Mark Rylatt

GIS-based decision support for solar energy planning in Urban environments

This paper describes the development of a solar energy planning system, consisting of a methodology and decision support software for planners and energy advisers. Intended primarily to predict and realise the potential of solar energy on an urban scale, the system will support decisions in relation to the key solar technologies: solar water heating, photovoltaics and passive solar gain. The prototype discussed here relates to the first of these. Based on a methodology for predicting the solar energy potential of domestic housing stock, it is implemented as a relational database application linked to a customised geographical information system (GIS). The methodology takes into account baseline energy consumption and projected energy saving benefits. To support this, the system incorporates a domestic energy model and addresses the major problem of data collection in two ways. Firstly, it provides a comprehensive set of default values derived from a new dwelling classification scheme that builds on previous research. Secondly, novel GIS tools enable key data to be extracted from digital urban maps in different operational modes. The paper concludes with a discussion of possible planning scenarios to illustrate how the system may be deployed at various levels of granularity to assist targeting of individual properties or city neighbourhoods, or for whole-city projections.

Predicting the urban solar fraction: a methodology for energy advisers and planners based on GIS

This paper describes the development of the underlying methodology of a solar energy planning (SEP) system for energy advisers and policy makers. The methodology predicts the baseline energy consumption of domestic properties and determines the potential for reducing this using the three key solar technologies of passive solar design, solar water heating and photovoltaic (PV) systems. A new dwelling classification system has been developed to address the major problem of data collection for city-wide domestic energy modelling. The system permits baseline energy demands to be estimated using assumed values or more accurately calculated using dwelling survey data. The methodology integrates existing models with new approaches to both identify suitable dwellings for installing solar water heating and PV systems and to quantify the potential energy savings and reductions in carbon dioxide emissions. Guidance on improving estate layouts to enhance passive solar conditions is also given. Results can be presented using a geographical information system (GIS). The paper concludes with a discussion of possible planning scenarios to illustrate how the methodology may enable planners to consider the urban-scale application of solar energy with greatly increased confidence.

Irradiation mapping of complex urban environments: an image-based approach

Abstract This paper describes a novel approach for evaluating the total annual/monthly irradiation incident on building facades in urban settings. The analysis is founded on a physically-based rendering approach and uses data-visualisation techniques to generate ‘maps’ (i.e. false-colour images) of annual/monthly irradiation. The irradiation ‘maps’ are derived from hourly time-series data for 1 year and take accurate account of shading by, and inter-reflection from, other buildings and surfaces. The sun and sky irradiation images are evaluated separately. The sky contribution is calculated using realistic, non-isotropic models for the sky radiance distribution. The ‘maps’ can be used to confidently identify facade-locations where there is high irradiation, for example to aid the siting of photovoltaic (PV) panels. The technique can be applied to scenes of arbitrary complexity from a single building to fully ‘worked-up’ city models. The results of the analysis have been linked to a geographical information system (GIS)-based solar energy planning system. The system is targeted at city planners and one of its aims is to encourage the consideration of solar energy in the urban planning process.

Putting solar energy on the urban map: a new GIS-based approach for dwellings

This paper describes some aspects of prototype software designed to assist local authority planners and energy advisers in their efforts to increase the uptake of solar hot water systems in cities. To estimate the potential yield from installed systems, the Solar Energy Planning system implements an adaptation of the method for calculating the thermal performance of solar heating systems for domestic hot water in BS5918. A much-enhanced version of the BREDEM-8 domestic energy model provides the basis for predicting the delivered energy savings. Reductions in CO2 emissions can also be quantified. A trial of the prototype in an urban area of Leicester, UK, is illustrated and some encouraging results are reported.

Enabling urban-scale energy modelling: a new spatial approach

Urban-scale energy modelling provides an ideal tool for studying non-domestic energy consumption and emissions reduction at the community level. In principle, an approach based on the characteristics of individual commercial premises and buildings is attractive, but it poses a number of challenges, the most immediate of which is deciding precisely what to model. For a range of reasons connected with their self-contained nature, individual non-domestic buildings would ideally be selected. However, the main information sources available – digital mapping and business taxation data – are not based on ‘buildings’ and do not use the concept, thus making an automated approach problematic. At the same time, manual identification of the distinct buildings in a city is not a practical proposition because of the numbers involved. The digital mapping and business taxation data are brought together in the Local Land and Property Gazetteer (LLPG). An analysis of the relationships between the relevant elements, namely building polygons and premises attracting business taxation, allowed a unit to be defined that matches the definition of a ‘building’ in most circumstances and can be applied without the need for human intervention. This novel approach provides a firmer basis for modelling non-domestic building energy at the urban scale.

Using GIS to Estimate the Replacement Potential of Solar Energy for Urban Dwellings

This paper focuses the novel GIS-related aspects of a prototype planning support system for urban planners and energy advisers. The system design combines commercial database and GIS packages to provide a flexible means of predicting the solar energy potential and energy consumption of dwellings. By incorporating customised tools designed to derive useful data directly from digital maps and aerial photographs, it addresses the significant problem of data collection for urban-scale energy modelling. In conjunction with data generated by a new dynamic default data system, the map-derived data provide the necessary input for an embedded domestic energy model and a solar energy calculation engine. In this way, robust estimates can be obtained, at almost arbitrary scales of resolution, of the potential for solar energy to replace delivered domestic energy and to mitigate emissions of carbon dioxide.

Energy flow management of a hybrid renewable energy system with hydrogen

This paper presents a preliminary study on a hybrid renewable energy system at the Ostfalia University of Applied Sciences Wolfenbüttel, Germany. The test-bed is made up of solar photovoltaics (PV), a micro wind turbine (MWT), a micro-CHP, a fuel cell system (FC), and two storage devices (a battery system and an electrolyzer). All the installations are in the range of 1 to 6 kW electrical power output/input; the focus of this research is renewable energy systems for residential applications. In addition to the presentation of experimental test results, a model of the hybrid system will be introduced.