Help needed: Process Energy / Water - 25% Default vs. Actual

In my opinion this topic needs a lot more discussion and attention. For most projects the 25% is probably based on a typical office building. Many buildings are not office buildings.

First off process energy must be equal for both baseline and design case, unless otherwise quantitively supported AND process energy must be >= 25% unless otherwise quantitively supported.

This means that for a "normal" building, you are straight away robbed of 25% of the change to put a dent in the efficiency performance improvements on your proposed design. Which means, for example if you aim for a 10% improvement you need to improve all areas other than process energy consumption by 13.33% (my math may be a little faulty, but you get the point).

In buildings that have less than 25% process loads, adding a fictious process load to achieve 25% will decrease the performace gains attributed to the other areas, due to the decreased weighting of these areas.

In buildings that have more than the required 25% process energy, decreasing the slice will increase the weight with which the other areas could contribute to the overall performace gains.

Shortly said:
decreasing process load = increased performance
increasing process load = decreased performance

Process Load Definition:
ASHRAE 90.1..."the load on a building resulting from the consuption or release of process energy." "process energy: energy consumed in support of a manufacturing , industrial, or commercial process other than conditioning spaces and maintaining comfort and amenities for the occupants of a building."

LEED: no clear definition, but includes elevators, telecom, refrigeration amongst others.

As per ASHRAE appendix G, service hot water is not included with "Receptacle and Other Loads" which according to my interperatation are the LEED process loads, because these must be equal unless otherwise supported.

Comming back to your questions:
- In a building that has substantial process loads, you should quantify design case improvements and not let baseline process loads equal design case process loads, else you're cutting out too much of the pie from which you can possibly win gains.

- Service Water Heating: ASHRAE 90.1 "heating water for domestic or commercial purposes other than space heating and process requirements." I would classify kitchen uses as "process" whether hot water or otherwise.

- You can't exclude process loads for manufacturing, so why would you be allowed to exclude process loads for kitchen.

Closing notes: In my opinion the importance is placed in improving energy savings against a "average" building of the same sort. If you were manufacturing, you would have to define a industry standard for energy consumption of that manufacturing process to quantify your "special" process energy savings.

The math looks right to me. In order to get 10% total calculated savings you need 13.33% energy savings in allowed areas. To get 50% savings you need 66.7% savings in allowed areas. It really makes the Achitecture 2030 Challenge difficult when you think we're already suppose to be getting 50% savings compared to the average building. Lighting and HVAC haven't changed so much that we can do everything at 1/3 of the energy. And then net zero energy in just 20 more years. On-site power can't make that much.

I completely agree. Many buildings (building types) will become completely imposible to certify, meaning they won't even try to be green. This outcome is even worse. A better approach may be to simply lift or add the upper certification levels, i.e. what's better than platinum?

Titanium level.
Diamond level.
Adamantium level.

Just throwing out ideas.

We have been talking about this issue a lot in my office. Since LEED says under EAP2 & EAC2 Credits.....

"the default process energy cost is 25% of the total energy cost for the building. If the building's process energy cost is less than 25% of the baseline energy cost, the LEED submittal must include documentation substantiating the process energy inputs are appropriate"

My questions therefore, is it possible to just use the default receptacle/equipment load densities specified in the Ashrae 90.1 reference guide (i.e. along with a 'best judgement' profile? Alternativily, in the absense of a profile can we just assume 100% of the load densites on a continuous 24 hour basis? Either way, the total process energy works out to be atleast half of the so called 25% default.

This porcess of justifying lower process power seems logical to me, especially considering that the power densities are directly referencable to ASHRAE. However, I have never heard of anyone getting around this 25% default rule.

Would be keen to hear everyones views on this.

I'm working on a project that is a Laboratory. Interior and exterior lighting, HVAC system and envelope have been very well designed. As the project is a laboratory, it has many equipments with high process load, e.g., resonance, tomography, etc., which accounts to 60% of the total building energy usage. In spite of the systems efficiency, we couldn't achieve the minimum saving required.
I really would like to know if you could use the default rule of 25% for process load for the baseline and proposed building.

I will highly appreciate to hear about anyone view.

There is no 25% default rule that would allow what you propose. The word "default" is unfortunately misleading in the credit language. You must model all energy associated with the building project and within your LEED project boundary.

The "default" is based on a typical office building which will have about a 25% process energy load. If your project is above this based on modeling everything there is no additional documentation required to justify it. If below additional details on the actual process loads in the building need to be provided (narrative and/or spreadsheet containing room-by-room estimate of process loads).

The 25% simply triggers whether additional documentation is needed to justify being below that value.

Let me address some of the other items discussed above.

It is perfectly fine to be under 25%, just account for how you determined it in your model. Never add fictious loads to your models! Projects justify being under everyday.

Process energy loads for LEED is anything not regulated by ASHRAE 90.1. So service hot water is regulated and therefore not process. Process water is water use not addressed by the National Energy Policy Act. So both are loads not regulated by the referenced standard. For kitchen hot water the energy is regulated and the water is not (except for the kitchen faucets which are regulated).

Jean you indicate that project teams are "robbed" of the 25% of energy use. The purpose to address all energy use is to actually encourage the design team to talk to the owner about how to reduce those process loads. We have routinely captured savings from high process load facilities by addressing the process loads.

Bottom line is that the environment does not care if the kWh was used for lighting or a conveyor belt so we need to address it all.

Higher than Platinum? Maybe we need to move away from the minerals from the lithosphere model to one based on the biosphere. Right now one could argue that above Platinum is the Living Building Challenge.