ZEMCH 2019 International Conference Proceedings April.2020 | Page 112
A baseline model was developed based on ASHRAE 90.1 Appendix G method and this baseline was
used it for evaluating the expected performance of the case study building to the benchmark. The
benchmark model is the ‘as‐designed model’, which was the uncalibrated model before the energy audit
and POE data have been used for calibration. After calibrating with the energy audit and POE data, which
is the ‘in‐use model’, it provided level of the case study building’s energy efficiency and the level of
performance gap between as‐designed building and in‐use building.
4. Results and Discussion
The energy audit and POE were conducted for one week from 23 rd June to 01 st July, and dynamic
simulation was carried out for annual energy consumption study. From these studies, several
deficiencies of energy performance gap were found in the case study building. It is also studied for
calculating energy reduction by energy audit and POE analysis in the case study building.
4.1. Energy audit analysis
Through several stage of energy audit, four major deficiencies were found. One was that
during HVAC operation and performance check where the AHU units’ fans were operated as CVA
rather than VAV, which could increase the operation time and the energy consumption. These fans
continuously work with full power and supply air temperature, which was also quite lower due to
satisfying internal setting temperature during occupied hours (around 21.5°C), and even during
unoccupied hours (around 23.8°C). Similar problems were indicated in lighting controls and
scheduling. The electrical lighting stayed on during daytime in the corridors, those lights were located
next to the curtain walls in the case study building (Figure 3. d). Another similar operation and
maintenance problems were indicated doors that connect to outside as entrances. These doors were
widely opened during occupied hours, which can cause for failing to secure airtightness and return air
amount to AHUs for maintaining mixed air temperature with indoor target temperature. Figure 3
shows some examples of IR images and current situations.
a) Remaining the main door open
c) Failing to secure airtightness from doors
b)Remaining the doors open
d) Leaving lights on during daytime
Figure 3. Deficiencies from energy audit
4.2. POE study analysis
From the mobile and fixed monitoring data logger and devises, the results were summarized
in table 3. During the occupied hours, the indoor temperature was around 21.5°C in both enclosed
offices and open offices. The monitored indoor temperatures were quite lower than ASHRAE
recommend temperature, which is 24°C for occupied hours and 28°C for unoccupied hours. This indoor
setting temperature could have an effect on energy performance gap in the case study building. To
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ZEMCH 2019 International Conference l Seoul, Korea