Tag Archives: economics

2016 heating savings

It is friggin cold outside, and I can’t shake the urge to keep talking about heating related matters, so here we go again:

One goal of our deep energy retrofit was to save energy, and along with it, some Benjamin Franklins. The money we invested in tightening and insulating the building was meant to save us dollars on our heating bill, for instance.

But how would we measure how much we save? Our problem was that we had no starting point. We bought our building as a foreclosure in 2009 and thus had no data – no access to utility bills – that would tell us what it took to keep the building heated and comfortable.

That said, there are plenty of buildings in our neighborhood that could serve as a comparable (comp). Not only are they the same construction type, but also in the same energy deficient shape as our building was before we started with our deep energy retrofit.

I found a building that was a good match, and the owner that was happy to share their utility data with us.

To compare apples to apples – or in this case, therms to therms – I calculated the amount of therms used per square foot per month for both buildings. Our building’s natural gas consumption is reflected in the blue bars, while the comp, or pre-retrofit state, is reflected in the red bars.

Data reflections

Why is there natural gas used during the summer months (off heating season)? Because in both cases natural gas is used to produce domestic hot water, i.e. washing the dishes, running the washing machine on warm or hot cycle, taking a shower, etc.

You may have seen me bragging about turning our heat on as late as mid November. If you look at the consumption for November 2016, you see that we mostly used domestic hot water while our neighbor in the comp building had the boiler already buzzing away.

Looking at the big picture, our building consumed 0.200 therms/square foot over the course of one year, while the comp usage was at 1.464. Our deep energy retrofit improvements appear to have reduced our natural gas consumption by 1.264 therms/square foot/year. That equals a reduction in our heating needs from November 2015 through December 2016 by a whopping 86%!

For our metric friends (i.e. the world with the exception of the U.S.): Our natural gas consumption equated 63.04 kWh (or 226.95 MJ) per square meter, while the comp came in at 461.83 kWh (or 1662.59 MJ) per square meter.

I typically don’t like to measure the improvements in cost savings, as supply cost and taxes may vary between jurisdictions or energy companies. In addition, the fixed costs on the gas bill, although often small, prevent accurate scaling to a square foot basis.

Yet getting an approximation of the monetary savings would give us a sense of the potential return on investment. We paid $0.27 for natural gas per square foot over the course of a year. The cost of the comp were $1.47. The estimated total cost savings for the 2,900 square foot of conditioned space in our building from November 2015 through December 2016 would be in the range of $3,400.

Yes – I am beaming right now! Yet, this somehow seems too good to be true. I think the flaw with my analysis is that I have based it on one comp only. I plan to find another couple of buildings that I could include in the analysis. That should give me a number that would be easier to defend.

Stay tuned, because I will keep you posted!

Related posts:

Buying a foreclosure – Part 8

Welcome waste (energy)

Start of the 2016 heating season


Last rock wool pick up

We had started to frame out the perimeter walls on the second floor, and at the same time insulate them with rock wool.

Well, the time had come to make one last trip to pick up the last batch of rock wool. If I measured and calculated correctly, this last batch should allow us to complete the 2nd floor insulation. I may need another bag for an odd job here or there. But the big task – the insulation of the building envelope – was about to be completed!


This felt like another milestone. The numbers are certainly impressive:

To insulate our building envelope I purchased 194 bundles (or bags) of rock wool.

That took care of the basement and 1st floor2nd floorand attic.






We unpacked, handled, fitted, and installed a total of 2,328 rock wool batts, each measuring 15 ¼ inches wide, 47 inches long and 3 ½ inches in depth (stud depth). At 4.975 square feet per batt, we installed a total of 11,581.80 square feet.

The total material cost added up to $6,348.37, including taxes. That translates into $0.55 per square foot of 3 ½ inch batts, or $0.16 per board foot (one board foot is one inch over one square foot).

That leaves us with a nice, comfortable, and quiet building interior. That’s right! The rock wool does not just provide thermal insulation, but also sound insulation.

Related posts:

Price check, and – surprise!

I needed more rock wool insulation – a whole lot more. It’s for the second floor exterior walls and the attic.

My primary rock wool supplier, the Chicago Green Depot, went out of business about a year ago. I needed to find a new supplier!

