Adventures in Ventilatory Home Cooling

a couple off top of my head:
- whole house fan
- timers for your fans

whole house fan probably won't save energy but will cut down on noise, and the timers would take care of turning you fans on/off.

 

Yeah. It will only take about 3 box fans and $40 from Walmart to try this out. They have a 90 day return policy so you don't have anything to lose really.

Take two chairs or boxes and put the fan across of them to get the upward air flow. Put one downstairs blowing air in. Put one upstairs blowing air out.

Once you figure this works well for you, you can then get nicer looking ceiling fans.

I do this all the time I can easily get 10 degrees of cooling in about 1 hour according to the thermometer on my thermostat.

If it doesn't work, return the fans. I don't think there's any moral issue with returning something you bought to try out, if it doesn't work for you.

I wanted to add that if one of your bathrooms upstairs has an ventilation fan, you can turn that on to force warm air to escape. If anyone has tried this before and said "it doesn't work", that's because they don't give it time to work. More often than not, later than sooner, that tiny fan will create such a vacuum in the house that it will force in huge amounts of air from downstairs if the windows are open.

A small quiet ventilation fan plus a short section of ducting and an exterior exhaust port can be installed for less than $100 between the joists of your ceiling to the outside wall. If you are handy that is, and can do the work yourself.

 

How noisy is that? When we were house-shopping 10 years ago, our realtor demonstrated a whole-house fan on a house we were looking at (the house we bought didn't have that), and while it was powerful, it was also rather loud. I would think we could handle the noise for maybe an hour (enough to flush the air completely), and then would have to turn it off before going to bed. My wife doesn't even like the ceiling fan running in the bedroom, complains that it makes too much noise when she's trying to sleep. But she's fine with sleeping in front of the TV

Does it have to have an attic? The attic is just the place it normally vents to, but I would think you could vent directly outside as well.

You don't mention if you have a basement (I'm guessing not). We added a cold-air return in the basement to our house HVAC system. Then on cooler days, we don't run the house fan, and cool air builds up in the basement. Then on warmer days, we turn on the house fan and the cool air is brought up to the rest of the house.

I'm not so sure about that. What you're saying is true, but it leaves air untouched upstairs. But with his current approach, you have air moving across the upper floor creating a low pressure area. If the windows are open on the bottom floor, air will be naturally sucked up from the bottom floor and join that air flow, affecting more of the house. (I think back to a science guy who gave an interesting show at my son's science fair, and he showed how to use the power of low-pressure air in interesting ways). I imagine it's affected by how fast the air is moving and where your windows are (and the winds), so I'm not going to guarantee anything. But it's worth experimenting a bit. I agree with getting the hot air off the ceiling.

Lastly, I would think box fans right in the window would work better than having fans outside your window blowing air approximately to your screened window - that would definitely reduce losses. We use this double-fan for our son's bedroom, it works pretty well. The frustrating thing about the Chicago area is that there might be a nice breeze in the evening, but as soon as the sun goes down and the temperature drops, the breeze usually fades away. So fans are the only way to exchange air at night.

Pelonis 9 in. Twin Window Fan - FW23-A1 at The Home Depot

 

Maybe it's the house design, but I don't use any fans, and the air flows quickly enough all by itself. The windows are the good old wooden-framed double hung design - not so good for keeping the heat in, but great for managing air flow. I leave the upper part of the upstairs windows open so the heated air can get out, and open the lower part of the downstairs windows so the cooler air can get in. In Summer, I often add the basement door to the routine to let in even cooler air, and more of it. The trick is to do this at the right times - late at night, and first thing in the morning while the outside air is cooler. During the heat of the day, everything is closed to keep the warmer air out. I'd do this in Winter, too, but my wife's thermostat has much different settings than mine and she isn't nearly as much of a fresh air freak. And to her, the layering technique of clothing is for outside, not in her own house.

 

I have a 16" Lasko window fan I use as a whole house fan. It moves 2400 cfm at 100 Watts on high speed. This works fairly well in our 2600 square foot home but I am considering purchasing another to cool the house faster. They cost about $70.

