Slash summer air conditioning costs two ways....

Today's post: Wednesday, 6-22-2010

We need an 80% reduction in fossil fuel use by 2050 to avoid the worst global warming effects.

And, practically speaking, we need to also double our electricity generation and double the useful work done per unit of electricity & other energy sources as well during that same time to have a decent economy.

At some point, the oil that we’ve been using to power much of our economy will begin to run low enough that our world economy will shrink due to lack of supply or excessive costs or both. Kuwaiti scientists recently predicted peak oil in 2014 – just 3 years from now.

And, once the demand for oil picks up again with the apparent economic recovery or supply begins to plateau or drop, the prices will again go back up. That will cause more hard times economically unless we have enough alternative sources of energy to turn to.

Today’s post: Slash summer air conditioning costs two ways....

I. The first way is for your home if you are a homeowner.

(In some areas you can save $2,000 or more in one summer.) And, in all areas, your home will be dramatically more comfortable to live in. This can be very important in having your home cool off at night on hot days!

II. When you go outside on a hot day and have to cool your car from over 120 degrees inside, it’s obnoxious and uncomfortable at first. But you also have to pay for the extra gas or electricity to do that job. The second part of this post has a way to prevent this that also actually generates electricity. (It’s just after the first part.)
I. This part of this post reviews some information that was in previous posts for those of you who didn’t see them or know the information otherwise.
1. In the Northern hemisphere we are now having truly hot summer temperatures in many places. And, in many parts of the United States, a major energy use is for residential air conditioning.
In fact, during the hottest days, it is exactly that air conditioning use that dictates what your utility needs to be able to deliver for peak demand.
Did you know that for many people you can drop your electricity use for air conditioning so much you do pay off the costs in one year and save literally hundreds to thousands of dollars on your summer electric bill for every year after that?
You can. And, it even has a bonus. Your home will be dramatically more comfortable. And the night time temperature in your home will be so much lower that you’ll sleep much better and have a good deal more energy each day!
Here’s our post on this method from April, 2008.:
Slash your Air Conditioning bills this summer....

Today’s post: Weds, 4-9-2008

How does cutting your bill to zero or by 70 % sound?

Hot weather is coming soon to where you live & work this year. In some areas you already have it!

(In our area, in the Silicon Valley, after below average temps recently, our first hot weather of this year just started a few days ago.)

Unfortunately, in many homes & buildings a huge amount of money & energy is spent on air conditioning to pump heat out of buildings it could easily never have gotten into to begin with.

For many buildings & most homes, moderately inexpensive fixes can keep enough heat from getting in to cut well over 50% from air conditioning costs & energy use or even eliminate them totally & do it each summer after they are installed.

In addition, the more people do this, the less new electric generating capacity has to be built to manage peak demand for electricity which is now driven by afternoon air conditioning use on the hottest days.

In climates where the temperature falls enough at night, you can let in cool night air to remove any left over heat from the day before by opening the windows &/or by using fans to pull in air from outside & push out the inside air. Often, if you have things well set up to prevent heat from getting in &/or have ceiling fans to lower the perceived temperature a few degrees, from 76 actual to 72 perceived, for example, on most days you then will need NO air conditioning use at all.

In climates where it is much hotter or only falls to a level where you still need to run the air conditioning, if you have things well set up to prevent heat from getting in &/or have ceiling fans to lower the perceived temperature a few degrees, you can get a triple play. You only will need to run your air conditioner at night on most days. That means you can get maximum efficiency per unit of energy as the AC works better with cooler temps to dump the excess heat into so your bill is less. And, you use the electricity at night when it often costs less per kilowatt than at peak times in the afternoon. Lastly, you no longer need to add a lot of load in the afternoon to overstress your local power grid. The idea is to have the house at or office at 68 degrees F or even a bit less in the early morning when it’s coolest outside & have it not set to turn back on until the inside gets to 76 degrees (or perhaps 72 if you don’t have ceiling fans yet. Then, if your heat proofing is good enough, your AC will rarely need to come back on. And, if it does, it will need to run a LOT less.

Well insulated buildings with a lot of thermal mass, ideally with few windows or with double pane windows, that also have good passive design to prevent heat from entering do this very well.

New buildings with part underground or with thick walls made of rammed earth or adobe or straw or well insulated concrete block & heat resistant roofs do this well.

But in most homes today & some commercial buildings, the main problem is in the roof crawl space.

Usually there is no insulation between the roof & the crawl space -- & in some areas not much below it. In addition, the crawl space has almost no ventilation. As a result, instead of the under the roof temperature being only slightly above the outside air, it can be as much as 70 or 80 degrees hotter. Then this trapped heat re-radiates into the rooms beneath acting as a solar heater all afternoon. Even worse, this heat continues to radiate well into the night making the people inside miserable or running up their AC bills like crazy.

