Jorge Kubie

A design guide for performance assessment of solar light-pipes:

Due to an increasing demand for an improvement in environmental conditions for living and a need for energy saving, development of daylight exploitation products has accelerated. The invention of light-pipes which bring natural light indoors where sunlight cannot reach without generating excessive heat is one such example. Mathematical modelling activities aimed at predicting the daylighting performance achievable by light-pipes with various configurations under all weather conditions in the UK are being undertaken. Two models, one for straight light-pipes and the other for elbowed light-pipes are described. The models enable estimation of daylight provision of the light-pipes with a high degree of accuracy i.e., R2 values of 0.95 and 0.97 for regression between predicted and measured illuminance were respectively obtained for the above models. The maximum Mean Bias Error (MBE) and Root Mean Square Error (RMSE) were -2 lux and 27 lux. A design guide for light-pipe assessment is presented that will obviate the need for use of mathematical models.

Life cycle assessment of a medium-sized photovoltaic facility at a high latitude location

Abstract Performance of a 160 m2photovoltaic installation at the Napier Universitys Merchiston Campus, situated 3 km from Edinburghs city centre, is presented. The alternative current and direct current electrical outputs were recorded since the installation of the facility was completed in April 2005. An analysis of the efficiency of the facility, as well as energetic, environmental, and monetary life cycle assessments, using long-term meteorological data is presented in this article.

THE MEASUREMENT OF VEHICULAR DRIVING CYCLE WITHIN THE CITY OF EDINBURGH

In this paper, the development of a driving cycle for the urban area of the city of Edinburgh is presented. The driving cycle was obtained from recorded data in actual traffic conditions, using the car chase technique. A new statistical method of analysing the recorded data was developed. The proposed TRAffic Flow IndeX (TRAFIX) enables the calculation of a representative driving cycle from the various measurements undertaken during two stages of experiments. Data from the City of Edinburgh Council traffic monitoring stations were weighted in proportion to traffic flows on the constituent driving routes. A comparison between the European ECE cycle and the presently proposed Edinburgh driving cycle (EDC) has also been made.

A review of vehicular emission models and driving cycles

Abstract This article reviews the latest and relevant work on both vehicular emission models and driving cycles. The three main types of emission models, namely emission factor models, average speed models and modal models, are covered. Each project is analysed regarding its characteristic parameters, such as data collection technique, methodology, statistical analysis and pollutants covered, where appropriate. Other parameters were taken into account, such as the project objectives, results and relevance regarding the wider spectrum of the road traffic situation.

Models for Estimating Solar Radiation and Illuminance From Meteorological Parameters

Sunshine fraction, cloud amount, temperature, and global irradiation are the most commonly measured meteorological parameters. In this article five models based mainly on the abovementioned variables for the determination of irradiation and illuminance components are presented. These models are divided into three categories. Category 1 includes three solar radiation models: (a) Meteorological Radiation Model (MRM), developed by present authors based on sunshine fraction and temperature data, (b) Cloud-Cover Radiation Model (CRM)-modification of an earlier model for the UK by the present authors based on cloud-cover in oktas, and (c) Page Radiation Model (PRM), developed by Page based on simultaneous sunshine and cloud data. Category 2 comprises of a new Diffuse Ratio Model (DRM), developed by authors, for estimating diffuse irradiation when global irradiation is provided as the input parameter. The third category includes luminous efficacy models that enable estimation of diffuse and global illuminance once the respective irradiation components have been obtained from category I models.

Evaluation of a New Photodiode Sensor for Measuring Global and Diffuse Irradiance, and Sunshine Duration

