In evaluating our Climate Zone 2A / cooling dominated project, it comes as no surprise that 3-7pm in August is the peak occurrence for the (currently) proposed design, with cooling as the predominate energy (KW) electric demand.
When internally considering peak event (afternoon/evening) load shedding options for our 24/7/365 facility design, one potential strategy to reduce peak cooling energy demand included shifting primary cooling energy from the peak time period via an ice storage tank system, which could serve the project's currently planned air cooled chiller system.
However, if pursued, this strategy would become the "revised" proposed building design. As such, it would reduce the building's peak time load in general.....but it wouldn't necessarily be "DR event conditional." (i.e. - would NOT exclusively be a semi- or fully-automated DR response control sequence dependent solution).......whereas, any Cooling equip KW demand reduction resulting from a "temporary" temperature set-back (raising from 75F to 80F for example) WOULD appear to meet the DR credit objectives?
Along the same vein, a warehouse or less process intensive building might find that lighting is a significant KW load during peak events. Although aggressively integrating daylighting with automatic photocell controls could reduce the project's "peak demand" by >10%, it would really be a permanent design improvement, not DR event responsive/ reserved for such scenarios.......... whereas, any lighting equip KW demand reduction resulting from a control sequence to dim / extinguish non-critical interior lighting (irrespective of any daylight ambient light sources to augment) WOULD appear to meet the DR credit objectives?
In closing, could any "permanent" load shedding design strategy realistically qualify toward the DR event load shedding quota?
I would NOT think so, but would appreciate another perspective in case I am mistaken. In general, it seems strategies that would contribute toward Optimize Energy Efficiency would NOT qualify for this credit, so really just seeking a confirmation on this "rule of thumb."
Thx!
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5907 thumbs up
February 14, 2018 - 3:58 pm
I think your rule of thumb is essentially correct. When reading the Reference Guide is certainly concentrates on load shedding type of strategies in response to a utility demand peak and not load shifting strategies although load shifting is mentioned in passing. In the rates I am used to this is often referred to as a curtailment program and it is often a part of some commercial rate structures. Load shifting programs are incentivzed by offering off-peak rates but as far as I can tell this type of strategy is not allowed for this credit.
Joanna Switzer
Sustainability Project ManagerAtkins
59 thumbs up
February 15, 2018 - 10:31 am
Thank you Marcus. I do appreciate the feedback.
Hoping the forthcoming LEEDv4.1 might offer some additional tips. I also look forward to any lessons learned from other LEED users. It would be helpful to hear of strategies as well as to learn the duration of various Utility provider DR events. To date, I have heard of DR program curtailment events lasting 2-3 hrs at a time. Curious to know if that's the "norm", as duration certainly factors into the most appropriate strategies.
My initial observations:
1) Initial studies on our Climate zone 2A projects have suggested that simply adjusting cooling temp set-point (even by 6 degF) would not be sufficient to satisfy the 10% minimum quota as compared to the Proposed case energy model peak demand assumptions.
2) When seeking lessons learned from another non-LEED utility demand response program participant, they mentioned slowing fan speeds but I assume that is only justifiable if it does not impact ASHRAE 62.1-2010 compliance (either on supply or exhaust side).
3) In projects that may have sufficiently utilized local occupancy/vacancy sensors for 90.1 compliance and to optimize efficiency, they may find a central lighting controls panel would still be needed to leverage lighting dimming energy savings during DR events.
4) In order to take credit for process load reductions - particularly within the energy model/10% quota calculations, greater owner team/project Elec engineer/energy modeler time may need to be invested to more fully itemize the KW loads of anticipated Owner furnished equipment, particularly higher KW items. Default "w/sqft" receptacle load/panel sizing assumptions to work around a lack of owner information, at times a necessity during design, may become an added challenge to overcome for this credit.
5) Given our findings to date, I suspect this credit could be pretty readily attainable for Facility types that notably decrease occupancy and/or end operations around 5pm AND are large enough in size to naturally include a relatively robust building automation system (BAS) or central Mechanical control system at a minimum. In this scenario, the building operator can more aggressively adjust ventilation rates / temperature set-points without notable impact to either IAQ/ ASHRAE 62.1 compliance or ASHRAE-55 / thermal comfort for the waning occupant load. Likewise, DR participation can be accomplished without the need to add additional control systems to satisfy the 10% min shed quota. For example, maybe the typical operating procedure is to keep systems fully operating until 6pm, but during DR events the control sequences call for Cooling/Heating/Fans significantly ramp down / shut off as appropriate starting at 4pm.
2) In evening operation & 24/7 facilities, options for short-term load shedding may require additional non-HVAC measures, as the operator likely cannot aggressively adjust the primary HVAC systems serving the occupied building for a 3+ hr duration. Likewise, the project may not hit the 10% quota from temperature set-backs alone. In these cases, likely unoccupied equipment and storage rooms could still have their terminal units/systems shut down for a DR event's duration, much easier if a terminal unit (FCU) tied to the control system. However, depending on the project's unique energy profile....even this may not reach the 10% quota to satisfy credit requirements, thus requiring lighting/misc equipment load shedding to be investigated.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5907 thumbs up
February 15, 2018 - 10:46 am
These issues are often among the reasons cited for most projects not buying into a curtailment rate. In my experience this is most often done but kicking on a generator to carry part of the building load. I agree that you would need a very large building with pretty robust controls to pull this off. In a climate zone 2 the peak periods should be related to the afternoon peak cooling load which is probably between 3 and 5, so your 2-3 three hours sounds about right to me.
I too would love to hear from others with more experience pursuing this credit. I can tell you that this credit is one of the least frequently earned.