Back in the day, the Chicago Green Depot had the best priced rock wool. I got the last batch in early 2012 for around $35.00 per bundle (60 square feet of 3 1/2 inch rock wool batts). All other sources I contacted, including your typical big box home improvements stores, always came in more expensive.

This time around, April 2013, didn’t seem to be any different. The Home Depot had the bundle of rock wool listed for around $43.00! I thought, though, that it couldn’t hurt to double check the pricing for 120 bundles at the Pro-Desk in my local store.

The printout I was handed listed a total of $3,340.80. That breaks down into a unit price of $27.84 per bundle plus tax (or $0.13 per board foot). That is a considerable price drop from the listed $43.00 … around 35%! This is even less that the first batch I bought for the basement installation.

Do I need to say that I was a very happy camper?

Why that 35% price drop? If I go to the Home Depot and place an order over $2,500, I am referred to – what they call – the bid room. Because I am buying in bulk, I have access to a different pricing structure. That said, I would be surprised if that 35% discount will last for long; this may be part of a current promotion.

The significance is that this is the first time that I bought a substantial amount of building materials from a typical big box home improvement store. Materials for a deep energy retrofit like ours were in the past not available, hard to get special orders, and/or too expensive.

Is this a sign that green building materials are on their way into the mainstream?

Related posts:

Painting, equipment and sidetracking

Thanks to our friends Scott and Carlos, priming the drywall was like eating cake! And – because we got the priming done so quickly – I now can shift gears and start with the proper paint.

While looking for a suitable zero VOC paint product, I ran again into the issue of finding something that has a price point of $30/gallon or less and is not a special order.

After some back and forth, we settled on Behr Premium Plus Interior Eggshell Enamel. It meets our price point and zero VOC requirement, and is labeled low odor.

I found out that low odor does not mean odor free. Don’t get me wrong – it is not obnoxious. In fact, it is really nice to paint without being engulfed in the fumes of other conventional paints that still contain some level of volatile organic compounds (VOC’s). But, as I said, it is not odor free.

While I was in the store, waiting for the color to get mixed, I browsed through the various rollers that were on display. I picked up a rather pricy one to give it a try.

To my surprise, it lasted through the entire paint job, and it still in such good shape that I probably will use it on the second floor. Compare that to the cheap rollers I started with. They lasted for one day and had to go into the trash.

That got me thinking – about the trash we produce because we fall for a lot of cheap stuff. Plus, economically it made sense to get the expensive but good quality roller. By now it has paid for itself, outlasting God knows how many cheap rollers.

It is also a microcosm of what happens with green buildings and deep energy retrofits like ours. A lot of people shy away from the green or more energy efficient option because it appears so expensive when compared the the conventional (cheap) options.

But if green building technologies are executed wisely, they begin to pay for themselves – and may even begin to save some real money at the end.

Wow, I really had a lot to say about painting – didn’t I?


1st floor priming

Our freshly restored hardwood floors are all carefully covered up, because its time to start painting.

There are two components to this task: the straightforward and the not so straightforward parts.

Getting the paint on the wall is what I would call the straightforward part. Actually, we won’t start with paint. We’ll start by priming all the drywall.

The not so straightforward part has to do with the product choice. We are set on zero VOC primer and paint products. This is non-negotiable, as it has an direct impact on the indoor air quality (IAQ).

Back when we painted the garden unit, I sourced the primer and paint from the Chicago Green Depot, which has gone out of business since. With that, I lost a convenient and affordable source for zero VOC paint products.

“No problem, there must be other products and suppliers.” Yep! But few of them are conveniently accessible (i.e. brick and mortar business), and even fewer have zero VOC products at a reasonable price point.

I mean, if you look around and online, you can find coolest products under the sun out there. But we are not about to spend $60, $50 or even $40 per gallon for paint or primer. Our threshold is at $30/gallon, or preferably less.

That really begins to narrow it down!

For the primer we settled on Bulls Eye Zero Primer-Sealer by Zinsser. Even though it is water based, it has a really thick consistency – almost too thick. We diluted it to the maximum recommended ratio, and it still was thick, but we were able to get a few additional square feet of coverage out of it.

Thank you to our dear friends Scott and Carlos who master roller and brushes like few others do!