[Bldg-sim] BPI-2400-S-2011 (formerly BPI-107) Standardized Qualification of Whole House Energy Savings Estimate

[Chris Balbach]

All:

I'm writing this post to share with you something you might find both interesting and pertinent to our growing industry. As many of you are aware, qualified energy simulation software is increasingly being applied to buildings for retrofit analysis purposes, and savings predictions generated from simulation software are in many cases being linked to the awarding of financial incentives by outside stakeholders.

Recently BPI (Building Performance Institute) published a standard related to energy simulation which you may be interested in reading: BPI-2400-S-2011 (formerly BPI-107) "Standardized Qualification of Whole House Energy Savings Estimate".  Electronic versions of the standard can be found here: http://bpi.pnl.gov/forumdisplay.php/16-BPI-2400-S-2011-%28formerly-BPI-107%29-Standardized-Qualification-of-Whole-House-Energy-Savings-Estimate.

The standard covers RESIDENTIAL buildings of 4 units or less, and was developed to support the introduction of RESIDENTIAL energy performance based legislation having bi-partisan support. This legislation, titled "Cut Energy Bills at Home Act" was sponsored by Senators Jeff Bingaman (D-NM), Olympia Snowe (R-ME) and Diane Feinstein (D-CA) and was introduced into the US Senate in late 2011.  It is often referred to as the "25e" bill.  More information on the 25e bill can be found here: http://www.efficiencyfirst.org/static/files/25EFactSheet.pdf

One important thing to understand is that 25e would not have been introduced without the publishing of BPI-2400-S-2011.  The proposed 25e legislation, while providing RESIDENTIAL building owners similar tax benefits to COMMERCIAL focused IRS 179D existing legislation, differs in many key ways:


a)      25e provides tax credits to building owners, while 179D provides tax deductions to building owners

b)      25e (through referencing BPI-2400-S-2011) provides a procedure for determining standardized estimates of energy savings for existing buildings. This procedure includes elements which account for both the quality of pre-retrofit actual energy bills and standardized operating conditions used for generating standardized savings estimates related to thresholds defined by 25e.

c)       25e (through referencing BPI-2400-S-2011) provides acceptance criteria for error between simulation predicted values and weather normalized end-use energy during the baseline period.

d)      25e (through referencing BPI-2400-S-2011) provides different compliance pathways related to the different levels of data quality of pre-retrofit actual energy bills of an existing building.

After I read the BPI-2400 standard carefully, I interpret it as including an attempt to define a calibration standard for applying qualified energy simulation tools to existing RESIDENTIAL buildings. Interesting!  I began to see the potential benefits related to wide-scale adoption, and could not help thinking about how it might somehow be adapted to be applicable to appropriate commercial buildings.  While acknowledging that calibrated modeling of larger, more complex existing commercial buildings (mixed use office towers, buildings with both process and comfort loads, etc.) should demand a more rigorous approach, I believe a large number of existing commercial buildings such as smaller, stand-alone office/retail/ service buildings could be cost effectively modeled to represent their existing performance using qualified whole building energy simulation tools.  I believe a performance based procedure aimed at these buildings (including qualified energy modeling tools as the core technology) could be a market motivator for driving deep performance improvements. This is because when we start talking about deep retrofits to existing buildings (i.e. projects estimated to save 30,40,50+ % of energy usage) I believe energy simulation tools (even with their shortcomings) represent the best available technology for cost effectively and realistically quantifying the significant interactive effects of multiple ECMs which influence multiple end-uses.

It would seem to me, some adaptation of BPI-2400 to fit another building stock would be useful. For example, with some careful inclusion of COMNET defaults for Input Constraints, and some revision of the Utility Bill criteria to incorporate handling multiple meters of the same fuel, we could have something that, though arguably not perfect, would be 'good enough' to encourage dialogue with stakeholders outside of our community such as IOU and other policy influencers.  If we are able to by consensus craft a vehicle for linking potential incentive awards to actual pre-retrofit performance of commercial buildings along with quality assurance procedures (M&V) for evaluating post retrofit performance as exhibited by utility bill history (considered the truth standard of performance), I think we really have something. I want to start thinking about what an ASHRAE standard representing this might look like.

Regardless of whether 25e passes through Congress and is eventually enacted, it seems to me the purpose and intent of the BPI-2400 standard is now positioned to be referenced by other, more agile institutions, and can and will be applied - and improved over time.  A quality reference standard becomes a very valuable chess piece which can be played over and over again, and I think if carefully crafted,  it will increase the market value and acceptance of energy modeling tools.

Anyways - I'm curious to how others on this listserve who engage in the COMMERCIAL building segments react to what is unfolding in the RESIDENTIAL community. While there is certainly a great deal to  learn - can you also see any opportunities?  One strength of our community is its diversity, and I want to leverage this.  I suspect this listserve includes representation from practitioners, academia, researchers, equipment manufacturers, policy analysts, students, and many other interests - bonded together by a common goal to increase the responsible use of building energy simulation tools in the world we live in.

Next move(s)?

All the Best,

_Chris

Chris Balbach, PE, CEM, CMVP, BEMP, BESA, BEAP
Vice President of Research and Development
Performance Systems Development of NY, LLC
124 Brindley Street, Suite 4, Ithaca, NY 14850
http://www.psdconsulting.com
ph: (607)-327-1647


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