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• evaporative coolers

Steps:

• Measure energy input to system (i.e, electricity, natural gas, hot water or steam).

• Measure thermal output of system.

• Measure temperature of space where system is operating.

• Calculate efficiency as output/input. If efficiency does not agree to within 5% of manufacturer's performance data then use method #2, #3 or #4.

• Adjust efficiency, using manufacturer's data if surrounding environmental conditions vary significantly over the year (i.e., ambient temperatures that the HVAC unit is exposed to).

• Calculate savings by comparing differences in before-after component efficiency calculations applied to continuously measured post-retrofit thermal output energy requirements or sampled thermal load profiles.

Method #2: Multiple point with manufacturer's performance data

Measure at multiple points: i) energy input to system (e.g., electricity, natural gas, hot water or steam), ii) thermal output of system, iii) temperature of surrounding environment (adjust for differences in efficiency with manufacturer's data).

Applications:

• single zone (constant or varying)

• ventilating and heating units (constant or varying)

• window air conditioners (constant or varying)

• evaporative cooling (constant or varying)

• 2-pipe induction units (varying)

• single zone with variable speed fan and/or compressors

• variable speed ventilating and heating units

• variable speed window air conditioners

Steps:

• Measure energy input to system at multiple points (i.e., electricity, natural gas, hot water or steam).

• Measure corresponding thermal output of system at multiple points.

• Measure temperature of space where system is operating during all tests.

• Calculate efficiency as output/input. If efficiency does not agree to within 5% of manufacturer's performance data then use method #3 or #4.

• Adjust efficiency, using manufacturer's data if surrounding environmental conditions vary significantly over the year (i.e., ambient temperatures that the HVAC unit is exposed to).

• Calculate savings by comparing differences in before-after component efficiency calculations applied to continuously measured post-retrofit thermal output energy requirements or sampled thermal load profiles.

Method #3: Multiple point using short-term data and manufacturer's performance data

Continuously measure over a short-term period: i) energy input to system (e.g., electricity, natural gas, hot water or steam), ii) thermal output of system, iii) temperature of surrounding environment (adjust for differences in efficiency with manufacturer's data).

Applications:

• single zone (constant or varying)

• ventilating and heating units (constant or varying)

• window air conditioners (constant or varying)

• evaporative cooling (constant or varying)

• 2-pipe induction units (varying)

• single zone with variable speed fan and/or compressors

• variable speed ventilating and heating units

• variable speed window air conditioners

Steps:

• Continuously measure over a short-term period energy input to system (e.g., electricity, natural gas, hot water or steam).

• Measure corresponding thermal output of system at multiple points.

• Measure temperature of space where system is operating during all tests.

• Calculate efficiency as output/input. If efficiency does not agree to within 5% of manufacturer's performance data then use method #4.

• Adjust efficiency, using manufacturer's data if surrounding environmental conditions vary significantly over the year (i.e., ambient temperatures that the HVAC unit is exposed to).

• Calculate savings by comparing differences in before-after component efficiency calculations applied to continuously measured post-retrofit thermal output energy requirements or sampled thermal load profiles.

Method #4: Short-term monitoring and calibrated, simplified simulation

Measure over a representative range: i) thermal and electric energy input to system (e.g., electricity, natural gas, hot water or steam), ii) thermal output of system, iii) temperature of surrounding environment (may be used to adjust for losses to space), iv) develop an air-side simulation model that is representative of the system (Knebel 1983), v) calibrate the air-side model to the measured data for both pre-retrofit and post-retrofit conditions.

Applications:

• single zone (constant or varying)

• ventilating and heating units (constant or varying)

• window air conditioners (constant or varying)

• evaporative cooling (constant or varying)

• 2-pipe induction units (varying)

• single zone with variable speed fan and/or compressors

Table 27.14 (Continued)
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