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Review Comments: 7.4.5 Power

Document Title

BSR/ASHRAE/USGBC/IESNA Standard 189.1P, Standard for the Design of High-Performance Green Buildings Except Low-Rise Residential Buildings 


7.4.5 Power 

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Date Submitted

8/8/2008 4:00 PM 



Comment Text

7.4.5 Power. The power shall comply with Section 8 of ASHRAE/IESNA Standard 90.1 with the following modifications and additions:


(a) In addition to ASHRAE/IESNA Standard 90.1, transformer efficiency: Transformers shall comply with the minimum requirements in Table C-21 in Normative Appendix C.



(b) In addition to ASHRAE/IESNA Standard 90.1, load factor/peak load reduction: Building projects shall contain automatic systems such as demand-limiting or load shifting, not standby emergency power generation, to reduce peak capacity of the building by not less than 5.0% of the service overcurrent protection device rating for the building project.


        Exception to 7.4.5:

                (a)  Building  projects with residential spaces

Substantiating Statements_0




Comment Approval Date


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Replied To - Resolved 



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Last Action Request Further Contact


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New Comment 

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Not OK - Resolved 

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Response Sent


Substantiating Statements

Peak demand limiting is accomplished through reducing discretionary loads (e.g. dimming perimeter lights, turning off escalators, increase thermostat settings, running mechanical equipment at partial loads, raise cooling water temperature, etc.).  The costs for peak demand limiting systems are incurred through the use of extra controls, computers, hardware, software, training, and labor necessitated by this method.  Costs are not linearly scalable with the size of the load being curtailed, because these elements are required regardless.  Estimates for peak load reduction systems fall into the range of $30,000 to $40,000 per project site, which agrees with an ASHRAE Journal article that estimated a cost of $32,000 for central switching controls for lighting, HVAC, and escalators for a building in NYC with a summer daytime peak of 3 MW.


The 7.4.5(b) requirement places a completely disproportionate burden upon smaller buildings, where the loads that could presumably be controlled with such a system would not yield energy savings or peak load benefits commensurate with the costs for the load control system.  Requiring small buildings to install such systems simply adds costs to projects without real energy savings benefits.


The 7.4.5(b) requirement is also unrealistic to implement in multifamily buildings, which often have widely distributed loads throughout the building, often in privately owned spaces (condos).  Mandating load controls in this type of building would go far beyond voluntary load shedding measures and introduce legal issues for building owners and managers.


Finally, requiring load shifting systems will not result in meaningful energy savings benefits in any building project located in an area that does not have peak load limitations on the regional electrical infrastructure or utility tariffs for the building that have TOU pricing.  The benefits of a peak load reduction systems lie in their ability to shed load when 1) the regional power infrastructure is nearing its limits at peak, or 2) when energy costs at peak are significantly higher (based on kWh and/or kW peak load), giving consumers an incentive to diminish consumption during this time window.  Many building projects will occur outside of these two circumstances, and should therefore not be subject to this provision because it adds cost without benefit.


Content Type: Review Comment
Created at 8/8/2008 4:00 PM  by 
Last modified at 6/19/2011 12:10 AM  by oldtownit