Adequacy of current design tools and methods for solar architecture – results of IEA-SHC Task 41’s international survey

The International Energy Agency’s (IEA) Task 41: Solar Energy and Architecture gathers researchers, academics and practicing architects from 14 countries in a project pursuing the objectives to identify and address obstacles that architects are facing in solar design. Part of this three-year project is the development of an international survey -intended for practicing architects- addressing a broad range of issues from passive and active solar design to the availability and adequacy of existing digital tools. This paper presents parts of the results of this international survey related to Task 41 Subtask B: Tools and methods for solar design. The results show that there is still a need to improve tools and methods for architects such as increased support needed for decision-making and for solar design in CAAD tools. The results also state that architects’ skills with regards to solar design in tools are ‘poor’ or ‘very poor’. Furthermore, results indicate that decision-making for the integration of solar technologies in the conceptual phase is mainly handled by the architects alone. Finally, the results show that tools need to be simpler, that the interoperability between software needs to be improved, that tools should provide key data about solar energy aspects as well as explicit feedback to the architect, and that tools need a better visualisation especially for active solar energy systems

Assessing combined object and mutual shading on the performance of a solar field

To make well-informed decisions on the implementationof solar energy on roofs within the urban environment, anew method was developed and described that couldsupport such decision-making. This method takes both themutual shading and shading from external objects intoaccount. The method consists of the following six steps:1) construction of the scene, 2) performance of annualsolar irradiation analyses, 3) performance of statisticalanalyses, 4) calculation of the energy output, 5)calculation of the parameters payback time and profit, 6)displaying the results. Analysing the data by setting ownpreferences will make more informed decision-makingpossible. The outputs from the method are mapsindicating which locations surrounded by objects that areprofitable for PV installations. Alternatively, the mapscan be used to show payback times for the PV installation

The solar map as a knowledge base for solar energy use

Our existing urban environment has a significant potential to increase the use of renewable energy, mainly by using solar irradiation for heat and electricity. Quantification of the solar potential by means of a solar map is the first step in the acceleration process for using more solar energy in our urban environments. A solar map is a GIS system providing the annual solar irradiation on building surfaces, mostly accompanied by information of the output of solar thermal or photovoltaic systems. Many solar maps are already in place today; almost all of them are however using different approaches. In this paper, an analysis is done of current solar maps in order to see on which principles the solar maps were based upon

Typical Values for Active Solar Energy in Urban Planning

There is an urgent need to start generating energy within cities in order to pave the way for a more sustainable and resilient society. Renewable energy by means of active solar energy systems (solar thermal, ST and/or photovoltaics, PV) can be generated using roofs and facades of buildings. In this study, the annual solar energy potential of typical Swedish city blocks was analysed in order to develop guidelines for urban planners and architects. The results show that the design of the city blocks has a significant effect (up to 50%) on the total annual solar energy production. The study also shows that the contribution from active solar energy can be significant even in the urban environment, but shading by adjacent buildings may greatly limit the total amount of energy produced

Identifying Potential Indicators of Neighbourhood Solar Access in Urban Planning

Solar access describes the capacity of urban spaces to receive sunlight and daylight. Rapid urbanization and unbridled densification pose a threat to sustainable solar access, reducing the penetration of sunlight and daylight into cities. To effectively assess solar access at such an early design stage, at the urban planning level, it is critical that evaluation metrics are simple and reliable. This paper examines a cross section of solar metrics, from simple to more complex ones, to find potential solar performance indicators for urban planning evaluations. The metric datasets were created based on iterations of homogeneous neighbourhood designs, based on the three commonest typologies in the Swedish context: courtyard, slab, and tower. The results were validated using case studies sampled from districts of Malmö. The findings indicate that simple geometrical and latitudinal metrics may be suitable for assessing the solar access of urban designs due to high correlation with built density. Potential performance indicators aimed at indoor and outdoor evaluation of daylighting (VSC, SVF) and sunlighting (ASH_F, RD_G) in urban planning stages were suggested. Possible methods of applying the provided metric database into assessments were proposed. Future work should find evidence-based thresholds for the metric values to establish performance benchmarks

Selection of Weather Files and Their Importance for Building Performance Simulations in the Light of Climate Change and Urban Heat Islands

Building performance predictions and their reliability rely heavily on weather data inputs. Climate is affected by spatial and temporal differences related to climate change and urban heat island effects, but the weather files used in building performance simulations (BPS) often remain unchanged and may represent weather observations generated from inadequate space and time for their application. This study investigated Swedish weather data using statistical methods and analysed i) the local differences related to rural and urban microclimates and ii) the country-wide differences linked to climate change; by comparing recent observation data to the respective EnergyPlus Weather (EPW) files. The findings reveal that there are significant differences between rural and urban temperature means, and that outdated model years of weather data files make them unsuitable for BPS. The impact of using an inadequate weather file based on changes in recent climate in Sweden can lead to an overestimation of heating demand by 6.5 % on average, while the impact is higher for warmer climates-up to 12 %. The combined impact including climate change and urban heat island effects can lead to a heating energy overestimation by 12 % to 19 %, based on the Stockholm example. On the other hand, it was found that although the global radiation means saw a slightly increasing trend, its impact on the BPS remains inconclusive. The study highlights the importance of selection of adequate weather data for BPS keeping in mind the spatial and temporal influencing factors

Energy use of buildings in relation to occupancy rates

This paper presents basic data of the energy demand for district heating and plug loads logged by a building management system of an energy-efficient academic building located in Lund, Sweden. The data refers to the years 2019 and 2020 when occupancy varied significantly due to the Corona pandemic. The data shows that the building energy demand adapts poorly to fluctuating occupancy rates. With a possible increase of smart working in the future, building codes should account for more fluctuating occupancy rates in the modelling of the energy demand of buildings

Towards the development of legislative framework for solar neighborhoods

The growing implementation of sustainable urban infrastructure, utilizing solar energy for heat and power generation, daylighting, and thermal comfort, has intensified the focus on sustainability standards and guidelines. Nevertheless, a noticeable deficiency persists in regulations that specifically address solar energy access and protection, posing a barrier to the diffusion of solar-centric neighborhoods. This paper examines the traditional urban regulatory frameworks and the state of solar energy regulations and practices within five countries (i.e., Canada, Italy, Norway, Sweden, and Switzerland). The aim of the study is to (i) identify gaps in existing regulations, standards, and codes, (ii) highlight the need for future regulations to protect solar access and rights, and (iii) support the deployment of solar technologies on a large scale. The results underline that climate-related regulations often fall short of specificity tailored to regional and local climates, relying on generalized climate considerations. Solar energy legislation is generally scarce and lacks comprehensive planning. Finally, despite various financial incentives for the installation of active solar strategies, their impact remains limited, impeding the wide spread of solar technology as a primary source of energy production in urban environment

The communication process

In order to stimulate an increased use of solar in energy conscious building design, the Task 41 participants have developed a Communication Guideline as a tool to support architects in their communication process with especially clients, authorities and contractors. Today the energy performance of solar solutions is well documented and well known especially in the “technical environment”. This knowledge, however, needs to be communicated in a convincing way to the decision makers in order to ensure a broad implementation of sustainable solar solutions in future building design. The Communication Guideline includes convincing arguments and facts supporting the implementation of solar based design solutions. The Communication Guideline is divided in three main parts: • Part 1: Convincing clients to request and commission solar buildings • Part 2: Communication strategies at the design/ construction team level • Part 3: Tools and Reference

Planning for Solar Buildings in Urban Environments

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