Thermal Analysis

[Anonymous]

Hi

I have just bought Ecotect and I am starting to use the thermal analysis. I have some problems with my windows, because it seems like there are coming to little energy though the windows into the room (very simple room).

I have tried to change the values of the windows, both U-value, Solar Heat Gain Coeff. and Alt solar Gain (lightwt) but no matter what I do the temperature in the room does not rise as much as it should doing the daytime.

I have also tried to find the total amount of energy coming though the window into the room but cannot find that result in Ecotect. In the thermal calculation you can pick the Direct Solar Gain - Qg but the values from this, I do not know how to interpret, because it vary widely a lot if you pick Monthly Averages or Actual Hourly

Hope that anybody can help me with this problem. I have attached the model if anyone would like to have a look at it.

Regards
Lars

[Anonymous]

Hi Lars,

I was just going to post a similar problem so I join this discussion and I add my contribute to the problem. I encountered similar troubles in assessing indoor teperatures for different zones.

However I will explain my troubles later hoping someone else can help. As you can see from the attached picture there are 3 charts. What affects the indoor temperature more is the Alt Solar Gain alongside with the SHGC factor. In fact from the first two charts it is clear that changing the window U value or even more deleting some of them affects the indoor temperature very little. I don't know how to explain this. I think it depends on the calculation method Ecotect uses (admittance method). It is not clear to me what are the exact calculation algorithms though. I obviously exaggerated the Alt Sol Gain and SGHC coefficient to appreciate the charts difference but I can't suggest you what valies are suitable for the case you are analysing. Finally If you want to know the energy (Wh) on a given surface you can run an insolation analysis by using a grid or subdviding the surface.

As far as I am concerned, and about this point it would be very useful If Andrew can give a feedback, I don't understand if the admittance method can take into account inter zonal temperature or it can't. I explain it a bit more. If I have a heated zone (always 18°C) close to a non heated zone, can ecotect calculate the effect in terms temperature of the first on the second zone? I did not succeed sofar and I assumed ecotect does calculation only based on the exterior temperature cyclical swing. Another case is when I have a solar greenhouse attached to another zone. It would be useful to understand the temperature effects of such a greenhouse on the indoor temperature of a close zone. But again I did not succeed. In fact in this latter case I run a thermal analysis but I found that the temperatures variations of greenhouse and the attached room were not linked at all but they were depending mainly on other factors such as U values or outdoor temp only.

Am I wrong or can ecotect calculate inter zonal temprature effects? What about this Andrew?

Cheers

Giulio

[Anonymous]

Regarding Alternating Solar Gain and CIBSE Admittance method I found this useful link
http://ecotect.com/node/1559
hope this will help a bit more

Giulio

[Anonymous]

Hi Lars

I am also having problems with the Salor Gain in my ecotect model. It seems like the temperature does not rise doing the day, with leaves me with temperature inside the room there are to low be to corret. I have tried to maximise the Solar Gain as must as possible ( Solar Heat Gain Coeff = 1, Alt Solar Gain (lightwt) = 1, Visible Transmittance = 1 and a low U value for windows and other building elements) Is that not the optimal setting for the windows if you want to get as much solar heat gain from though the windows?

But still this does not have a great effect on the temperature...

If Ecotect cannot make simple calculation on Solar Gain from windows then i cannot see you can use the Thermal analysis in the program to anything!!!! Hope that i am wrong.

Niels

[Anonymous]

Hi Giulio

I am both glad and sorry to hear that there are others there are having problem with Ecotect and heat gain from windows. Glad because that i am not the only one, and sad because that it seem to be a general problem with Ecotect.

Have you found any solution on the problem?