Author Topic: Weighing the Energy Saving Alternatives  (Read 3221 times)

jhomme

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Weighing the Energy Saving Alternatives
« on: May 01, 2015, 11:11:23 AM »
I live in sunny Arizona in the Phoenix metro area.  If you're not familiar with our happy climate, we have an average high of 67F in December and 106F in July.

I've read MMM's many posts on energy saving tips.  But I'm struggling with two things: 1) how to prioritize them in terms of bang for the buck and 2) how they may or may not apply to my climate.

If any have some thoughts on this, I would appreciate you sharing your experience.

Some data on my situation:
  • My home lies East-West with the backdoor facing South.
  • None of my south-facing windows receive direct sunlight (except for maybe a little in the winter).
  • 75% of my floorspace is tiled
  • Almost all of lights are LED
  • I am married with 4 kids.  Lots of laundry.  About half is air-dried.
  • Our attic has a couple layers of insulation.  The youngest layer (12yrs old) is fiberglass and is looking pretty thin.  The oldest I believe is practically dust by now.
  • We have two whirlybird roof vents.
  • We have a about an 8-yr old air conditioner (not sure of rating) that is well maintained and in good condition.
  • Most of the windows are original (30yrs old), single pane.
  • The hottest place in the house is the dining room that was added on about 15 yrs ago by a prior owner and touches the south part of the house.
  • Our home is 1800 sqft.
  • We keep the temp indoors at 78 in the summer (no possibility of convincing the family of increasing this) and 68 in the winter.  We don't use A/C in the middle months as we can leave doors open at night and morning.
  • We spend about $140/mo on average for the year.
  • For people who know the area, we are on the EZ-3 plan with SRP.

Actions we're considering:
  • New windows
  • New insulation, then there's the fiberglass or foam decision
  • Sealing the building envelope (not sure how this is different than insulating)
  • Electric attic fan
  • Anything else?

We've got the funds to invest in all the above items, if the payoff makes sense.

Mother Fussbudget

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Re: Weighing the Energy Saving Alternatives
« Reply #1 on: May 01, 2015, 11:27:13 AM »
Contact your utility, and see if they provide a free home energy audit.  You *can* DIY this if you research it - using a door seal fan / negative air pressure in the house.  But if the utility does this for free... why not do it?

JLee

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Re: Weighing the Energy Saving Alternatives
« Reply #2 on: May 01, 2015, 11:28:44 AM »
SRP is currently (or was a week or two ago) offering a $99 energy audit.

$140 average year round is low! I'm at $236/mo :(  I did recently replace my old inefficient pool pump with a new Energy Star variable speed pump, and I am replacing my 4500w water heater with a heat pump water heater, so hopefully that will help.

nawhite

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Re: Weighing the Energy Saving Alternatives
« Reply #3 on: May 01, 2015, 11:33:35 AM »
Put awnings on windows and vigilant use of blackout/insulating blinds and opening closing windows. Arizona gets hot during the daytime but is pretty cool at night and has large temperature swings in day and night. If you close the windows during the day and cover them with insulating shades, then in the evening when it cools down, open the windows, open the blinds and stick a fan in a window and you'll probably decrease your heating and cooling bills significantly.

In Denver (similar large temperature swings) our house stays below 75 all year round without the AC ever turning on, it just takes being active about letting the house breath.

Single pane windows are also probably killing you but an infrared scan of your house by an HVAC/Efficiency guy will tell you better. If you have windows you never open, at least put thin film over the frames to get another layer to stop air movement. You can buy it at a hardware store, $20 should get you the film and 2 sided tape for about 4 windows.

If the house has a "hottest place" it is most likely either a lack of insulation compared to the rest of the house or more or less windows compared to the rest of the house. Since it's an addition the lack of insulation is pretty likely. Look into just insulating that room more. If you have giant windows in that room and it gets too hot, think about blinds.

My house is a little smaller with no kids but before we put solar panels on, we were at $40-60/month in electricity and gas bills.

jhomme

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Re: Weighing the Energy Saving Alternatives
« Reply #4 on: May 01, 2015, 12:02:05 PM »
Thanks, everyone.

@nawhite:
I do have wood shutters on all the windows (except in the "hot" room french doors).  Keeping them closed is an option when no one is home.

I'll look into the insulation for the hot room.

I'll check into the infrared scan as well.

