Friday, August 9, 2013

Turn Off the AC

Even though we're having unusually cold weather in Northern California for one of the hottest months of the year, I know some of you out there are still experiencing extreme heat.  This is an article on how to save a little on your PG&E bill by using some techniques to naturally cool down your house.  For some places, this may be enough for you to not have to us the AC, for others it's just to keep it a little cooler.  Use your judgment.

I grew up without air conditioning, so these tips seem second nature to me but I realized that a lot of people don't really understand when it's best to open your window, keep it shut, use a fan, etc.

Step 1: Use Your Blinds

The first step is all about keeping the hot sun out.  Of course this leaves your house a little dark so some people might not like it.  But if you are not home during the day, you don't mind the darkness, then this will be fine or you can just open the blinds near the window you are at.

shadesThe trick is to follow the sun throughout the day.  I would hope that by now everyone understands that the sun rises in the east and sets in the west.  If you are directionally challenged, like me, you may not really know all the time which direction is east and which is west but you should be able to realize which windows face the sun as it's rising, which face it during midday, and which face it when it's setting.

So since the sun rises in the east, those are the windows you want covered first.  And, unless you're a really early riser, you should do that at night before you go to bed.  If you'll be gone all day, cover your south facing windows as well.  The western windows you can usually do yourself when you get home later but it might be a good idea to keep all windows covered while you're gone since it really doesn't matter and can really keep it cool.

Follow the sun around.  You can put the blinds up once there isn't direct sunlight there.  If you really want to reflect the light, you can put up a bunch of those car windshield reflectors to reflect the sun.  Or, if you don't care about looks as much, you can make your own by cutting cardboard to fit your window and wrapping it in foil.

Step 2: When to Use a Fan

Lots of people think that a fan works like an air conditioner, if you have it on it makes it cooler.  Unless it is drawing air from a cooler source, that is not true.  Generally, a fan will be in a place where there isn't much difference in temperature.  This means that you should only have it on when you are in that room, otherwise you're just wasting energy.  A fan cools you just by circulating and blowing air on you, it doesn't actually cool the room.

Two exceptions that I can think of where it would be drawing cooler air from another place.  1.) A window fan.  I will get more to when you should have your window open next.  2.) If you have a long hallway and the rooms at one end of the hallway are hotter than the rooms at the other end.  This happens in our house.  The living room is well shaded and stays fairly cool, but the large room at the end of the long hallway doesn't have much shade and gets pretty warm which heats up the other rooms nearby.  For this, it gets annoyingly loud, but you want a large industrial grade fan to put in the cooler room and shoot it down the hallway.  It's taking the cooler air from the cooler room and shooting it down and circulating in the hotter areas.  It doesn't do much but it does help.

Step 3: When to Open a Window

bird in windowThis is another thing that people often get wrong.  They think that opening a window will get air circulating which makes a room cooler.  WRONG!  The air outside MUST be cooler than inside for that to be effective, otherwise you're letting hot air in, even if there is a breeze.  Hopefully your house by now has newer double or triple paned windows.  These aren't just made to keep out noise, they are made for better insulation too.  That means keeping hot air out in the summer and keeping cool air out in the winter.  Let them do their job!

If you live in a place, like me, where it cools off at night, it can be a great idea to eventually open your windows.  I'm often surprised when people in the bay area keep their air conditioners on all day and don't even realize that it's cooled off so much outside that they could just open all their windows and it would be fine.  That is key.  If it's cool outside, and especially if there is a good breeze, OPEN ALL YOUR WINDOWS!  This is when circulation is important.  For example, if you have a room that has windows on two opposite walls, but you only open the windows on one wall, it will let in some cool air.  If you open windows on both walls, the air will flow freely between them.  Not only will it let in cool air, but there will be a constant circulation of cool air.

Going back to fans.  There are some great fans that you stick in your window.  Again, only do it if the air outside is cooler, otherwise you will just be blowing hot air in your room.  But if the air is cooler outside, it draws the cool air from outside and blows it more directly into your room.

In summary:
  • Keep out direct sunlight
  • Only use fans when in room or drawing cooler air from another place
  • Keep windows shut, unless it's cooler outside then open them!

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