B Cooling the room with a ceiling fan and skylight window

[Cats869]

TL;DR Summary

Trying to figure out the best way to cool a room during the hot summers with a ceiling fan and a skylight window

Hello,

So I know that a ceiling fan either operate clockwise (winter mode) or counter-clockwise (summer mode) and while the fan is meant for just moving air around, I'm wondering if utilizing a ceiling fan and an opened skylight window only a few feet near the ceiling fan would help move the hot air outside quicker when it is cooler outside. I may also open some windows at my height level so cool air can come in when the hot air leaves through the roof.

I'm guessing the counter clockwise orientation is what I'm after but part of me is uncertain since the fan may just push that hot air back down so it may not necessarily help and maybe I'm better off opening the windows alone. Thanks.

 

[Baluncore]

I'm guessing the counter clockwise orientation is what I'm after but part of me is uncertain since the fan may just push that hot air back down so it may not necessarily help and maybe I'm better off opening the windows alone. Thanks.

Open the widows alone.

Without the fan, hot air will rise to the top of the room. If it is cooler outside, open the skylight to let the hot air escape. You must also open a lower window to let cool air into replace the hot air from below.

If you operate the fan either way, the air in the room will not stratify, and you will not convect as much heat through the skylight.

 

[Bystander]

"Summer/Winter" modes are a "snare and delusion;" (they've no clue what your building's architect/renovator had in mind) what's comfortable for you?

 

[sophiecentaur]

If it is cooler outside, open the skylight to let the hot air escape.

That can work very well in some places. I cannot fit a skylight in my present conservatory (the roof glazing panels are all triangular and not big enough) but the glazing is all 'posh' glass which pretty much does the job when the door is open. (That super glass stuff is amazing - does what it says on the tin.)

It's very much a matter of the actual layout. I once built a sunny conservatory and 'invented' a system which used a large 'extractor' fan backwards, mounted near the floor at the end of the conservatory that was always in shade. The cool(er) air that was pushed in, hit my legs when seated at the end with the chairs in. It worked very well, subjectively. I tried the smoke test but that was inconclusive as I avoided using ta lot of smoke. My circulation system didn't fight the natural convection and there was very little stirring.

The construction was cheapo and the bottom metre of the walls was foam filled plastic so I didn't need to remove any bricks. A c/h thermostat made the whole system automatic and it gave me that smug feeling every time it kicked in.

 

[berkeman]

Summary:: Trying to figure out the best way to cool a room during the hot summers with a ceiling fan and a skylight window

I'm wondering if utilizing a ceiling fan and an opened skylight window only a few feet near the ceiling fan would help move the hot air outside quicker when it is cooler outside.

Are you familiar with "Whole-House Fans"? They are mounted in your ceiling or attic to exhaust hot air at night, and you open your windows to draw in cool air. They are more economical than air conditioning, usually, and much easier to install. Depending on the size of the electric fan motor, they may need their own dedicated electrical feed and breaker -- check your local building codes.

So one possibility is to install an exhaust fan in the skylight for the summer months and turn it on at night and open your windows. How close is your ceiling fan to the skylight?

http://redhawkelectric.net/wp-content/uploads/2017/08/whole-house-fan-illustration3.jpg

 

[Mark44]

So one possibility is to install an exhaust fan in the skylight for the summer months and turn it on at night and open your windows.

This is what my parents did in their house some years after I had left the nest. They lived inland in So. Calif. in an older house with no AC. A whole-house fan works pretty well if the outside temp is less than the inside temp, which usually was the case in the evening. You definitely don't want to use such a fan when the temps outside are hotter.

One difficulty they had with the fan was that it would often blow out the pilot light on their gas water heater, which probably could have been solved by redirecting the vent of the water heater, which probably vented into the attic.

 

[sophiecentaur]

I am always surprised by the automatic use of AC in wealthy hot countries and the all too common ignorance about tackling the problem at source. If the house is regularly subjected to a lot of sun then the answer is window blinds or shutters plus the sort of wall insulation that is found in cold climates.
The advice that's given when abnormally hot weather is expected (becoming normal and not abnormal) is to keep windows closed all day and draw curtains but it should really be done all the time during even just warm weather.
Heat pumps are being encouraged for domestic heating but, strangely, it is acknowledged that available ground or air sourced heating is not enough for normally insulated homes. Exactly the same problem applies for AC - except that people seem quite prepared to throw kiloWatts of electrical power into cooling homes. That's just as irresponsible as using many kW of conventional heating in winter.

I applaud the OP for seeking a solution to house cooling that doesn't rely on vast amounts of wasted energy. I would suggest, however, that increased air circulation could be supported by considering improving the thermal performance of the house itself with a better régime (free) and better insulation (not free and perhaps an unattractive pay back time).
Every sun-facing window could be letting several 1kW of solar heating straight into the house for half the day at least.

 

[Keith_McClary]

Are you familiar with "Whole-House Fans"? They are mounted in your ceiling or attic to exhaust hot air at night

Alternatively, it may be cheaper/easier to put the fan where the air comes in:

(In this case, the basement.)

