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

Miscalculations in Ecodesigner (shipped with ArchiCAD 17)

Not applicable
This pertains to EcoDesigner's Operational Profiles. In my case I have a building that is only open two-days per week for 9 hours per day. When sizing the heat recovery ventilation system and defining its daily schedule, EcoDesigner shows correctly that the vent system will be operational for 936 hours for the year.

All good so far. However, when I define a corresponding Operational Profile for the building (two days per week for 9 hours per day) EcoDesigner calculates the annual hours of operation as 2,496 hours which is patently incorrect. This miscalculation overstates the usage of the building by over 200%, which translates into much higher energy consumption (kWh/cubic foot/annum) than should be the case.

The algorithm doing the calculation of operational hours per annum need to be looked into and fixed.

BTW I use kWh/cubic foot/annum because kWh/square foot/annum can sometimes be misleading. Higher ceilings (10ft-14ft) in a small, 3,000 sf community building will yield a different energy consumption profile than a 3,000 sf building with 8ft ceiling plate for the same number of occupants.

Any thoughts or perspectives on what I think are miscalculations in EcoDesigner's Operational Profiles would be much appreciated.


Not applicable

I set the hours of operation per day as 9 and the number of days of operations as 2 for the whole year (9x2x52 = 936). Nothin particularly extraordinary about this

The screen shot show Wednesdays and Sundays for 9 hours each day.

My Operational Profile containing the temperature ranges, occupancy, equipment loads etc is also set to 9 hours per day for only Two days per week - Wednesdays and Sundays.

I've attached a screen shot of the daily schedule to address your point.

Hope this clarifies the situation for you. 9hrs x 2 days per week x 52 weeks = 936 hours of operation.


Not applicable

Totally different topic - Perth WA. What a fantastic city that is. My best man at our wedding whom I've known for very many years - Steve Brown - lives in Perth - the Shenton Park area. He's an architect whom I've been trying from time to time to persuade to switch from Autocad to ArchiCAD.


Barry Kelly
Your kidding - Steve Brown from Shenton Park!
Never heard of him.

As I say I don't know a lot about Ecodesigner but I think your calculation might still work out.
I'm not sure why it shows the 2496 hours usage.
There is a 24 hour time span but you are setting the min/max temperatures as well as lighting etc. for only a 9 hour period.
So my guess is it will calculate that correctly and ignore the rest of the day.

The only way to check for sure is to run your calculation based on what you have set up.
Then change it to say 12 hours in the day and see if the calcs increase.

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Not applicable

Thanks - as I've always joked with Steve Brown that he's well known in concentric circles (an old Goon show reference).

But to EcoDesigner. Per your suggestion, I tried a few different daily schedules to see what the internal algorithms produce as far as hours of operation per annum. No change. The calculations assume a 24 hour occupancy.

Somehow I think there's an errant algorithm in the portion of the code behind the Operational dialogue that is producing the wrong hours of operation per annum.



Not applicable
pallsopp42 wrote:
But to EcoDesigner. Per your suggestion, I tried a few different daily schedules to see what the internal algorithms produce as far as hours of operation per annum. No change. The calculations assume a 24 hour occupancy.
This is not correct.

If you create two different daily schedules (one with no temperature range and one with specified low and high temperatures) and properly assign them to the thermal blocks - the calculations will differ and, no, calculations do not assume 24 hours of operation.

What you are struggling with is the fact that EcoDesigner shows 2000+ hours of operation (poor wording, I agree), but think about this number as a NUMBER OF DAYS your operational profile is in effect, not the number of hours that your systems are running.

The number of hours your systems are running are dependent on many factors within operations profile (temperature control, occupancy, if you have bodyheat turned on, lighting heat emissions, equipment, etc.) as well as outside factors like solar gain and heat transfer between blocks.

Basically, what you are referring to as a bug does not appear to be one in my opinion.

Not applicable

Well, I guess we have to differ. I think there may be a bug.

When a completed operational profile (occupied with systems running and thermal blocks properly allocated) is defined as 960 hours a year yet another calculation in the same application (Ecodesigner) sets the hours of operation per annum as 2496 for that same daily operational profile, then there is something seriously amiss. The number is defined in EcoDesigner as the number of hours per annum NOT the number of days the operational profile is in effect as you suggest.

Hours of operation: 2 days per week at 9 hours per day for 52 weeks per year = 936 hours of operation.

If it is not a bug, would you - or someone - please explain to me why the defined hours of operation (936 hours per annum) calculate out to be 2496 hours within the same application and for the same operational profile??

I continue to be very curious about this and the discrepancy makes no logical sense based on the information I have and the feedback thus far.

If I'm off base then perhaps I'm misinterpreting nomenclature within EcoDesigner e.g. "Days of Operation." If this IS the case, then EcoDesigner needs to make it crystal clear to users how it is interpreting the operational profiles. Thus, when a 936 hours per annum of operation turns into 2496 hours of operation for the same profile, this difference needs to be explained as well as how calculations of energy usage are not being compromised by this apparent discrepancy.


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