I do use the fan method at the moderate temperature times of the year.  However, in the summer when it's really hot, the overnight low is frequently above 80F.  So A/C is running constantly and opening windows/doors would do no good whatsoever.

@JLee:
Ouch!  That's quite a bill.  Yes, I think we do ok on ours.  It's a small house and we don't have a pool.  So that helps.

I'll definitely look into the energy audit.


Any more input on the cost effectiveness of insulation, or will the energy audit provide some insight on that question?

velocistar237

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Re: Weighing the Energy Saving Alternatives
« Reply #5 on: May 01, 2015, 12:10:48 PM »
Storm/secondary windows instead of new windows.

Definitely air sealing.

http://www.greenbuildingadvisor.com/blogs/dept/musings/fans-attic-do-they-help-or-do-they-hurt

Once you think this through a bit, register on Green Building Advisor and submit a Q&A question before doing any work. Be wary of the numbers energy auditors give you, both because they're based on general rules rather than your specific house, and because in some cases there's a conflict of interest.

JLee

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Re: Weighing the Energy Saving Alternatives
« Reply #6 on: May 01, 2015, 12:36:30 PM »
Put awnings on windows and vigilant use of blackout/insulating blinds and opening closing windows. Arizona gets hot during the daytime but is pretty cool at night and has large temperature swings in day and night. If you close the windows during the day and cover them with insulating shades, then in the evening when it cools down, open the windows, open the blinds and stick a fan in a window and you'll probably decrease your heating and cooling bills significantly.

In Denver (similar large temperature swings) our house stays below 75 all year round without the AC ever turning on, it just takes being active about letting the house breath.

Single pane windows are also probably killing you but an infrared scan of your house by an HVAC/Efficiency guy will tell you better. If you have windows you never open, at least put thin film over the frames to get another layer to stop air movement. You can buy it at a hardware store, $20 should get you the film and 2 sided tape for about 4 windows.

If the house has a "hottest place" it is most likely either a lack of insulation compared to the rest of the house or more or less windows compared to the rest of the house. Since it's an addition the lack of insulation is pretty likely. Look into just insulating that room more. If you have giant windows in that room and it gets too hot, think about blinds.

My house is a little smaller with no kids but before we put solar panels on, we were at $40-60/month in electricity and gas bills.

Opening windows at night can work in March/April, but in July-August when it's 100f overnight, not so much. :)

Jeremy E.

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Re: Weighing the Energy Saving Alternatives
« Reply #7 on: May 01, 2015, 02:15:25 PM »
Some companys will provide an electric rebate or credit if you update your house and make it more efficient, contact your electricity provider and ask about any possible rebates or credits, if the rebates are close to the price of the upgrade it's a no brainer. If you learn to update your house yourself rather than hiring contractors, then you almost always win, your house becomes nicer and more comfortable for you, more efficient and costs you less, becomes more valuable if you ever decide to sell it, and lastly you gain skills and experience. A win win win win win win win situation :)
« Last Edit: May 01, 2015, 02:44:13 PM by Jeremy E. »

greenmimama

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Re: Weighing the Energy Saving Alternatives
« Reply #8 on: May 01, 2015, 02:19:16 PM »
IDK, I am just amazed that your average temp is 67 in Dec. and you turn the heat on at all :)

Our average in Dec is maybe 30 and we have our heat set at 58 :)

Just so weird to think about.

JLee

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Re: Weighing the Energy Saving Alternatives
« Reply #9 on: May 01, 2015, 02:24:32 PM »
IDK, I am just amazed that your average temp is 67 in Dec. and you turn the heat on at all :)

Our average in Dec is maybe 30 and we have our heat set at 58 :)

Just so weird to think about.

Average high of 67f, not average overall temperature. Lows in the 40's.  When you're used to 115f summers, 55 degrees inside is cold!

velocistar237

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Re: Weighing the Energy Saving Alternatives
« Reply #10 on: May 01, 2015, 02:30:08 PM »
When you're used to 115f summers, 55 degrees inside is cold!

Put on a sweater! And get off my astroturf!

JLee

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Re: Weighing the Energy Saving Alternatives
« Reply #11 on: May 01, 2015, 02:31:55 PM »
When you're used to 115f summers, 55 degrees inside is cold!

Put on a sweater! And get off my astroturf!

Pft! If I freeze my roommates out, I lose $13k a year!