Onset of nerdiness

Strange things happen once one embarks onto the deep energy retrofit road. For instance, a level of nerdiness sets in.

You don’t just turn on the thermostat in fall. You make a note about when exactly you turned it on. This year, it was the evening of November 1st.

Not nerdy enough? How about this:

Back in the day, when I was more than young – when I was a kid – a hybrid of joy and eager anticipation clocked in once a week, triggered by the release of the next episode of a science comic book.

Some may argue that things haven’t really changed that much, except that the comic book was replaced by the monthly arrival of our utility bills. I devour them almost immediately, and they almost always make for some interesting reading.

Such as our natural gas bill for last month, which claims that we used more gas in October 2013 than October 2014!


Therms 10/2013: 32.51
Therms 10/2014: 22.52

Average daily therms used 10/2013: 1.02
Average daily therms used 10/2014: 0.75

That seemed strange, particularly because this October seemed so unseasonably cold.

Well, let’s separate fact from fiction. October 2013 was cooler, at an average daily temperature of 50 degree Fahrenheit, compared to 51 degree Fahrenheit for October 2014.

That still doesn’t explain away the difference in natural gas consumption. Nor do the extra two days on the October 2013 bill, although they could account for as much as 2.04 therms. To get to the bottom of this, I have to turn to the Energy Recovery Ventilator (ERV).

With an almost airtight house like ours, mechanical ventilation is less a choice than a necessity. It maintains good indoor air quality (IAQ) by removing pollutants and excess moisture, and as such protects us from what is known as the sick building syndrome.

The ERV doesn’t just ventilate the building, but it also has a built-in heat exchanger, the enthalpy wheel. This makes it an extremely useful piece of equipment, particularly during the heating season, as we get a supply of fresh air without the typical heat loss.

We had our fair share of ERV problems last year, starting in October. The air in the building got stale rather quickly, with no functioning mechanical ventilation. To maintain good indoor air quality, we fell back on the age old method of non-mechanical ventilation – opening the windows.

The problem for us was that there is no heat exchanger when you open the windows. We got plenty of fresh air – but is was cool October air. With that we had a lot of heat loss, which led us to turn the heat on about a month earlier than usual.

And that, ladies and gentlemen, probably explains the difference of 10 therms in the gas bill between this and last year.

If you find this remotely interesting, you have officially joined the club of nerds!

Related posts:

Blower door test – after insulation

Picking an ERV

Design workshop

ERV – keeping the heat!

ERV performance test

ERV croaked – Part 1

About Marcus de la fleur

Marcus is a Registered Landscape Architect with a horticultural degree from the School of Horticulture at the Royal Botanic Gardens, Kew, and a Masters in Landscape Architecture from the University of Sheffield, UK. He developed a landscape based sustainable pilot project at 168 Elm Ave. in 2002, and has expanded his skill set to building science. Starting in 2009, Marcus applied the newly acquired expertise to the deep energy retrofit of his 100+ year old home in Chicago.

2 thoughts on “Onset of nerdiness

  1. Hey I love the blog. I’ve been going through your posts for awhile now. I have a question for you. We bought a 1959 brick ranch in NC that has newer windows. Do you think its worth going through all of the trouble to make it super efficient? Our weather is pretty moderate here, so heating and cooling doesn’t take a great deal of energy.

  2. Hi Casey. I couldn’t tell you if it is worth taking your 1959 building through a deep energy retrofit. There are too many variables that I don’t know about. Like, is the construction of your building of such quality that it holds long term promise? Or, what is the bottom line for you? Do you expect returns in 5, 10 or 25 years?

    What you should do is commission a thorough energy audit. It will cost you a buck or two, but it will provide you with an detailed analysis of what improvements you should do, what improvements are possible, and how much they would cost. That is critical information helping in the decision making process. Once you have the energy audit results in hand, you should have a much better idea on what your first steps could be, what is necessary, and what makes sense.

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