My wife & I had a house like that which was also badly insulated and had no air conditioning. On sunny days much above 79 degrees for a high, it was often well over 80 or even 90 until about the time the next morning we had to get up to go to work. This was NOT fun. And, if we had decent air conditioning then, we would have run it a LOT.

We then discovered & installed a system that uses NO OUTSIDE ENERGY AT ALL which prevented this under the roof heat build up. And, we installed ceiling fans.

We didn’t even get to upgrading the insulation and got this result.:

After doing this, we experienced a day well into the high 90’s outside. It would have been over 100 inside from 3 PM to midnight before. After installing this system & adding ceiling fans, it only got up to about 75 inside & then only from about 3 to 6 PM – AND the 75 felt Ok with just the ceiling fans alone. It was in the high 90’s outside and we needed NO air conditioning at all. And, remember, that was before we upgraded our ceiling insulation to R19 or better.

Here is the magic trick we used that I cannot recommend more highly after this experience.:

Hot air rises. So, what we did is to install several very well screened air intake vents around the perimeter of our roof’s crawl space that were under the shade of the roof & we had a competent workman also install several convection powered turbines in the roof near its peak. Then we added ceiling fans to our bedrooms & living room. The entire project cost less than $1,000. And, this was a one time fee.

The very same hot air that was giving us such grief before now happily spun the turbines as it rose & drew the much less hot outside air in behind it. This was all solar powered. We needed no outside energy at all to run it.

If we had more money at the time, I would have liked to add the extra ceiling insulation & a radiant heat barrier in our attic and installed wood frame double pane windows.

Even better would have been to add a decent heat pump system also to deliver efficient air conditioning if we ever needed it for days above 100 degrees & install enough solar panels to run it all. And, added window shading on the west & south sides of the house would have also helped.

But, much to my delight, we got close to 100 % of the cooling we needed from this single inexpensive fix that still needs no energy bills at all to operate these several years later.

So, if you have a roof that traps heat the way our roof then did, you can add all sorts of useful extras as I would have liked to do. But for about $2500 or less you can heat proof your house better than you might imagine with this simple system.

(In our area we bought the convection powered turbines & ceiling fans at Home Depot.)

The next part is from our 7-7-2010 post.:

These relatively inexpensive fixes can save enough on electricity bills for air conditioning to pay for themselves in one summer in some places while in others, it may take more like 4 summers. But the savings start the minute they are installed. The increased livability and comfort start the minute they are installed. And, once installed, they save money and electricity use every year at virtually no added cost.

2. Consider adding solar photovoltaic cells to your roof. By using this electricity during the time when you are most likely to use your air conditioning, you save paying the higher costs for grid electricity at those times. Even better, at those same times, you will have extra sun to produce extra electricity.

This does cost more than heat proofing and venting the air from under your roof. But there are now some innovative programs to pay the upfront costs for solar installation.

Sungevity and SolarCity now have this kind of no upfront cost financing. And, Sungevity needs no in home appointment to know what solar you can build on your roof. (They have a website and are also available at Lowe’s stores.)

3. Best of all, if most homeowners in a community do both things, they can cut the peak use of electricity by a great deal on the hottest summer days.

II. When you go outside on a hot day and have to cool your car from over 120 degrees inside, it’s obnoxious and uncomfortable at first. But you also have to pay for the extra gas or electricity to do that job. The second part of this post has a way to prevent this that also actually generates electricity.

Quite often, particularly at work and at large shopping centers, you have this problem. BUT, in these large, open parking lots, it’s possible to install an inexpensive canopy or roof that will give you shade on hot sunny days. (These also enable you to get into and our of your car with far less hassle on rainy days.)

That means on hot, sunny days, your car will be LESS hot inside than the air outside instead of 20 to 40 degrees hotter.

This would give a competitive advantage to shopping centers that install them.

But here’s the great added value. In most cities and towns today, many such parking lots exist. That totals millions of square feet of such parking in most states!

If each owner of such parking lots of any size installed such canopies over these parking lots AND added solar cells, they could almost power their own air conditioners each summer at no added cost.

This would be great for the utilities too since this added electricity would peak just when their load on the grid peaks now. (This is so much so, it would pay utilities to help finance such solar canopies or give price breaks to companies who do it.)

Any shopping center owner or owner of real estate where businesses are located or businesses wanting to add more solar could do this. (Applied Materials in Santa Clara, California is the only company I know of to do this so far. There may be others.)

It would also pay states and cities and counties to make permits for such solar canopies easy to get or even offer financial incentives for building them.