Net Zero Victorian Q & A: Part 2 – What Is Net Zero?

Welcome back to Net Zero Victorian Q&A. Today I will address the following questions:

    • What exactly is Net Zero anyway?
    • What are the main design strategies to achieve Net Zero?
    • We heard that this project is also expecting to also achieve high levels of Green Certification, what is the difference between Green Certification and Net Zero Certification
  • What exactly is Net Zero anyway?

Simply stated, Net Zero Energy means that the home will produce as much power over the course of a year as it consumes for everything in the home including heating, cooling, lights, appliances, etc. Different approaches are possible, but a common one is for the house to be connected to the electrical grid. When the house produces more than it consumes the extra electricity is sold to the utility company and feeds into the overall grid. At night or other times, when the house is consuming more than it is producing, it draws electricity from the grid. In Minnesota, ‘net metering’ laws require the utility company to pay the homeowner the same price per kWh for electricity they receive from the homeowner as they charge the homeowner for electricity they sell to them.

This graph shows how the total production vs. consumption changes over the year and even dips below zero at times. This is to be expected.

SALA Architect Marc Sloot

Graph by Mark Hanson

        • What are the main design strategies to achieve Net Zero?

Theoretically any project could be Net Zero if enough electricity producing renewable energy equipment like photovoltaic (PV) panels were installed. Of course the limitation is cost and space on the property to install the panels or other equipment.

Thus there are three main steps to reach Net Zero in the most economical way and should be implemented in this order of priority.

Step 1. Passive Energy Conservation.
Ensuring the home is well insulated and not leaky is always the first priority. Hiring an Energy Rater to test your house is always a good investment to diagnose existing conditions, finding air leaks and insulation gaps. If you are building new, have them come do inspections and testing during construction.

Before work began, Net Zero Victorian had nearly 3,900 cfm50 leakage determined with a typical “blower-door” test. We reduced it to about 350 cfm50 by the end of the project representing about 90% reduction!

Following good passive solar design principles will also help, but compact urban lots do not always allow for much passive solar tempering. One of our goals with the Net Zero Victorian house was to show net zero energy can still be achieved on lots with very little access to passive solar.

This following diagram shows how we wrapped the entire house with an insulating and air sealing barrier. See also the previous blog for more images of this being installed.

SALA Architect Marc Sloot

Good insulation and air sealing also reduces the size of the mechanical equipment. This saves money and makes step 2 easier and less expensive as well.

Step 2. Active Energy Conservation.
Installing high efficient lights, appliances and mechanical equipment also reduces energy consumption and the amount of production equipment needed in Step 3. Use LED lights, ENERGY STAR rated appliances or better, and mechanical equipment that has heat pump technology as much as possible.

One thing that is intentionally NOT seen in the yard of Net Zero Victorian is any mechanical equipment. Aside from being extremely energy efficient, the exterior component of the geothermal heat pump system consists of silent underground pipes rather than an above ground noisy fan unit which is needed with conventional air conditioning or air source heat pump systems. The backyard is only 28×40 feet showing that this can be installed in a very small space.

Photo of the drilling process to install the underground pipes.

SALA Architect Marc Sloot

Photos of the finished back yard.

SALA Architect Marc Sloot

SALA Architect Marc Sloot

Step 3. Active Energy Production.
Generate the remaining energy that you still consume using renewable sources. Photovoltaic panels are a great option, but keep in mind that they do require sun exposure. If you do not have good solar access or space to install them, you may be able to get credit for purchasing off-site renewable energy through a community solar garden. Wind turbines may be another option but typically only on rural sites with the right wind currents.

SALA Architect Marc Sloot

SALA Architect Marc Sloot

        • We heard that this project is also expecting to achieve high levels of Green Certification, what is the difference between Green Certification and Net Zero Certification?
          Net Zero is an extremely high energy performance target. However it is strictly focused on energy performance and following best practices for fresh air exchange. Building assembly details that prevent accumulations of moisture that could cause mold or rot are also emphasized.Green Certification is more broad and inclusive of all of the main categories affecting sustainability, which are:

          • Energy Efficiency
          • Material Resource Efficiency
          • Indoor Environmental Quality (including indoor air quality and thermal comfort)
          • Water Conservation (reducing potable water consumption)
          • Site and Community Impact (reducing waste to the landfill, pollution, storm water runoff, etc.)

More information about the GreenStar and LEED for Homes certifications that this home is expecting to receive can be found at the Green Institute Website.

These were just a few more of the high points. Please remember, if you want to see this house in person you will have another chance on October 7th from 10am – 3pm when it will be open for touring again as a part of the Minnesota Renewable Energy Society’s Sustainable Home Tour.

Also, please remember to check out this blog again in the upcoming weeks to see more information addressing these other questions I heard on the tour:

          • How did you run new duct work in an old house like this?
          • Is the house too airtight?
          • Why not just tear it down and build new?
          • How do you keep snow off of the solar panels and do you have problems with squirrels damaging them?
          • What did it cost?

 

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