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solar roof ventilation

(7 posts) (7 voices)

Started 3 years ago by projects
Latest reply from vajras

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projects
Member

I want to find a way of removing the heat from our roof space.
I'm a real novice at all this so I hope I'm on the right track.

I have 3.5batts in ceiling and aircell retrofit under timber frame (of a cement tile roof) This has been in an effort to keep heat in during the winter and heat out during the summer)
As the roof space is now fairly well enclosed I need some form of exhaust method.
I've read information about the following:
Solarventi
Condor Kenetic roof vent
Envirofan
Solar Star (from SolarTube)
Maestro Solar

I have one of those whirly things but I don't think it's able to exhaust enough hot air (and it requires wind). If you have any suggestions/advice/ideas or experience of these or other ways of exhausting out the hot air in the roof it would be greatly appreciate.
I'm also considering some kind of internal exhaust system - to remove hot air from inside the house. Thanks

Posted Monday 19 Jan 2009 @ 5:25:38 am from IP #
norbert
Member

We start building soon and I'm going with the Edmonds Maestro.The extra 230$ for the solar version is to me rip off so I'm going with the electric powered version.
Having built 2 houses over the last 8 years, when it comes to heating/cooling my philosophy is if you don't let the heat in then you don't have to worry how to get it out.I live in cooler climate (Woodend VIC)so heating is important in winter.I therefore don't like the idea of cutting holes into the ceiling in order to put exhaust fans there.You can't have insulation where the holes are so in winter they are uninsulated pockets.I think rotating ceiling fans are the better option.There are now R6 ceiling batts available which are some 260mm thick.I believe they're expensive ($17per m2)and using them creates uninsulated spots around the trusses timber studs.
I'm going to use R2 wall bats (90mm thick) for the first layer as they're the same height then the 90mm studs and then put R 3.5(185mm thick) as a second layer over the top which does then cover the studs.Doing it that way reduces the cost to some $ 10 per m2 and the overall insulation thickness is actually 5 mm more (265mm) then R6 batts.

Posted Monday 19 Jan 2009 @ 9:48:49 am from IP #
Steve
Member

Have you heard of HRV before? They have a ventilation system on the market in Victoria that may deal with your problem. http://www.hrv.co.au
From what I understand it is a solar heating system and ventilation system during the winter. Then during the summer it dumps the heat out of the roof cavity during the day, so that you don't get as much heat transferring down into the house via the ceiling, and then filters and pumps the cooler evening/night air through the home. One of my friends had it installed last year and it really seems to be making a significant differance in the the home temperature as well as reducing his heating and cooling bills.

Posted Wednesday 4 Feb 2009 @ 8:35:54 pm from IP #
Eskimoau
Member

Take a look at whole of house fans. http://www.breezepower.com.au/home-cooling.html

The idea is you can change to whole volume of air in your house and roof space a couple of times an hour. This both creates a breeze in the house and prevents a build up of heat in the roof.

Posted Wednesday 11 Feb 2009 @ 9:29:14 pm from IP #
glenish
Member

Great suggestion by Norbett for insulating ceiling space with rafters or Truss Bottom Chords to R5-R6, and in the process seal the gaps around and over the rafters and save a little on ceiling batts material cost.

I have an Edmonds Maestro 12v DC Roof fan installed in my RAPS power shed that is driven during sunlight hours directly off a 12v 30W solar panel and connected to the panel through an adjustable thermostat (you can purchase the thermostat as an optional extra with the fan). The fan has been in continuous operation now for over 4 years and hasn't missed a beat. I have the thermostat set to 22 degrees so that during summer days the fan operates virtually every day until sunset (nights cool down to mid 20's where I am even in the middle of summer) but doesn't come on during the middle of winter, trapping what little heat has been generated through the day. These fans are expensive and not very well screened against insect entry. Also, if you live in a high bush fire prone area you will need to dismantle the fan and retrofit a stainless steel mesh screen over the existing open mesh that screens the fan. Sounds difficult but is actually very easy to do. Hope this helps.

Posted Sunday 8 Mar 2009 @ 7:48:31 am from IP #
vajras
Member

@ projects - we have installed a SV14 Solarventi as our passive, 12V heating system. i dare say it could be modified to be a ventilator but perhaps give the distributors a call to discuss?

Arne Hachmann
Global Eco & Environmental Solutions
Ph: 03 9808 1555
Fax: 03 9808 1455
Mob: 0401 071 424

Web: http://www.ges.com.au

Not long after, we installed the Universal Tile Ventilators, an Australian invention we saw on the ABC New Inventors program.

THey now have a new corrugated iron ventilator as well as their tile one.

It works for us and 4 ventilators @ $85 ea. were cheaper than whirlybirds.
http://www.universaltileventilators.com.au/

Posted Wednesday 18 Nov 2009 @ 3:55:29 am from IP #
Eamon
Member

I know the last post was a year ago, but the solution is more so important as new products hit the market. From the same supplier in Victoria GES and on the East Coast -Solair http://www.solair.com.au you can now get a solar fan (Solar Whiz) which draws a massive 2100 cubic meters per hour. Thats the inside space of over 60 large 40ft metal containers per hour. The most powerfull fan available on the market. It does come at a price higher than average roof fans but is well worth it when you consider its capability. If positioned correctly and with vents in the internal ceiling, the Solarwhiz will draw the heat out of the house. Therefore opening windows on the South of the house will cool it down beautifully. Its not an air conditioner but then again its not a carbon guzzler, in fact its carbon neutral.

Posted Friday 18 Feb 2011 @ 5:37:56 am from IP #

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