 

Really i hope the climate remains like this only always!

 

I've designed and built dozens of homes in Colorado. The key here is having several windows that can be left open in rain or shine.
Cross ventilation with fresh air beats AC both in comfort and cost.
To increase ventilation just add a window fan or open more windows.

 

If you check their website, the Airscape fans appear to be very quiet especially when run on low. Don't have any experience with them, though I am intrigued by this topic.

 

It is very quite. The fan is on one end of the hallway and the bedroom is on the other end. When it's on low, I can barely hear it in the bedroom.

We used to have a "traditional" whole house fan and it was VERY loud.

 

I'd be curious to see what a home designed around natural air flow and passive heating and cooling would look like. Never mind traditional design - go for maximising comfort at minimum energy cost. Would you angle the ceiling? Incorporate an underground air shaft? Add on a little greenhouse to function as a 'solar furnace'?

 

Basically just providing for good cross ventilation, preferably with windows that do not have to be closed everytime it looks like rain.
My last house had some high awning windows that were protected by the south overhang that I opened in early May and closed in September. To small and too high to be a security issue and no chance of rain getting in.

An open floor plan helps move air as does high and low windows.
It also helps to be in a climate where the night time temps in the summer are 25 deg below daytime temps.

Using an underground pipe to pre cool intake air is tempting until you start thinking about all the potential mold issues. The down side of a solar greenhouse in this climate is it is producing a lot of heat on sunny days when a well insulated passive solar home does not need heat. Very well insulated with 10-15% of the floor area in south facing windows with added thermal mass and good cross ventilation
and you will be amazed how little need for added heat there is.

 

Of course, the interior air doesn't need heating in Summer, but there's still a need for hot water. Simply running the domestic intake pipe through the 'solar furnace', with a few coils in the sunshine, could warm the water sufficiently to increase the overall efficiency of the water heating system. Even better would be a direct solar water heater - it wouldn't work in all climates all year, but might work enough of the time to make it worthwhile. In theory, given enough solar input, the water could be heated to boiling, and a steam turbine could produce electricity. Again, I'm just throwing out ideas - you're the house builder.

 

Solar Domestic Hot Water is far more cost effective than PV solar.
I am a big believer in a preheat system for DHW. In my climate, in the winter, water is entering a house at 45 deg +/- (55 in the summer). A simple uninsulated tank (or copper pipe coil) between the incoming water and the DHW tank, can raise the income water to 70 deg, lessening the work load of the water heater. This preheat tank or coil could be in a south facing greenhouse with even higher potential. But these are not free BTUs if you are paying to heat the space the preheat tank is in.

 

Perhaps 'greenhouse' isn't quite the right word. I'm not picturing a glassed-in porch with a few potted plants and some comfy chairs. I'm thinking of a solar *furnace* - designed to be as hot as possible, and not suitable for human habitation under normal operating conditions. The furnace would have to be well insulated to keep the heat from escaping to the rest of the house, and would heat all the DHW by solar means. Space heating could be provided by venting warm air from the furnace to the house, or the heat could be circulated and controlled by a hydronic system.

 

Most houses in large areas of Turkey have a solar water heater on their roof. Apartment buildings, hotels and businesses often have many solar water heaters.

In any given village or town they tend to look alike, probably made in some small facility not far away. In the cities there is more variety. The most common variety has one collector and a single horizontal tank at the top of the collector. Our guide, who was big into the environment, said basic units run around $400 to $500 and automatically drain to avoid freezing.

 

Some people run coils of tubing in their unfinished attics to preheat their incoming water.

 

Ventilatory home cooling doesn't work very well where it's 106 in June and August is the HOT month. Just saying.

 

This is a $15 fan that is installed in the laundry, which is in the opposite side of the house compared with the bedrooms.
At night i open the bedroom windows and start the fan. During the day the house accumulates a lot of heat in the hard wood floor furniture, and walls.
With the fan, my A/C starts only around 1-2 PM in the afternoon.
I'm still working to hide the power cord and install a switch. I already have a cover.