Timothy Nicholas Anderson

Studies of control strategies for Building Integrated Solar Energy System

Research and development work on Building Integrated Solar Energy Systems (BISES) has become an area of growing interest, not only in New Zealand (NZ) but worldwide. This interest has led to a significant growth in the use of solar energy to provide heating and electricity generation. This paper presents the theoretical and experimental results of a novel building integrated solar hot water system developed using commercial long run roofing materials. This work shows that it is possible to achieve effective integration that maintains the aesthetics of the building and also provides useful thermal energy. The results of a 6.73m2 glazed domestic hot water systems are presented. The key design parameters of the Building Integrated Thermal (BIT) system were identified and implemented in a TRansient SYstem Simulation (TRNSYS) model. Validation results comparing the simulation in TRNSYS and real experimentation show that experimental and simulation responses are close to each other. The coupling of TRNSYS and Matlab/Simulink shows the possibility to use Matlab/Simulink for developing appropriate control strategies for BIT roofing systems. Preliminary Fuzzy Logic (FL) intelligent controller was implemented in a Fuzzy Integrated System (FIS) toolbox in a Matlab/Simulink model and linked into TRNSYS model. Further work is needed to identify and design advanced predictive control strategies for the Building Integrated Photovoltaic Thermal (BIPVT) solar system and determine how the performance can be optimized.

Designing for thermal comfort near a glazed exterior wall

In many highly glazed buildings, the thermal comfort of the occupants will tend to be related to the incoming solar energy and the heat transfer behaviour of the glazing. In this study, several glazing systems were designed using the software tools VISION 3 (University of Waterloo 1992) and WINDOW-6 (Lawrence Berkeley National Laboratory 2011), with a view to improving thermal environment of occupants near the glazed wall of a commercial office. The systems were fabricated and experimentally tested to validate the software modelling results. Subsequently, the glazing systems were retro-fitted to the office and tested in situ for a summer month. Results of this testing, in the form of Fangers’ predicted mean vote (PMV) and the predicted percentage dissatisfied (PPD), are presented, and some options for improving the thermal environment in this near-façade zone are discussed.

Convection suppression in an attic shaped enclosure

In recent times there has been growing interest in the integration of solar collectors, for water heating, into the facade of buildings. However, the design methodology of these devices remains largely the same as typical “stand-alone” collectors. As such it is still common for materials with a high thermal resistance to be used for insulating the rear surface of these collectors. Unlike a “stand-alone” solar collector that is exposed to the atmosphere at all faces; a building integrated system allows the opportunity for air to act as an insulator at the rear surface of the solar collector. The use of convection suppression devices has been widely discussed in the literature as a means of reducing natural convection heat loss from the front surface of glazed solar collectors. However in this study the use of baffles in an attic was examined as a means of suppressing heat loss by natural convection from the rear surface of a roof-integrated solar collector. The aim of the study was to examine whether the use of baffles would allow the cost of building integrated collectors to be reduced by removing the cost of insulating material. To determine the effect of baffles in the attic space at the rear surface of the collector, a 3-dimensional triangular cross sectioned enclosure with a vertical aspect ratio of 0.5 and a horizontal aspect ratio of 3.3 was modelled. The flow patterns and heat transfer in the enclosure were determined for Grashof Numbers in the range of 106 to 107 using a commercially available finite volume CFD solver. It was found that the use of a single adiabatic baffle mounted vertically downwards from the apex, and extending the length of the enclosure, would alter the flow such that the heat transfer due to natural convection was reduced with respect to the length of the baffle. Furthermore, it was observed that a series of convection cells, not previously reported in the literature, appeared to exist along the length of the enclosure. As such, it may be possible to derive additional benefit in reducing the heat transfer by adding lateral baffles in addition to the single longitudinal baffle modelled in this study.

Prediction of Electricity Consumption for Residential Houses in New Zealand

Residential consumer’s demand of electricity is continuously growing, which leads to high greenhouse gas emissions. Detailed analysis of electricity consumption characteristics for residential buildings is needed to improve efficiency, availability and to plan in advance for periods of high electricity demand. In this research work, we have proposed an artificial neural network based model, which predicts the energy consumption of a residential house in Auckland 24 h in advance with more accuracy than the benchmark persistence approach. The effects of five weather variables on energy consumption was analyzed. Further, the model was experimented with three different training algorithms, the levenberg-marquadt (LM), bayesian regularization and scaled conjugate gradient and their effect on prediction accuracy was analyzed.

Maximizing photovoltaic array energy usage within a house using model predictive controla

In this study, the problems of modeling, energy dispatching and Photovoltaic (PV) array energy priorities for a grid connected residential house with PV array and battery storage using model predictive control (MPC) have been investigated. Artificial neural network (ANN) based global solar radiation forecast was used to plan in advance for periods of low sunshine. MPC was able to reduce electricity consumption in the house when solar radiation forecast was unfavorable. Quadratic programming optimization was used to maximize usage of the PV system. Excess energy from the PV array was used to further raise hot water cylinder (HWC) temperature, rather than exporting it to the utility grid. Performance of the overall model predictive control system was verified using simulation results.