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Backspin - What Net-Zero Looks Like

January 25, 2017


If you keep up with real estate, you may have heard the term “net-zero” recently.  It’s not a tennis drop shot, or an inventory accounting method.


Net-zero is a measurement of inputs and outputs in a home or building’s energy use, and the calculation can also be used for water, waste and other resources.


There are a number of ways to calculate and define net zero, including nerdy stuff like "thousand BTUs per square foot" and other metrics spat out of complex energy models.


The way I currently define net-zero energy is that the features in a home or building save and generate as much energy as the property requires.  Thus, (energy required) = (energy used + produced).  When those numbers zero out, you’re there.


The Department of Energy started a program in 2008 called the “ZERO Energy Ready Home”, and while technically the certification doesn’t require net-zero energy use, it stipulates that homes be convertible to net-zero easily.  Since 2008, the program has certified 14,000 homes, a sliver of the 1,166,400 new homes built just last year. 


But change is barreling our way fast.  California has a stringent energy code in place, Title 24, which requires all new residential construction be net-zero energy from 2020 on.  That’s three years.  And as bellwether California goes, so goes the nation.


MORE THAN A SKIN JOB - What net-zero looks like is more interesting.  Unless you’re building fringe properties with 18-inch walls full of insulation, spotting a net-zero property isn’t always easy or obvious.  And in truth, any style of home can be built net-zero as the energy-impacting features are often tucked away or hidden behind walls.  ‘Good news for you if you love your Queen Annes or Cape Cod bungalows.


METERS & BILLS - Where net zero shows itself more obviously is on electric meters and utility bills.  The image above is the solar net meter on my house, which is just over a year old.  Either I’ve used a ginormous amount of electricity in a year (not a stretch here in Colorado), or the meter has spun backwards.  The latter’s the case, helped in no small part by the 6.625 kilowatts of solar electric-generating panels we have on our roof (25 panels … for now).


Another way net zero may show up is the comparison billing utilities love to send out, though you’re the  butt-end of the comparison.  Our Denver utility loves to shame us all into reducing energy use by “keep-up-with-the-Joneses” contrast.  


“Neighbor Bob’s energy use is half mine, and he’s even growing pot on the DL in the basement.  Maybe I should get an energy audit, change out lights and bump up insulation.”  


It’s cheaper for the utility to reduce use through efficiency programs rather than build new power plants.


CHECKS AND MORE CHECKS - The biggest benefit of net zero is that the utility pays you for generating solar electricity – either by cutting you a check at year-end or in month-to-month debits and credits.  Our December bill shows a $43.63 credit balance that the utility provider owes us. 


CAVEATS – Calculating solar electric versus your actual use can be tough depending on what your utility discloses.  I spent a couple dozen hours trying to back out our “solar bank” (debit/credit balance), and my solar provider even threw up his hands with the exercise.  If your utility has easy-to-decipher documentation, consider yourself lucky.  If not, a few hints.


    ACCOUNTS – How many accounts do you have?  I’ve got two – one for gas and electric usage, and one for our solar net meter.

  • METERS – How many meters do you have?  Again, two here, but the utility changed the account number on one, and it was super-confusing.

  • Y2K CALCULATOR – Coming up with an elegant spreadsheet solution to calculate net metering was like working a Y2K solution – when computers worldwide couldn’t jump to 2000, and the entire planet was supposed to melt down.


My other half came up with the idea of zero equaling 100,000 kilowatt hours (since our meters go up to 99,999).  In positive-integer territory (net-negative usage), I subtract from 100,000, and below 99,999 (net-positive usage), the numbers calculate correctly.


If this makes your brain swim, email me, and I’ll send you a copy of my spreadsheet so you can customize it for your utility.


In the meantime, if you’re buying a new house, demand a net-zero one as anything less won’t be market-competitive soon.  And if you’re in an existing home, going zero isn’t as tough as you may think.  Check out some of my previous posts on the subject.

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