How long does it take to get use to no A/C?

[whtviper1]

Originally Posted by Jessica K

One of the options we're looking at is a whole house fan.

A whole house fan in a tropical climate are usually not a great idea unless you are at elevation and the night temperature drops to a point where you are actually circulating cooler air. The fan in daytime essentially is just blowing around hot air and in summer when temperatures don't drop a lot, it isn't helping much more either. So, winter - early Spring, late Fall it can be effective - Summer, not so much.

The only way to make it work effectively is AC with whole house fan.

[terracore]

A whole house fan makes a big difference if you don't have good breezes or if you close the house up when you leave. On my DIY version I didn't want to punch any holes in the ceiling so I cut a piece of wood the same size as the drywall for the attic hatch, cut a hole in the middle of it, painted it to match ceiling, and mounted a large DC powered fan in the hole. I installed one of those pull chain switches in case I want to turn it off because it's powered directly by a solar panel mounted on the roof. Not counting waiting for the paint to dry the whole install was about an hour including putting the solar panel on the roof and routing the power cable. One could skip the pull chain switch but it's nice to have if you want to get into the attic when the sun is out and don't want to deal with spinning blades or if you have air conditioning and want to run it without all your cold air getting sucked into the attic.

Before adding the fan I could put my hand up to the ceiling from inside and feel heat radiating off it. We have an uninsulated house. Since adding the fan- no heat, even on the side of the house opposite where the fan is.

I don't agree that you need to use a whole house fan with an attic fan. While it wouldn't hurt to add the attic fan I think its past the point of diminishing return. The house fan pushes the hot attic air out through the existing roof vents without adding anything additional.

[hotzcatz]

Originally Posted by Jessica K

We recently moved to Waikoloa Village and are considering options to help cool the house. One of the options we're looking at is a whole house fan. Terracore and others with experience -- would you recommend a whole house fan?

I just got a quote for a unit delivered to our house for around $2000 (sized for our approx. 1800 s.f. house). Does that sound reasonable? Cost is for the fan only, no install.

Thank you!

A lot of whole house fans I've met up with have been rather noisy, but that was decades ago, maybe they are better now.

For those not familiar with Waikoloa, it is hot and dry with lots of sun and wind. I've even heard some folks call it "Waikablowa". That was folks who live there, it may be an affectionate name among it's inhabitants?

A cool house is usually a whole lot of things, not any particular one thing unless you put a honking big A/C unit in and don't care about power use. But, with the amount of sun you have, a big photovoltaic system and A/C might work. Expensive to install, though.

Back to the multiplicity of how-to-keep-a-house-cool. These are all passive systems, you don't have to pay to run them or even turn them off and on.

1. Paint the roof white. That Sno-Coat stuff is good. White reflects heat and the less heat on the house, the less heat to get inside. While you're painting things, paint the parts of the house that the sun hits a white or light color.

On a sunny day, put something dark colored, light colored and white in the sun. Leave them there for a few minutes and then put your hand on them. Now you'll know why stark staring white is the best roof color. For awhile, there were tax credits if you installed a white roof, dunno if they're still there, that was a decade or two ago.

Hmm, wonder if painting the driveway a pale gray or white would help? My brother who likes soar planes mentioned once that they could get a really big lift by going over a black parking lot way down below. That much heat rising near a house would have to increase the amount of heat that works it's way into the house. Houses surrounded by lawn are cooler than houses surrounded by cement.

2. Insulate the ceiling, that also helps to keep the heat out.

3. Ventilate the attic to let hot air out. Just a big passive fixed louver & screened vent, no need for an actual fan.

4. In the living areas, provide a place for the hot air to go away. Hot air rises, have heat escape vents up near the ceiling or in the ceiling. This is why transom windows above doors were so popular before A/C.

5. Air can't go away unless it's moving. Add some vents down near the floor to bring in as cool of air as possible and then move the hot air up at the ceiling out. Louvered windows are 100% ventilated, sliding glass windows are only 50% ventilated. Either add more windows or replace some pane windows with louvers.

6. You'll want at least a 3' eave on the house if not a lanai all the way around. This prevents sun from hitting the sides of the house and with the lanai provides a shady spot to cool the breeze down before it enters the house. If nothing else, put up a trellis on the sunny side of the house and plant beans or lilikoi on the trellis to create shade for the side of the house.

[hotzcatz]

Originally Posted by terracore

A whole house fan makes a big difference if you don't have good breezes or if you close the house up when you leave. On my DIY version I didn't want to punch any holes in the ceiling so I cut a piece of wood the same size as the drywall for the attic hatch, cut a hole in the middle of it, painted it to match ceiling, and mounted a large DC powered fan in the hole. I installed one of those pull chain switches in case I want to turn it off because it's powered directly by a solar panel mounted on the roof. Not counting waiting for the paint to dry the whole install was about an hour including putting the solar panel on the roof and routing the power cable. One could skip the pull chain switch but it's nice to have if you want to get into the attic when the sun is out and don't want to deal with spinning blades or if you have air conditioning and want to run it without all your cold air getting sucked into the attic.

Before adding the fan I could put my hand up to the ceiling from inside and feel heat radiating off it. We have an uninsulated house. Since adding the fan- no heat, even on the side of the house opposite where the fan is.

I don't agree that you need to use a whole house fan with an attic fan. While it wouldn't hurt to add the attic fan I think its past the point of diminishing return. The house fan pushes the hot attic air out through the existing roof vents without adding anything additional.

Good job with the attic fan, using the attic hatch door is brilliant. How big is the fan? Would a car radiator fan work? Those are DC and easy to get.

[rya96797]

Originally Posted by whtviper1

A whole house fan in a tropical climate are usually not a great idea unless you are at elevation and the night temperature drops to a point where you are actually circulating cooler air. The fan in daytime essentially is just blowing around hot air and in summer when temperatures don't drop a lot, it isn't helping much more either. So, winter - early Spring, late Fall it can be effective - Summer, not so much.

The only way to make it work effectively is AC with whole house fan.

makes big difference in areas without good trades. if your area has good trades and you leave some windows open, that's already circulating sufficiently, so your returns aren't going to be as noticeable.

But in areas that are super still in leeward and central areas your house is essentially an oven. It does help A LOT.

[grantw]

We're from DFW and have adjusted fine to no AC. We are at 3,100' in HOVE so that helps us stay cool. The heat is definitely noticed when we get down to sea level or get to Kona.