Defining Utility rates - proposed building different than reference building?

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Hello everyone.

A quick question for you.

We're modeling a building to evaluate its performance for LEED Canada-CS, using EE4/MNECB as the modeling tool.

My question is whether or not if we should/need to define different utility rates for the proposed building and the reference building. Is this allowed?

The motivation for this is because the electrical utility rate for our region is set with a minimum kW to pay each month, which is equal to 65% of the max demand over a period of 12 months. So, if a given monthly kW demand is lower than that minimum, you pay a "penalty" for un-demanded kW.

Since both proposed and reference buildings have a different monthly demand profile, the min kW to pay, and the total "penalty", would differ. This influences the total energy costs for both building, and the % energy savings used to evaluate the LEED points.

So, can we set different rates, defined to match the actual utility demand of each case? My guess is yes, but I want to check...

Thanks.

Frederic Genest, P.Eng.

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Frederick,
If the reference building were to be constructed instead of the proposed
building would it actually have a different utility rate by virtue of its
size or other characteristic?
Dennis

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I'm not familiar with LEED Canada specifically, so these thoughts are applied to Appendix G modeling in general. The rate structures should be the "same" based on the utility tariffs that apply to the building.

Each of the proposed and baseline cases will set their own demand "ratchet". So the Baseline will have a 65% of its maximum, and the Proposed will have a different 65% of its own maximum. When you calculate the average $/kWh for each of the two models, they could be different between the two cases.

I'm not sure if EE4 includes this ratchet capability as a built in feature, but many other software programs do. If the baseline system selections end up with equipment that suffers under the ratchet, while the Proposed case minimizes the penalty, the Proposed model would justifiably be rewarded.

To take this credit the actual tariff will have to be modeled with all of the demand and energy based components. Credit probably wouldn't be allowed if you had used a weighted average utility price including all factors. If that was the case, then the rates should be identical in both models. I'm not sure how this impacts LEED Canada projects.

Under some scenarios the Proposed and Baseline cases might fall into different tariffs with the utility, this would also be allowable if you can provide the documentation on each being subject to different requirements. Similarly it would not be allowed if you use a weighted average utility price instead of modeling the actual tariffs.

David S. Eldridge, Jr., P.E., LEED AP BD+C, BEMP, BEAP, HBDP

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Frederic,

This is an interesting scenario. It seems that the utility has decided to incetivize buildings with a high base-to-peak ratio. So if you have a high peak, most of the time the actual demand will be above 65% of the peak, and no penalty is incurred. Buildings with a low base-to-peak ratio will be below 65% more often and have to pay. Makes good sense from a utility perspective, since a flat demand profile means fewer utility plants that must be built and kept idling when demand is low.

I'm not sure how the CaGBC would treat this case. At first glance, the proposed building is benefiting from utility pricing rules. If this building was built elsewhere, it would not benefit from this utility structure. So your LEED points shouldn't take this demand penalty into account. In some sense this is similar to campus buildings which might pay a discount campus DES rate (which is not allowed under DES rules to ensure fair comparisons).

But on the other hand, LEED cares about making smart decisions within the regional context, so you could argue that your proposed design should be rewarded if it can take advantage of this regional utility structure. You could argue that your design provides a wider benefit since it helps the utility smooth-out the demand profile, which is clearly one of the utility's goals and a benefit to the wider grid.

My recommendation would be to submit a CIR or discuss this with a CaGBC peer reviewer (if you are considering engaging one for a 3rd party review). If you can afford to leave these cost savings on the table, maybe they can qualify as an innovation point (for regional priority). My gut feel is that the demand penalty would not be eligible toward LEED points.

Cheers,

Luka Matutinovic, P.Eng., LEED? AP BD+C

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Hello Dennis.

It would be the same "general" rate (i.e. rate "M"), but its implementation would be different (i.e. "min monthly billable rate").

Is it allowed under ASHRAE 90.1 App G to define different rates, or different implementation of the same rate? If so, I guess the same rule would apply for EE4/MNECB modeling.

Thanks for any input!

Frederic.

De : Dennis Knight [mailto:dknight at wholebuildingsystems.com]
Envoy? : September 19, 2012 4:43 PM
? : Genest, Frederic
Cc : bldg-sim at lists.onebuilding.org
Objet : Re: [Bldg-sim] Defining Utility rates - proposed building different than reference building?

Frederick,
If the reference building were to be constructed instead of the proposed building would it actually have a different utility rate by virtue of its size or other characteristic?
Dennis

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Joined: 2011-10-02
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Hello Luka.

You have it right, I expect. The utility (Hydro-Quebec, in this case) seems to try to have designers/operator flatten the demand profile. Or, from another point of view, that they try to avoid the winter electrical heating peak if they can.

OTOH, when you reach a sufficiently high monthly energy consumption (i.e. 210 000 kWh), the excess kWh is billed about 30% cheaper.

And since the reference building is in fact consuming more energy, it pays cheaper a bigger fraction of its kWh. The averages are 8 ?/kWh for the reference building, compared to 9 ?/kWh for the proposed building.

Hence, following your reasoning, since the rate is already penalizing the proposed building for being energy efficient (on a $/kWh basis), somewhat offsetting this by compensating with a corrected kW rate might be seen as "acceptable" by the CaGBC.

Thanks for the comment, I'll think on that.
Frederic.

-----Message d'origine-----
De?: Matutinovic, Luka [mailto:LMatutinovic at halsall.com]
Envoy??: September 19, 2012 5:08 PM
??: Genest, Frederic; bldg-sim at lists.onebuilding.org
Objet?: RE: [Bldg-sim] Defining Utility rates - proposed building different than reference building?

Frederic,

This is an interesting scenario. It seems that the utility has decided to incetivize buildings with a high base-to-peak ratio. So if you have a high peak, most of the time the actual demand will be above 65% of the peak, and no penalty is incurred. Buildings with a low base-to-peak ratio will be below 65% more often and have to pay. Makes good sense from a utility perspective, since a flat demand profile means fewer utility plants that must be built and kept idling when demand is low.

I'm not sure how the CaGBC would treat this case. At first glance, the proposed building is benefiting from utility pricing rules. If this building was built elsewhere, it would not benefit from this utility structure. So your LEED points shouldn't take this demand penalty into account. In some sense this is similar to campus buildings which might pay a discount campus DES rate (which is not allowed under DES rules to ensure fair comparisons).

But on the other hand, LEED cares about making smart decisions within the regional context, so you could argue that your proposed design should be rewarded if it can take advantage of this regional utility structure. You could argue that your design provides a wider benefit since it helps the utility smooth-out the demand profile, which is clearly one of the utility's goals and a benefit to the wider grid.

My recommendation would be to submit a CIR or discuss this with a CaGBC peer reviewer (if you are considering engaging one for a 3rd party review). If you can afford to leave these cost savings on the table, maybe they can qualify as an innovation point (for regional priority). My gut feel is that the demand penalty would not be eligible toward LEED points.

Cheers,

Luka Matutinovic, P.Eng., LEED? AP BD+C

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See example below (open website & download from URL) which shows why commercial bldgs in downtown Chicago use electricity for winter heating. The location used was Minneapolis (severe winters) but the utility rates are for Chicago. ComEd Rate GL for summer with Rider 25 for winter which makes winter electric heating cheaper than the gas rate (Nicor). ComEd power plant is not idle in winter
http://bepan.info/proj-bldgs/p13-high-rise-bldg
Varkie
http://www.iit.edu/arch/faculty/thomas_varkie.shtml

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