# Next best investment to save energy



## StockDogLovr (Apr 13, 2009)

We bought a home going on two years ago that is in a very hot part of the country, the Central Valley of California near Fresno. My husband had to take a job here due to losing a previous job, otherwise I never would have chosen to move to such a hot place!

Our home is 25 years old, has double pane windows with 25 year old technology, has one roof-mounted evaporative cooler and two HVAC units. Last summer, we had 30+ consecutive days of triple digits, and our June electric bill was over $600! They went down to $500 for July and the $400's for August and September. :run:

Our home is about 2500 sf. On the inspections, we were told our attic insulation was below par. So, recently we upped it to code, blown in, not cheap. Seems to have done nothing for savings. May had pretty hot weather in the 90's and we just finished some triple digit spans, and my bill just came in at $392 :Bawling:

When it was 102 the other day, the swamp cooler was blowing air that was in the high 80's. Just a bit much so had to switch to the HVAC.

We've thought about solar but wonder if it is the kind of investment that can be made back in a sale should we have to leave. We already invested $25k in a perimeter fence - we have 40 acres and the old barbed wire fence wouldn't hold anything. It sounds like we'd have to lay down a large chunk of cash to get the kind of system that would run the meter backwards with those kinds of summer usages. How does DIY installation compare and can you get the same rebates with that route?

Just wondering what our next best move is to improve things. I was researching attic fans, and first read that they could really reduce power usage for A/C, but then elsewhere I read that your bill could go up if you have ceiling leaks that cause your A/C to try to cool your attic!

When the insulation was blown in, the outfit we used suggested that the next best move was to replace our windows with today's double pane windows which are about 90% efficient. Again, BIG investment, and can it be recouped through an increased sale price?

Sorry so long, but I'm freaking out as we enter into the summer with triple digits becoming the norm in this area


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## roberte (Nov 8, 2009)

Do a pressure test, then fix leaks first. 

Look at wall insulation and windows, ext color, window awnings, attic vent, water spray roof. Plantings, trees.

Zoning of AC/heat system.

A good energy audit should include estimates on payback.


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## TnAndy (Sep 15, 2005)

The technology of dual pane windows has not changed much in 25 years. You most likely won't recover the cost of new windows in energy savings.

Now they add LowE glass, (an option with certain brands) which would help, and argon gas, which by all accounts I read leaks out in a couple years (they use it to boost energy ratings a little at the time of testing), and other than that, a dual pane window is a dual pane window.


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## nosqrls (Jun 9, 2012)

Check doors for air leaks. A water mister on hvac condenser will make it more efficient (pulls more heat out of gas so it cant pull more heat out of inside air).


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## Gray Wolf (Jan 25, 2013)

How old are your ac units and what is their efficiency?


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## SolarGary (Sep 8, 2005)

Hi,
One of the largest sources of heat gain is direct sun through windows that face south, east or west. If you have that situation you can save a lot of energy with awnings, landscaping that shades the windows, solar screens... Any thing that blocks the sun before it gets to the window. We use exterior roll up shades that block the sun on the outside, but let enough light through for a view.
If you can't put something outside the window to shade it, than a reflective inside shade can help.

If you can get a good energy audit (maybe from your utility) that would help you decide what is most cost effective to do next. Its not likely to be windows or a PV array.

Some cost effective cooling ideas here: http://www.builditsolar.com/Projects/Cooling/passive_cooling.htm

I'm not sure about the Fresno climate, but if its hot during the day, but cools off at night, you should look into a whole house fan. This kind of fan is used at night (when its cool outside) to pull cool air into the house. It not only cools at night at very low cost, but it precools the house thermal mass so that on the next day the house stays cool a ways into the day.
There is a section on the whole house fans at the link above, or just google them.



Gary


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## Harry Chickpea (Dec 19, 2008)

30 days of triple digits and a bill of $600 on a 2500sf house is not terribly unexpected. You have some very good advice above.

Your options boil down to:

Limiting hot air intrusion. When using a swamp cooler, the home is at positive pressure, so this is not a factor. With HVAC it is.

Insulation. You covered the attic, that is most important. South and west facing walls would be next.

Shade. Anything that shades and/or limits reflected heat can keep exterior walls/windows/roof cooler. Also, reflective surfaces on the house and NON-reflective surfaces on the south and west ground can help.

Evaporative cooling. You may be limited in this because of the water restrictions and water pricing may limit the cost effectiveness of some things. In Florida I used misters outside to good effect. Pre-cooling the air to the HVAC coils can give an UP TO 11% increase in efficiency. It won't do more than that, because of a few factors. AC pump motors and compressors are fairly flat in the amperage draw under load and no-load conditions, and the compressor/scroll works by changing the refrigerant gas to a liquid. That is where the big energy consumption is, and cooling the incoming gas has a surprisingly minimal effect. (It has to do with the gas laws and percentage of change in temperature above absolute zero.)

It is hard to take advantage of thermal cycles. If the dew point is low, you might find that drawing air into the swamp cooler from underground pipes on the hottest days could help a little.


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## used2bcool13 (Sep 24, 2007)

What about a solar powered attic exhaust fan? Its easier for the cool air in the room to displace the hot air in the room, your swamp cooler or a/c might work less or at least more efficiently. Might be eligible for a rebate, I see them in Home Depot for about 229.


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