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How can I reduce my home cooling costs/energy usage?

BrettS

Active Member
Mar 28, 2017
2,155
2,575
Orlando, FL
If you're ok with only cooling the part of the house that's occupied you could install a split system for far less than replacing your main HVAC. I've been doing some research into the Mr Cool DIY units. I thought they were kind of gimmicky but they're actually pretty legit. Here's a 20 SEER for ~$2k.

It’s an interesting thought, but I’m not sure it’s really a good fit for my house. The house is a single story with a pretty open floor plan and is just under 1500 square feet. There’s not really a lot that could be divided off.
 

nwdiver

Well-Known Member
Feb 17, 2013
9,176
13,919
United States
It’s an interesting thought, but I’m not sure it’s really a good fit for my house. The house is a single story with a pretty open floor plan and is just under 1500 square feet. There’s not really a lot that could be divided off.

An open floor plan is even better. One might be enough to cool the entire house; That would drop the cost of upgrading your HVAC from $10k to ~$2k.

I also doesn't need to assume the full cooling load to save you $$$. If 80% of your cooling load is replaced by a 20 SEER unit from a 13 SEER unit that alone will save you a lot.
 
Yeah, I feel like the single pane windows are definitely causing some heat gain in the summer. I also just found out that my utility offers a rebate for window upgrades as well. It looks like it might only be around $200, but hey, a $200 rebate is better than no rebate.
Additionally, note there is a 10% tax credit (excludes labor,) capped at $500 lifetime for energy efficient items like windows (which is capped at $200) and doors, among other things. So if you haven't used that in the past decade or so, you can claim that credit as well.
 
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If you have single pane windows then replacing them is the first thing I would do. Not only will you save some money but you will be more comfortable. As someone mentioned, if you have low energy costs then it might be a while before they pay off economically.
Some places tout an inert gas between the panes to increase efficiency. The payoff probably isn't there and after a period of time the gas leaks out anyway. The main benefit of triple pane is noise reduction. If energy costs are low and you don't have a lot of outside noise then the best bang for the buck is probably double pane.
Low-E coatings are generally worth the extra money when you replace windows but you need to use the right coatings in the right locations. While they reduce heat intrusion in the summer they also reduce natural heating from the sun in the winter.
A good window retailer will do an analysis and walk you through the options, a bad one will just want to sell you the most expensive windows.
 
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SSonnentag

埃隆•馬斯克
Apr 11, 2017
1,836
2,491
Arizona
I doubt that an HVAC upgrade from a SEER 14 would save you any money by the time it needed replaced again. Insulation is the most cost effective solution, whether it be blown in attic insulation or multi-pane windows. Trees and grass help with cooling too, but then there’s the watering and maintenance expenses.
 
So as I’ve read through your suggestions here and done some of my own research I think I’m going to do the following:

My utility has a program where I can get a duct leak inspection for only $30. Since my ducts run through the attic I think it makes sense to do that.

As I mentioned above, they also have a rebate on attic insulation and it seems that it’s recommended for houses more than 15 years old, which this house is. They claim that after the rebate the cost should be somewhere around $300, so I figure I’ll get that done too.

Finally it looks like replacing my single pane windows with low e double pane windows makes sense as well, so I’ll go ahead and get that done too.
I find it hard to believe a house built in FL in 2001 has single-pane windows - must have been a REALLY cut-rate builder!

New windows, properly installed, will usually reduce air leaks as well as radiant heat gain/loss. So, the low-E double- or triple-pane windows should help a lot. Adding insulation in the attic can't hurt, but that depends on what's already up there...

Solar screens on south-facing windows can also help a lot. Inside drapes, etc. don't prevent the solar radiation from entering the house, and may leave it darker than you want. I have solar screens on the west side of my Seattle-area house to block the late-afternoon sun, and they help a LOT! Generally, you can get 90 or 95% (% of IR blocked) screens, and still see through them well enough. With electric drive and remote controls, they are very convenient.

Since we're on a Tesla forum, don't forget that solar panels will both generate electricity to reduce your bills, and shield the roof from the hottest part of the sun. Even if you don't generate enough for all your needs, you can certainly reduce the bills...
 
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The low hanging fruit usually includes more attic insulation, sealing duct leaks, duct insulation, and sealing window leaks. In a warm climate like Florida you could also use a heat pump water heater to get some cooling benefits (pull incoming air from outside, the outgoing air is cool and can vent inside. Painting the south facing wall white can also reduce surface warming a surprising amount.
 
If you want cheap, add film to the windows and replace the heat pump with the 19-20SEER. Without replacing the heat pump, your savings on any other improvements will be limited.

You might also want to check if you are getting moisture ingress somehow. Collect the condensate from your AC unit in a bucket and see how long it takes to fill up. Latent cooling can dominate easily in humid climates.
 

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