Solar radiation and daylight illuminance modelling and implications for building integrated photovoltaic system designs
太陽輻射與日光之模擬及其對建築物附設光伏系統設計的意義
Student thesis: Doctoral Thesis
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Detail(s)
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Award date | 16 Feb 2009 |
Link(s)
Permanent Link | https://scholars.cityu.edu.hk/en/theses/theses(da4d5779-6a0e-48f7-a615-fcc58b2cf752).html |
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Other link(s) | Links |
Abstract
Recently, there has been an increasing awareness of building energy conservation.
Renewable energy can produce energy without emitting pollutant and requires no fuel.
Energy-efficient building designs can reduce electricity consumption and provide clean
and sustainable energy via renewable energy facilities. Daylighting schemes can
improve visual comfort for the building occupants and effectively reduce both artificial
lighting energy and cooling load due to heat gains from artificial lighting. In many
cities worldwide, particularly Hong Kong, high-rise commercial buildings are dominant
in urban areas. The applications of building integrated photovoltaics (BIPV) are
appropriate for these buildings in order to allow daylight penetration, reduce solar heat
gain and generate electricity. The opaque and semi-transparent BIPV panels can serve
as the solar façade and window glazing of the buildings, respectively. The knowledge in
solar radiation and daylight illuminance on sloped surfaces can enhance the design
strategies of BIPV systems. This thesis analyses the solar radiation, daylight
illuminance, sky radiance and luminance data recorded from long term data
measurements, develops models for predicting the solar radiation and daylight
illuminance on inclined surfaces, performs field measurements and case studies for
daylight-linked lighting controls and BIPV systems, and evaluates the design
implications for BIPV systems in energy, environmental and financial terms.
The data measurements include the long term seven-year horizontal solar radiation and
daylight illuminance (global and diffuse components), vertical solar radiation and
illuminance, sky radiance and luminance distributions, and one-year sloped solar radiation on 30°, 45° & 60° planes. The measured data were analyzed via statistical and
graphical methods.
The measured data were further applied to develop models for determining solar
radiation and daylight illuminance on sloped surfaces. The annual solar radiation on
various inclined surfaces was determined by a sky radiance model and measured
radiance data. A simple design tool for the prediction of annual solar radiation on
sloped surfaces was developed based on measured horizontal solar radiation, sky
radiance and sunshine duration data. The daylight availability is affected by the
dynamically changing sky conditions. The determination of luminous efficacy under
CIE standard skies can provide a reliable method for the calculation of daylight
illuminance on inclined surfaces using recorded solar irradiance data. The performance
of each prediction model has been assessed by statistical approaches.
To observe the effectiveness of utilising daylight illuminance and solar radiation, field
measurements for daylighting schemes and BIPV systems were conducted to evaluate
their energy performance. Measured results were analyzed systemically. It has been
found that an office room integrated with daylight-linked controls can provide electric
lighting energy saving at a satisfactory level of over 30% annually. Two semitransparent
BIPV systems, namely horizontal skylight and vertical glazing, can cut the
solar heat gain without greatly lowering the daylight benefits. Apart from electricity
generation, the semi-transparent BIPV systems can help reducing cooling load and
lighting energy.
Detailed assessment of energy performance of building employing opaque BIPV and
daylighting schemes has been conducted by using a building energy simulation tool.
Analysis of annual energy consumption, peak cooling and electrical demand, and
renewable energy generation was carried. A parametric study was performed to obtain
an optimum design of building façade. Furthermore, case studies for semi-transparent
BIPV systems (skylight and vertical glazing) have been completed by various
calculation techniques. The evaluation is carried out in terms of the annual electricity
use, cooling and lighting energy consumption, peak cooling load, electricity production,
environmental and financial impacts. Design strategies are discussed based on the
results.
- Building-integrated photovoltaic systems, Daylighting, Solar radiation, Energy conservation, Buildings