Agenda - 06-07-2011 - 9a - Laserfiche WebLink

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25 Appendix A - Definition of Terms Example: On a summer day the high was 90 degrees and the low was 70 degrees. The average temperature was 80 degrees (90 + 70 = 160 / 2 = 80). The average temperature of 80 minus the base temperature of 65 yields 15 cooling degree days (80 - 65 = 15). Cooling degree days can be used to calculate the amount of energy needed to cool homes or businesses. Example: On a winter day the high was 40 degrees and the low was 20 degrees. The average temperature was 30 degrees (40 + 20 = 60 / 2 = 30). The base temperature of 65 minus the average temperature of 20 yields 45 heating degree days (65 - 20 = 40). Heating degree days can be used to calculate the amount of energy needed to heat homes or businesses.22 Energy audit: An energy audit is an inspection, survey and analysis of energy flows for energy conservation in a building, process or system to reduce the amount of energy input into the system without negatively affecting the output(s). Beyond simply identifying the sources of energy use, an energy audit seeks to prioritize the energy uses according to the greatest to least cost effective opportunities for energy savings.23 Common typesllevels of energy audits are distinguished below, although the actual tasks performed and level of effort may vary with the consultant providing services under these broad headings. Generally, four levels of analysis can be outlined (ASHRAE): • Level 0 -Benchmarking: This first analysis consists of a preliminary Whole Building Energy Use (WBEU) analysis based on the analysis of the historic utility use and costs and the comparison of the performances of the buildings to those of similar buildings. This benchmarking of the studied installation allows determining if further analysis is required; Level I -Walk-through audit: Preliminary analysis made to assess building energy efficiency to identify simple and low-cost improvements but also a list of energy conservation measures (ECMs, or energy conservation opportunities, ECOs) to orient the future detailed audit. This inspection is based on visual verifications, study of installed equipment and operating data and detailed analysis of recorded energy consumption collected during the benchmarking phase; • Level.ll -Detailed/General energy audit: Based on the results of the pre-audit, this type of energy audit consists in energy use survey in order to provide a comprehensive analysis of the studied installation, a more detailed analysis of the facility, a breakdown of the energy use and a first quantitative evaluation of the ECOs/ECMs selected to correct the defects or improve the existing installation. This level of analysis can involve advanced on-site measurements and sophisticated computer based simulation tools to evaluate precisely the selected energy retrofits; • Level III -Investment-Grade audit: Detailed Analysis of Capital-Intensive Modifications focusing on potential costly ECOs requiring rigorous engineering study. Benchmarking: The impossibility of describing all possible situations that might be encountered during an audit means that it is necessary to find a way of describing what constitutes good, average and bad energy performance across a range of situations. The aim of benchmarking is to answer this question. Benchmarking mainly consists in comparing the measured consumption with reference consumption ofi other similar buildings or generated by simulation tools to identify excessive or unacceptable running costs. As mentioned- before, benchmarking is also necessary to identify buildings presenting interesting energy saving potential. An important issue in benchmarking is the use of performance indexes to characterize the building. These indexes can be: • Comfort indexes, comparing the actual comfort conditions to the comfort requirements; • Energy indexes, consisting in energy demands divided by heated/conditioned area, allowing comparison with reference values of the indexes coming from regulation or similar buildings; 22 http://www.erh.noaa.gov/rah/faq/ 23