TRNSYS Modeling of a Hybrid Lighting System: Energy Savings and Colorimetry Analysis

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Date
2004Author
Burkholder, Frank W.
Publisher
University of Wisconsin-Madison
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Show full item recordAbstract
The TRNSYS (TRaNsient SYstems Simulations) Hybrid Lighting Model was
revised so that two colorimetric indices pertinent to indoor illumination, the correlated
color temperature (CCT) and color rendering index (CRI), could be predicted by the
model. For calculation of the CCT and CRI relevant to the hybrid lighting system, the
spectral power density (SPD) of beam normal radiation was needed. Though TRNSYS
provides algorithms to calculate the magnitude of beam normal radiation on any surface,
no methods were provided in TRNSYS to determine the SPD of solar radiation. This
thesis describes the inclusion of a spectral model in TRNSYS: Gueymard's SMARTS2
(Simple Model of the Atmospheric Radiative Transfer of Sunshine) algorithm. This
algorithm was used to calculate the SPD of beam normal radiation as a function of solar
position, atmospheric turbidity, moisture content, and other atmospheric parameters.
The TRNSYS hybrid lighting model, augmented by SMARTS2, was used to
analyze building illumination and energy loads for a 2500 m2 office building equipped
with a hybrid lighting system (HLS). The HLS uses two-axis tracking collectors to
collect beam normal radiation that is later divided into visible and infrared components.
The visible radiation is piped to luminaires inside the building using optical fibers, while
the infrared radiation is focused on thermal photovoltaic arrays and used to generate
electricity. The TRNSYS model calculated annual building energy loads (lighting,
cooling, and heating) and energy savings in office buildings located in six U.S. cities:
Honolulu, HI; Tucson, AZ; Reno, NV; Atlanta, GA; Seattle, WA; and Madison, WI; that
were equipped with hybrid lighting systems. Using local utility rates and assuming 52
lm/W lamps efficacies (the commercial average in the U.S.), the annual energy savings
per m2 collector area in these cities were: $240-Tucson, $140-Reno, $320-Honolulu, $40-
Atlanta, $50-Madison, and $60-Seattle.
For the colorimetry analysis, four representative lamp SPDs - warm white
fluorescent, full spectrum fluorescent, tungsten incandescent, and halogen incandescent -
were defined as standard indoor light source spectrums. Two cities were chosen to
perform the analyses in: Tucson, which represented a clear climate with consistent beam
normal radiation values, and Seattle, a cloudier climate. The CCT and CRI were
calculated each hour during office working hours. When cloudy, the CCT and CRI of the
illumination inside took on the values of the lamp providing it, but when beam normal
radiation was available these values were influenced by the 5000-5500 K CCT and 80
CRI of the beam normal radiation transmitted though the HLS. Histograms showing the
number of hours at varying CCT and CRI ranges for different locations and with different
lamps are presented in Chapter 7.
Subject
Thesis (M.S.)--University of Wisconsin--Madison, 2004.
Dissertations Academic Mechanical Engineering.
University of Wisconsin--Madison. College of Engineering.
Permanent Link
http://digital.library.wisc.edu/1793/7600Description
Under the supervision of Professors William Beckman, Sanford Klein, and Douglas Reindl.
Citation
Burkholder, F.W. (2004). TRNSYS Modeling of a Hybrid Lighting System: Energy Savings and Colorimetry Analysis. Master's Thesis, University of Wisconsin-Madison.