Author Topic: Was able to reduce gas heat by almost 70%  (Read 671 times)

MrSal

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Was able to reduce gas heat by almost 70%
« on: December 28, 2018, 11:32:01 AM »
Hey guys,

I have shared a few topics regarding my DIY projects that I have been doing in the house for the past couple years and was really excited to share the last data but was waiting for more agressive temperatures.

I guess now that December is over I can already rely on the data - I was able to estimate the exact therm consumption for this month 30 days before hand using data from November and average HDDs! - I think it will be pretty accurate for the rest of the heating season as well.

For some background, I have a 1200 sq foot ranch house built in the late 50s. Insulation was not the best at least in the attic and I assume the walls don't have much.

Well, during one of our DIY projects of tearing down our kitchen and building an island and making it open space: https://forum.mrmoneymustache.com/do-it-yourself-forum!/diy-backyard-officeextra-room/  we took advantage and insulated the whole attic with celullose to around R60 - less at the eaves since we have a low pitch roof. Cost was pretty low at 500-600$ per 100 cellulose bags (at my Lowe's it costs 13$ per bag but I was able to play the price match in my favour - price matching a building center + 10% price match and then using 40$ off of $200.) All in all I remember I paid around the 6$ per bag ... to which I received 125$ back from my electric supplier and also another 10% rebate for efficiency.)

Anyhow, that was November 2017 and we saw immediate savings (around 40%).

This summer we fully insulated our sill plates and our basement walls with 2" foamboard. So around R10-R13. While I know the ROI probably is not worth it in terms of heat savings, especially considering how low our heat is, we did so in order to finish the basement and make sure we wouldn't have moisture problems. So far so good. Making some rough calculations however, I calculated that just from insulating the basement we could get around 20-30% further improvement in heat savings.

I can tell you I WAS NOT WRONG!

Our last bill for December was 49$ of heat and we live in Central PA. Out of this 49$, 13.50$ was just the good old customer charge. Supply+Distribution are currently around the same price at 40 cents per therm. Total usage was 45 therms of which I calculate 7 therms for water heating (it's around that during summer to keep the water tank working).

November we only used half at 19 therms for the heat!

As an example, back in 2014 our usage for December was 140 therms! So this right here is 73% !!

And we are heating 2400 sq ft of house (the basement has as many heat vents as the normal area so I think we should consider for heating purposes 2400 sq ft? - I think the previous owner had a little workshop downstairs and wanted it heated).

Because everyone likes a graph here is our usage of NG :



Our average winter is about 5900 HDDs and we are currently using:

(19+38 therms)/2400/1753(the heating degrees for the period) = 1.35 BTUs/sq foot per HDD

Since heat escapes faster when the difference of temperature if higher I think we should solely rely on Dec calculations at 1.58 BTUs.

For comparison, back in '14 we were using 6.20 BTUs/sq ft per HDD ... so in essence we have achieved 80% savings on a HDD basis (the fact it doesn't relate to therm usage is because we increased our inside temperature from 65F to 68F and at night, before we used to keep it at 50-55F and nowadays is at 60F)

Comparing to between 17 and 18:

Nov+Dec 2017 = 1490 HDDs
Nov+Dec 2018 = 1752 HDDs

So this winter, so far, has been 17.58% colder and yet, we have saved 70% in actual costs compared to other years!

At this point, I estimate our heating costs for full season will be on an average winter: 5900HDDs*2400*1.58 = 223 therms (it might be lower since the shoulder seasons the consumption is not 1.58BTU but 1.3's as we've seen above).

At a cost of 0.9$ per therm, that's about $200 of heating!

So how much are we saving with the insulation?

5900 HDDs (avg winter)*2400 (sq ft)*6.2 /100000 * 0.9$ = $790

5900 * 2400 * 1.58 /100000 * 0.9 = $201

Almost $600!

I consider both the attic insulation and basement insulation a success! More so the attic insulation, since the payback of the basement insulation wasn't as attractive (we paid 700$ for 1300+ sq ft of 2' foam board but the savings were only to be 20% of an already very low base - I consider savings of around 40-50$ from it per year, so it's almost 15 years - but as said previously we didn;t do it because of ROI but to avoid moisture, condensation, etc).

Attic is definitely in a ROI perspective the best investment you can have done! Our insulation projects cut our gas bill into the 70% range!! I cringe at friends when they tell me their bill for the winter is 2500-3000 dollars (they have heating oil)

Even though our walls are probably not insulated or very badly - as well as our windows are not that good - I don't see how or why to even think of upgrading it. While I would love to have the walls insulated and have a house like a YETI cooler, financially it does not make any sense whatsoever. In our case, the payoff was at about 1 year which is great!

So go ahead and insulate the heck out of your attic making sure to seal everything. You will be rewarded!
« Last Edit: December 28, 2018, 11:35:17 AM by MrSal »

OmahaSteph

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Re: Was able to reduce gas heat by almost 70%
« Reply #1 on: December 28, 2018, 07:30:44 PM »
Thanks for the data and great job!

I bought my house last year and I have no idea what the attic insulation looks like, but the house is only about 12 years old. They started to drywall the basement but gave up halfway through. We plan to turn it into an office/den, so insulating has been one of the top improvement projects on our radar (walls, floor AND ceiling - if guests are sleeping down there, you can hear every little movement).

MrSal

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Re: Was able to reduce gas heat by almost 70%
« Reply #2 on: December 28, 2018, 08:03:04 PM »
Thanks for the data and great job!

I bought my house last year and I have no idea what the attic insulation looks like, but the house is only about 12 years old. They started to drywall the basement but gave up halfway through. We plan to turn it into an office/den, so insulating has been one of the top improvement projects on our radar (walls, floor AND ceiling - if guests are sleeping down there, you can hear every little movement).

Even newer houses can have poor insulation. As for your basement project, make sure not to use fiberglass - due to moisture problems. Foamboard is best, although pricey. We bought salvaged foamboards from a builder at about 10-12$ per sheet instead of the 36$ at Lowe's brand new. They are the same although mine was just a bit dirty which makes no difference in the end.

For sound purposes, from my research - also redoing the basement - mass is key! If you apply Mass Vinyl sheet before you apply the drywall ceiling it will reduce the noise by like 30 dB ... Mass Vinyl is about 1/8 thick and has a lot of mass at around 1.5 lbs per sq ft. It's the best thing to eliminate sound really. You can buy online at around $1 per sq ft or so... you can also use rockwool between the joists however the mass vinyl I think is the best option.