I have performed Exceptional calculations in EAC1 credit for internal

hard-wired lighting. I achieved savings up to 40%.

In Preliminary review, I received below comment

"It is does not appear as if the reduction in heating consumption was

considered. Address the reduction in space heating and ensure the

consumption is appropriately reduced, and provide a revised template and

updated energy model output summaries reflecting the changes."

As light generates heating, so leed reviewer is requesting to provide the

heating consumption calculations and to achieve more savings as it directly

impact on cooling, even though calculations performed exceptionally.

Could you please guide how to perform these heating consumption calculations

and how to incorporate in energy model and Template with reference?

Thanks,

Ashraf Khan

I think something is missing in the story here...

A reduction of lighting consumption is claimed to reduce heating

consumption?

As you say, lights are an internal heat source to some extent...

reducing the lighting energy consumed by a significant fraction should

cause a relative increase in heating and a reduction of cooling

energies, right? I'm going to assume the reviewer's vocabulary is

simply flipped around and this is the point they were trying to make:

Changing lighting should affect heating/cooling consumptions.

As to how you document this - It would seem simplest if you simply

worked your "exceptionally calculated" reduction back into the model.

strategy is that's chopping off 40%, but applying a factor to the space

LPD's may be a decent approach. You could then demonstrate before/after

results showing lighting/heating/cooling consumptions moving about by

setting up a parametric run and using those reports.

NICK CATON, P.E.

Well, my understanding is that exceptional calculation is used to document

meansres that may not be adequately modelled in a simulaiton program. Some

examples are lab exhaust system, appliance efficiencies in high-rise

residential building, etc. How do you define your hard-wired lighting

calculation from this point of view?

Remodeling with reduded LPD is necessary provided your hard-wired lighting

reduction affects internal heat gain and you would expect more heating

energy in this manner. I guess it is what the reviewer expect to see unless

you can prove him/her that your reduction will not trigger heating/cooling

energy variation.

Regards,

Cheney

Good point Cheney!

I suppose I have a more general understanding that "exceptional

calculations" exist for when you have designed energy saving measures

which cannot be credited following 90.1/LEED "to the letter."

To use your example of improved appliance efficiencies, my intuition

would be to produce extra documentation/calculations to substantiate a

certain % reduction in installed plug loads, then I'd apply that

reduction to the proposed model. These calculations and a brief

description of how they were compiled and applied to the proposed model

would be uploaded and referenced alongside the modeling templates.

Perhaps my terminology is off and this is not really an "exceptional

calculation?"

But to clarify for the topic at hand, I suppose my response might best

include another query: what is this hard-wiring strategy and why isn't

it already in the model? It's possible an LPD reduction would not

adequately reflect whatever is really going on.

NICK CATON, P.E.

Hi Nick,

I can not agree with you more. Ashraf will have to answer why such 40%

reduction is not reflected in the original energy modeling.

The only divergence is the example with which you believe the appliances

fall into "plug loads" whereas I believe they could be "process one". Again,

it really depends on which LEED system (2009 or older version) we are using.

No process loads will be included in modeling under the old LEED system. In

another words, no penalty for heating due to reduced process load. However,

your methodology is accurate under the new LEED since both plug load and

process load should be involved in energy modeling.

Regards,

Cheney

Exceptional calculations performed for Residential building, LEED NC V2.2.

Interior lighting calculations performed based on the CIR dated on

3/23/2007.

As CIR states that all hard-wired lighting in living units that is shown on

the building plans should be modeled identically in the Baseline and

Proposed building simulations as shown in the plans. This lighting shall be

considered process energy. Also it states that credit can be taken for an

efficient lighting design in the living unit using the Exceptional

Calculations Methodology. It suggests the figures schedule near 2 hours a

day or less for hard-wired residential fixtures.

For an example in Bedroom baseline calculated as 2 W/sqft with occupancy of

2 hours a day and for propose case 1 W/sqft with same 2 hours a days. A

similar calculation has performed for entire building and I achieved 40%

savings in wattages.

Then reduction of wattage we are showing in Section 1.7 - Exceptional

Calculation Measure Summary. So leed reviewer is requesting to provide

heating impact on cooling and shown the calculations with zone wise and to

incorporate in energy model and Template.

Regards,

Ashraf

Ashraf -

I believe it is acceptable for your "exceptional calculation" to actually be an additional energy model case.

I agree that you are taking the right approach with respect to the CIR mentioned.

Based on earlier correspondence I'm assuming you have provided adequate documentation assuring the reviewer that your selected lighting power reductions are justified.

Could you then incorporate these revised LPD numbers into an additional case of the proposed model, done to the side?

This would give you an "exceptional savings", incorporating lighting savings as well as potential cooling savings / heating increases...

Aaron Dahlstrom , PE, LEED(r) AP

Whether the models already incorporate these loads in some fashion will

determine whether you need to add or subtract to illustrate the point.

Aaron's suggestion should be fairly straightforward:

* Save a copy of your proposed/baseline models as they are -

you'll reference them later.

* Either add the loads under discussion to both models or make

them distinct from other lighting/miscellaneous loads as appropriate. I

would intuitively use an additional line under space lighting inputs -

but keep in mind you're being told to report these as a process energy,

in LEED terms... I expect this is a matter of terminology for your

calculations.

* Space equipment loads and lighting loads will by default

reject wattage as sensible heat to the space and/or plenum in some

fraction. Modify if necessary. Defining these as a lighting load would

make inputs simpler if you desire to reject a percentage to plenum.

* Since this tangent came up recently on another thread: Note

that treating lighting input wattages as a 100% sensible heat load is

entirely appropriate for conventional lighting sources in a building.

Generally only a small fraction of input watts is converted into light

energy in our visible spectrum. Some (not most) LED solutions, green

lasers and oddball stars in the sky are exceptions to the rule in strict

terms of luminous efficacy, but even then it's a moot point unless

you're largely directing your lights outside a window - it's all

ultimately a heat load in your space.

* These loads should have unique scheduling assigned to match

your description/calculations

* The baseline and proposed loads should differ in magnitude per

your description/calculations

* When done, your models will reflect the savings targeted, and

these lights' effects on cooling/heating consumption. The models figure

out the heating/cooling impact stuff in the course of an ordinary

simulation

* When done, set up a few parametric runs in any one model: Use

that "based on another file" parametric run option, and simply reference

your proposed/baseline models (.inp) with and without the

added/re-defined loads. A parametric run will result in reports that

show all consumptions for all 4 iterations side-by-side. Should be a

perfect illustration to include with your response.

NICK CATON, P.E.

Ashraf - just to close the loop - Nick and I had some off list discussion. We agreed to an edit to his procedure, which I've added in red below.

Aaron Dahlstrom , PE, LEED(r) AP