 

[Cats869]

Hello everyone. Thanks for all the responses!

Open the widows alone.

Without the fan, hot air will rise to the top of the room. If it is cooler outside, open the skylight to let the hot air escape. You must also open a lower window to let cool air into replace the hot air from below.

If you operate the fan either way, the air in the room will not stratify, and you will not convect as much heat through the skylight.

Thanks for confirming that. I wondered if that would be the case so I ended up leaving it off (actually it's rarely used and we usually just leave the skylight open but I always wondered if the ceiling fan could help somehow. Just recently cleaned the ceiling fan since it accumulated so much dust. I know that the ceiling fan would only be good at making one feel cooler but not actually make the room cooler.

"Summer/Winter" modes are a "snare and delusion;" (they've no clue what your building's architect/renovator had in mind) what's comfortable for you?

Agreed. I only call it summer and winter mode since that's what those HVAC or mostly the ceiling fan companies refer the counter clockwise and clockwise rotation as.

Are you familiar with "Whole-House Fans"? They are mounted in your ceiling or attic to exhaust hot air at night, and you open your windows to draw in cool air. They are more economical than air conditioning, usually, and much easier to install. Depending on the size of the electric fan motor, they may need their own dedicated electrical feed and breaker -- check your local building codes.

So one possibility is to install an exhaust fan in the skylight for the summer months and turn it on at night and open your windows. How close is your ceiling fan to the skylight?

http://redhawkelectric.net/wp-content/uploads/2017/08/whole-house-fan-illustration3.jpg

I never really knew the name but I'm aware of the concept. Actually, before I created this thread. I thought several times to myself if there was a quick way to replace all of the air in the house with the outside cool evening air, that would be way more efficient than an air conditioner. I even went as far as to thinking of having a jet engine suck all the air out of the house quickly so cool air from the outside would flow in (though on a serious note, that wouldn't be very efficient and probably not safe even though it would be a cool sight to behold). I'll have to look into this kind of fan more. Thanks for mentioning that.

So here is a picture of the ceiling of the room I was talking about:

This is the kitchen area (should be good to use the fan during the winter at least with all of the heat coming from the appliances). Only one of the skylight windows can be opened however which is shown above.

I am always surprised by the automatic use of AC in wealthy hot countries and the all too common ignorance about tackling the problem at source. If the house is regularly subjected to a lot of sun then the answer is window blinds or shutters plus the sort of wall insulation that is found in cold climates.
The advice that's given when abnormally hot weather is expected (becoming normal and not abnormal) is to keep windows closed all day and draw curtains but it should really be done all the time during even just warm weather.
Heat pumps are being encouraged for domestic heating but, strangely, it is acknowledged that available ground or air sourced heating is not enough for normally insulated homes. Exactly the same problem applies for AC - except that people seem quite prepared to throw kiloWatts of electrical power into cooling homes. That's just as irresponsible as using many kW of conventional heating in winter.

I applaud the OP for seeking a solution to house cooling that doesn't rely on vast amounts of wasted energy. I would suggest, however, that increased air circulation could be supported by considering improving the thermal performance of the house itself with a better régime (free) and better insulation (not free and perhaps an unattractive pay back time).
Every sun-facing window could be letting several 1kW of solar heating straight into the house for half the day at least.

Thanks haha. Some may consider me a strange guy but besides liking to reduce energy footprint and saving money in the process, I also like to make things very efficient. I somehow find fun in doing that. I have been closing blinds during the day in rooms that no one really ever uses and then opening the blinds and windows when it is cool outside during the summer and have been leaving the blinds open during the winter.

Alternatively, it may be cheaper/easier to put the fan where the air comes in:

(In this case, the basement.)

Ha, I was actually thinking about doing this at one point. I have like 3 or 4 of those big floor fans and a couple other kinds of fans I could probably put to good uses. So far, what I have been doing was opening most of the windows upstairs and also downstairs and I can feel quite the updraft when standing at the staircase. The fans would certainly help a bit with increasing airflow around the house though not sure how much it will help versus electricity used.

Also, I have a couple dumb temperature sensors that I can lay around the house and then take a look at later to help determine how hot it gets during the day and how much the temperature drops overnight.

 

[sophiecentaur]

Experimentation rules!

I have been closing blinds during the day in rooms that no one really ever uses

That's a good start but no one needs full brightness sunlight in doors so even partially drawn curtains on the sunny side will also help in the battle. Watching daytime TV is more restful in a shaded room (not that I ever seem to have time for day time TV).

Also, keeping internal doors closed in the day time will suppress convection from hot rooms to not-so-hot rooms.

 

[MikeeMiracle]

We need to look at the architecture of the house during the design phase to solve this long term globally. Fitting vents in the ceilings to allow hot air out is an obvious solution when building from scratch and not an expensive one either. If you are fortunate enough to live very close to a water source like a lake or river, you can also run pipes which draw in air, run through the water to "cool" the air inside and pipe those into vents near the bottom of the house. In effect it's free cooling.