Step 7 Application Opportunity Screening Process

From the master list of identified potential application opportunities (which can be based on the checklist of potential measures presented in Figure 41-1), different types of screening methodologies can be employed to qualify measures as eligible for inclusion in the detailed study. As part of the site visits, project implementation costs should also be estimated by qualified members of the study team. Once preliminary costs are established, the screening tool models developed in the preparation phase will be used to evaluate the economic performance potential of each application opportunity. Levels of certainty will vary amongst technologies and will depend on the quality of the data available during the site visits.

Lighting system upgrade applications, for example, can be assessed with a fairly high degree of accuracy during the preliminary study phase. Based on record drawings or site visit take-offs, fixture counts can be established along with existing wattage. A reasonable assessment of hours of operation can be identified through interviews with operating personnel. Based on these data and the difference in wattage between existing fixtures and logical replacements, monthly usage and demand savings can be determined with reasonable accuracy. Standard cost estimates for equipment and installation can also be done in a fairly accurate, yet cost-effective manner.

In contrast to lighting systems, central chilled water, steam, or hot water system upgrade programs present a broad range of complexities that tend to obviate accurate prediction of economic performance. Quantification of cost and savings is complicated by the variations in cooling or heating loads over time and the changing performance of chillers and auxiliary equipment with load and ambient conditions. With cooling systems featuring electric chillers, the structure of seasonal, time-differentiated demand-oriented utility rate schedules adds to the complication.

The central plant screening process includes utility bill analysis, which will often reveal a cooling or heating related load profile, review of operating records, and cooling or cooling degree day analysis. Discussion with operating personnel may also be extremely helpful. Ultimately, a gross estimate of effective full-load hours (EFLH) of operation can be generated and applied to an estimated average efficiency or COP for the system. With cooling systems, it is common to use the integrated part-load value (IPLV) to establish commodity usage. For electric chillers, peak demand, inclusive of ratchet effects, will significantly impact operating costs. An assessment of the peak demand on a monthly basis is therefore also important in developing reasonable estimates.

Alternatively, a preliminary model of the chiller loads, systems, and equipment can be developed using the many competent building simulation software packages available. While much of the detail (e.g., metering data) required to produce highly accurate results may not yet be available, default values can be used to allow for development of reasonable estimates without a great deal of time expenditure. If simulation modeling is ultimately to be used during the Phase 2 detailed study, it may be advantageous to begin using it at this stage, thereby allowing for continual refinement as more validated data becomes available.

With chiller replacements, there are also numerous options that should be initially considered, including a variety of electric chillers, fuel-fired, steam- or hot water-powered single-effect or double-effect absorption chillers, and a variety of prime mover-driven chillers, with and without use of heat recovery. Options for use of thermal storage should also be considered.

Project costing estimates should be developed with a similar level of accuracy as the savings estimates. Generalized equipment costs can be estimated based on rules of thumb for a given equipment type and capacity (e.g., $/ton, $/hp, etc.). Installation costs are modified for identified site difficulties, such as rigging, piping, and structural modifications. Preliminary estimates should also be made for projected OM&R savings and additional OM&R costs.

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