[Equest-users] Process Load & LEED Documentation

[Dahlstrom, Aaron]

Dan -

(wrote this up before I saw all the great responses. Will send anyway to provide the page citation you can cite with any reviewer, as needed, to justify why you would like to document your actual process loads.)

I understand from GBCI that the 25% process loads threshold is a default, where the actual process load is unknown. This applies rather clearly to Core and Shell jobs or jobs where the connected process load is unknown / unknowable.

That said, we have found on a case-by-case basis that LEED Reviewers are sympathetic to a well-reasoned and well-documented case showing the actual process loads for a facility, enabling us to use them in both the proposed and baseline. (See LEED 2009 BDC reference manual p273, Baseline Column)

If you have full fitout drawings, you may be able to document the total design electrical power intended for the facility rather easily, via the VA shown on the electrical panel schedules, plus the draw of any larger loads fed direct from the panelboards/switchgear (ie elevators, etc).

If not, does the 3.7W/sf exceed the electrical or air conditioning capacity of the actual designed building? If 3.7 W/sf is far beyond the actual power, you may end up with many un-met load hours in your proposed case. If the artificially high process load exceeds the building's capacity, you may be able to document an assumed lower amount that matches the actual Electrical or HVAC capacity of the facility.

Aaron Dahlstrom , PE, LEED(r) AP
In Posse - A subsidiary of AKF| 1500 Walnut Street, Suite 1414, Philadelphia, PA 19102
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From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Sami, Vikram
Sent: Friday, March 02, 2012 11:48 AM
To: Daniel Kaler; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Process Load & LEED Documentation

First off - 3.7 is high, but not unreasonable for an office. It depends on what you are doing in the space. I would recommend trying to get a good representation of power loads on a space by space basis rather than spreading a uniform power intensity across the whole building - this makes a big difference with CAV & VAV systems - especially with reheat issues. If you assume 50 ft2 per workstation and around 175 W per station - that's  over 3w/ft2. Remember - connected peak power and actual peak power are different - you need to factor in some level of diversity in your usage schedules. If you have any kind of server room - I would definitely model that as a separate space with its own system and equipment load.

Relative to the GBCI & LEED - if you document your equipment assumptions properly and can make the case that you have modeled this close to reality (I would provide a space by space table along with a usage profile), you should be fine. The 25% is a minimum unless you can reasonably document otherwise.

Hope this helps


Vikram Sami, LEED AP BD+C
Sustainable Design Analyst
1315 Peachtree St. NE, Atlanta, GA 30309
t: 404-443-7462    f: 404.892.5823       e: vikram.sami at perkinswill.com<mailto:vikram.sami at perkinswill.com>   www.perkinswill.com<http://www.perkinswill.com/>
Perkins+Will.  Ideas + buildings that honor the broader goals of society


From: equest-users-bounces at lists.onebuilding.org<mailto:equest-users-bounces at lists.onebuilding.org> [mailto:equest-users-bounces at lists.onebuilding.org]<mailto:[mailto:equest-users-bounces at lists.onebuilding.org]> On Behalf Of Daniel Kaler
Sent: Friday, March 02, 2012 10:04 AM
To: equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>
Subject: [Equest-users] Process Load & LEED Documentation

Hello All,

My question is regarding the 25% process load as required by LEED online. I'll give a little background on the building first...

The building is located in northern Minnesota, rendering it a heating dominate building. Our HVAC system is a geothermal water-to-air heat pump system with an electric back up boiler. There will be no gas usage. For this scenario, system type 4 was used for the baseline case. Since a majority of the winter will be spent below the heat pump operating temperature, in heating mode, electric resistance is the main source of heating. This being said, my baseline system has a very large annual heating consumption.

Now to my dilemma. With the large heating consumption in the baseline design, the process load was below the 25% threshold. I was advised to increase the plug load until I was able to surpass the 25%. After multiple iterations, I came to a value of 3.7 W/sqft for the office spaces (the building is primarily offices). Obviously this is much greater than anticipated for offices spaces.

Initially the process load was 30% with my proposed design, but after the modifications the process load was roughly 50% of my total energy consumption. To my knowledge the only other option we have to is document each piece of equipment contributing to the process load.

Has anyone encountered the problem before and have advice on a solution?

Thanks in advance.

Daniel Kaler
Energy Engineer, EIT


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