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Sustainable design
About EcoDesigner, Energy Evaluation, Life Cycle Assessment, etc.

Using Ecodesigner to make a zero C02 emission house?

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I started playing around a little bit with Ecodesigner.
I was wondering if I can create a totaly zero-CO2 emissions house using Ecodesigner? Is this possible?

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thank you for the help Mr. Boniulari.
The natural cooling did dropped by, like you said. Here is the new pdf:

And here is the comparison between the old and new pdf results:

What I am confused now are two different ways of assigning the shading on facades. One is by assigning the shading to a specific curtain wall (I edited the shading of these curtain walls) and the other is the shading of the general sides of the object. It seems that in the other way, by "shading" they mean the vegetation?

Here is the screenshot of the "first and second way" (in attachment)
Now I am confused about, which one of this two I need to change? Both of them?

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I don't know what to say about the two ways to simulate sun shading in ED: it is not derived from the BIM model geometry, so it really depends on the assumptions that were made by Strusoft when they wrote the software. No idea.

Please be careful about your U values for the opaque envelope: they are now worse than the first time. Can you set them to be all around 0,17 W/m2K? This will help cutting down the Transmission heat gains in summer (the pink component in the graph).

What settings are available for the glazings? On the market are now available selective glazings that will allow light into the building but will reflect heat (long and short infra-red). Both Saint-Gobain and Pilkington have these options. Any chance you can customize more value other than the U-value? This can also allow your building to stay cooler during summer.
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thank you for the reply.

What do you mean by "opaque envelope"?
What settings are available for the glazings?
I guess "TST - Total Solar Transmission compared to transparent glass (%)" is the option that we are looking for.

But I do not know which value should I take?
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The "building envelope" is made by the elements (walls, windows, slabs, roof etc.) that separates the heated/cooled volume of the building from the outside and from other parts of the buildings (garages, stairwell etc.) that do not require heating/cooling. The envelope is the insulated "box" that keeps your building warm in winter and cool in summer.

The "opaque envelope" means all elements that do not allow sun radiation to reach the inside of the envelope: this means: all walls, roofs and slabs that are not transparent. Normal walls, slabs and roofs belong to the opaque envelope.

Back to the glazing, yes the TST is the parameter we need. Unfortunately, ED only allows you to set the TOTAL solar transmission, without making any difference between light radiation and infra-red radiation.

Anyway, keep in mind that the glazing standard for passive houses follows these two rules:

Ug (U-value of the glass alore, without the frame) <= 0,7 W/m2K (I don't know if you can set this value in ED)

Uw (U-value of the whole window, including the frame. In this case, not including the thermal bridge caused by the installation of the window) <=0,8 W/m2K (this is the U value you need to enter in ED). You entered Uw=0,60 W/m2K: did you calculate that? It seems very low to be realistic.

Ug - 1,6 * g <= 0

where "g" is your TST value

If you keep your Uw=0,60, then you need to have a 3-pan low-e glazing with Xenon gas (I hope you're not paying for this project personally) with 6-16-4-16-6 glazing and Ug=0,40 W/m2K. A typical g value for such glazing is about 0,43-0,48 (also see "Technologie und Wirtschaft des Passivhauses by Stefan Echterholter, published by, in German).

0,40 - 1,6*g <=0

In this case:
0,40 - 1,6*0,43 <= 0
-0,77<0 : the glazing is suitable for a passive house.

To summarize:

U-value = 0,60 (to include the Uf value of the window frame)

TST/ g value = 0,43

This will let less energy into the building, allowing for less passive heating in winter (which you do not need) and protecting your building better from overheating in summer.

Further development for your project would be to study which part of the glazing needs to have this kind of Formula-1 glass, and where you can use cheaper options.
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ED does not allow to enter the Ug and Uw values separatelly.
It only allows us to enter the "U" value (take a look at the attachment in this post).

And you are right. I made a mistake:
You entered Uw=0,60 W/m2K: did you calculate that?
I did not, as I did not know how to do it. 0,60 W/m2K is in fact Ug I got from the prospect(catalog) of the curtain wall producer.

If I take 0,60 W/m2K for Uw, what will be the value of my TST for that kind of windows?

also see "Technologie und Wirtschaft des Passivhauses by Stefan Echterholter, published by, in German
I do not speak German. I will try to find the same book in English.
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I don't think you can find that book in English: if you do, please let me know.

As far as U value for windows, remember that:

Ug = the U value for the glass only ("g" stands for "glass")

Uf = the U value for the window frame (wood, aluminum, PVC...) ("f" stands for "frame")

Uw = the average U value for the window (glass + frame). This value depends on the kind of glass you have (Ug), the window frame (Uf) and the geometry of the window. Normally, the glass insulates better than the window frame, so that if you have large windows with large glass surfaces and little frame area, they have a lower (better) Uw.The Uw that you see in catalogues is calculated on a standard window size.

In the case of Ecodesigner: Uw = U-value

Try and do your ED evaluation with these values:

U-value = 0,8 W/m2K

TST = 0,43
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Thank you for the help once again Mr. Bonilauri.

I was sick, sorry for such a delay.

I tried to search for the book "Technologie und Wirtschaft des Passivhauses" on English, but you were right - it seems there is not English edition, until now.

I entered the values you specified:
U-value = 0,8 W/m2K
TST = 0,43

And the results are better than before. Take a look at the image in the attachment.

Now what is still bothering me is why I can not set a "solar panel" as a source for "Hot water generation". Instead of this I need to choose Electricity or Natural gas or something else, and then I am getting a significant amount of CO2 emissions.
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Great article!
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