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regenerative elevators

asked 2014-10-23 09:46:49 -0500

301_Hours's avatar

updated 2015-07-10 21:09:56 -0500

Has anyone successfully modeled a regenerative elevator for LEED compliance?

I see a lot of literature claiming 50%-75% savings, but I'm not sure if/how I should change the schedule and/or peak load in the model.

Or should I just put the elevator on a separate electric meter, and take a percentage cut in an exceptional calc.

It's a 25 story building with 4 passenger elevators.


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Thanks for everyone's help.

The exceptional calculation I put together for LEED was accepted, which added over 5% energy cost savings for my project.

The only independent supporting information I found was an ACEEE paper from 2005. Hopefully something newer will be published eventually.

Thanks again.

301_Hours's avatar 301_Hours  ( 2014-11-23 21:57:36 -0500 )edit

Is it possible for you to share how you put together your exceptional calculation? Will appreciate any guidance. Thank you.

dannyllim's avatar dannyllim  ( 2015-01-19 22:08:10 -0500 )edit

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answered 2014-10-23 12:59:09 -0500

Regenerative elevators can generate power on descents when the elevator has a load heavier than the counterweight and on ascents where the counterweight is heavier than the elevator load:

image description

I would imagine that to really capture the effect of regenerative elevators you would have to shift your schedule, so that it is typical when occupants are entering the building (heavily loaded ascents, lightly loaded descents) and negative when occupants are leaving (lightly loaded ascents, heavily loaded descents).

You would have to make an assumption about what percentage of the occupants are going up vs going down throughout the day. When there are more occupants going up you will be using energy and when occupants are going down, you will be generating energy. The energy generated bringing occupants down will roughly mirror the energy used bringing them up, but will also have losses due to the efficiency of the generator.

This is probably a bit overkill for some applications. At the end of the day the meters are all summed up anyway, so applying a percent reduction off the peak load for the elevator schedule is probably a reasonable approach. You just won't get the impact of the time of day impacts on the HVAC system that offsets the heat generated by the elevator motor (which is usually not in a conditioned space anyway).

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@Neal Kruis I think the time of day variation in heat load you discuss is so minimal that it never has to be a concern. The uncertainty in actual elevator usage dwarfs any possible effects on heating load. I agree that just changing the peak load should be fine. The hardest part is going to be getting justifiable data from the manufacturer to back up the reduction claim.

Ralph Muehleisen's avatar Ralph Muehleisen  ( 2014-10-23 14:10:13 -0500 )edit

answered 2014-10-23 18:58:26 -0500

updated 2014-10-23 19:00:42 -0500

I'd like to offer a slightly shorter answer - apparently "yes"

This manufacturer will provide an exceptional calculation spreadsheet for you -

Also pass this PDF along to your LEED consultant/architect, they may count the elevator in additional credits, and also not embarrass themselves by claiming credit where elevators are excluded.

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The link to the spreadsheet is broken. Do you know of a revised link or can you send the spreadsheet?

JasonGlazer's avatar JasonGlazer  ( 2015-07-10 06:32:18 -0500 )edit

answered 2017-04-07 14:56:24 -0500

CR Jones's avatar

This calculator includes kWh and energy cost: Elevator Calculator

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answered 2015-09-17 20:52:21 -0500

301_Hours's avatar

So somehow 9 months has passed and I forgot to post what I submitted to GBCI, and which they have subsequently approved on this and one additional project.

Is there a way for me to upload a .pdf here? When I try to attach a file to this post it only allows images.

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It's great that you're coming back to give feedback. You could always have the pdf uploaded somewhere and post the link (google drive, dropbox, wetransfer, etc)

Julien Marrec's avatar Julien Marrec  ( 2015-09-18 02:02:48 -0500 )edit

Yes, it would be great to see your submission. The CaGBC has started pushing back on energy savings from regenerative elevators. Their reasoning is that regenerative elevators have been around long enough that they should be considered as typical practice, not an ECM.

Chris Jones's avatar Chris Jones  ( 2015-09-18 03:38:20 -0500 )edit

answered 2017-04-07 12:35:19 -0500

bull0082's avatar

Here is an online calculator for traction elevators using regen technology:

It allows you to adjust some basic parameters and calculates the annual savings in $. From there, it is pretty easy to work back to get the annual kWhr savings.

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Asked: 2014-10-23 09:46:49 -0500

Seen: 3,834 times

Last updated: Apr 07 '17