Thermal Gain

[hilltop_watt]

What does Safaira say about the shape of the window?

[Elmtec-Adam]

There was a difference between a horizontal or vertical oriented window - this is to what I was referring.

Of course , this will also confined to change based upon the orientation of the facade on which the window sits and the position in the world of said hypothetical building.

The great thing is you can quickly test these things in Sefaira.
A 3 minute job to check that.

[Alan4]

@Elmtec-Adam

There was a difference between a horizontal or vertical oriented window

I have never seen that in calculations, in standards, in international ISO standards. Never, regardless of other factors. It is the same glazed surface and the gain is counted per unit of surface (see below Aw,i).

Note: Window Frame Factor (Ff,i) is the percentage of window frame, to only count the transparent glass part in the calculations.

[Elmtec-Adam]

That would be the standard method of measuring the solar gain as a specification of a window and its frame right?

The part 0 regulation uses simplified calculations such as that (it’s something like a ratio of floor space to window size in south facing aspects only) , but also allow for dynamic modelling which accounts for other things.

The fact we can do this type of dynamic modelling so simply and not needing to rely on rules of thumb or simple static calculations is pretty amazing really.

[ateliernab]

this is a nice formula. it doesn’t account for the dephth of the wall though. it considers all windows as a flat panel flush with the wall.
Engineers love to do that, approximate stuff into a theoretical shape that is never completely right but not exactly wrong either. a chicken is a sphere. a person is a cylindre. gravity is rounded up to 10. wall thickness doesn’t count.

real walls have depth. and windows are not flush. in my current appartement, they are 30cm deep. in my previous one, they were 50cm deep. and trust me on this, it matters.

see brief demo here.

Thermal Gain

yeah, I would apply the same logic as sun blockers. in the south, the sun tend to be higher, so we use horizontal protection. Therefore, an horizontal window would get less sunlight through it, through the year. maybe not a lot, in winter it wouldn’t make a difference, and it also depends on the thickness of the wall (a 150mm wall won’t make a diff, a 600mm one will) East west, we use vertical protection. on instinct, I would say that a vertical window would get a bit less light then. In bot…

so yeah, if you consider windows as an abstract panel of glass sure. this would be grand for skyscrappers or US houses with walls as thin as the frames.
But in buldings with actual wall thickness, orientation matters. and optimal orientation of the windows will change with NSEW orientation of the wall.

@Elmtec-Adam

The fact we can do this type of dynamic modelling so simply and not needing to rely on rules of thumb or simple static calculations is pretty amazing really.

exactly.

[Alan4]

@Elmtec-Adam

That would be the standard method of measuring the solar gain as a specification of a window and its frame right?

The part 0 regulation uses simplified calculations such as that (it’s something like a ratio of floor space to window size in south facing aspects only) , but also allow for dynamic modelling which accounts for other things.

The fact we can do this type of dynamic modelling so simply and not needing to rely on rules of thumb or simple static calculations is pretty amazing really.

I don’t know what exactly you mean by “dynamic modeling”. The principle of this calculation is used in all thermal software. What could be made more sophisticated, or “dynamic”, is the calculation of solar radiation, in the second part of the formula. But this precision is not of much interest, because no calculation, no software can accurately predict, for example, disturbances in the sky. Thermal calculation is only an approach to reality, the precision of the calculation has no meaning, this is why we speak of conventional calculation.

@ateliernab

this is a nice formula. it doesn’t account for the dephth of the wall though. it considers all windows as a flat panel

The formula takes this into account, it is Fsh,m,i parameter (shading factor of surrounding object and shading devices on window) which is the result of a calculation. Calculating shadows is another topic.