A question about how is Ecotect Analysis workng

[archiii]

Hello everyone,

I am a student of architecture and I am currently writing my master work. One of my main subjects in it is the Ecotect Analaysis, whic I am using to do make some parametric analysis...

I was wondering on whic standards does Ecotect base on? Whic standards are included in it and are calculated in the analysis?

So I am kindly asking you if you can give me any information about it or at least give me ha hint where I can find that information..

thany you

[Pennetier1]

Hello Archiii, 

Ecotect offers many different type of calculations; thermal or daylighting are the 2 main ones.

For thermal analyses, Ecotect uses the Admittance method.

For Daylighting, Ecotect uses the BRE Split Flux method.

These are the two "standards" I can quickly think of for Ecotect.  A lot of the other calculations are based on standard methods, such as solar angles etc.

Quite a few methods and formulae used by Ecotect are highly influenced by the work of Steven Szokolay.

Let me know if you have more questions on this topic, otherwise please accept as a solution so that others can benefit from this information.

Cheers,

[archiii]

Thank you for your answer!

There is still one thing I wuld like to know. I am not sure if this statement is correct: "that Ecotect Analysis works based on american standards?"

In comparicon with the program PHPP (Passsiv House Planing Package) - whic was developed in Germany by Passive House Institute...

A while ago I was doing a comparison beetwen the two programs, using the same simple house whic was calculated and the problem was, that the results were totaly different... I know, different programs calculate in many different ways, but still... I am trying to understand why there is such a difference...

We did also a manual calculation of transmission losses and the results were closer to the PHPP calculation than the Ecotect calculations...

Thank you

[Pennetier1 · Accepted solution]

Hello archiii, 

To answer your first question, no, that is not correct.  Ecotect is not based on American Standards, if there is such a thing.

Ecotect is originally an Australian software and it utilizes various standards, depending on the type of analysis to perform.

While many American thermal engines uses DOE2 for thermal calculations, Ecotet uses the Admittance method, which is mainly used, and is from the UK if I recall correctly.  It may not be as accurate" as using a complex thermal engine such as DOE2, but does not require as much input either, which makes it faster for quick calculations and appropriate for fast relative comparisons of various designs.

The Daylighting protion uses the Daylight Factor method, which is also quite typical of UK standards.

I am not surprised about the variation of results compared to the PHPP program.  In fact, comparisons with any other thermal engine will show variations.  One of the cause for this variation is that Ecotect does not account for such systems as HVAC - it only calculates thermal loads, not the actual energy spent by the HVAC system as some other engine do - or energy used for hot water heater etc...

Also, the ventilation losses or gains are calculated differently and vary based on the ACH that is input within the software, which can be tricky to set correctly in most cases.  If set to "Natural Ventilation", Ecotect uses a formula that detect the amount of window area and whether there is potential for cross ventilation within the thermal zone or not.  It then grab the wind speed data from the weather file to estimate infiltration gains or losses.

The weather files that are used will also have great influences on the results.  They would have to be exactly the same to be able to compare accurately the various engine.  I am not sure PHPP uses the same weather file as Ecotect, but I do not think so if I recall correctly.

For the transmission losses, Ecotect uses pretty standard formulae similar to many thermal engines, aside from the infiltration as stated above.  One area that is not very well known to users is the way to input thermal data for the glazing elements.  There is an input for SHGC as well as Transmittance.  For thermal calculation, the user must enter 1.0 in either one of these entry (typically transmittance), and set the SHGC to that of the manufacturer, other wise the numbers will multiply each other and create a false property.  For daylighting, the transmittance should be set correctly to the manufacturer's data.

I would encourage you to read up the help file > Content > Analysis > Thermal Performance > Simulation Engine for additional detail.

I hope this clarifies things a bit.

Let me know if you have more questions on this topic, otherwise please accept as a solution so that others can benefit from this information.

Cheers,