Net Positive!

By Tracee

The results are in! We’re very excited to share that our house achieved a -3 HERS rating score, which means we make more energy than we consume and that we are positioned to contribute energy to society.

What is a HERS rating and what does it mean to me?

The HERS Index is an energy efficiency measure used to make comparisons between buildings. For example, a typical new home built by a developer using standard building techniques these days (built around 2004 -2006), will likely have a HERS score of 100. A typical resale home has a score of 130 (30% less efficient than a new home). Homes where deliberate measures are taken to be more efficient start to get into the 30 or 40 range. A home whose score is 0 is considered a net zero home; it produces as much energy as it consumes.

HERS Index diagram used to explain relative differences in home scores.

This means that you have two strategies for lowering your HERS rating and becoming more energy efficient:

1) construct (or retrofit) your home to require less energy to heat, cool and run your home (i.e. make your house less leaky, install more insulation, create ways for passive energy gain, use LED lights, etc), and

2) compensate for the energy you’re consuming (i.e. install solar panels, wind turbines, etc).

Consider both strategies simultaneously for biggest impact.

How is a HERS score calculated?

A HERS score is done by certified RESNET Home Energy Rater, using software that aids in calculating the following:

PE=purchased energy, E= energy

E=energy consumption, wh=water heating, la=lights and some appliances, PE=purchased energy (fraction)

The part of the rating we directly witnessed was a blower door test to determine leakiness, and an inventory of our appliances and light bulbs.

We had XRG Concepts do our HERS rating and highly recommend them. The rating consisted of an insulation inspection, two blower-door tests and the HERS calculations. They also gave specific recommendations on improvements that can be made for a lower score:

Our biggest opportunities for improvement were in the sill plates of windows and doors as well as around the minisplit and attic hatch.

How will we experience a low HERS score?

We are already feeling the effects of an energy efficient home:

  • The one we experience every single day is a reduction of temperature fluctuations, making it more comfortable. We’re expecting this to not only provide us with improved comfort, but improved health as well.
  • We won’t have to deal with the fluctuating prices of energy costs the way we did in NY when the cost of oil would vary widely from year to year. In fact, as a net positive house, we expect that we will be providing more energy to the grid than what we take from it.
  • Less evident in our daily lives is the reducing greenhouse gases and cutting carbon emissions. But the fact that it’s hard to experience this concept directly doesn’t mean we enjoy it any less 🙂

To get energy efficiency, you need to be proactive.  

Now that you know about HERS rating, see if you can work it into your next conversation when talking about home-ownership. Help spread the word and get more people acquainted with the concept. Builders pay attention to what passes code and usually not more … unless the home-owner drives that conversation. It will take informed home-owners asking for energy efficiencies to drive changes.

You can also take action now. If you’re fed up with your heating/cooling costs, feeling uncomfortable in your home, or aspire to improve Earth sustainability, you can do a few things to your home to become more energy efficient.

Energy suppliers usually offer services to help detect and prioritize efficiency efforts. Things like adding insulation don’t seem like very much fun to do, but neither does paying a high energy bill or being uncomfortable. Less drastic measures include buying energy efficient appliances, installing LED lights and eliminating ‘vampire’ power (stand-by power). You can also install solar panels or buy into a solar farm to help offset your energy costs.

Passive solar energy at work! Ahhhhhh…….

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