Passive Design - But the view is to the south!!

Dobly · Mar 06, 2007 3:32 pm

Hi

My wife and I have found a block of land that we both love. It is remote enough, yet close enough to town.

The block is plenty big enough for our permaculture and aquaponics and big enough for our kids and dogs to run about..

The view is wonderful.. The block is high up and the view looks out to the SOUTH...

From my understanding, this posses a problem? The North facing end of the house will have a garage, and little else. All the big open plan, glass etc, would need to be at the South to take advantage of the views.

What can we do??? We have not bought the block yet. And despite this orientation issue, the block is amazing and at the right price for us.

Can a passively heated house be achieved in a south facing house?

Thanks

Casa · Mar 06, 2007 9:29 pm

Dobly,

A few months ago I purchased a property with a view to the south. Like you, I want to exploit the view and have a passive solar house.

A south facing view certainly presents challenges when designing a passive solar home. I'm envisaging that I will be successful in exploiting the view AND having a good passive solar design.

There are really two challenges:

1) A place with a view

The problem is that any place with a view that is exploited will have large areas of glass. On a winter’s night, normal glass presents little thermal resistance. The remedy is to use double glazed low emissivity glass. This will roughly triple the cost of the glazed area - but you get a view

2) South facing glazing

The problem is, in mid-summer from 6:00 am to 9:30 am and 4:30 pm to 8:00 pm (Sydney), the sun is to the south of due east/west. At sunset it will be at 30 degrees south of due west. This solar energy streaming into the house will quickly warm it up. The remedy is to have an overhang. This will reduce the wide open view to the skies but will prevent your place becoming a hot box. Not sure of the optimal overhang at the moment, but currently envisage it will be something like 3.2 m. This would be the depth of the balcony and its cover. I will have an exact figure once I get to that stage of the design.

On top of the double glazing and overhang the best approach is to have large thermal mass inside the house. A double brick house will do the trick.

You will still need glazing on the north side to allow sunlight to enter during winter days. This can be windows on the north side or clerestory windows. Better still, both. The right amount of overhand will ensure that the low winter sun enters the house and warms it, while the high summer sun is excluded form entering.

In summary, you need high thermal mass inside plus:

1) Winter day warming – north facing glazing (with approx. 750 mm overhang)
2) Winter night warmth retention – double glazed low emissivity glass
3) Summer day “cooling” – deep overhangs to the south and keep doors closed
4) Summer night cooling – open the house up for night air cooling

There are many low energy strategies that can also be tacked on.

Cheers,
Casa

Dobly · Mar 06, 2007 11:01 pm

Casa

Thanks so much for that. I learned enough to know that all is not lost. The view is pretty amazing at this block, looking mostly south and little west,we might almost get that summer time sunset.

I had this (noob) idea that one could have a roof in the living area that can be opened with some reflective stuff inside so that in winter you could just 'open up the roof' on sunny cold days and get the sunlight reflected right into the living area.
I imagine that would be impossible to get approval on.. Not even sure if it would be possible.. But it would be nice.. Bit like a sun roof on the car, but one that reflects the sunlight in.

As you can probably tell, I am not a builder.

Casa · Mar 06, 2007 11:08 pm

Dobly,

Don't give up on your open roof mirror idea. With clerestory windows you can let the light in without opening the rooof and the council will have no objection. No need for the mirror, but if you want to include it then it would fit just inside the clearstory windows towards the top.

Cheers,
Casa

ausdesign · Mar 07, 2007 8:22 am

All of what Casa mentioned Dobly.
One of the major design considerations will be to incorporate the correct overhangs and screening to suit the orientation of the home.
The exact direction the windows face will determine what sizes and locations will be required to halt the low summer sun penetrating the southern windows - usually external vertical screening is the only total solution as no matter how wide the eaves are they cannot entirely block the morning & afternoon summer sun.
Having solved that problem a larger one will be to stop winter heat loss and still be able to retain the views.
LowE glass, double glazing, heavy drapes & pelmets etc etc
All in all it's really comes down to adapting all the low energy design principals that you would normally incorporate & adapting them to the required orientation.

Dobly · Mar 07, 2007 9:11 am

That is all great info..

So in other words, I should not let the south facing aspect of this block stop me from buying it in the first place..

I just need to be sure the location/environment is taken into consideration in the design.

Thanks guys..

azi · Apr 29, 2007 6:52 pm

We also have views to the south. We are going for a design that has living areas accross the width of the house so the same room that has south views also gets north light.
Still its probably more glass than is ideal for passive design, but it should make for a lovely light open space.

Casa2 · Apr 29, 2007 8:02 pm

azi,

Are you going for double glazed low emissivity glass for your windows? I think this will help enormously in your situation.

Cheers,
Casa

Yak_Chat · Apr 30, 2007 11:37 am

Nothing is ever impossible.

South is not ideal, but with the right design, and stopping the heat soaking out through the south facing windows, (double glaze etc) it would be wonderful.
Go with a experienced enviro architect and use celestral windows to get some northern sun onto a large heat pad inthe house, (The open roof thing will work, but think about how to keep the cold air at the same time)Sunroofs are nice but how long do we actaully have them open when it's blowing gale and the sun is still shining and we are not home?

I'd highly recommend chatting with this guy.

I have seen some of his projects in SA and he is a non convential architect who is passionate about efficient houses and works throughout Australia.

http://www.emilis.sa.on.net/

Good luck, and with the right design it will do everything you need.

PS the price is right for a reason? It just takes some lateral thinking and maybe some more bucks, to get a great house in a less than ideal location that works in a pssive design.

My thoughts
Steve

3timesbuilda · May 01, 2007 12:44 pm

You may be able to use overhanging creepers (think deck covering with grape vines above) and trees that lose their leaves in winter as a method of heat control. In summer the leaves provide shade thereby providing cooling and in winter they fall off letting the sun through providing warming.

3xb