A new integrated device (called the BF3) has been developed, which enables the simultaneous measurement of horizontal global and diffuse irradiance as well as sunshine presence at any time. The sensor needs no specific polar alignment or routine adjustment, and works at any latitude. To evaluate the performance of this new device, a BF3 sensor was installed on the roof of a six-story building in the Merchiston Campus of Napier University, Edinburgh from February 22–July 3, 2001. Horizontal global and diffuse irradiance data were collected from the BF3. To enable a cross check, two Kipp and Zonen CM11 sensors, one with a shade ring, have also been installed beside the BF3 sensor on the same roof. These were used to give a reference measure of the horizontal global and diffuse irradiance. To evaluate the BF3 sunshine duration performance, the direct beam normal irradiance was calculated from the CM11 global and diffuse readings, and compared with a threshold of 120 W.m–2 to give sunshine presence according to the WMO definition. This was compared against the BF3 output, and also with data from two Campbell-Stokes sunshine recorders on the same site. The results show a stable performance on the part of the BF3 sensor for the measurement of horizontal global and diffuse irradiance. The global irradiance measured by the BF3 showed values 4.7% high, with a standard error of 16.5 W.m–2 compared to the Kipp and Zonen sensors. Diffuse values were 1.4% high with a standard error of 13.4 W.m–2. The BF3 sunshine duration was within 2% of that calculated from the WMO definition over the study period, with a typical daily error of less than 20 min. This is well within the WMO requirements for a sunshine recorder. In comparison, the Campbell-Stokes recorders gave readings up to 7% different from the WMO values, with a typical daily error of almost an hour.

Sustainability analysis of window frames

The characteristics of the frame materials have significant impacts on the properties of a window. A window itself plays a crucial role in determining the overall energy performance of the building. This article analyses four different frame types; aluminium, aluminium-clad timber, Polyvinyl chloride (PVC) and timber make, from the sustainability perspective. These frame types have been studied on various parameters such as; environmental impacts during production/extraction of frame materials and disposal of frames; embodied energy, durability and service life; and maintenance and repair of frames. A price comparison and market scenario has also been discussed. It has been found that timber- and aluminium-clad timber windows are sustainable products due to their environment-friendly characteristics i.e., low embodied energy, low environmental impacts, better durability and longer service life. While aluminium and PVC frames have high values of embodied energy and associated environmental impacts. Practical application: In the present sustainability-conscious age, the window industry is emphasising how to enhance the energy and environmental performance of their products. This article will be of interest not only to modern window manufacturers but also to customers as it addresses the key sustainability features of windows, i.e., energy and environmental performance, durability and service life, and maintenance and life cycle costing.

Design of a PV driven low flow solar domestic hot water system and modeling of the system collector outlet temperature

Abstract The system under consideration comprises a new freeze tolerant flat plate collector connected directly to a domestic hot water storage tank. Water is circulated by means of a small 12 V DC pump, driven directly by a PV module. It is desired that the system will operate with a variable low flow to provide a relatively constant outlet temperature and promote thermal stratification in the storage tank. The rationale behind employing this operational strategy is outlined, and an overview of the benefits of employing such a system is given. In respect of controlling the flow to optimize the performance of the present system, through a thorough examination of their respective characteristics and interactions, the process of selecting the most suitable combination of system components is highlighted. Furthermore, a method for determining the degree of PV output control that is required to best meet the optimum operating condition is given. System performance is then analyzed in relation to the desired operating condition. For a given pump and hydraulic system, an algorithm for predicting the collector outlet temperature in relation to the peak PV output, degree of control, collector efficiency characteristics and irradiance is presented. Predicted and measured outlet temperatures are compared, and the results discussed.

A value engineering analysis of timber windows

Cost effectiveness of products and services has become very important in today’s highly competitive market. The customer needs a product that accomplishes its required functions with economy. Value engineering is a very interesting management technique that analyses alternative solutions and identifies the best possible option. The presented work analyses various designs of timber and aluminium clad timber windows on value energy parameters to determine their overall functional performance and cost effectiveness. Life-cycle costing of windows has been carried out over a 40-year life span taking into account all the major cost factors involved. Running cost, the dominant element in life-cycle cost of windows, has been calculated for four possible maintenance options. Results have indicated that an ‘air-filled triple-glazed aluminium-clad timber window’ is the value engineered choice amongst the range of window designs studied; it is the most cost effective when employed with gas and paint for space heating and maintenance purposes respectively.

Modelling of a low temperature differential Stirling Engine.

Abstract A full theoretical model of a low-temperature differential Stirling engine is developed in the current paper. The model, which starts from the first principles, gives a full differential description of the major components of the engine: the behaviour of the gas in the expansion and the compression spaces; the behaviour of the gas in the regenerator; the dynamic behaviour of the displacer; and the power piston/flywheel assembly. A small fully instrumented engine is used to validate the model. The theoretical model is in good agreement with the experimental data, and describes well all features exhibited by the engine.