Typical energy audits are sufficiently expensive and time-consuming that many
owners and managers of buildings are not willing to invest the time and money required
for a full audit. This dissertation provides a methodology to identify buildings with large
potential energy savings using limited information, specifically, utility bills, total area
and weather data. The methodology is developed based on the hypothesis: if a
commercial building is properly designed, constructed, operated, and maintained, the
measured energy consumption should approximately match the simulated value for a
typical building of the same size with the most efficient HVAC system; otherwise, there
may be potential for energy savings. There are four steps in the methodology: 1) testing
to determine whether the utility bills include both weather-dependent and weatherindependent
loads; 2) separating weather-dependent and weather-independent loads
when both are present in the same data; 3) determining the main type of HVAC system;
4) estimating potential energy savings and recommending an energy audit if appropriate.
The Flatness Index is selected to test whether the utility bills include both weatherdependent
and weather-independent loads. An approach to separate the utility bills based
on thermal balance is developed to separate utility bills into weather-dependent and
weather-independent loads for facilities in hot and humid climates. The average relative
error in estimated cooling consumption is only 1.1% for 40 buildings in Texas, whereas it is -54.8% using the traditional 3P method. An application of fuzzy logic is used to
identify the main type of HVAC system in buildings from their 12-month weatherdependent
energy consumption. When 40 buildings were tested, 18 systems were
identified correctly, seven were incorrect and the HVAC system type cannot be identified
in 15 cases. The estimated potential savings by the screening methodology in eight large
commercial buildings were compared with audit estimated savings for the same
buildings. The audit estimated savings are between 25% - 150% of the potential energy
savings estimated by the screening procedure in seven cases. The other two cases are less
accurate, indicating that further refinement of the method would be valuable. The data
required are easily obtained; the procedure can be carried out automatically, so no
experience is required. If the actual type of HVAC system, measured weather-dependent,
and weather-independent energy consumption are known, the methodology should work
better.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/3179 |
| Date | 12 April 2006 |
| Creators | Zhu, Yiwen |
| Contributors | Claridge, David E. |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | 7856128 bytes, electronic, application/pdf, born digital |
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