Recent Spike in Gas Bills Has Alameda Residents Wondering - It was colder and more expensive

One of the things that Autodesk is about is impact and sustainability. It's for this reason that we have Insight 360.

Learn more about Insight 360

Insight 360 is our collection of easy to use tools that allow designers to make informed choices with regard to carbon footprint, environmental impact, and the projected cost of energy for the buildings they design, make, and use.

Nextdoor is a private social network for neighbors and the nearby community. It is an easy way for neighbors to talk online and make all of their lives better in the real world. It's free. Neighbors use Nextdoor to: quickly get the word out about a break-in, ask for help keeping an eye out for a lost dog, or find a new home for an outgrown bike.

Recently, there was a post of Nextdoor regarding unexpectedly high gas bills in Alameda (where I live):

In support of Autodesk's sustainability efforts, I have made improvements to my Alameda home (e.g., tankless hot water heater, more insulation) and have been tracking my energy costs as a result.

Check out the series of blog posts.

In response to the Nextdoor post, I decided to examine my gas bills. In terms of natural gas usage, the cost data I have collected looks like:

In terms of costs before and after the improvements we've made to our home, the ideal scenario looks like:

I had been collecting only costs data instead of actual usage because the rate changes have been modest over the years. Now that appears not to be the case. Check out how this year is stacking up:

I can see why my neighbors are expressing concern on the Nextdoor site, so I thought I would look more closely at my gas bills by comparing this year and last year for the month of February.

A therm equals 100,000 British Thermal Units (BTUs). A BTU is the amount of energy necessary to raise 1 pound of water (at maximum density) 1 degree Fahrenheit. For the month of February, I used 34 therms to warm the air inside and take hot showers. That's enough energy to bring 3,016 gallons of room temperature water to a boil.

My 2017 bill was $13.47 higher than my 2016 bill because I used 7 more therms and the cost per therm increased by 25.91%. Using 7 more therms of gas had me question what the average daily temperatures were in each year? If it were colder, it would certainly make more sense that I used more gas to keep the house at 68 degrees when we are home, 62 degrees when not home, and 65 degrees when we sleep. The set-back thermostat does bump it up to 70 degrees for the hour in the morning that we normally shower.

Here is the weather data for where I live from weatherdatadepot.com:

The HDD column shows heating degree days. The CDD column shows cooling degree days. Since my home only has a heater and no air conditioner, only the heating degree days apply. A higher number means the year was more severe. With an HDD score of 62 for February 2016, and an HDD score of 145 for February 2017, you can see that using 7 more therms (a 20.59% increase from the prior year) is reasonable given that the heating degree day score increased by 133%. The rate increase of about $0.33 per therm only added to the perceived problem. The net result is that I paid $2.70 more because of the rate increase and $10.77 more because I used more gas since it was colder.

Mystery solved.

Gas guzzling is alive in the lab.