data shows that an average building in Canada constructed per the building code uses 60 to 70 percent of its energy for heating and cooling. Making Canada’s building sector more energy efficient is a cost-effective way to reduce greenhouse gas emissions while also saving households and businesses money.

Net zero and passive house designs in Canada

From the street, most people can’t identify a net zero or passive house from any other recently built home. And, aside from the thick walls and deep window sills, there are often few clues inside. The advantages become very apparent, however, when viewing the utility bills.

The certification labels “Net Zero” and “Passive House” in Canada are for ultra-low energy buildings with little energy consumption for heating and cooling. This article highlights the key similarities and differences between the Net Zero and Passive House buildings.

Net zero homes

A net zero home produces its own energy locally, and the aim is to generate as much energy as it consumes. The homes have an energy-efficient building envelope, premium windows, and high-efficiency heating and ventilation systems to maintain the overall energy consumption as low as possible.

The buildings operate with the help of renewable energy sources that allow them to store excess energy when they produce more than they need. Net zero houses are 80% more energy efficient than new structures built to the minimum requirements of the current building codes.

Benefits of net zero houses

Key drivers behind net zero houses are the rising cost of energy, increased awareness of climate change, and rising carbon emissions. Most homeowners are looking for homes that guarantee thermal comfort, better indoor air quality, durability, and a healthier environment for their families.

Although still somewhat of a rarity in British Columbia, various net zero construction and renovation projects can be found sprinkled across West Vancouver and along the Sea to Sky Corridor in communities like Squamish, Whistler, and Pemberton.

Key advantages of net zero homes are;

1. Enhanced comfort

Net zero homes are very airtight, to help keep drafts, temperature fluctuations, moisture, outdoor pollutants and allergens out of the home. Net zero homes must achieve an airtightness of 1.5 air changes per hour (ACH) or better.

2. Air quality

An air-tight net zero house uses Energy Recovery Ventilators (ERV) or Heat Recovery Ventilators (HRV) to supply fresh air without wasting energy. An HRV/ERV acts as the lungs of the home, circulating fresh air in and the bad air out.

3. Durability

Net zero houses are better equipped to resist severe weather interruptions and offer shelter during stressful times like an extended power outage. Superior ventilation offers protection in the event of wildfires or other incidents that bring in contaminates from the outdoors while reducing humidity and preventing mould growth.

High performance, warm windows and better-insulated walls and roof protect the structure from condensation and moisture damage.

4. Energy efficiency

You’ll need less energy to keep your Net Zero house warm in the winter and cool in the summer. This results in decreased energy bills, which aid in offsetting any extra expenses linked to more energy efficiency measures.

5. High resale value

Net zero houses are valued more on the market because of their outstanding durability, increased comfort, and lower energy costs.

Passive houses

A passive house uses environmental elements to reduce energy use while maintaining energy efficiency and strict design standards. These houses are built using precise design principles to achieve stringent and quantitative energy efficiency while maintaining a certain level of quantifiable comfort.

Compared to typical homes built to building codes, passive houses use up to 90% less energy for heating and cooling. The “passive building” certification also guarantees that architects and consultants are professionally trained to develop a structure that fulfills the criteria and is adaptable to nearly any building design.

Airtightness, ground insulation, wall insulation, roof insulation, thermal bridge, free construction, certified passive house windows, and ventilation are the seven fundamental principles builders must follow when designing a passive house.

Benefits of passive houses

The Passive House standard sets absolute targets for maximum energy use. Builders and designers are reaching Passive House Institute performance levels,  a top standard for high-performance buildings.

Vancouver has also moved ahead of the BC Energy Step Code with its Vancouver-specific additional requirements and revisions. The city’s Zero Emissions Buildings Plan targets all new buildings by 2032.

Passive houses in Canada must meet the internationally required standards. The benefits of employing these building standards include;

1. Better indoor air quality

The houses feature easy-to-use, long-lasting systems that employ precise control over indoor air quality and temperature. This makes them incredibly quiet and comfortable throughout the changing seasons.

2. Reduced energy expenditure

A passive house is designed to reduce energy use by 90 percent. The reductions in these costs make up for the additional costs associated with construction.

