Greenhouse Gables Facing North/South or East/West ?

[PaulZone8b]

Have read a few things that say gable ends should face North/South...right now, our plan to position our new one is East/West for the gable ends (see backyard pic). I was thinking the one side of gh would get sun all day and the other (less sun) would be good for plants that dont want so much sun. I am planning on installing shade cloth on the sun side for late afternoon when the sun gets brutal.

What is the best way ? Logic behind it ?

 

[Susan BBPM]

Ours runs along the side of the house, and as such the gable ends are facing NE and SW. It gets sun from first thing until about 5pm.

The benefit to the long sides facing south is more sun. However, I'm in Scotland which is far from sunny and we find the polytunnel gets too hot even at this time of the year. Already we've got shade cloth over it.
So, I would suggest two issues to consider:

1. What results in the most sun, and in your climate what is your biggest problem (reducing or increasing the amount of sun).
2. Protection from cold winds. Our house protects ours from the North winds and a fence behind protects from the East winds.

I don't know enough to give you a definitive answer to your question, but these are my observations from my own experience.

 

[Oliver Buckle]

Good answer Susan.
I have one running one way, one the other. I find the East West more useful for just the reason you say, so tomato and peppers on the south side, cucumbers on the North. South facing is generally more useful, here anyway, and I get much more of it with a side than with just the end, that also means it warms up better too.
As Susan says it depends to a large extent on local conditions and what you want to grow.

" Already we've got shade cloth over it." I would be trying to increase ventilation rather than decrease light, will the sides roll up at all?

 

[Susan BBPM]

Good answer Susan.
I have one running one way, one the other. I find the East West more useful for just the reason you say, so tomato and peppers on the south side, cucumbers on the North. South facing is generally more useful, here anyway, and I get much more of it with a side than with just the end, that also means it warms up better too.
As Susan says it depends to a large extent on local conditions and what you want to grow.

" Already we've got shade cloth over it." I would be trying to increase ventilation rather than decrease light, will the sides roll up at all?

I hadn't even considered that.

It came with roll up vents but we recovered it with a high quality thermal plastic which is great at cooler times of the year. I had planned to cut a window at the other end to improve airflow but as the shade cloth seemed to do the trick last year I haven't bothered. Maybe I need to re-think that.

 

[PaulZone8b]

I had a thought with my upcoming GH build... it will be located about 15 ft away from a crawlspace door to under the house which usually is cooler even in the summer...so I was thinking maybe I could run some kind of pipe from the crawlspace to the GH. Attach it low on the GH wall and maybe even insert a pipe fan inside it to "pull" the cooler air in...and the exhaust fan (up top of gable end of GH) will pull the hot air out...so I should have good circulation.

Only thing I wonder about is the amount of "moisture" in the cooler air from under the house which may cause more fungal issues in the GH. Hmm. You folks have any thoughts about this idea ?

 

[NigelJ]

Colder air holds less moisture for a given humidity than warm air, so the air from under the house will not add to the fungal problems caused by the naturally warm humid conditions of your summer.
More likely is extra condensation under the house; as warm air will flow in from outside to replace what you extract, cool down and then the surplus water appears on the cold surfaces.