FYI: Energy Efficiency (Dallas, Allen, Live Oak: how much, house, buying)

[lh_newbie]

I'm finally getting gas bills for times when we had our heat on and thought I could pass on some info, as people have asked many times about utility bills:

When we moved into our home (2576 sq ft, single story, built in 1976), it had barely any insulation, had single-pane aluminum windows and an HVAC system that was 17 years old. With that old setup, here's the numbers:

Original HVAC system, no changes
2-week electric bill last September: $229. This means the month of Sept, if we had been in the home for the whole month, would have been over $450. It's worth noting that the end of Sept in '06 wasn't that hot. The first two weeks of Sept were much hotter - so the bill probably would have been in the $500-550 range.

During the month of Dec '06, we had a gas bill of $191.

New HVAC, upgraded insulation in 70% of home
I just haven't crawled back into the attic to finish the job yet - will do in Feb when I have time. Old insulation was basically non-existant - where it had any, it was 2-3" thick; new insulation is roughly 16" thick and is the DOE recommendation of R-49. Replaced the HVAC system with a 16-SEER dual speed, dual stage system. Furnace is still only an 80% efficient unit - my HVAC guy convinced me the cost of upgrading to a 90-95% efficient unit just wasn't worth it since our heating season is so short.

In August '07, we had a $227 electric bill for the entire month - so at peak cooling season, we saved roughly 50% on our cooling.

I just received our December gas bill - it was $165. Looking at the actual usage, and normalizing the data based on "heating degree days" published by the national weather service for Dallas, I calculated our overall gas usage to have dropped by 25.7% - just by increasing attic insulation.

Conclusion
If you have an older home and your HVAC system is over 10 years old, you might save some serious cash by upgrading insulation (cheap) or HVAC (not so cheap).

Like I said, I'll be finishing the insulation job in Feb. I also have new windows for the master bath and master bedroom that I'll install that month also. I'm estimating that with the insulation alone - we'd drop gas usage by a total of 30-35%. If we were to replace all the windows (won't happen for some time), since they're aluminum and single-pane, we would see another 15% in the winter and probably 10% in the summer.

I am rather amazed at how well our 70's home responded to the rather simple efficiency upgrades.

We just recently changed our electric plan, dropping our price per KWH from 12.5 cents down to 10.1 cents. Based on that and our historic usage, I'm projecting our overall yearly energy cost of gas + electric to be about $2200. Not bad for an older home. If we were to replace all the windows (and if anyone wants to donate to the "new window fund", please let me know), we'd see that drop to $2000/year.

Hopefully this info is helpful to someone.

Brian

[jerlap]

Thank you for the info. We are planning a move to the Dallas metro area this summer and we have been trying to find just such info. My husband and I are debating back and forth over new construction vs. 2-15 yr old home with trees. It is very hard to nail down such specific data, but you did a very good job. Thanks!

[Tta]

Great analysis. I have a few questions for you though.
Do you have any large trees providing shade?
What direction does your house face?
How much did the HVAC work cost?

Thanks for the in depth look into making an older home more energy efficient. My wife and I are looking at older homes and will probably be doing similar updates.

[lh_newbie]

Originally Posted by jerlap

Thank you for the info. We are planning a move to the Dallas metro area this summer and we have been trying to find just such info. My husband and I are debating back and forth over new construction vs. 2-15 yr old home with trees. It is very hard to nail down such specific data, but you did a very good job. Thanks!

What can I say... I'm an engineer. We're data freaks.

I don't have my old bills from the house I had in Allen, but it was built in 2001, was 2-story, 2680 sq ft, dual-pane windows and separate HVAC for downstairs and upstairs. My energy usage in that home, even though it was built to all the new specs and had an upgraded SEER on the A/C (2001 regulations required 10 SEER, I had it upgraded to 12 SEER during construction), my energy usage in that home was slightly higher than my current (and older) home by about 5-10% - even though the "new" home in Allen had dual-pane windows. Two story homes are less efficient (it's called the heat-stack effect or something like that) + the fact that the "new" home in Allen was exposed to the sun since the trees were about 15-20' tall when I sold it in Feb '06.

Based on my experience, I don't think I'll ever buy a home without shade, nor a 2-story again. I love the single story layout - and if should something happen to my wife or I, we don't have to contend with stairs if our mobility is affected. I know my mother-in-law likes the layout (she has only one leg).

[lh_newbie]

Originally Posted by Tta

Great analysis. I have a few questions for you though.
Do you have any large trees providing shade?

Yes, two large shade trees on the South side of our home. The trees are Live Oaks, so they do not shed their leaves in the winter so we aren't getting "free heat" during the heating season from the sun. In a perfect world, they would be Red Oaks or some tree that drops it's leaves in the winter.

Originally Posted by Tta

What direction does your house face?

North-south - as you are probably aware based on this question, having most of your windows N/S is the most energy efficient.

Originally Posted by Tta

How much did the HVAC work cost?

We have a friend that turned us on to her HVAC guy. Super nice guy, great prices, just not the most responsive, but I'd certainly recommend him to people because he's honest and has great prices. We paid $6600 for the entire system (including adding another cold-air return as the old one was undersized).

Originally Posted by Tta

Thanks for the in depth look into making an older home more energy efficient. My wife and I are looking at older homes and will probably be doing similar updates.

FYI: I put in cellulose insulation myself... when all is said and done... 132 bags of it (about $1100). That's a ton of insulation, but it's also 2600 sq ft of space that needed R-49 insulation.

[nsumner]

Thank you so much for the data Brian especially that the costs are included... I will share with clients who debate upgrading to new vs remodeling what they already have, or those thinking of buying new vs older.

[loves2read]

what kind of windows are you using to replace for the olds ones?
we have double pane windows that are original with our 25 year old home--we have lots of windows as well--
would be interested to know if you got gas-filled or just the filmed windows and what brand

[ladysrodgers]

Sounds like you did a great job, newbie! Another simple thing people can do who have older homes, is go into the attic and replace their existing ducting - or at the least, check it and make sure there are no holes in it, or connections that have come undone.

Replacing the ducting is simple. You can buy ducting that comes like a slinky in a box. Get fasteners (metal straps) and just connect it where the existing ducting is.

It is very common for the ducting to get holes due to various critters, or simply aging, and equally as common for the ducting to come undone due to a home settling, etc.

[lh_newbie]

Yes, many older homes have leaky duct work that may be either inadequately, or simply not at all, insulated.

[lh_newbie]

Originally Posted by loves2read

what kind of windows are you using to replace for the olds ones?

We bought Jeld-Wen "Premium" Vinyl windows, dual pane with low-E coating. They're nice, simple windows. Their specs are great: U-factor of 0.34 (R-value of ~3) and Solar Heat Gain Coefficient of 0.30 (blocks 70% of heat from the sun).

I was appauled at the leaky installation of the old windows. Basically, they put the window in place and nailed around the flange. No caulk, no sealant of any kind. Sure, there's caulk between the window and the brick, but nothing between the window and the wall framing/rough opening. No wonder the old windows don't stop any sound from coming through - let alone wind of any type. My installation gets caulk on both sides and filled with the "flexible" type foam insulation - no wind will make it through that! Add to that I wrap the opening with butyl rubber... and no water is going to damage my window openings.

Brian