3. Better temperature control

Passive houses are designed with insulated walls, air-tight construction, and a compact building shape to capture the sun’s heat when it’s most needed. This efficiently helps to save on heating and cooling energy costs.

What are the similarities shared by net zero and passive houses?

Net Zero and Passive Houses are more sustainable and energy-efficient than typical homes. The obvious advantages for homeowners who build or remodel their homes using either of these two models are greatly reduced greenhouse gas emissions and lower energy costs.

Net Zero or Passive Houses have much in common. Both strive to have energy consumption that is as low as possible. Here are the main characteristics that these dwellings share.

Air-tight building envelope. The building envelope (walls, foundation, and roof) must be air-tight. Preventing air leakage and controlling air inside allows mechanical systems to run less and conserve energy. Preventing warm air from reaching the outer perimeter also prevents moisture problems.

Elimination of thermal bridging. A thermal bridge is a thermal conductor between the inside and outside of the house. Minimizing thermal bridging through the building envelope is a key design aspect for achieving net zero and passive house buildings.

Use of highly efficient windows. Optimized windows allow heat in, but only when desired. Beyond double glazing with argon gas, which is typical of Energy Star windows, passive buildings usually have triple glazing.

Thick and continuous insulation throughout the entire building envelope. By completely wrapping a building with insulation, heat is no longer lost through framing, which has a lower R-value than the insulation between the studs.

Mechanical ventilation. The role of mechanical ventilation is to keep the air inside fresh. Ventilation is necessary considering net zero and passive houses have tight building envelopes leaving the air inside with nowhere to go.

Efficient mechanical systems and appliances. These include home appliances like hot water heaters, washers, dryers, stoves, refrigerators, and HVAC systems. They must be energy efficient and designed correctly for the needs of the specific home’s size and floorplan.

Shading. Net zero or passive houses need well-optimized shading on the roof to allow warmth during the winter when the sun is lower in the sky. Shading is also important for the windows in the summertime.

Renewable Energy. A net zero or passive house generally still needs to generate some energy even with the energy-efficiency measures and stringent passive house standards. Options include solar energy, small wind turbines, geothermal, or even small microhydropower systems.

What are the differences between net zero and passive houses?

Both net zero and passive houses are primarily concerned with energy efficiency. A net zero home produces as much energy as it uses over the course of one year, whereas a passive house requires the heating/cooling load to be no more than 15kwh per square meter of living space.

The main difference is that they use different strategies to obtain their targets. Passive houses must adhere to strict regulations for insulation, airtightness, and passive solar energy usage to lower the building’s energy requirements. As a result, achieving net zero in these houses requires little solar energy. The passive house design principles also instruct contractors on controlling the amount of heating, cooling, and airtightness in the structure.

On the other hand, net zero homes may need more solar energy to reach zero because of less stringent rules. They focus more on maintaining energy balance, which frequently ensures a building produces as much energy as it uses. Most often, renewable energy sources are added to construction projects to achieve net zero homes.

The extra mechanical systems added to net zero houses can make the buildings expensive. Still, they will enable the house to run significantly more efficiently over the long term. Overall, both methods of home construction aim at the same thing. Passive houses are more common in Western Canada and are currently being applied in different single-family homes and multi-residential structures across Canada.

What is the Cost of Constructing Energy Efficient Houses?

Various factors determine the overall cost of energy-efficient houses in Canada. These costs are five to ten percent or higher than typical homes constructed under different energy codes. The certification procedures further increase these expenditures.

Most of these expenses can be recovered through rebates and long-term energy efficiency. For instance, the net zero home will save on energy on average much more each month than a conventional building. Some municipalities offer floor area and height relaxations for passive certified housing.

Additionally, British Columbia offers financial incentives to move to high energy efficiency through its EfficiencyBC Plan. This involves incentivizing homeowners to install high-efficiency heating systems and renovate their buildings’ building envelopes.

Final Thoughts

One of Canada’s most effective strategies in combatting the effects of climate change is the development of net zero and passive houses. Both are effective approaches in the context of sustainable neighbourhoods, where the goal is to achieve maximum energy efficiency, fulfill operating energy requirements from renewable sources, and reduce carbon emissions.

 

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