Planning for Solar Buildings in Urban Environments

University dissertation from Lund University

Abstract: Energy use in buildings accounts for a significant proportion of the total energy use in many countries. While past and current buildings have solely been energy consumers, future buildings will, besides using less energy, also need to produce (part of ) the required energy on site with renewables. Solar energy is generally very suitable for producing this on-site renewable energy. Although solar technology is widely available, the installed effect is still very low. This is not only due to legislation and solar energy prices, but also because of decisions made throughout the design process for buildings. This research focuses on the decisions taken during the design process and by which player, and also the impact of such decisions, by using a mix of quantitative and qualitative research. In the first research phase, semi-structured interviews were held with Scandinavian architects who had worked with solar energy during the building design process. The architects identified several crucial points for designing buildings with solar energy – the importance of collabora¬tion and teamwork, the lack of attractive solar products, and that clients are actually not prioritising solar energy. The interviews also showed that architects rarely used any sophisticated tools to quantify solar energy, and that zoning plans can hinder the possibilities for implementing solar energy in buildings. The next research phase focused on the implementation of solar energy in urban planning. Action research, and analytical and parametric studies were used to examine how decisions in the urban planning process affect the possibilities for implementing solar energy, as well as how these deci-sions were supported by tools. Solar maps have become a popular tool for assessing the potential of solar energy in existing buildings, but an analysis of 19 solar maps showed that the underlying assumptions and methodology of such maps varied greatly. The amount of information provided to the user also varied greatly. While solar maps are used to analyse existing buildings, a proper solar assessment of new buildings requires the use of advanced simulation tools. In this research, such tools are used in three cases – an analysis of flat roofs, the development of a new facade assessment tool, and an analysis of typical Swedish building blocks. A parametric study was performed to analyse the energy output and financial consequences of varying row distances and inclination angles of a solar system on a flat roof. Results indicated that, in order to maximise energy production, the inclination of the panels should be 0° and rows should be placed directly next to each other. In the future, facades may become an appropriate place to harvest solar energy. To assess the solar potential of a facade, a tool called FASSADES was developed. This tool consists of four steps: 1) an hourly irradiation analysis, 2) calculation of the photovoltaic/solar thermal output, 3) calcula¬tion of the economic value of the energy production, and 4) calculation of the payback time. Urban planners can create a favourable environment for solar energy by designing a solar-friendly zoning plan. A parametric study examined how design decisions – density, orientation, roof shape and design – taken in the urban planning phase affect the solar potential. Density was found to be the most sensitive parameter and, for higher densities, the study showed that attaining a net zero energy balance is difficult.